JP2005116581A - Method for detection, method for exposure, detecting device, exposure device, and method of manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately detect the defocusing amount of the area of a surface to be inspected. <P>SOLUTION: In a step 607, the data row function H(N) of the reflectivity of an object to be detected is estimated from the data row function G(N) of the image intensity distribution of a surface having uniform reflectivity and the data row function F(N) of the image intensity distribution of a surface having uneven reflectivity. Then, in a step 613, the estimation of the data row function H(N) of the reflectivity of the object to be detected is terminated when the estimated results start to converge, and, in a step 617, the defocusing amount of the area of the surface to be inspected is calculated based on the data row function H(N) of the reflectivity. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a detection method, an exposure method, a detection apparatus, an exposure apparatus, and a device manufacturing method, and more specifically, a detection method for detecting a test surface of an object via a detection optical system, and the detection method. The present invention relates to an exposure method, a detection apparatus that detects a test surface of an object via a detection optical system, an exposure apparatus including the detection apparatus, the exposure method, and a device manufacturing method using the exposure apparatus.

  In a lithography process for manufacturing a semiconductor element, a liquid crystal display element, or the like, a wafer or glass on which a pattern formed on a mask or a reticle (hereinafter collectively referred to as “reticle”) is coated with a resist or the like via a projection optical system An exposure apparatus that transfers onto a substrate such as a plate (hereinafter collectively referred to as a “wafer”), such as a step-and-repeat reduction projection exposure apparatus (so-called stepper), or a step-and- A sequential movement type projection exposure apparatus such as a scanning type projection exposure apparatus (so-called scanning stepper) is mainly used.

  When manufacturing semiconductor devices, etc., different circuit patterns are stacked and formed on a wafer in several layers. Therefore, a reticle on which a circuit pattern is formed and a pattern already formed on each shot area on the wafer are formed. Accurate overlay is important.

  In order to accurately overlay patterns, first, it is necessary to accurately detect the position of the reticle on which the circuit pattern is formed. The position detection of the reticle is performed by detecting the position of an alignment mark (alignment mark) formed on the reticle. In this case, exposure light is generally used as a detection light beam. For example, a VRA (Visual Reticle Alignment) type sensor that irradiates exposure light onto an alignment mark formed on a reticle and processes the image data of the alignment mark imaged by a CCD camera to measure the mark position is known. It has been.

  Second, it is necessary to accurately detect the position of an alignment mark (alignment mark, hereinafter also referred to as “wafer mark”) formed on the wafer together with the circuit pattern. Various methods are known as a wafer alignment system for detecting the position of the alignment mark. Recently, for example, an FIA (Field Image Alignment) system is used that measures the mark position by illuminating with light having a wide wavelength bandwidth using a halogen lamp as a light source and processing image data of an alignment mark imaged by a CCD camera or the like. A relatively large number of off-axis alignment sensors are used. According to this FIA-type alignment sensor, it is possible to detect the position of an aluminum mark, an asymmetric mark, or the like with high accuracy without being affected by thin film interference caused by a resist layer.

  The alignment between the reticle and the wafer using these optical alignment sensors is performed in the following general procedure. First, the alignment mark image on the reticle is detected by the VRA sensor simultaneously with the image of the reference mark on the wafer stage via the projection optical system, and the projection position of the reticle pattern is calculated based on the detection result. Next, the wafer stage is moved by a predetermined distance, for example, the reference mark on the wafer stage is detected by the above-described FIA sensor, the detection result, the position information of the wafer stage at the time of detection, the calculation result, Based on the set value of the baseline, an FIA baseline is obtained. Thereafter, an alignment mark on the wafer is detected by an FIA sensor, and predetermined calculation processing is performed based on the detection result and the position coordinate of the wafer stage at the time of detection, and the position of each shot area on the wafer is detected. Find the coordinates.

  Then, based on the above results, controlling the relative positional relationship between the reticle (reticle stage) and the wafer (wafer stage), and performing exposure by the step-and-repeat method or the step-and-scan method, It is possible to sequentially transfer the reticle pattern onto each shot area on the wafer.

  Recently, the required accuracy for alignment (alignment) between the reticle and the wafer has become strict as the pattern becomes finer, and accordingly, the required accuracy for detecting the position of the alignment mark has also become strict. There are various points to be considered in order to meet the demand for higher precision, but one of the most important points is the focus position of the alignment mark on the wafer with respect to the imaging type alignment sensor. There is. In other words, when detecting the position of the alignment mark using the imaging type alignment sensor as described above, it is desirable from the viewpoint of accuracy to detect the alignment mark at the best (best) focus position.

  Therefore, conventionally, an image forming type alignment sensor is provided with an autofocus mechanism for positioning the alignment mark at the best focus position. In this autofocus mechanism, first, an illumination light beam, for example, through a slit or the like, that is, an imaging light beam for forming an image of a predetermined shape is applied to a target on a wafer via a detection optical system such as an objective lens of an alignment sensor. Irradiate near the alignment mark formed on the surface. Then, the reflected light beam of the imaging light beam via the detection optical system of the alignment sensor is divided into left and right by a light beam splitting member such as a pupil splitting prism provided at the pupil conjugate position of the detection optical system of the alignment sensor. Further, the two divided luminous fluxes are received by an imaging element such as a line sensor formed by a one-dimensional CCD, for example. Thereby, an image having a predetermined shape by the two split light beams is formed at a certain interval on the light receiving surface of the image sensor. Note that the light receiving surface of the imaging element is a conjugate position with the position of a slit or the like that defines the shape of the image with respect to the detection optical system of the alignment sensor in a state where the surface to be tested of the wafer is in a focused position. In this state, the slit image is set so as to form an image on the light receiving surface of the image sensor.

  The reflected light beam incident on the image sensor has its telecentricity destroyed by the light beam splitting member, so that if the wafer is displaced in the optical axis direction of the detection optical system of the alignment sensor, an image is formed on the light receiving surface of the image sensor. The interval between the two slit images changes. If the distance between the two slit images on the light receiving surface of the image sensor is measured using such properties, the position of the alignment mark (focus) on the surface to be tested of the wafer with respect to the optical axis direction of the detection optical system of the alignment sensor. Position) can be detected.

  Specifically, in this autofocus mechanism, the centroid position of the image intensity distribution corresponding to each slit image is obtained, and the center of the image intensity distribution corresponding to each of the two slit images, for example, the interval between the centroid positions (hereinafter referred to as appropriate). , Abbreviated as “interval between two slit images”). Here, with respect to the detection optical system of the alignment sensor, if the distance between two slit images obtained when the test surface of the wafer is located at the best focus position is known (design value), the measured 2 The difference between the interval between the two slit images and the interval between the two slit images at the best focus position corresponds to the defocus amount from the best focus position of the test surface with respect to the detection optical system of the alignment sensor.

  Therefore, the autofocus mechanism obtains a difference between the measured interval between the two slit images and the interval between the two slit images at the best focus position (for example, a known interval obtained in advance as a design value). Using the conversion coefficient to convert the difference into the actual defocus amount, the defocus amount from the best focus position of the detection optical system of the alignment sensor is obtained, and the alignment sensor is detected based on the obtained defocus amount. The position of the wafer in the optical axis direction of the optical system is adjusted (see, for example, Patent Documents 1 to 4).

By the way, the irradiation position (measurement area) of such a predetermined imaging light beam is usually set to be on a street line on the wafer W in the vicinity of the area where the alignment mark to be detected is formed. Yes. Recently, in order to improve exposure accuracy, various marks (for example, alignment marks, for example, in order to ensure that the alignment marks are positioned within the detection field of the alignment sensor, also on the street line, in the vicinity of the alignment mark to be detected). A large number of search alignment marks and other alignment marks) are formed. In this case, since it is conceivable that other marks happen to be provided at the irradiation position of the predetermined imaging light beam on the wafer W (that is, the position where the slit image is formed), these marks are There is a concern that it may affect the calculated value of the focus amount.
JP-A-1-202708 JP-A-6-214150 JP-A-10-223517 JP 2001-257157 A

  The present invention has been made under such circumstances, and a first object thereof is to provide a detection method capable of accurately detecting a surface to be detected with respect to a detection optical system.

  A second object of the present invention is to provide an exposure method capable of realizing highly accurate exposure.

  A third object of the present invention is to provide a detection apparatus that can accurately detect a surface to be detected with respect to a detection optical system.

  A fourth object of the present invention is to provide an exposure apparatus capable of realizing highly accurate exposure.

  A fifth object of the present invention is to provide a device manufacturing method capable of producing a highly integrated device.

  In order to solve the above-mentioned problems, the present inventor has examined how the mark affects the calculation of the defocus amount when a mark is formed at a predetermined imaging light beam irradiation position. Was analyzed. Hereinafter, the result of the analysis will be described with reference to FIG. 1 (A) and FIG. 1 (B).

  FIG. 1A shows a state in which the above-described imaging light beam is irradiated around a wafer mark (not shown) on the wafer W. In FIG. 1A, the position (focus position) of the alignment mark in the optical axis direction of the detection optical system of the alignment sensor (hereinafter simply referred to as “detection optical system”) is the Gaussian image plane ( The position corresponding to the object plane is the only image plane that the detection optical system has, and the position of the image plane does not vary depending on the structure of the wafer mark to be measured). The vertical axis indicates the state in which the wafer W is positioned above the Gaussian image plane of the detection optical system and the Gaussian image plane (focus position is 0) along the vertical axis. The three states of the state located below the Gaussian image plane are schematically shown.

  Further, a circuit pattern or the like is already formed on the wafer W. In FIG. 1A, as an example of the circuit pattern or the like, a base pattern Pt (a mark on a street line) as a part of the wafer mark is formed. Shown representatively. The portion where the base pattern Pt is formed has a higher reflectance than the other portions. A photoresist layer, an antireflection film, and the like are further formed on the surface of the wafer W, but the illustration thereof is omitted in FIG. Further, since the reflectance of the surface of the wafer W is equivalent to the reflectance of the background of the photoresist, this reflectance will be referred to as “underground reflectance” as appropriate below.

  As shown in FIG. 1A, the wafer W has, for example, a slit-shaped imaging light beam (predetermined imaging light beam) having a predetermined incident angle from the upper right side as shown by a solid arrow. The oblique incident light having is incident. With this oblique incident light, a slit image indicated by a two-dot chain line is formed on the surface of the wafer W.

  As described above, the reflected light beam of the imaging light beam reflected by the wafer W is split into two split light beams by the light beam splitting member as described above through the detection optical system (objective lens, etc.), and then the slit image. As a result, an image is formed on the light receiving surface of the image sensor. As a result, a signal indicating the light intensity distribution on the light receiving surface of the image sensor when the image of the two split light beams is formed is output from the image sensor.

FIG. 1B shows an example of signals indicating the light intensity distribution output from the image sensor when the wafer W is in the three states shown in FIG. As shown in FIG. 1B, the signal output from the image sensor has two peaks P _A and P _B. Since these two peaks P _A and P _B correspond to the slit image formed by the reflected light beam, they are hereinafter referred to as “slit images P _A and P _B ”. The slit images P _A and P _B are symmetric with respect to the mirror surface when the mirror surface is placed between the slit images (having so-called mirror symmetry).

Here, when the wafer W is positioned on the Gaussian image plane of the detection optical system, the interval between the two slit images P _A and P _B is d _A. When the wafer W is positioned on the detection optical system closer than Gaussian image plane of the detecting optical system, the interval is greater d _U next than d _A, detection optical than Gaussian image plane of the wafer W detection optical system When it is located in a direction far from the system, d _L is smaller than d _A. In particular although not shown in FIG. 1 (B) is omitted, when the wafer mark best focus position is located, the two slit images P _A appearing in the signal corresponding to the light intensity distribution of the light-receiving surface of the imaging device , P _B interval d ₀ is obtained in advance.

As described above, the autofocus mechanism reduces the defocus amount to the difference between the distances d _U , d _A , d _L and d ₀ between the two slit images P _A and P _B in each state, for example, d _U −d ₀ . Is multiplied by the conversion coefficient to obtain a signed defocus amount for positioning the test surface of the wafer W at the best focus position (the sign is expressed by d _U , d _A , d _L and d ₀ ). It depends on the size relationship).

By the way, the image intensity distribution of the two slit images P _A and P _B formed on the light receiving surface of the image sensor becomes non-uniform due to the difference in reflectance between the base pattern Pt and other portions. In FIG. 1B, the non-uniformity of the image intensity distribution of the slit images P _A and P _B caused by the base pattern Pt is schematically represented as three protrusions on the slit images P _A and P _B. .

  Further, as shown in FIG. 1A, the image formation position on the wafer W of the slit image indicated by the two-dot chain line is shifted on the surface of the wafer W in accordance with the focus position of the wafer W. The position of the base pattern Pt is always constant regardless of the focus position of the wafer W. For this reason, when the wafer W is positioned on the Gaussian image plane of the detection optical system, the reflected light from the center of the slit image and the reflection from the center of the base pattern Pt with respect to the obliquely incident light incident from the upper right. If the wafer W is positioned above the Gaussian image plane of the detection optical system even if the light is coincident with each other, the reflection from the central portion of the slit image with respect to the obliquely incident light incident from the upper right The light (solid line) and the reflected light (dotted line) from the central portion of the base pattern Pt are shifted to the right side when the wafer W is positioned on the Gaussian image plane of the detection optical system of the alignment sensor. And about the shift | offset | difference, the reflected light from the center part of the base pattern Pt becomes a half of the reflected light from the center part of a slit image. When the wafer W is positioned below the Gaussian image plane of the detection optical system, reflected light (solid line) from the center of the slit image with respect to oblique incident light and the center of the base pattern Pt. The reflected light (dotted line) is shifted to the left side when the wafer W is positioned on the Gaussian image plane of the detection optical system of the alignment sensor. And about the shift | offset | difference, the reflected light from the center part of the base pattern Pt becomes a half of the reflected light from the center part of a slit image.

From this, the shape of the image intensity distribution of the two slit images P _A and P _B formed on the light receiving surface of the image sensor corresponds to the positional deviation in the focus direction of the wafer W from the Gauss image plane of the detection optical system. And deform. For example, as shown in FIG. 1B, when the wafer W is positioned on the Gaussian image plane of the detection optical system, the three projections of the two slit images P _A and P _B are slit images P _A and P _Although appearing in the vicinity of the center of _B , when the wafer W is located on the upper side (positive side) of the Gaussian image plane, the three projections of the two slit images P _A and P _B are formed on the slit image P _A. by reflection symmetry between P _B, from the center of the slit images for each slit image, on the right side for the slit image P _a, so that the shift to the left for slit image P _B. The wafer W is, when positioned below the Gaussian image plane of the detecting optical system (negative side), two slit images P _A, 3 one projection of P _B, like slit image P _A, P _B to each other Due to the mirror symmetry, for each slit image, the slit image P _A is shifted to the left side and the slit image P _B is shifted to the right side from the center of the slit image. That is, when the wafer W is positioned on the Gaussian image plane of the detection optical system of the alignment sensor and when it is not, the image intensities of the two slit images P _A and P _B formed on the light receiving surface of the image sensor. The distribution shape is different.

As described above, the defocus amount of the wafer W is calculated based on the interval between the gravity center positions of the two slit images P _A and P _B. Therefore, the deformation of the two slit images P _A and P _B due to the positional deviation of the wafer W from the Gaussian image plane of the detection optical system affects the calculation of the centroid position of the two slit images P _A and P _B. The deformation may cause a detection error of the detected defocus amount. That is, as shown in FIG. _1A , the distances d _U and d _L between the center positions of the two slit images P _A and P _B when they deviate from the Gaussian image plane of the detection optical system are both focused. now it includes an error due to signal components which depends on the underlying pattern Pt due to positional deviation of the wafer W from the Gaussian image plane of the detecting optical system of the alignment sensor during measurement, signed based on the interval d _u, d _L The reliability of the defocus amount is not necessarily high. Further, the deformation due to the defocusing of the distribution shape of the image intensity distribution of the two slit images P _A and P _B is different because the irradiation position of the imaging light beam on the wafer W differs depending on the focus position of the wafer W. It is also very difficult to specify an irradiation position in advance and predict a signal component depending on the base pattern Pt.

  The present invention has been made on the basis of the new findings obtained from the analysis results described above, and employs the following configuration.

  The invention according to claim 1 is a detection method for detecting a test surface of an object via a detection optical system, wherein a part of the test surface of the object is formed on a Gaussian image plane of the detection optical system. A first step of positioning a region; a second step of measuring a focus state of the region with respect to the detection optical system after performing the first step; and the detection optics based on a measurement result of the second step A third step of determining a focus position of the region with respect to the system.

  According to this, in the first step, the detection target area on the object surface to be detected is positioned on the Gaussian image plane of the detection optical system, and then the focus state of the area with respect to the detection optical system is measured. In addition, it is possible to reduce an error caused by the positional deviation of the region from the Gaussian image plane of the detection optical system, which is included in the measurement result of the focus state of the region with respect to the detection optical system. Thereby, based on the focus state, the in-focus position of the region to be detected on the surface to be detected can be detected with high accuracy.

  In this case, as in the detection method according to claim 2, the third step determines whether or not the region is located at a focus position with respect to the detection optical system based on a measurement result of the second step. A discriminating step for discriminating; and in the discriminating step, when it is discriminated that the region is not located at a focus position with respect to the detection optical system, the detection optical system and the region in the optical axis direction of the detection optical system And a control step of adjusting the relative position to position the region at the in-focus position.

  In the detection method according to claim 1 or 2, as in the detection method according to claim 3, the in-focus position of the region with respect to the detection optical system determined in the third step is stored in a storage device. A fourth step; when measuring the focus state of the detection optical system in a region other than the region on the surface to be measured, based on the in-focus position stored in the fourth step, the other And a fifth step of positioning the region.

  In the detection method according to any one of claims 1 to 3, the detection optical system determined in the third step after performing the third step, as in the detection method according to claim 4. An imaging step of imaging the mark formed in the region via the detection optical system in a state where the region is located at a position different from the in-focus position with respect to can be included.

  In this case, as in the detection method according to claim 5, in the imaging step, the position of the area when imaging the mark is set to a position where the contrast in the imaging result of the mark is maximized. Can do.

  In the detection method according to any one of claims 1 to 3, the detection optical system determined in the third step after performing the third step as in the detection method according to claim 6. It is possible to further include an imaging step of imaging the mark formed in the region via the detection optical system in a state where the region is positioned at the in-focus position with respect to.

  The invention according to claim 7 is a detection method for detecting a test surface of an object via a detection optical system, and is a predetermined method for a measurement region in the vicinity of a partial region of the test surface of the object. A first step of irradiating the imaging light beam and detecting a signal corresponding to the reflected light beam from the measurement region; and only the surface shape of the measurement region included in the signal detected in the first step A second step of estimating at least one of a dependent first signal and a second signal independent of the surface shape; and based on at least one of the estimated first signal and second signal, the detection optical system A third step of obtaining a focus state of the measurement target area with respect to

  According to this, in the first step, a predetermined imaging light beam is irradiated to a measurement area in the vicinity of a part of the area to be measured of the object, and a signal corresponding to the reflected light beam from the measurement area is generated. To detect. In the second step, at least one of the first signal that depends on the surface shape of the measurement target area and the second signal that does not depend on the surface shape included in the signal detected in the first step is estimated. Further, in the third step, an in-focus state of the region with respect to the detection optical system is determined based on at least one of the estimated first signal and second signal. In this way, regardless of the difference between the first signal and the second signal in accordance with the positional deviation of the measurement area from the Gaussian image plane of the detection optical system, the area is focused on the detection optical system. It becomes possible to detect the state with high accuracy.

  In this case, as in the detection method according to claim 8, prior to the second step, the predetermined imaging light beam is irradiated onto a reference surface having a substantially uniform reflectance, and the reflection obtained by the irradiation. The method may further include a fourth step of detecting a signal corresponding to the light beam, and the estimation may be performed using the signal detected in the fourth step in the second step.

  In this case, as in the detection method according to claim 9, in the fourth step, the predetermined imaging light beam is irradiated while sequentially changing the focus position of the reference surface with respect to the detection optical system, and A signal corresponding to the obtained reflected light beam is detected every time the focus position is changed. In the second step, a part of the plurality of signals detected in the fourth step is selected, and the selection is performed. The first signal can be estimated by dividing or subtracting the signal detected in the first step from the generated signal.

  In the detection method according to any one of claims 7 to 9, as in the detection method according to claim 10, in the second step, the object to be detected with respect to the detection optical system is based only on the first signal. First information related to the focus state of the measurement region is obtained, second information relating to the focus state of the measurement target region with respect to the detection optical system is obtained based only on the second signal, and the first information and the second information are obtained. The estimation can be continued until the predetermined relationship is obtained.

  In this case, as in the detection method according to claim 11, the predetermined relationship may be a relationship in which the second information is twice the first information.

  The detection method according to any one of claims 7 to 11, wherein, as in the detection method according to claim 12, in the third step, the first signal with respect to the signal detected in the first step or Selecting at least one of the first signal and the second signal according to the degree of contribution of the second signal, and determining a focus state of the measurement target region with respect to the detection optical system based on the selected signal; can do.

  In this case, as in the detection method according to the thirteenth aspect, the contribution can include information on the amplitude of each of the first signal and the second signal.

  In this case, as in the detection method according to claim 14, the signal detected in the first step includes a luminance value obtained by a plurality of image sensors, and the contribution degree includes the first signal and the first signal. It can be obtained from the relationship between the standard deviation of each luminance value of each of the two signals and the standard deviation of each luminance value of the signal detected in the first step.

  The detection method according to any one of claims 12 to 14, wherein, as in the detection method according to claim 15, in the third step, the first signal with respect to the signal detected in the first step and Using the weight according to the contribution degree of the second signal, the focus state obtained from the first signal and the focus state obtained from the second signal can be weighted averaged.

  In the detection method according to any one of claims 7 to 15, based on the focus state obtained in the third step after performing the third step as in the detection method according to claim 16. And a fifth step of imaging the mark formed in the region through the detection optical system in a state where the region is positioned at the determined focus position with respect to the detection optical system. be able to.

  The invention described in claim 17 is an exposure method for transferring a pattern to an object held by a moving body, and using the detection method according to any one of claims 4 to 6 and 16, Detecting the position information of the mark on the moving body; and transferring the pattern to the object while controlling the position of the object held on the moving body based on the detection result. Is the method.

  According to this, the position control of the object is performed using the position information of the mark detected based on the imaging result of the mark imaged well by the detection method according to any one of claims 4 to 6 and 16. Since the transfer is performed while performing high-precision exposure, high-precision exposure can be realized.

  The invention described in claim 18 is a device manufacturing method including a lithography process, wherein the exposure is performed using the exposure method according to claim 17 in the lithography process. In such a case, since the exposure is performed by the exposure method according to the seventeenth aspect, the exposure accuracy is improved, so that a highly integrated device can be produced.

  The invention according to claim 19 is a detection device for detecting a test surface of an object via a detection optical system, wherein the relative position between the object and the detection optical system in the optical axis direction of the detection optical system. An adjustment device for adjusting the focus of the region with respect to the detection optical system in a state where a partial region of the test surface of the object is positioned on the Gaussian image plane of the detection optical system by the adjustment of the adjustment device A detection device comprising: a measurement device that measures a state; and a determination device that determines an in-focus position of the region with respect to the detection optical system based on a measurement result of the measurement device.

  According to this, at least one region on the surface to be measured of the object is positioned on the Gaussian image plane of the detection optical system by the adjusting device, and the focus state of the region with respect to the detection optical system is measured by the measurement device As a result, it is possible to reduce an error due to the displacement of the surface area to be detected from the Gaussian image plane of the detection optical system, so that the detection target area on the surface to be detected can be accurately detected. .

  In this case, as in the detection device according to claim 20, the image processing apparatus further includes a storage device that stores a focus position of the region with respect to the detection optical system determined by the determination device. The measurement device measures the focus state of the other region with respect to the detection optical system in a state where another region different from the region of the inspection surface is located at the in-focus position stored in the storage device. It can be.

  The detection device according to claim 19 or 20, wherein, like the detection device according to claim 21, a position different from a focus position with respect to the detection optical system determined by the determination device by adjustment of the adjustment device. Furthermore, it is good also as an image pick-up device which picturizes the mark formed in the field in the state where the field is located via the detection optical system, and like the detection device according to claim 22, The mark formed in the region is imaged through the detection optical system in a state where the region is located at the in-focus position with respect to the detection optical system determined by the determination device by the adjustment of the adjustment device. An imaging device may be further provided.

  The invention as set forth in claim 23 is a detection device for detecting a test surface of an object via a detection optical system, and is predetermined for a measurement region in the vicinity of a partial region of the test surface of the object. A signal detection device that irradiates the imaging light beam and detects a signal corresponding to the reflected light beam from the measurement region; and only the surface shape of the measurement region included in the signal detected by the signal detection device An estimation device that estimates at least one of a first signal that depends and a second signal that does not depend on the surface shape; and for the detection optical system based on at least one of the first signal and the second signal that is estimated And a calculation device that obtains the focus state of the measurement area.

  According to this, at least one of the first signal that depends on the surface shape of the measurement target region and the second signal that does not depend on the surface shape included in the signal detected by the signal detection device is estimated by the estimation device, Based on at least one of the first signal and the second signal estimated by the estimation device, the focus state of the region with respect to the detection optical system is determined by the determination device. In this way, regardless of the difference between the first signal and the second signal due to the positional deviation of the measurement target area from the Gaussian image plane of the detection optical system, the focus state of the area with respect to the detection optical system is It becomes possible to detect with high accuracy.

  In this case, as in the detection device according to claim 24, the signal detection device responds to the reflected light beam obtained by irradiating the predetermined imaging light beam on the reference surface having a substantially uniform reflectance. A storage device that stores signals as signals corresponding to a plurality of different focus positions with respect to the detection optical system, and the estimation device selects a part of the plurality of signals stored in the storage device; The first signal can be estimated by dividing or subtracting the signal detected by the signal detection device with the selected signal.

  25. The detection optical system according to claim 23 or 24, wherein, as in the detection apparatus according to claim 25, the detection optical system determined based on a focus state obtained by the calculation device by adjustment of the adjustment device. An image pickup apparatus for picking up an image of the mark formed in the region through the detection optical system in a state where the region is located at a focus position with respect to the image forming apparatus can be further provided.

  The invention described in claim 26 is an exposure apparatus for transferring a pattern to an object held by a moving body, and the detection apparatus according to any one of claims 21, 22, 25; An exposure apparatus comprising: a transfer device that transfers the pattern to the object while performing position control of the object held by the moving body based on the position information of the mark on the moving body obtained from the imaging result of is there.

  According to this, using the detection device according to any one of claims 21, 22, and 25, for the alignment mark of the movable body and the pattern, or the alignment of the shot area formed on the object For example, if the pattern is transferred to the object while controlling the position of the object held by the moving body based on the position information of the mark obtained from the imaging result, High precision overlay exposure is possible.

  A twenty-seventh aspect of the present invention is a device manufacturing method including a lithography process, wherein exposure is performed using the exposure apparatus according to the twenty-sixth aspect in the lithography process. In such a case, since exposure is performed by the exposure apparatus according to the twenty-sixth aspect, the exposure accuracy is improved, and thus a highly integrated device can be produced.

<< First Embodiment >>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 2 shows a schematic configuration of an exposure apparatus 100 according to the first embodiment suitable for carrying out the detection method and the exposure method according to the present invention. The exposure apparatus 100 is a step-and-scan projection exposure apparatus. The exposure apparatus 100 includes an illumination system 10, a reticle stage RST that holds a reticle R, a projection optical system PL, a wafer stage WST on which a wafer W as an object is mounted, a main controller 20 that performs overall control of the entire apparatus, and the like. I have.

The illumination system 10 includes an illuminance uniformizing optical system including a light source, a fly-eye lens, a relay lens, a variable ND filter, a reticle blind (fixed reticle blind and A movable reticle blind), a dichroic mirror, and the like (both not shown). The illumination system 10 is a reticle that is defined by a fixed reticle blind (not shown) (movable reticle blind in addition to a fixed reticle blind at the start of scanning and at the end of scanning) and extends in the X-axis direction (left and right in the drawing in FIG. 2). A predetermined pattern-shaped illumination area on R is illuminated with substantially uniform illuminance by exposure illumination light (hereinafter abbreviated as “exposure light”) EL. Here, as the exposure light EL, far ultraviolet light such as KrF excimer laser light (wavelength 248 nm) or ArF excimer laser light (wavelength 193 nm) or vacuum ultraviolet light such as F ₂ laser light (wavelength 157 nm) is used. . As the exposure light EL, it is also possible to use an ultraviolet bright line (g-line, i-line, etc.) from an ultra-high pressure mercury lamp.

  On reticle stage RST, reticle R having a circuit pattern PA formed on its pattern surface (lower surface in FIG. 2) is fixed, for example, by vacuum suction. Reticle stage RST is XY perpendicular to the optical axis of illumination system 10 (corresponding to optical axis AX of projection optical system PL described later) by a reticle stage driving unit (not shown) including actuators such as a linear motor and a voice coil motor. It can be driven minutely in a plane and can be driven at a scanning speed designated in a predetermined scanning direction (here, the Y-axis direction which is a direction perpendicular to the paper surface).

  The position of the reticle stage RST in the stage moving surface is always detected by a reticle laser interferometer (hereinafter referred to as “reticle interferometer”) 16 with a resolution of about 0.5 to 1 nm, for example. Position information of reticle stage RST from reticle interferometer 16 is supplied to main controller 20. Main controller 20 drives and controls reticle stage RST via a reticle stage drive unit (not shown) based on the position information of reticle stage RST.

  The projection optical system PL is disposed below the reticle stage RST in FIG. 2, and the direction of the optical axis AX is the Z-axis direction. As the projection optical system PL, for example, a birefringent optical system having a predetermined reduction magnification (for example, 1/5, 1/4) is used. For this reason, when the illumination area of the reticle R is illuminated by the exposure light EL from the illumination optical system, the circuit of the reticle R in the illumination area is passed through the projection optical system PL by the exposure light EL that has passed through the reticle R. A reduced image (partial inverted image) of the pattern PA is formed on the wafer W whose surface is coated with a resist (photosensitive agent).

  Wafer stage WST is disposed on a base (not shown) below projection optical system PL in FIG. 2, and is moved in the X and Y directions (including rotation about the Z axis) by a wafer stage driving unit (not shown) including a linear motor and the like. And can be driven minutely in the Z-axis direction and the tilt direction with respect to the XY plane.

  The position of wafer stage WST in the XY plane (including rotation around the Z axis (θz rotation)) is, for example, 0.5 to 1 nm by a wafer laser interferometer system (hereinafter abbreviated as “wafer interferometer”) 18. It is always detected with a resolution of the order. Wafer interferometer 18 includes a Y interferometer that irradiates an interferometer beam along the Y axis, and an X interferometer that irradiates the interferometer beam along the X axis, and the movement position of wafer stage WST. Is defined by the measurement axes of the Y and X interferometers of the wafer interferometer 18. Hereinafter, this stationary coordinate system is also referred to as a “stage coordinate system”. Note that the Y interferometer and the X interferometer of the wafer interferometer 18 are multi-axis interferometers having a plurality of measurement axes, and these interferometers rotate the wafer stage WST around θz (yaw) and around the X axis. Θx rotation (pitching), and θy rotation (rolling), which is rotation around the Y axis, are also measured.

  Position information (or speed information) of wafer stage WST in the stage coordinate system is supplied to main controller 20, and main controller 20 passes a wafer stage drive unit (not shown) based on the position information of wafer stage WST. Controls wafer stage WST.

  Under the control of main controller 20, wafer stage WST performs not only movement in the scanning direction (Y-axis direction) but also a plurality of shot areas on wafer W to be positioned in an exposure area conjugate with the illumination area. It is also possible to move in a non-scanning direction (X-axis direction) orthogonal to the direction, and thereby, an operation for scanning (scanning) exposing each shot area on the wafer W and scanning for exposure of the next shot area. A step-and-scan operation that repeats the movement to the start position (acceleration start position) becomes possible.

  Furthermore, a wafer holder 25 is provided on wafer stage WST for holding wafer W by vacuum suction or electrostatic suction with a high degree of flatness using a large number of pins. A reference mark plate 40 is fixed on wafer stage WST. The surface of the reference mark plate 40 is set at substantially the same height as the surface of the wafer W held by the wafer holder 25. On the surface of the reference mark plate 40, a plurality of measurement marks to be described later, a so-called baseline measurement reference mark, a reticle alignment reference mark, and other marks are formed.

  Further, a TTR (Through The Reticle) alignment system using light having an exposure wavelength for simultaneously observing the reticle mark on the reticle R and the mark on the reference mark plate 40 via the projection optical system PL above the reticle R. A pair of reticle alignment detection systems (hereinafter abbreviated as “RA detection system”) RA1 and RA2 are provided. The detection signals of these RA detection systems RA1 and RA2 are supplied to the main controller 20. In this case, the deflection mirrors 50A and 50B composed of prisms for guiding the detection light from the reticle R to the respective RA detection systems RA1 and RA2 are movably arranged, and when the exposure sequence is started, the main controller 20 , The deflecting mirrors 50A and 50B are retracted by a mirror driving device (not shown). The configuration equivalent to the RA detection systems RA1 and RA2 is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-176468, and detailed description thereof is omitted here.

  The exposure apparatus 100 further includes an off-axis alignment sensor 14. The alignment sensor 14 irradiates illumination light (alignment light) having a predetermined wavelength width to a mark on the reference mark plate 40 or an alignment mark on the wafer W, and an image of the mark and the reference mark plate 40. The image of the index mark on the index plate arranged in a plane conjugate with the wafer W is formed on the light receiving surface of the image sensor (CCD or the like) by an objective lens or the like. Then, the imaging signal obtained as a result is output to the main control device 20, and the main control device 20 performs predetermined image processing on the imaging signal to calculate the position information of the mark with respect to the center of the index mark. .

  As shown in FIG. 3, the alignment sensor 14 includes a housing 130, a light source 103 provided outside the housing 130, a light guide 104 that guides alignment light AL emitted from the light source 103 to the housing 130, and the housing 130. The condenser lens 105, the shutter 106 </ b> B, the field stop plate 106 </ b> A, the lens system 107, the first beam splitter 108, and the light reflected by the first beam splitter 108 are sequentially arranged in the light emission direction from the light guide 104. Objective lens 109 arranged in the traveling direction (−X side), lens system 111 arranged sequentially on the + X side of the first beam splitter 108, second beam splitter 112, and sequentially on the + Z side of the second beam splitter 112. Placed on the + X side of the placed mark detection system 124 and the second beam splitter 112 The light shielding plate 113 are provided with the placed focus detection system 123 or the like to the rear of the light shielding plate 113 (+ X side).

  Here, a halogen lamp is used as the light source 103. This is because the wavelength band of the emitted light of the halogen lamp is 500 to 800 nm, the photoresist applied on the upper surface of the wafer W is not exposed to the emitted light, and the wavelength band is wide as described above. This is because the influence of the wavelength characteristic of the reflectance on the surface of W can be reduced.

As shown in FIG. 4A, the field stop plate 106A is made of a disk-shaped member, and a substantially square measurement opening OP is formed at the center thereof, and outside the measurement opening OP. Two slit-like openings SO ₁ and SO ₂ whose longitudinal directions are orthogonal to each other are formed. Accordingly, the alignment light illuminates the field stop plate 106A, whereby images of the measurement opening OP and the pattern openings SO ₁ and SO ₂ are formed on the wafer W (see FIG. 6). The shutter 106B provided in front of the optical path of the field stop plate 106A has a function of limiting the optical path of the alignment light AL. As will be described later, alignment is performed according to the position of the alignment mark to be measured on the wafer W. Incidence of the light AL to the predetermined pattern openings SO ₁ and SO ₂ is selectively limited.

  The mark detection system 124 disposed on the optical path of the light reflected by the second beam splitter 112 includes an index plate 120, a lens system 121, an imaging unit 122, and the like.

  In the in-focus state, the index plate 120 is disposed in a conjugate manner with the surface of the wafer W with respect to the synthesis system of the objective lens 109 and the lens system 111, and is disposed in a conjugate manner with the light receiving surface of the imaging unit 122 with respect to the lens system 121. ing. In the indicator plate 120, an indicator mark is formed of a chromium layer or the like on the surface of the transparent plate, and a portion other than the central portion where the indicator mark is formed is a light shielding portion. The index mark is a position reference in a direction conjugate with the X-axis direction or the Y-axis direction on the wafer W.

  The imaging unit 122 is made of, for example, a two-dimensional CCD, and captures and photoelectrically converts an alignment mark image formed on the light receiving surface and a projected image of the index mark. In addition, an image signal obtained by photoelectric conversion is output to the main controller 20.

  On the other hand, as shown in FIG. 4B, the light shielding plate 113 disposed on the optical path of the light that has passed through the second beam splitter 112 is formed from a rectangular region 113a for light shielding at the center of the transparent plate. A part of the incident light (that is, light emitted from the measurement opening OP and reflected by the surface of the wafer W) is shielded by the light shielding part 113a. Yes. On the other hand, the light transmitted around the light shielding region 113 a of the light shielding plate 113 enters the focus detection system 123.

  The focus detection system 123 includes reflection plates 114A and 114B, reflection plates 115A and 115B disposed on the rear side (+ Z side) of the light reflected by the reflection plates 114A and 114B, and reflection plates 115A and 115B. The lens system 116 includes a lens system 116, a pupil division mirror 117, a lens system 118, and a line sensor 119 that are sequentially arranged behind the optical path of the reflected light.

In this case, the reflectors 114A and 114B are arranged as shown in FIGS. 5 (A) and 5 (B). That is, as shown in FIG. 5B, the reflectors 114A and 114B are arranged so as not to overlap each other when viewed from the + Z direction, and when viewed from the −X direction, the pattern of the field stop plate 106A. They are arranged corresponding to the illumination light beams (IL ₁ , IL ₂ ) emitted from the openings SO ₁ and SO ₂ .

  The pupil splitting mirror 117 is composed of prisms formed in a mountain shape with an obtuse angle close to 180 degrees on the two surfaces, and the two surfaces are finished as reflecting surfaces. In the first embodiment, the intersection line (mountain ridgeline) of the two surfaces that are the reflecting surfaces intersects the optical axis of the incident light, and is tilted so that the optical axis is swung sideways by approximately 90 degrees. ing. The line sensor 119 is composed of a one-dimensional CCD or the like.

  A prism mirror 110 for bending the optical path of the alignment light AL by 90 ° and guiding it to the surface of the wafer W along the Z-axis direction is provided near the −X side of the objective lens 109 of the housing 130 of the alignment sensor 14. It has been.

  The operation of the alignment sensor 14 configured in this way will be described. The alignment light AL from the light source 103 is guided to a predetermined position in the housing 130 through the light guide 104. The alignment light AL emitted from the exit end of the light guide 104 enters the field stop plate 106A via the condenser lens 105, and the shape of the illumination light beam (imaging light beam) irradiated onto the wafer W is defined.

The light beam of the alignment light AL that has passed through the field stop plate 106A is reflected by the first beam splitter 108 through the lens system 107, passes through the objective lens 109, and is then emitted from the housing 130. Then, the emitted light beam is reflected by the prism mirror 110 and irradiated, for example, in the vicinity of a wafer mark formed on the wafer W. In the case where the shutter 106B does not block the illumination light, the wafer W has an illumination beam ML having a substantially square shape that has passed through the measurement opening OP, and an illumination beam (that has passed through the SO ₁ and SO ₂ described above). Illuminated by the imaging light beams IL ₁ and IL ₂ , the shutter 106B normally shields _{one of} the illumination light beams IL ₁ and IL ₂ . For example, as shown in FIG. 6, the illumination light beam ML is irradiated to the wafer marks AM1, a case where the illumination light beam IL ₁ is irradiated onto the street line SL, the illumination light beam IL ₂ is irradiated onto the shot area SA Think. In this case, the shutter 106B transmits only the illumination light beam IL ₁ and blocks the illumination light beam IL ₂ so as not to adversely affect the focus measurement described later. That is, in the example shown in FIG. 6, the irradiation region of the illumination light beam IL ₁ becomes a measurement target region for focus measurement described later (when the irradiation region of the illumination light beam IL ₂ is on the street line). , the irradiation region of the illumination light beam IL ₂ becomes the measurement region naturally).

The reflected light of the illumination light beams ML, IL ₁ , and IL ₂ reflected on the surface of the wafer W travels in the reverse direction of the optical path that has traveled previously, and again passes through the prism mirror 110 and the objective lens 109 to the first beam splitter 108. Incident. The illumination light beams ML, IL ₁ , and IL ₂ that have passed through the first beam splitter 108 are incident on the second beam splitter 112 via the lens system 111.

  Of the light reflected by the second beam splitter 112, the illumination light beam ML is received by the light receiving surface of the imaging unit 122 via the index plate 120 and the lens system 121. Thereby, a reflected image of the wafer mark and a projected image of the index mark are formed on the light receiving surface of the imaging unit 122. Then, light corresponding to these images is photoelectrically converted by the imaging unit 122, and an imaging signal obtained by this photoelectric conversion is output to the main controller 20. In the main controller 20, positional information regarding the wafer W in the X-axis direction or the Y-axis direction is based on the index detected from the imaging signal, the positional relationship between the wafer marks, and the output of the wafer interferometer 18 at that time. Thus, it is obtained as the X coordinate or Y coordinate of the wafer mark in the stage coordinate system described above.

On the other hand, the illumination light beams ML, IL ₁ , and IL ₂ transmitted through the second beam splitter 112 enter the light shielding plate 113. The light shielding plate 113 shields the reflected light beam of the illumination light beam ML from the wafer W.

Then, the two illumination light beams IL ₁ and IL ₂ (the reflected light beams) from the wafer W transmitted through the light shielding plate 113 are reflected by the reflection plates 114A and 114B constituting the focus detection system 123 disposed on the optical path. The In this case, the reflected light beam of the illumination light beam IL ₁ is incident on the reflection plate 114A, and the reflected light beam of the illumination light beam IL ₂ is incident on the reflection plate 114B (see FIG. 5A).

The illumination light beams IL ₁ and IL ₂ (the reflected light beams) reflected by the reflection plates 114A and 114B are reflected again by the reflection plates 115A and 115B, and enter the pupil division mirror 117 through the lens system 116. Here, in the pupil division mirror 117, the two incident lights (illumination lights IL ₁ and IL ₂ ) are each divided into two luminous fluxes, and the total of the four luminous fluxes divided is a line. An image is formed on the sensor 119. Thereby, on the line sensor 119, an image by the illumination light beam IL ₁ (two images divided by the pupil division mirror 117) and an image by the illumination light beam IL ₂ ( _two images divided by the pupil division mirror 117) are obtained. A total of four images are formed. FIGS. 7A to 7C representatively show a state where two images of the illumination light beam IL ₂ are formed on the line sensor.

Here, when the position of the detection target (that is, the alignment mark) on the surface of the wafer W coincides with the best focal plane of the alignment sensor 14 (that is, when the alignment mark is positioned at the best focus position), The distance between the two images of the illumination light IL ₂ imaged on the line sensor 119 (the distance between the center positions of the images) is set to be a distance d ₀ as shown in FIG. 7B. . At this time, when the surface of the wafer W is at a position (−Z side) lower than the best focal plane of the alignment sensor 14, as shown in FIG. 7A, it is at a position in front of the optical path from the line sensor 119. Since it has a focal point, it can be seen that the distance d _L shorter than the distance d ₀ in FIG. 7B is measured by the line sensor 119 as the distance between the centroid positions of the two images. On the other hand, when the surface of the wafer W is at a position higher (+ Z side) than the best focal plane of the alignment sensor 14, it has a focal point at a position behind the line sensor 119 as shown in FIG. It can be seen that the distance d _U longer than the distance d ₀ in FIG. 7B is measured by the line sensor 119 as the distance between the centroid positions of the two images.

Thus, since the measurement result in the line sensor 119 differs depending on the position of the wafer W, the value of the distance d ₀ between the two images when the wafer W is at the reference best focal plane is stored as a reference value later. by storing the device 60, the main controller 20 reads out the reference value stored in the storage device 60, the reference value d ₀ and based on a difference between the measured value (amount of defocus and the difference By multiplying the conversion factor), the defocus amount of the surface of the wafer W can be detected.

The defocus amount on the surface of the wafer W using the other illumination light beam IL ₁ can also be measured in the same manner as described above.

  Thereafter, the line sensor 119 captures an image formed on the light receiving surface and performs photoelectric conversion. The photoelectrically converted electric signal is output toward the main controller 20.

As described above, the stored reference value d ₀ (line sensor) with respect to the position in the light receiving surface of the image formed on the light receiving surface of the line sensor 119 by the reflected light of the illumination light beam IL ₁ or the illumination light beam IL _2. From the lateral displacement amount and the direction of occurrence of lateral displacement with respect to the illumination light beam IL ₁ or the image interval of the illumination light beam IL ₂ at the time of focusing on 119, the wafer mark's Z-axis position displacement (position displacement direction and displacement amount), That is, the signed defocus amount) can be measured.

  The exposure apparatus 100 further supplies an imaging light beam for forming a plurality of predetermined pattern images toward the best imaging surface of the projection optical system PL from an oblique direction with respect to the optical axis AX direction (not shown). An oblique incidence type multi-point focus detection system comprising an optical system and a light receiving optical system (not shown) that receives each reflected light beam of the imaging light beam on the surface of the wafer W through a predetermined pattern is a projection optical system. It is fixed to a support portion (not shown) that supports the system PL. As this multipoint focus detection system, one having the same configuration as that disclosed in, for example, Japanese Patent Laid-Open No. Hei 6-283403 is used, and the main controller 20 performs this multipoint focus during scanning exposure or the like. Wafer stage WST is driven in the Z direction and the tilt direction based on the position information of wafer W from the detection system. The multi-point focus detection system described in the publication has not only the exposure area on the wafer W but also a function of pre-reading the undulations of the wafer W in the scanning direction. The shape of the light beam irradiated by the irradiation optical system may be a parallelogram or other shapes.

  The main control device 20 includes a microcomputer or a workstation (ie, includes a CPU and a main memory), and controls each component of the device in an integrated manner. Further, a storage device 60 is connected to the main controller 20. The main control device 20 can write data to the storage device 60 and read stored data.

  Next, a series of operations when the exposure apparatus 100 according to the first embodiment configured as described above performs exposure of the second layer (second layer) and subsequent layers on the wafer W will be described. The processing algorithm of the CPU in the control device 20 will be described with reference to a flowchart of FIG. Here, it is assumed that the exposure of the first layer on the wafer W has already been completed and the second and subsequent layers are exposed. In order to simplify the description, a layer already formed on the wafer W is referred to as a source process layer, hereinafter simply referred to as a “source process”, and a layer formed in the current exposure process is referred to as a current process layer ( Hereinafter, this is simply referred to as “current process”.

  As shown in FIG. 8, in step 201, a reticle R is first loaded on a reticle stage RST using a reticle loader (not shown). After loading of the reticle R, baseline measurement of the alignment sensor 14 which is a reticle alignment and off-axis alignment detection system is performed.

  Specifically, in step 203, based on the measurement results of the reticle interferometer 16 and the wafer interferometer 18, for example, four pairs of reticle alignment reference marks (hereinafter referred to as the reference marks) formed on the reference mark plate 40 on the wafer stage WST. A reticle stage driving unit and a reticle stage driving unit at a position where a predetermined pair of first reference marks and a corresponding image of the reticle mark on the reticle R can be simultaneously observed. The reticle stage RST and wafer stage WST are moved via a wafer stage drive unit (both not shown).

  Next, using the reticle alignment detection systems RA1 and RA2, the amount of positional deviation of the image of the pair of reticle marks corresponding to the predetermined pair of first reference marks is measured.

  Next, the reference mark plate 40 and the reticle R are moved stepwise in synchronization with the Y-axis direction at the projection magnification ratio, thereby sequentially measuring the positional deviation amount of the reticle mark image with respect to the other three pairs of reference marks.

  Then, from the positional deviation amounts of these four pairs of reticle marks, the offset of the positional deviation amount of the projected image of the reticle R with respect to the reference mark plate 40 and consequently the wafer stage WST, the rotation angle, the angular deviation in the scanning direction, etc. are calculated. The calculation result is stored in the main memory. This reticle alignment operation is disclosed in detail in JP-A-7-176468.

  After the above reticle alignment, in step 205, wafer stage WST is moved so that fiducial mark plate 40 is positioned directly below alignment sensor 14, and a second fiducial mark different from the first fiducial mark on fiducial mark plate 40 is obtained. The amount of positional deviation with respect to the detection center of the alignment sensor 14 (the center of the above-mentioned index (mark)) is detected, the detection result of this positional deviation amount and the above-mentioned reticle alignment result, and the measurement value of the wafer interferometer 18 at this time Based on the design baseline and the positional relationship between the first reference mark and the second reference mark, a so-called baseline of the alignment sensor 14 is calculated.

  Next, in step 207, wafer loading onto wafer stage WST is executed via a wafer loader (not shown). Here, the first wafer W of one lot is loaded. At this time, the wafer coordinate system (array coordinate system) defined by the array of shot regions formed in the original process on the wafer W is made to coincide with the stage coordinate system to some extent by a pre-alignment apparatus (not shown). Further, it is assumed that the orientation of the wafer W on the wafer stage WST is adjusted.

  Next, a wafer alignment subroutine 209 is executed. FIG. 9 shows a flowchart of the subroutine 209. As shown in FIG. 9, first, in step 301, a counter value (hereinafter abbreviated as “counter value n”) n provided therein is initialized to 1. In step 303, 1 out of the wafer marks respectively attached to the specific shot areas (sample shots) selected in advance among the plurality of shot areas already formed on the wafer W in the original process. Wafer stage WST is moved so that the second wafer mark to be measured is positioned within the detection field of the detection optical system of alignment sensor 14 (below prism mirror 110 in FIG. 3). Thereby, the area where the first wafer mark is formed becomes the detection target area of the test surface.

  Next, in step 305, wafer stage WST is moved in the Z-axis direction via a wafer stage drive unit (not shown) so that the surface of wafer W is positioned on the Gaussian image plane of the detection optical system of alignment sensor 14. Note that the position corresponding to the Gaussian image plane of the detection optical system of the alignment sensor 14 is determined in advance as a design position.

In the next step 307, focus measurement is performed. Specifically, the light source 103 is instructed to emit light, and a signal corresponding to the image intensity distribution for the measurement target region near the first wafer mark is detected from the line sensor 119, and pixel data corresponding to the signal is detected. It waits for a line, that is, an image intensity distribution data string to be sent from the line sensor 119. Here, assuming that the first wafer mark is wafer mark AM1 shown in FIG. 6, main controller 20 instructs light source 103 to emit light and drives shutter 106B, so that field stop plate 106A The opening SO ₁ is set to an open state, and the opening SO ₂ is set to a shielding state. Therefore, only the reflected light beam of the illumination light beam IL ₁ is imaged on the light receiving surface of the line sensor 119. As described above, when the focus is measured to detect the wafer mark, it is determined whether the irradiation region of the illumination light beam IL _{1 or} the irradiation region of the illumination light beam IL ₂ is located on the street line. The shutter 106B is driven so that only the illumination light beam irradiated on the street line reaches the wafer W, obtained in advance based on the positional relationship between and the shot area. In the following, when measuring the focus, the operation is the same as described above, including the operation of driving the shutter 106B and setting _one of the openings SO ₁ and SO ₂ of the field stop plate 106A to the shielding state. Therefore, in the following, detailed description of the focus measurement operation is omitted.

  Note that the defocus amount measured in step 307 is measured with the wafer mark forming surface positioned on the Gaussian image surface of the detection optical system of the alignment sensor 14, and thus the deviation from the Gaussian image surface. This is a measurement value with reduced error due to.

Then, when the image intensity distribution data string sent from the line sensor 119 of the focus detection system 123 is received, the image intensity distribution data string is used (for example, considering its mirror symmetry or translational symmetry). By detecting the center-of-gravity position interval between the two slit images in the data string (for example, this interval is d _R ), and using this as information on the in-focus position, by multiplying d _R −d ₀ by the defocus conversion coefficient The defocus amount is calculated.

  In the next step 309, it is determined whether or not the calculated defocus amount is within a predetermined range, that is, whether or not it is at the in-focus position. If it is determined that the lens is in the focus position, the process proceeds to step 315. If it is determined that the lens is not in the focus position, the process proceeds to step 311. Here, it is assumed that the calculated defocus amount is not within the predetermined range and is not in the in-focus position, and the process proceeds to step 311.

In the next step 311, the position of wafer stage WST in the Z-axis direction is adjusted by the defocus amount. In the next step 313, focus measurement is performed again in the same manner as in step 307, and the distance d _R between the centroid positions of the two slit images in the image intensity distribution data string obtained at that time is detected.

After step 313 is executed or when the determination in step 309 is affirmative, the process proceeds to step 315. In step 315, the interval d _R acquired in step 307 or step 313 is stored in the storage device 60 as information regarding the in-focus position.

  Next, in step 317, the first wafer mark is imaged. Specifically, the light source 103 is instructed to emit light. Then, the first wafer mark is imaged by the imaging unit 122 of the mark detection system 124 of the alignment sensor 14, and the imaging signal is sent to the main controller 20, so that the imaging signal and the wafer interferometer 18 are obtained. Based on the position information of the wafer stage WST, the position information of the wafer mark (X coordinate or Y coordinate of the wafer mark in the stage coordinate system) is detected, and the position information of the wafer mark is stored in the storage device 60.

  In step 319, the counter value n is incremented by 1 (n ← n + 1), and in the next step 321, the wafer mark to be measured nth is within the detection field of the detection optical system of the alignment sensor 14 (the prism mirror in FIG. 3). Wafer stage WST is moved so as to be positioned below (110). As a result, the region where the second wafer mark is formed becomes the detection target region of the test surface.

In the next step 323, the wafer is so positioned that the n-th (here, second) wafer mark is located at the position corresponding to the information (interval d _R ) related to the in-focus position stored in the storage device 60. The position of stage WST in the Z-axis direction is adjusted.

In the next step 325, focus measurement is performed. Specifically, when the image intensity distribution data string sent from the line sensor 119 of the focus detection system 123 is received, the image intensity distribution data string is used (for example, considering its mirror symmetry and translational symmetry). Te), 'detects the), the distance d _R' distance of the center of gravity positions of the two slit images in the data sequence (for example, the distance d _R and the d _R stored in the storage device 60 at step 315 The signed defocus amount is calculated by multiplying the difference between d _R ′ −d _R by the defocus conversion coefficient. In the next step 327, the position of wafer stage WST in the Z-axis direction is adjusted according to the defocus amount.

  Next, in step 329, the nth (here, second) mark is imaged. Specifically, the light source 103 is instructed to emit light. Then, the second wafer mark is imaged by the imaging unit 122 of the mark detection system 124 of the alignment sensor 14, and the imaging signal is sent to the main controller 20, so that the wafer obtained from the imaging signal and the wafer interferometer 18 is obtained. Based on the stage WST, position information of the wafer mark (X coordinate or Y coordinate of the wafer mark in the stage coordinate system) is detected, and the position information of the wafer mark is stored in the storage device 60.

In the next step 331, it is determined whether or not the position information of all the wafer marks to be measured has been acquired, that is, whether or not the counter value n has exceeded a predetermined value n _c (> 3). If the determination is negative, the process returns to step 319, and if the determination is affirmative, the process proceeds to step 333. Here, since the position information of the second (n = 2) wafer mark has only been acquired, the determination is negative and the processing returns to step 319.

Thereafter, in step 331, until until the determination is affirmative, that is, the position information of all of the wafer mark to be measured (n _c pieces of wafer marks) is obtained, step 319 → Step 321 → Step 323 → Step 325 → Step 327 → Step 329 → Step 331 is repeatedly executed. In step 321, the position of the test surface on the wafer W (the area where the measurement target wafer mark is formed) is adjusted to be the in-focus position determined when the first wafer mark is obtained. Therefore, at this time, the wafer W is already located in the vicinity of the in-focus position. Therefore, in step 325, it is not necessary to move wafer stage WST significantly in the Z-axis direction, so that the time required for focus adjustment can be shortened.

  If the determination in step 331 is affirmative, in the next step 333, using the wafer mark position information calculated so far, that is, the position coordinates of the wafer mark, for example, in Japanese Patent Application Laid-Open No. 61-44429. The statistical calculation using the disclosed least square method is executed, and the rotation coordinate, the scaling component, the offset component of the array coordinate system and the stage coordinate system of each shot area of the wafer W, the X axis and the Y axis of the stage coordinate system Parameters such as the orthogonality component are calculated, the parameters are substituted into a predetermined arithmetic expression, the array coordinates of each shot area on the wafer W, that is, the overlay position, are calculated, and the processing of the subroutine 209 ends.

  As a result, the wafer alignment is completed, and then, in step 211 of FIG. 8, a step-and-scan exposure operation is performed as follows.

  In this exposure operation, scanning for exposure of the first shot (first shot area) of the wafer W while monitoring the measurement value of the wafer interferometer 18 based on the result of wafer alignment and the measurement result of the baseline. Wafer stage WST is moved to the start position (acceleration start position).

  Then, scanning of reticle stage RST and wafer stage WST in the Y-axis direction is started via a reticle stage driving unit and a wafer stage driving unit (not shown), and when both stages RST and WST reach their respective target scanning speeds. Then, illumination of the pattern area of the reticle R by the exposure light EL is started, and scanning exposure is started.

  At the time of the above scanning exposure, the movement speed Vr of reticle stage RST in the Y-axis direction and the movement speed Vw of wafer stage WST in the Y-axis direction have a speed ratio corresponding to the projection magnification (for example, 1/5) of projection optical system PL. The reticle stage RST and wafer stage WST are synchronously controlled so as to be maintained.

  Then, different areas of the pattern area of the reticle R are sequentially illuminated with the exposure light EL, and when the illumination of the entire pattern area is completed, the first shot scanning exposure on the wafer W is completed. As a result, the circuit pattern of the reticle R is reduced and transferred to the first shot via the projection optical system PL.

  When the first shot scanning exposure is thus completed, wafer stage WST is moved stepwise in the X and Y axis directions, and a scanning start position (acceleration starting position) for exposure of the second shot (second shot area). ). Then, scanning exposure similar to the above-described operation is executed for the second shot.

  In this manner, the scanning exposure of the m-th (m is a natural number) shot area on the wafer W and the stepping operation for the (m + 1) -th shot area exposure are repeatedly executed, and all the exposure target shot areas on the wafer W are executed. Then, the circuit pattern of the reticle R is sequentially transferred.

  In step 213, the wafer W is unloaded via a wafer loader (not shown).

  In step 215, it is determined whether or not the exposure of all wafers to be exposed, for example, one lot of wafers, has been completed in the current process. If there is still a wafer to be exposed, the determination is denied and the process returns to step 207. Then, in step 215, step 207 (wafer load) → subroutine 209 (wafer alignment) → step 211 (exposure) → step 213 (wafer unloading) until the completion of exposure of all wafers to be exposed is confirmed. Load) → Step 215 (end determination) is repeatedly executed. If it is determined in step 215 that exposure of all wafers has been completed, a series of exposure processing operations are terminated.

  As described in detail above, according to the detection method of the first embodiment, in step 305, the region where the wafer mark is formed on the surface of the wafer W is displayed as a Gaussian image of the detection optical system of the alignment sensor 14. Since the focus state of the region where the wafer mark is formed with respect to the detection optical system is detected after being positioned on the surface, from the Gaussian image plane of the detection optical system of the alignment sensor 14 included in the measurement result of the focus state Since the error due to the positional deviation of the surface on which the wafer mark is formed can be reduced, the focus state (defocus amount) of the region on the wafer W where the wafer mark is formed can be detected with high accuracy. .

  In the first embodiment, when it is determined in step 309 that the first wafer mark is not at the in-focus position of the detection optical system of the alignment sensor 14 based on the focus measurement result in step 307. In step 311, the position of wafer stage WST is adjusted again. In this way, the region where the wafer mark is formed can be reliably positioned at the in-focus position of the alignment sensor 14.

Further, when the second and subsequent wafer marks are detected, the regions where these wafer marks are formed are substantially on the same plane on the same test surface, so that the focus position of each region with respect to the detection optical system of the alignment sensor 14 Can be considered to be nearly identical. Therefore, in the first embodiment, the focus position d _R in the first wafer mark is stored in step 315, and the first wafer mark forms the position of the area where the second and subsequent wafer marks are formed. It is located at the in-focus position of the marked area. In this way, the in-focus position of the area where the second and subsequent wafer marks are formed can be detected efficiently and quickly.

  Further, according to the first embodiment, since the wafer mark is imaged by the alignment sensor 14 based on the in-focus position measured with high accuracy as described above, the imaging result of the wafer mark is improved. Can be.

  In addition, according to the exposure method of the first embodiment, the position control of the wafer W is performed using the position information of the wafer mark detected based on the imaging result of the wafer mark imaged favorably by the detection method described above. Since the transfer is performed while performing high-precision exposure, high-precision exposure can be realized.

  In the first embodiment, when the wafer mark is imaged in step 327, the wafer mark is positioned at the in-focus position stored in the storage device 60 in step 315 and then the wafer mark is recorded. Although imaging was performed, the present invention is not limited to this. A plurality of imaging images obtained at different Z-axis positions by imaging the mark while sequentially moving wafer stage WST in the Z-axis direction with reference to the in-focus position. An imaging signal that maximizes the contrast of the image from the signal may be adopted as the imaging result of the mark. That is, the wafer mark may be imaged at a position different from the in-focus position stored in step 315 (for example, a position with the maximum imaging contrast).

  Further, the driving of wafer stage WST in steps 303 and 305 may be performed simultaneously, or the driving of wafer stage WST in steps 321 and 323 may be performed simultaneously.

  Note that when the reference mark formed on the reference mark plate 40 is detected, that is, when the baseline measurement in step 205 is executed, if the same processing as in steps 303 to 317 is executed, the reference mark of the reference mark is detected. The imaging result can be improved, and as a result, highly accurate exposure can be realized.

  As is apparent from the above description, in the first embodiment, the main control device 20 corresponds to the adjustment device, the measurement device, and the determination device of the detection device of the present invention. That is, the adjustment device is realized by the process of step 305 (FIG. 9) performed by the CPU of the main controller 20, the measurement device is realized by the process of step 307 (FIG. 9), and steps 309 to 315 (FIG. 9). The determination apparatus is realized by the above process. However, it goes without saying that the present invention is not limited to this.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the detection method and the exposure method according to the present invention are performed using the same or equivalent exposure apparatus as that of the first embodiment. Therefore, in the following, from the viewpoint of preventing repeated description, the same reference numerals as those in the first embodiment are used for these devices and the respective components, and the processing contents are different from those in the first embodiment. Only the wafer alignment process of the subroutine 209 shown in FIG.

  In the subroutine 209, as shown in FIG. 10, first, in step 401, it is determined whether or not the loaded wafer is the first one in one lot. If the determination is affirmed, the process proceeds to subroutine 403, and if the determination is negative, the process proceeds to step 405. Here, since it is the first sheet, the determination is affirmed and the process proceeds to subroutine 403.

  In the subroutine 403, a process for creating a table indicating the correspondence between the signals detected by the line sensor 119 of the focus detection system 123 and the intervals between the two peaks corresponding to the plurality of focus positions is performed.

  FIG. 11 shows a flowchart of the subroutine 403. As shown in FIG. 11, first, in step 501, an area having a uniform reflectance on the wafer W (for example, an area where no pattern is formed in the original process) is directly below the prism mirror 110 of the alignment sensor 14. Wafer stage WST is moved so as to be arranged.

  Next, in step 503, the focal position of the alignment sensor 14, that is, the predetermined position Zc as the reference position of the wafer W in the optical axis direction of the detection optical system (prism mirror 110, objective lens 109, etc.) of the alignment sensor 14, and the focal position. The measurement range L and the focus position measurement interval ΔZ are set. In this subroutine 403, as will be described later, the position of the wafer W in the Z-axis direction is sequentially moved by the interval ΔZ within the measurement range L with respect to the reference position Zc, and the focus detection system of the alignment sensor 14 is moved. The signal corresponding to the image intensity distribution on the light receiving surface is detected at each position by the 123 line sensor 119. Here, the reference position, the measurement range, and the interval are set. As the reference position Zc, for example, a design value related to the detection optical system of the alignment sensor 14 or a focus position obtained by simulation can be set, but any position close to these positions can be set. good. Further, the measurement range L of the focus position is not particularly limited, but it is preferable that the Gaussian image plane of the detection optical system of the alignment sensor 14 is included. The interval ΔZ is preferably set in consideration of the resolution of the line sensor 119 of the focus detection system 123 and the like.

  Here, the predetermined position Zc or the like may be set using an input device (not shown) or the like, and the value of the predetermined position Zc or the like is stored in the storage device 60 in advance as an apparatus parameter. A predetermined position Zc or the like may be set by reading out the apparatus parameters by the main controller 20. In the exposure apparatus of the second embodiment, since the alignment sensor 14 is not movable in the optical axis direction of the detection optical system, the wafer W in the optical axis direction of the detection optical system of the alignment sensor 14 is not affected. When the position is determined, the relative position between the alignment sensor 14 and the wafer mark is determined.

  In the next step 505, the position of wafer stage WST in the Z-axis direction is positioned at Zc−L / 2. In step 507, it is determined whether or not the position of wafer stage WST in the Z-axis direction exceeds Zc + L / 2. Here, since the position of wafer stage WST in the Z-axis direction does not exceed Zc + L / 2 (current position is Zc−L / 2), the determination is negative and the routine proceeds to step 509.

  Next, in step 509, focus measurement is performed. The signal corresponding to the image intensity distribution of the reflected light beam with respect to the surface having the uniform reflectance of the wafer W sent from the line sensor 119 of the focus detection system 123 is pixel data (brightness) detected by each image sensor of the line sensor 119. Value) data string (image intensity distribution data string). Based on this image intensity distribution data sequence, main controller 20 detects the interval between the centroid positions of the two peaks formed in the image intensity distribution, and associates the image intensity distribution data sequence with the interval. And stored in the storage device 60.

  Next, proceeding to step 511, the position of wafer stage WST in the Z-axis direction is shifted to the + Z side by ΔZ, and the process returns to step 507.

  Thereafter, in step 507, step 507 → step 509 → step 511 is repeatedly executed until it is determined that the position of wafer stage WST in the Z-axis direction exceeds Zc + L / 2, and Z-axis of wafer stage WST is executed. Each time the position related to the direction is changed by ΔZ to the + Z side, the image intensity distribution data string detected by the line sensor 119 is obtained by the main controller 20 based on the data string. And stored in the storage device 60. If the determination in step 507 is affirmative, the process proceeds to step 513. In step 513, two peaks obtained from the image intensity distribution data string of the surface having a uniform reflectance stored in the storage device 60 and the data string are obtained. The correspondence relationship with the barycentric position is collectively tabulated, and the process of subroutine 403 ends. Hereinafter, a function indicating a data sequence stored in the storage device 60 is referred to as an image intensity distribution data sequence function G (N) (see FIG. 13B). N is a natural number indicating the number of each pixel in the line sensor 119, and G (N) represents a luminance value (pixel data) in the pixel N.

  Returning to FIG. 10, in step 405, the counter value n is initialized to 1. In step 407, of the plurality of shot areas already formed on the wafer W in the original process, the wafer mark to be measured n-th out of the wafer marks respectively attached to the specific shot areas (sample shots). However, the wafer stage WST is moved so as to be positioned within the detection visual field of the detection optical system of the alignment sensor 14. Here, since n = 1, the wafer mark to be measured first is located in the detection field of the detection optical system of the alignment sensor 14.

Next, a focus adjustment subroutine 409 is executed. FIG. 12 shows a flowchart of the subroutine 409. In the subroutine 409, as shown in FIG. 12, first, in step 601, focus is measured. Here, a signal (pixel) corresponding to an image intensity distribution by a reflected light beam from an area to be measured in the vicinity of the n-th wafer mark (for example, one of the illumination areas IL ₁ and IL ₂ shown in FIG. 6). A data string of data, that is, an image intensity distribution data string) is obtained. Here, a function indicating the received image intensity distribution data string is an image intensity distribution data string function F (N) (see FIG. 13A).

In the next step 603, a standard deviation σ _F indicating the data variation of the image intensity distribution data string function F (N) is obtained. In the next step 605, an interval d _F between the centroid positions of the two peaks of the image intensity distribution data sequence function F (N) is obtained, and an image intensity distribution data sequence function of a surface having a uniform reflectance corresponding to the interval. G (N) is read from the table stored in the storage device 60.

  Then, in the next step 607, the background reflectance is estimated. The image intensity distribution formed by the reflected light beam obtained by irradiating the measurement region near the wafer mark with a predetermined imaged light beam is the image intensity distribution (second signal of the second signal) of the image formed by the imaged light beam. Component) and the reflectance (first signal component) of the surface of the detection target on which the imaging light beam is incident. Therefore, the difference between the information regarding the image intensity distribution for the detection target (here, the region where the nth wafer mark is formed on the wafer W) and the information regarding the image intensity distribution for the surface having a uniform reflectance, for example, If the ratio is calculated, information on the reflectance of the detection target can be estimated from the ratio.

Specifically, in step 607, the image intensity distribution data sequence function G read from the storage device 60 from the data values (luminance values) of the image intensity distribution data sequence function F (N) received in step 601. A function H (N) (= F (N) / G (N)) obtained by dividing (N) is calculated. Among the data of the data string function H (N), the value is set to 0 for data whose value is lower than a predetermined value. The result of the division, that is, the data string function H (N) is estimated as a data string (background reflectance data string) corresponding to the background reflectance around the wafer mark to be detected (measured area). FIG. 13A shows an example of the image intensity distribution data sequence function F (N) received in step 601, and FIG. 13B shows the data read from the storage device 60 in step 605. An example of the image intensity distribution data sequence function G (N) is shown. FIG. 13C shows the data sequence function F (N) shown in FIG. 13A, and FIG. The base reflectance data string function H (N) obtained when the division in step 607 is performed is shown in the data string function G (N). In step 607, the standard deviation σ _H indicating the variation in the data of the estimated background reflectance data string function H (N) is also calculated.

In the next step 609, it is determined whether or not the standard deviation ratio σ _F / σ _H is equal to or greater than a predetermined value. If the determination is affirmative, the process proceeds to step 611, and if the determination is negative, the process proceeds to step 619. Here, the discussion proceeds assuming that the judgment is affirmed.

In the next step 611, based on the background reflectance data string function H (N) estimated in step 607, the interval d _H between the centroid positions of the two peaks is detected. As shown in FIG. 13C, the distribution shape of the base reflectance data sequence function H (N) corresponds to the reflectance of the surface of the wafer W irradiated with _{one of} the illumination light beams IL ₁ and IL _2. In many cases, the distribution shape does not have two distinct peaks (see FIGS. 13A and 13B). Therefore, here, the focus of the alignment sensor 14 is measured using statistical calculation processing.

For example, as shown in FIG. 13C, first, a scope having a sufficiently wide width is set by the walls W1 and W2, and the scope is set to the left and right sides of the paper with respect to the base reflectance data sequence function H (N). when went by scanning in a direction (N axis), the center position C ₀ when mirror symmetry of the distribution shape of the data string in the scope with respect to the center position C ₀ in its scope the highest The center position for determining the focus is determined. In FIG. 13C, the distance between the center of gravity of the data string on the left side of the determined center position and the center of gravity of the data string on the right side of the center position is the distance d _H corresponding to the focus of the alignment sensor 14. Calculate as

In next step 613, main controller 20 determines whether or not the difference between 2 (d _H −d ₀ ) and d _G −d ₀ is within a predetermined range. Here, d _G is an interval corresponding to the image intensity distribution data string function G (N) read out in step 605, as shown in FIG. 13B. As shown in FIG. 1B, doubling d _H −d ₀ is a result of the deviation in the N-axis direction of the reflectance distribution (first signal) caused by the base pattern Pt due to defocusing. Since the deviation in the N-axis direction of the image (second signal) due to the image light flux is doubled, the conversion coefficient from the interval obtained from the base reflectance data string function H (N) to the defocus amount is the image intensity distribution. This is because the conversion coefficient from the interval between the centroid positions of two peaks obtained from the data string function G (N) to the defocus amount is considered to be doubled. If the determination is negative, the process proceeds to step 615. If the determination is positive, the process proceeds to step 617. Here, the determination is denied, and the description will proceed assuming that the process proceeds to step 615.

In step 615, the image intensity distribution data string function G (N) corresponding to the interval 2 (d _H −d ₀ ) + d ₀ is read from the table in the storage device 60. After executing Step 615, the process returns to Step 607.

  Thereafter, in step 613, the processing of step 607 → step 609 → step 611 → step 613 → step 615 is repeatedly executed until the determination is affirmed. In this loop process, if the determination in step 609 is negative, the process proceeds to step 619.

When such a loop process is executed, the interval d _H detected from the background reflectance data string function H (N) gradually converges to a certain value (that is, the interval determined by the true background reflectance).

If the determination in step 613 is affirmative, the process proceeds to step 617, where 2 (d _H −d ₀ ) calculated from the function H (N) at that time is multiplied by the defocus amount conversion coefficient to defocus. Calculate the amount. If the determination is negative in step 609, the process proceeds to step 619, where the background reflectance around the wafer mark is substantially uniform, and the image intensity distribution data string function G currently selected in step 601 is assumed. Using (N), the distance d _G between the centroid positions of the two peaks in the data string is detected, and the defocus amount is calculated by multiplying d _G −d ₀ by the defocus conversion coefficient.

  After step 617 or step 619 is executed, the process proceeds to step 621. In step 621, the position of wafer stage WST in the Z-axis direction is adjusted by the calculated defocus amount. Then, after executing step 621, the subroutine 409 is terminated.

  Returning to FIG. 10, in step 411, the mark is imaged. Here, main controller 20 determines the wafer mark position information (in the stage coordinate system) based on the wafer mark imaging signal imaged by imaging unit 122 and wafer stage WST position information obtained from wafer interferometer 18. The wafer mark X coordinate or Y coordinate) is detected, and the position information of the wafer mark is stored in the storage device 60.

When the acquisition of the position information of the wafer mark is completed, the process proceeds to the next step 413, where n is incremented by 1 (n ← n + 1). Then, in step 415, whether acquired positional information of all of the wafer mark to be measured, i.e. the counter n it is determined whether more than a predetermined value n _c. If the determination is negative, the process returns to step 407, and if the determination is positive, the process proceeds to step 417. Here, since only the position information of the first (ie, n = 1) wafer mark has been acquired, the determination is negative and the processing returns to step 407.

Thereafter, step 407 → subroutine 409 → step 411 → step 413 → step until determination in step 415 is affirmed, that is, position information of all wafer marks (n _C wafer marks) to be measured is acquired. The process 415 is repeatedly executed.

  If the determination in step 415 is affirmative, in the next step 417, using, for example, the position information of the wafer mark calculated up to now, that is, the position coordinates of the wafer mark, Japanese Patent Laid-Open No. 61-44429, etc. The statistical calculation using the disclosed least square method is executed, and the rotation coordinate, the scaling component, the offset component of the array coordinate system and the stage coordinate system of each shot area of the wafer W, the X axis and the Y axis of the stage coordinate system Parameters such as the orthogonality component are calculated, the parameters are substituted into a predetermined arithmetic expression, the array coordinates of each shot area on the wafer W, that is, the overlay position, are calculated, and the processing of the subroutine 209 ends.

  Since the processing performed after the end of the subroutine 209 is substantially the same as the processing shown in FIG. 8 in the first embodiment, description thereof is omitted.

  As is apparent from the above description, in the second embodiment, the main control device 20 corresponds to the detection device estimation device and calculation device of the present invention. That is, the function of the estimation device is realized by the processing of the subroutine 409 (FIG. 12) such as step 607 performed by the CPU of the main control device 20, and the function of the calculation device is realized by the processing of step 617 and step 619 (FIG. 12). It has been realized. However, it goes without saying that the present invention is not limited to this.

As described above in detail, according to the second embodiment, in step 601 of FIG. 12, _one of the illumination light beams IL ₁ and IL ₂ is irradiated to the measurement area around the wafer mark to be measured. A signal corresponding to the image intensity distribution of the image obtained by the reflected light flux is detected, and in step 607, the first signal (image intensity distribution data depending on the reflectance of the measurement target area included in the detected signal is detected. Column function H (N)), and in step 617 or step 619, the estimated first signal (image intensity distribution data string function H (N)) is used as the second signal when estimating the first signal. Based on the image intensity distribution data string function G (N) to be used, the defocus amount of the wafer mark with respect to the detection optical system of the alignment sensor 14 is calculated. In this way, the first signal (signal corresponding to the image intensity distribution data sequence function H (N)) and the second signal (signal corresponding to the image intensity distribution data sequence function G (N)) are defocused. The focus state (defocus amount) of the region where the wafer mark is formed with respect to the detection optical system of the alignment sensor 14 can be accurately detected regardless of the corresponding difference in the N-axis direction.

In the second embodiment, in step 607 of FIG. 12, the reflectance data string function H (N) around the wafer mark (measurement area) is estimated until the estimation accuracy reaches a predetermined level or higher. (In other words, until the determination in step 613 is affirmed), the background reflectance data string function H (N) of the measurement target region is repeatedly estimated. When the estimation accuracy becomes a predetermined level or higher (that is, when the defocus amount calculated from the function H (N) becomes twice the defocus amount calculated from the function G (N)). The defocus amount is detected using the background reflectance data string function H (N). In this way, the substrate reflectance around the wafer mark on which the image of the illumination light beams IL ₁ and IL ₂ is projected is not uniform, and the wafer mark is defocused with respect to the detection optical system of the alignment 14. Thus, even when the image intensity distribution detected by the line sensor 119, that is, the distribution shape of the function F (N) is deformed, the defocus amount of the alignment sensor 14 with respect to the detection optical system can be accurately detected. It becomes like this.

  Note that when the background reflectance around the wafer mark is estimated as in the second embodiment, the measurement target area is a Gaussian of the detection optical system of the alignment sensor 14 as in the first embodiment. There is no need to position it on the image plane. This is because the defocus amount can be accurately detected based on the estimation of the background reflectance even if the position of the measurement target region is deviated from the focus position of the detection optical system of the alignment sensor 14.

  Further, in the second embodiment, before the above-described background reflectance data string function H (N) is estimated, in the subroutine 403 shown in FIG. While sequentially changing the relative position with the uniform reflectance surface, the image intensity distribution data string function G (N) for the uniform reflectance surface is detected, and the distance between the centroid positions of two peaks obtained from the function G (N) And a table in which the function G (N) is associated. In step 605, a function G (N) used for estimation is selected from a plurality of functions G (N) registered in the table. In this way, every time the background reflectance data string function H (N) is estimated, it is necessary to detect information corresponding to the image intensity distribution with respect to the surface having a uniform reflectance (that is, the function G (N)) one by one. Therefore, the time required for estimating the function H (N) can be shortened.

  In the second embodiment, the table is created using the surface on which the pattern on the wafer W is not formed. However, the present invention is not limited to this. For example, when the exposure apparatus 100 is started up or maintained, for example, A mirror-processed reference wafer or the like may be placed under the prism mirror 110 of the alignment sensor 14, and the table may be created by executing steps 501 to 513 in FIG. In this way, it is not necessary to create a table during a series of exposure processes, so that the throughput of the exposure process can be improved.

  In addition, according to the second embodiment, the function H (N) (a signal dependent on the reflectance, that is, the first signal) is estimated, but a signal independent of the reflectance (second signal) is estimated. Anyway.

  Also, the detection method of the second embodiment is similar to the detection method of the first embodiment described above, even when a reference mark or the like is detected by the alignment sensor 14 in the baseline measurement of step 205 in FIG. Can be applied. In this case, for example, before executing step 205, when the exposure apparatus is started up or at the time of maintenance, for example, a mirror-finished reference wafer or the like is placed below the prism mirror 110 of the alignment sensor 14, and the subroutine 403 is executed. It is necessary to create a table in which the reflectance uniform plane image intensity distribution data string function G (N) is registered by executing the same processing as in FIG.

  Further, according to the exposure method of the second embodiment, an area on the wafer W where a wafer mark is formed is used as a test surface of the detection optical system of the alignment sensor 14, and the book described above. Since the position information of the wafer mark or the like can be detected with high accuracy by using the detection method of the second embodiment, the pattern is determined based on the detection result (position information of the wafer mark) of the detection optical system of the alignment sensor 14. If transferred onto the wafer W, highly accurate overlay exposure can be performed.

In the second embodiment, in step 613, the condition for ending the estimation of the background reflectance data string function H (N) is set to twice d _H −d ₀ obtained from the function H (N), Although the difference from d _G −d ₀ obtained from the function G (N) is within the predetermined range, the present invention is not limited to this. For example, when the difference between d _H −d ₀ obtained from the previous time and the obtained d _H −d ₀ falls within a predetermined range due to the degree of convergence of d _H −d ₀ obtained each time in step 607 from the estimated H (N), The estimation process may be terminated.

In the second embodiment, the defocus amount is calculated from the function H (N) (first signal) in step 617, but the function G (N) ( The defocus amount may be calculated from the second signal). In step 619, the defocus amount may be detected from the function F (N) (the signal detected in step 601) instead of the function G (N). In step 617, which function is used when detecting the defocus amount may be determined based on the contribution of the function H (N) and the function G (N) to the function F (N). . These contributions may be considered based on the amplitude of the function G (N) and the function H (N) and the standard deviation of the data. In step 617, using the weight according to the contribution of the function G (N) to the function F (N), the interval (interval d _H ) obtained from the function G (N) and the function F (N) The defocus amount may be determined by performing a weighted average with the interval (interval d _F ) obtained from the above.

  In the second embodiment, the background reflectance data string function H (N) is a ratio of the image intensity distribution data string function F (N) and the reflectance uniform plane image intensity distribution data string function G (N). However, the present invention is not limited to this, and the function H (N) may be estimated based on the difference between the function F (N) and the function G (N).

  In the second embodiment, the table stored in the storage device 60 is created only for the first wafer W in one lot. However, the present invention is not limited to this. That is, the table may be created for each wafer without performing the determination in step 401. Further, for the wafer of the next lot, the process of creating the table may be omitted, and the table already stored in the storage device 60 may be used for the estimation of the base reflectance data sequence function H (N).

  In the second embodiment, in the table created in the storage device 60, the image intensity distribution data sequence function G (N) of the reflectance uniform surface registered in the table is a discrete Z position. It is also possible to create an image intensity distribution data string function G (N) that is a discrete function composed of the obtained data strings but not registered in the table by interpolation.

For example, if you want to find the Z position Z _k, Z position away from the Z _k by [Delta] Z Z _{k + 1} of the intermediate Z-position Z _k 'image intensity distribution data string function G (N) is is, Z position Z _The image intensity distribution data string function G (N) corresponding to _k and the image intensity distribution data string function G (N) corresponding to the Z position Z _{k + 1} are read from the table, and the data string having the same number (N) is read. The function having the average of the corresponding data (luminance values) as the data of the number is set as the image intensity distribution data sequence function G (N) at the Z position Z _k ′, and the background reflectance data sequence function H (N) It may be used for estimation. If interpolation is performed according to the ratio of the distance from Z _k to the distance from Z _{k + 1} , not only at the intermediate position Z _k ′ but also at all Z positions between Z _k and Z _{k + 1} . The function G (N) can be obtained.

  In each of the above-described embodiments, the autofocus mechanism that measures the focus state (defocus amount) based on the image intensity distribution obtained by dividing the reflected light beam from the surface to be measured using the light beam dividing member. Although the case of applying the invention has been described, the present invention is not limited to this, and any apparatus that detects a focus state by a reflected light beam from a surface to be measured can be applied.

  In each of the above-described embodiments, an FIA type alignment sensor is used as the alignment sensor 14, or a laser beam is irradiated onto the alignment mark in the form of a dot on the wafer W, and is diffracted or scattered by the mark. The present invention can also be applied to an LSA (Laser Step Alignment) type alignment sensor that detects a mark position using light, or an alignment sensor that appropriately combines the alignment sensor and the FIA method. Further, for example, an alignment sensor that irradiates a mark on the surface to be measured with a coherent detection light and causes two diffracted lights (for example, the same order) generated from the mark to interfere with each other may be used alone, or the FIA method, the LSA. Of course, the present invention can be applied to an alignment sensor appropriately combined with a method or the like.

  In each of the above embodiments, the case where the present invention is applied to a scanning stepper has been described. However, the present invention is not limited to this and can be applied to a stationary exposure apparatus such as a step-and-repeat stepper. In such a case, when performing static exposure, the wafer can be accurately positioned at the exposure position (reticle pattern projection position), and the reticle pattern is accurately superimposed and transferred onto a desired partition area on the wafer. can do.

  An illumination optical system composed of a plurality of lenses, a projection optical system, and an alignment sensor 14 are incorporated in the exposure apparatus main body to perform optical adjustment, and a reticle stage and wafer stage composed of a large number of mechanical parts are incorporated in the exposure apparatus main body. The exposure apparatus of the above-described embodiment can be manufactured by attaching and connecting wirings and pipes and further performing general adjustment (electrical adjustment, operation check, etc.). The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

  The present invention is not limited to an exposure apparatus for manufacturing a semiconductor, but is used for manufacturing a display including a liquid crystal display element. An exposure apparatus for transferring a device pattern onto a glass plate and a device used for manufacturing a thin film magnetic head. The present invention can also be applied to an exposure apparatus that transfers a pattern onto a ceramic wafer, an exposure apparatus used for manufacturing an image sensor (CCD, etc.), an organic EL, a micromachine, and a DNA chip. Further, in order to manufacture reticles or masks used in not only microdevices such as semiconductor elements but also light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, etc., glass substrates or silicon wafers, etc. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern. Here, in an exposure apparatus using DUV (far ultraviolet) light, VUV (vacuum ultraviolet) light, or the like, a transmission type reticle is generally used. As a reticle substrate, quartz glass, fluorine-doped quartz glass, fluorite, Magnesium fluoride or quartz is used. Further, in a proximity type X-ray exposure apparatus or an electron beam exposure apparatus, a transmission mask (stencil mask, membrane mask) is used, and a silicon wafer or the like is used as a mask substrate.

  Furthermore, the detection method according to the present invention is not limited to an exposure apparatus, but can be applied to any apparatus provided with an imaging type detection optical system.

<Device manufacturing method>
Next, an embodiment of a device manufacturing method using the exposure apparatus 100 described above in a lithography process will be described.

  FIG. 14 shows a flowchart of a manufacturing example of a device (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, etc.). As shown in FIG. 14, first, in step 701 (design step), device function / performance design (for example, circuit design of a semiconductor device) is performed, and pattern design for realizing the function is performed. Subsequently, in step 702 (mask manufacturing step), a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in step 703 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.

  Next, in step 704 (wafer processing step), using the mask and wafer prepared in steps 701 to 703, an actual circuit or the like is formed on the wafer by lithography or the like, as will be described later. Next, in step 705 (device assembly step), device assembly is performed using the wafer processed in step 704. Step 705 includes processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation) as necessary.

  Finally, in step 706 (inspection step), inspections such as an operation confirmation test and an endurance test of the device created in step 705 are performed. After these steps, the device is completed and shipped.

  FIG. 15 shows a detailed flow example of step 204 in the semiconductor device. In FIG. 15, in step 711 (oxidation step), the surface of the wafer is oxidized. In step 712 (CVD step), an insulating film is formed on the wafer surface. In step 713 (electrode formation step), an electrode is formed on the wafer by vapor deposition. In step 714 (ion implantation step), ions are implanted into the wafer. Each of the above steps 711 to 714 constitutes a pre-processing process at each stage of the wafer processing, and is selected and executed according to a necessary process at each stage.

  At each stage of the wafer process, when the above pre-process is completed, the post-process is executed as follows. In this post-processing step, first, in step 715 (resist formation step), a photosensitive agent is applied to the wafer. Subsequently, in step 716 (exposure step), the circuit pattern of the mask is transferred to the wafer using the exposure apparatus 100 of the above embodiment. Next, in step 717 (developing step), the exposed wafer is developed, and in step 718 (etching step), the exposed member other than the portion where the resist remains is removed by etching. In step 719 (resist removal step), the resist that has become unnecessary after the etching is removed.

  By repeatedly performing these pre-processing steps and post-processing steps, multiple circuit patterns are formed on the wafer.

  If the device manufacturing method of this embodiment described above is used, the exposure apparatus 100 of each of the above embodiments is used in the exposure step (step 716), so that highly accurate exposure can be realized. As a result, it becomes possible to produce a device with a higher degree of integration.

  As described above, the detection method and apparatus according to the present invention are suitable for detecting the test surface of an object via the detection optical system, and the exposure method and apparatus according to the present invention include a semiconductor element, a liquid crystal The device manufacturing method according to the present invention is suitable for the production of micro devices.

FIG. 1A is a schematic diagram of a state when a combined light beam is irradiated on a wafer, and FIG. 1B is a diagram illustrating an example of an image intensity distribution detected by an image sensor in three focus states. It is. 1 is a drawing schematically showing an exposure apparatus according to an embodiment of the present invention. It is a figure which shows the internal structure of the alignment sensor of FIG. 4A is a diagram showing a field stop plate, and FIG. 4B is a diagram showing a light shielding plate. FIG. 5A and FIG. 5B are diagrams for explaining the arrangement of the reflecting plates. It is a figure which shows the state which is measuring wafer mark AM1. FIG. 7A is a diagram illustrating an imaging state on the line sensor when the wafer surface is at a position lower than the best focal plane, and FIG. 7B is a diagram when the wafer surface is at the best focal plane. FIG. 7C is a diagram showing an imaging state on the line sensor when the wafer surface is at a position higher than the best focal plane. It is a flowchart which shows the process algorithm of CPU in the main controller in a series of operation | movement in an exposure process process. It is a flowchart which shows the process of the subroutine of a wafer alignment in the 1st Embodiment of this invention. It is a flowchart of the subroutine which shows the process of the wafer alignment in the 2nd Embodiment of this invention. It is a flowchart which shows the process of the subroutine of a table creation process. It is a flowchart which shows the process of the subroutine of focus adjustment. FIG. 13A is a diagram illustrating an example of the image intensity distribution data sequence function received in step 601, and FIG. 13B is an image intensity distribution data sequence function read from the storage device 60 in step 605. FIG. 13C is a diagram illustrating an example of the estimated background reflectance data string function. It is a flowchart for demonstrating embodiment of the device manufacturing method which concerns on this invention. It is a flowchart which shows the detail of step 704 of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 14 ... Alignment sensor, 20 ... Main controller (Adjustment device, measuring device, determination device, estimation device), 60 ... Storage device, 100 ... Exposure device, 103 ... Light source, 104 ... Light guide, 105 ... Condenser lens, 106A ... Field stop plate, 106B ... Shutter, 107 ... Lens system, 108 ... First beam splitter, 109 ... Objective lens (detection optical system), 110 ... Prism mirror, 111 ... Lens system, 112 ... Second beam splitter, 113 ... Light shielding Plate, 119 ... Line sensor (measuring device, signal detection device), 122 ... Imaging unit (imaging device), 123 ... Focus detection system, 124 ... Mark detection system, AM1 ... Wafer mark, IL ₁ , IL ₂ ... Illumination beam, EL ... exposure light, R ... reticle, RA1, RA2 ... reticle alignment detection system, W ... wafer (object), WST ... Ehasuteji (mobile).

Claims (27)

A detection method for detecting a test surface of an object via a detection optical system,
A first step of locating a partial region of the test surface of the object on a Gaussian image plane of the detection optical system;
A second step of measuring a focus state of the region with respect to the detection optical system after performing the first step;
And a third step of determining a focus position of the region with respect to the detection optical system based on a measurement result of the second step. The third step includes
A discriminating step for discriminating whether or not the region is located at an in-focus position with respect to the detection optical system based on a measurement result of the second step;
If it is determined in the determining step that the region is not located at a focus position with respect to the detection optical system, the relative position between the detection optical system and the region with respect to the optical axis direction of the detection optical system is adjusted. And a control step of positioning the region at the in-focus position. A fourth step of causing the storage device to store the in-focus position of the region with respect to the detection optical system determined in the third step;
When measuring the focus state with respect to the detection optical system in a region other than the region on the test surface, the other region is positioned based on the focus position stored in the fourth step. The detection method according to claim 1, further comprising: a fifth step. After performing the third step,
An imaging step of imaging the mark formed in the region via the detection optical system in a state where the region is positioned at a position different from the in-focus position with respect to the detection optical system determined in the third step. The detection method according to claim 1, further comprising: In the imaging step,
The detection method according to claim 4, wherein the position of the region when the mark is imaged is set to a position where the contrast in the imaging result of the mark is maximized. After performing the third step,
The method further includes an imaging step of imaging the mark formed in the region through the detection optical system in a state where the region is positioned at the in-focus position with respect to the detection optical system determined in the third step. The detection method according to any one of claims 1 to 3. A detection method for detecting a test surface of an object via a detection optical system,
A first step of irradiating a measurement region near a partial region of the test surface of the object with a predetermined imaging light beam and detecting a signal corresponding to the reflected light beam from the measurement region;
A second step of estimating at least one of a first signal that depends only on a surface shape of the measurement target area and a second signal that does not depend on the surface shape, included in the signal detected in the first step;
And a third step of determining a focus state of the measurement target area with respect to the detection optical system based on at least one of the estimated first signal and the second signal. Prior to the second step,
A fourth step of irradiating the predetermined imaging light beam on a reference surface having a substantially uniform reflectivity and detecting a signal corresponding to the reflected light beam obtained by the irradiation;
The detection method according to claim 7, wherein in the second step, the estimation is performed using the signal detected in the fourth step. In the fourth step,
While sequentially changing the focus position of the reference surface with respect to the detection optical system, the predetermined imaging light beam is irradiated, and a signal corresponding to the reflected light beam obtained by the irradiation is detected every time the focus position is changed. And
In the second step, by selecting a part of the plurality of signals detected in the fourth step, and by dividing or subtracting the signal detected in the first step by the selected signal, The detection method according to claim 8, wherein the first signal is estimated. In the second step,
Obtaining first information related to a focus state of the measurement target region with respect to the detection optical system based only on the first signal;
Obtaining second information related to a focus state of the measurement target region with respect to the detection optical system based only on the second signal;
The detection method according to claim 7, wherein the estimation is continued until the first information and the second information have a substantially predetermined relationship. The predetermined relationship is:
The detection method according to claim 10, wherein the second information has a relationship that is twice the first information. In the third step,
Selecting at least one of the first signal and the second signal according to the contribution of the first signal or the second signal to the signal detected in the first step;
The detection method according to claim 7, wherein a focus state of the measurement target area with respect to the detection optical system is obtained based on a selected signal.   The detection method according to claim 12, wherein the contribution includes information related to amplitudes of the first signal and the second signal. The signal detected in the first step includes a luminance value obtained by a plurality of image sensors,
The contribution is obtained from a relationship between a standard deviation of each luminance value of each of the first signal and the second signal and a standard deviation of each luminance value of the signal detected in the first step. The detection method according to claim 13, characterized in that: In the third step,
Using the weight according to the contribution of the first signal and the second signal to the signal detected in the first step, the focus state obtained from the first signal and the second signal The detection method according to claim 12, wherein the focus state is weighted averaged. After performing the third step,
The mark formed in the region is imaged through the detection optical system in a state where the region is positioned at a focus position with respect to the detection optical system determined based on the focus state obtained in the third step. The detection method according to any one of claims 7 to 15, further comprising: a fifth step. An exposure method for transferring a pattern onto an object held on a moving body,
Detecting the position information of the mark on the movable body using the detection method according to any one of claims 4 to 6, and 16;
And a step of transferring the pattern to the object while controlling the position of the object held by the moving body based on the detection result. In a device manufacturing method including a lithography process,
The device manufacturing method according to claim 17, wherein exposure is performed using the exposure method according to claim 17. A detection device that detects a test surface of an object via a detection optical system,
An adjustment device for adjusting a relative position between the object and the detection optical system in the optical axis direction of the detection optical system;
A measuring device for measuring a focus state of the region with respect to the detection optical system in a state where a partial region of the test surface of the object is positioned on a Gaussian image plane of the detection optical system by adjustment of the adjustment device; ;
And a determination device that determines an in-focus position of the region with respect to the detection optical system based on a measurement result of the measurement device. A storage device that stores the in-focus position of the region with respect to the detection optical system determined by the determination device;
With the adjustment of the adjustment device, the measurement device is configured to move the other area with respect to the detection optical system in a state where another area different from the area of the test surface is located at the in-focus position stored in the storage device. The detection apparatus according to claim 19, wherein the focus state of the area is measured.   With the adjustment of the adjustment device, the mark formed in the region is placed in a state different from the in-focus position with respect to the detection optical system determined by the determination device. The detection device according to claim 19, further comprising an imaging device for imaging via the imaging device.   The mark formed in the region is imaged through the detection optical system in a state where the region is located at the in-focus position with respect to the detection optical system determined by the determination device by the adjustment of the adjustment device. The detection device according to claim 19 or 20, further comprising an imaging device. A detection device that detects a test surface of an object via a detection optical system,
A signal detection device that irradiates a measurement region near a partial region of the test surface of the object with a predetermined imaging light beam and detects a signal corresponding to a reflected light beam from the measurement region;
An estimation device that estimates at least one of a first signal that depends only on the surface shape of the measurement target region and a second signal that does not depend on the surface shape, included in the signal detected by the signal detection device;
And a calculation device that calculates a focus state of the measurement target region with respect to the detection optical system based on at least one of the estimated first signal and second signal. The signal detection device sends a signal corresponding to a reflected light beam obtained by irradiating the predetermined imaging light beam to a reference surface having a substantially uniform reflectance at a plurality of different focus positions with respect to the detection optical system. A storage device for storing the corresponding signal;
The estimation device selects a part of the plurality of signals stored in the storage device, and divides or subtracts the signal detected by the signal detection device by the selected signal, thereby obtaining the first signal. The detection apparatus according to claim 23, wherein one signal is estimated.   With the adjustment of the adjustment device, the mark formed in the region in the state where the region is located at the in-focus position with respect to the detection optical system determined based on the focus state obtained by the calculation device, The detection device according to claim 23 or 24, further comprising an imaging device for imaging through a detection optical system. An exposure apparatus for transferring a pattern to an object held on a moving body,
A detection device according to any one of claims 21, 22, 25;
A transfer device for transferring the pattern to the object while controlling the position of the object held by the moving body based on the position information of the mark on the moving body obtained from the detection result of the detecting device. Exposure device. In a device manufacturing method including a lithography process,
27. A device manufacturing method, wherein exposure is performed using the exposure apparatus according to claim 26 in the lithography process.

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