JP2010147249A - Optical characteristic measuring method, exposure condition determining method, exposure method, and device manufacturing method - Google Patents

Abstract

An optical characteristic of a projection optical system is accurately measured.
In step 417, based on the detection result of the formation state of the image of the measurement pattern formed in a plurality of regions on the wafer by the exposure processing in step 406, the optical property measurement for measuring the optical characteristics of the projection optical system is performed. An optimal dose amount for pattern exposure is temporarily determined. In step 424, the target dose amount is changed in a plurality of stages at a finer step pitch with the optimum dose amount as the center, and the pattern is exposed on the wafer via the projection optical system by the exposure process similar to step 406. Transferred to multiple areas. Accordingly, a part of the exposure condition for measuring the optical characteristics of the projection optical system is finely adjusted. Then, the optical characteristics of the projection optical system are obtained based on the detection result of the image formation state of the pattern formed in each region on the wafer by the exposure under the finely adjusted exposure condition (step 436). 438).
[Selection] Figure 4

Description

  The present invention relates to an optical property measurement method, an exposure condition determination method, an exposure method, and a device manufacturing method. More specifically, the present invention relates to an optical property measurement method for measuring optical properties of a projection optical system, and measures the optical properties of a projection optical system. The present invention relates to an exposure condition determination method for determining an exposure condition for preparing a sample to be performed, an exposure method using the optical characteristic measurement method, and a device manufacturing method using the exposure method.

  Semiconductor elements (integrated circuits) and the like have been highly integrated year by year, and accordingly, a projection apparatus such as a stepper, which is a manufacturing apparatus for semiconductor elements, has been required to have higher resolution. It is also important to improve the overlay accuracy of the pattern after the next layer with respect to the pattern already formed on the object to be exposed. For this purpose, it is necessary to improve the optical characteristics of the projection optical system, and as a premise, it is important to accurately measure and evaluate the optical characteristics (including imaging characteristics) of the projection optical system. Yes.

  Accurate measurement of the optical characteristics of the projection optical system, for example, the image plane of the pattern, is based on the premise that the best focus position at each evaluation point (measurement point) within the field of view of the projection optical system can be accurately measured.

  A so-called CD / focus method is typically known as a method for measuring the best focus position of a conventional projection optical system. In this method, a predetermined reticle pattern (for example, a line and space pattern) is used as a test pattern, and the test pattern is transferred to a test wafer at a plurality of positions in the optical axis direction of the projection optical system. Then, the line width value of the resist image (transferred pattern image) obtained by developing the test wafer is measured using a scanning electron microscope (SEM) or the like, and the line width value and the projection optical system The best focus position is calculated based on the relationship with the wafer position in the optical axis direction (hereinafter also referred to as “focus position” where appropriate).

  However, in the above-mentioned CD / focus method, for example, in order to measure the line width value of a resist image with an SEM, it is necessary to strictly focus the SEM, and the measurement time per point is very long. It took several hours to several tens of hours to make measurements at the time. For this reason, the throughput until the measurement result is obtained is greatly reduced. In addition to this, higher levels of measurement error and reproducibility of measurement results are required, and it has become difficult to cope with the conventional measurement methods.

  In addition, a resist image of a wedge-shaped mark is formed on a wafer at a plurality of focus positions as disclosed in Patent Document 1 and the like, and the length of the resist image in the longitudinal direction (using a mark detection system such as an alignment system) ( A so-called SMP focus measurement method is also known in which a change in the line width value of a resist image due to a difference in focus position is measured and the measurement result is used. However, in this SMP focus measurement method, since the measurement is usually performed with monochromatic light, the influence of interference differs depending on the difference in the shape of the resist image, which leads to a measurement error (dimension offset) and the current image capturing device. The resolution of (CCD camera etc.) is still not enough. Further, since the test pattern is large, it is difficult to increase the number of evaluation points.

  As a method for improving the disadvantages of the conventional measurement methods described above, the inventor has used a measurement system with a low resolution, for example, a measurement apparatus such as an imaging alignment sensor of an exposure apparatus, to improve the optical characteristics of the optical system with a high throughput. Has proposed a measurement method that can be measured by (see, for example, Patent Document 2).

  According to the measurement method described in Patent Document 2, optical characteristics are obtained based on detection results using objective and quantitative image contrast, the amount of reflected light such as diffracted light, and the like. In comparison, the optical characteristics can be measured with high accuracy and reproducibility. In addition, the number of evaluation points can be increased and the interval between the evaluation points can be narrowed. As a result, the measurement accuracy of optical characteristic measurement can be improved.

However, recently, the allowable value of the total overlay error is about several nanometers, and in order to realize this, the CD / focus method and the SMP focus are used as measurement methods for measuring the optical characteristics of the projection optical system. Regardless of the measurement method or the measurement method described in Patent Document 2, the exposure condition of the measurement pattern, for example, the energy dose (dose amount) per unit area given on the wafer is set with higher accuracy. There is a need. This is because, for example, the dose greatly affects the formation state of the image of the measurement pattern transferred and formed on the wafer.
U.S. Pat. No. 4,908,656 International Publication No. 02/091440 Pamphlet

  The present invention has been made under the circumstances described above. From the first viewpoint, the optical characteristic for measuring the optical characteristic of the projection optical system that projects the image of the pattern on the first surface onto the second surface. In the measurement method, a part of a plurality of exposure conditions including a position of the object with respect to an optical axis direction of the projection optical system and a setting value of an energy amount of an energy beam irradiated on the object are set to a predetermined first. The measurement pattern arranged on the first surface is changed to a plurality of regions on the object arranged on the second surface side of the projection optical system via the projection optical system while changing stepwise within the range. A first step of sequentially transferring; and detecting the formation state of the image of the measurement pattern in a plurality of regions on the object, and based on the detection result, the part for measuring optical characteristics of the projection optical system A second that temporarily determines at least a part of the exposure condition And changing the at least some of the exposure conditions in a plurality of stages within a second range narrower than the first range centered on the provisionally determined exposure conditions, and under each of a plurality of different exposure conditions. A third step of sequentially transferring the measurement pattern arranged on the first surface to a plurality of regions on the object arranged on the second surface side of the projection optical system via the projection optical system; A fourth step of detecting a formation state of the image of the measurement pattern in a plurality of regions on the object and obtaining an optical characteristic of the projection optical system based on the detection result; This is a measurement method.

  According to this, based on the detection result of the formation state of the image of the measurement pattern formed in the plurality of regions on the object by the exposure in the first step, the part for measuring the optical characteristics of the projection optical system At least a part of the exposure condition is provisionally determined (second step), and the at least part of the exposure condition is changed in a plurality of steps within a second range narrower than the first range centering on the provisionally determined exposure condition. The measurement pattern is sequentially transferred to a plurality of regions on the object via the projection optical system by exposure similar to the first step (third step). Accordingly, a part of the exposure conditions for measuring the optical characteristics of the projection optical system is finely adjusted, and the measurement pattern formed in a plurality of areas on the object by the exposure performed under the finely adjusted exposure conditions Based on the detection result of the image formation state, the optical characteristics of the projection optical system are obtained (fourth step). Accordingly, the optical characteristics of the projection optical system can be obtained with high accuracy.

  According to a second aspect of the present invention, there is provided an exposure condition determination method for determining an exposure condition for measuring an optical characteristic of a projection optical system that projects a pattern image on a first surface onto a second surface. , While gradually changing a part of a plurality of exposure conditions including the position of the object with respect to the optical axis direction of the projection optical system and the setting value of the energy amount of the energy beam irradiated on the object, A first step of sequentially transferring a first pattern arranged on one surface to a plurality of different areas on an object arranged on the second surface side of the projection optical system via the projection optical system; A plurality of regions on the object on which the image of the first pattern is formed by maintaining the condition and transferring the second pattern through the projection optical system so as to be superimposed on the image of the first pattern A part of the light is exposed through the projection optical system 2 steps; detecting the formation state of the image of the pattern formed in a plurality of regions on the object after the processing of the second step, and determining the exposure condition of the first pattern based on the detection result A third step; a fourth step of transferring the first pattern to a plurality of different regions on the object via the projection optical system according to the determined exposure condition; and changing the exposure condition, A portion of each of the plurality of regions on the object on which the first pattern image is formed is transferred onto the projection optical system by transferring the second pattern through the projection optical system so as to overlap the first pattern image. And a second step of detecting the formation state of the image of the pattern formed in a plurality of areas on the object after the processing of the fifth step, and based on the detection result Determine the exposure conditions An exposure condition determining method comprising: a sixth step and the.

  According to this, the exposure conditions for exposing a plurality of regions on the object using the first pattern are determined from the processing in the first to third steps, and the processing on the object is performed by the processing in the fourth to sixth steps. The exposure condition for transferring the second pattern via the projection optical system is determined by superimposing the first pattern image (latent image) formed on the plurality of regions under different exposure conditions. Accordingly, it is possible to determine the optimum exposure conditions for each of the first and second patterns when the measurement pattern is formed on the object by double exposure using the first pattern and the second pattern.

  According to a third aspect of the present invention, there is provided an optical property measurement method for measuring an optical property of a projection optical system that projects an image of a pattern on a first surface onto a second surface. Determining a first pattern exposure condition and a second pattern exposure condition by the method; and determining the first pattern arranged on the first surface according to the determined first pattern exposure condition. A first transfer step of sequentially transferring to a plurality of different areas on the object disposed on the second surface side of the projection optical system via the projection optical system; and the first transfer step according to the determined exposure condition of the second pattern A part of each of the plurality of regions on the object on which the first pattern image is formed is transferred to the projection optical system by transferring the second pattern through the projection optical system so as to overlap the image of one pattern. Second transfer worker exposing via And calculating the optical characteristics of the projection optical system based on the detection result of detecting the formation state of the pattern image formed in the plurality of regions on the object after the processing of the second transfer step. And a second optical property measuring method including:

  According to this, according to the exposure condition for each of the first and second patterns determined by the exposure condition determination method of the present invention, the second pattern is transferred via the projection optical system so as to be superimposed on the image of the first pattern. A part of each of the plurality of regions on the object on which the first pattern image is formed is exposed via the projection optical system. Thereby, for example, a pattern image from which a part of the first pattern is removed is formed in each of a plurality of regions on the object. Then, the optical characteristic of the projection optical system is calculated based on the detection result of the pattern image formation state formed in each of the plurality of regions on the object after the transfer of the second pattern. Therefore, even when it is difficult to accurately calculate the optical characteristics of the projection optical system based on the detection result of the image formation state of the first pattern, the optical characteristics of the projection optical system can be obtained with high precision. It becomes.

  From the fourth aspect, the present invention measures the optical characteristics of the projection optical system that projects the pattern image on the first surface onto the second surface by the first or second optical characteristic measurement method of the present invention. And adjusting at least one of the optical characteristics of the projection optical system and the position of the object with respect to the optical axis direction of the projection optical system in consideration of the measurement result of the optical characteristics; Projecting onto the object disposed on the second surface side through a system to expose the object.

  This makes it possible to form a pattern image on the object with high accuracy, that is, to expose the object with high accuracy.

  From a fifth aspect, the present invention is a device manufacturing method including a step of forming a pattern on an object using the exposure method of the present invention; and a step of processing the object on which the pattern is formed. .

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

  FIG. 1 shows a schematic configuration of an exposure apparatus 100 according to the first embodiment suitable for carrying out the optical characteristic measuring method of the present invention. The exposure apparatus 100 is a step-and-scan reduction projection exposure apparatus (a so-called scanning stepper (also referred to as a scanner)).

  The exposure apparatus 100 projects an image of the pattern formed on the illumination system IOP, the reticle stage RST holding the reticle R, and the reticle R onto the wafer W coated with a sensitive agent (here, a positive resist). A projection unit PU, a wafer stage WST that holds the wafer W and moves in the XY plane, a drive system 22 that drives the wafer stage WST, and a control system thereof are provided. The control system is mainly composed of a main controller 28 including a microcomputer (or a workstation) that performs overall control of the entire apparatus.

  The illumination system IOP includes, for example, a light source composed of an ArF excimer laser (output wavelength 193 nm) (or KrF excimer laser (output wavelength 248 nm)), and an illumination optical system connected to the light source via a light transmission optical system. . As an illumination optical system, as disclosed in, for example, US Patent Application Publication No. 2003/0025890, an illuminance uniformizing optical system including an optical integrator, a beam splitter, a reticle blind, and the like (all not shown) are used. Including. This illumination optical system shapes the laser beam emitted from the light source, and the shaped laser beam (hereinafter also referred to as illumination light) IL causes the X axis direction (the direction perpendicular to the paper surface in FIG. 1) on the reticle R. A slit-like illumination area that is elongated is illuminated with substantially uniform illuminance.

  Reticle stage RST is arranged below illumination system IOP in FIG. Reticle R is placed on reticle stage RST. The reticle R is sucked and held on the reticle stage RST via a vacuum chuck or the like (not shown). Reticle stage RST can be finely driven in a horizontal plane (XY plane) by a reticle stage drive system (not shown), and has a predetermined stroke in the scanning direction (here, the Y axis direction which is the horizontal direction in FIG. 1). Scanned in range. Position information of the reticle stage RST is measured by the laser interferometer 14 via the movable mirror 12 fixed to the end thereof, and the measurement value of the laser interferometer 14 is supplied to the main controller 28. Instead of the movable mirror 12, the end surface of the reticle stage RST may be mirror-finished to form a reflective surface (corresponding to the reflective surface of the movable mirror 12).

  Projection unit PU is arranged below reticle stage RST in FIG. The projection unit PU includes a lens barrel 40 and a plurality of optical elements held in a predetermined positional relationship within the lens barrel 40, and a pattern of a first surface (object surface) is formed on a second surface (imaging surface). Projection optical system PL for projecting onto the projector. Here, as the projection optical system PL, a bilateral telecentric reduction system is used, and a refractive optical system including a plurality of lens elements (not shown) arranged in a direction parallel to the optical axis AXp (Z-axis direction) is used. It has been. A plurality of specific lens elements are movable, and are controlled by an imaging characteristic correction controller (not shown) based on a command from the main controller 28, whereby the optical characteristics (imaging characteristics) of the projection optical system PL are controlled. Characteristics), for example, magnification, distortion, coma aberration, field curvature, and the like are adjusted.

  The projection magnification of the projection optical system PL is ¼ as an example. For this reason, when the reticle R is illuminated with uniform illumination by the illumination light IL as described above, the pattern of the reticle R in the illumination area is reduced by the projection optical system PL and projected onto the wafer W. A reduced image of the pattern is formed in a part of the exposed region (shot region). At this time, the projection optical system PL forms a reduced image in a part of its field of view (that is, an exposure area that is a slit-shaped area conjugate with the illumination area with respect to the projection optical system PL). Note that the imaging characteristic correction controller described above adjusts at least one optical element (lens) of the projection optical system PL in order to adjust the optical characteristics of the projection optical system PL, that is, the imaging state of the pattern image on the wafer W. However, instead of or in combination with it, the characteristics of the illumination light IL (for example, the center wavelength, spectrum width, etc.) can be changed by controlling the light source, and the optical axis of the projection optical system PL. At least one of movement of the wafer W in the Z-axis direction parallel to AXp (and inclination with respect to the XY plane) may be performed.

  Wafer stage WST is arranged below projection optical system PL (on the −Z side). Wafer stage WST is mounted on XY stage 20 that moves along an XY two-dimensional plane on a base plate (not shown), and a wafer that is mounted on XY stage 20 and holds wafer W by vacuum suction or the like via a wafer holder (not shown). Table 18 is included.

  The wafer table 18 finely drives the wafer holder holding the wafer W in the Z-axis direction and the tilt directions with respect to the XY plane (the rotation direction about the X axis (θx direction) and the rotation direction about the Y axis (θy direction)). , Also called Z-tilt stage. The moving mirror 24 of the wafer table 18 is irradiated with a laser beam (measurement beam) from the laser interferometer 26. Based on the reflected light from the moving mirror 24, position information of the wafer table 18 in the direction of 5 degrees of freedom, that is, the X axis, Y-axis, direction position information and rotation information (yawing (θz rotation which is rotation around the Z axis)), pitching (θx rotation which is rotation around the X axis), rolling (θy rotation which is rotation around the Y axis) Are measured). The end surface (side surface) of the wafer table 18 may be mirror-finished to form a reflecting surface (corresponding to the reflecting surface of the movable mirror 24).

  Further, the position of the surface of the wafer W in the Z-axis direction and the amount of inclination with respect to the XY plane are, for example, an oblique incidence method having a light transmission system 50a and a light reception system 50b disclosed in US Pat. It is measured by a focus sensor AFS comprising a multipoint focal position detection system. The measurement value of the focus sensor AFS is also supplied to the main controller 28.

  The measurement value of the laser interferometer 26 is supplied to the main controller 28, and the main controller 28 controls the XY stage 20 via the drive system 22 based on the measurement value of the laser interferometer 26, thereby XY of the wafer W. Controls the position in the plane (rotation in the θz direction). The main controller 28 controls the position of the wafer W in the Z-axis direction and the inclination with respect to the XY plane by controlling the wafer table 18 via the drive system 22 based on the measurement value of the focus sensor AFS.

  Further, a reference plate FP is fixed on the wafer table 18 so that the surface thereof is the same height as the surface of the wafer W. On the surface of the reference plate FP, a reference mark used for baseline measurement of the alignment system AS described below is formed.

  In the present embodiment, an off-axis alignment system AS is provided on the side surface of the projection optical system PL. The alignment system AS has at least two types of alignment sensors including two types of sensors called LSA (Laser Step Alignment) system and FIA (Field Image Alignment) system, and a reference mark and a wafer formed on the reference plate FP. Using the alignment mark formed on W as a detection target, position information in the two-dimensional direction (X-axis direction and Y-axis direction) of the detection target mark is measured.

  Here, the LSA system is a sensor that irradiates a mark with laser light and measures the mark position using the diffracted / scattered light, and the FIA system is marked with broadband light such as a halogen lamp. Is a sensor that measures the mark position by performing image processing on the mark image. For example, the alignment system AS irradiates a target mark with coherent detection light, and detects an alignment sensor that interferes with diffracted light generated from the target mark together with (or instead of) the LSA system and the FIA system. You may have.

  In the present embodiment, the above-described plural types of alignment sensors are properly used according to the purpose, and fine alignment measurement or the like for accurately measuring the position of the shot area on the wafer is performed.

  The alignment control device 16 performs A / D conversion on the output signal DS from each alignment sensor constituting the alignment system AS, performs arithmetic processing on the converted signal, and detects a mark position. The detection result is supplied from the alignment controller 16 to the main controller 28.

  Further, in the exposure apparatus 100 of this embodiment, although not shown, light having an exposure wavelength disclosed in, for example, US Pat. No. 5,646,413 is used above the reticle R. A pair of reticle alignment detection systems of the TTR (Through The Reticle) system is provided, and detection signals of the reticle alignment detection system are supplied to the main controller 28 via the alignment controller 16.

In the present embodiment, two reticles R _TH and R _TV are used to measure the optical characteristics of the projection optical system PL. FIG. 2 shows one of the reticles R _TH . FIG. 2 is a plan view of reticle _RTH viewed from the pattern surface side (lower surface side in FIG. 1). As shown in FIG. 2, the reticle R _TH is composed of a rectangular (exactly square) glass substrate 42, and a substantially rectangular pattern area PA defined by a light shielding band (not shown) is formed on the pattern surface. In this example (example in FIG. 2), almost the entire pattern area PA is a light shielding portion by a light shielding member such as chromium. Center (center of the reticle R _TH here (matching reticle center)) of the pattern area PA, and centered on the reticle center, and the rectangular area IAR '4 corners of the portion of the interior of the virtual to the X-axis direction is the longitudinal direction a total of five points, a predetermined width, for example, a side opening pattern (transparent regions) AP ₁ ~AP ₅ square 27μm is formed, measurement patterns to the aperture pattern AP ₁ ~AP ₅ (hereinafter, as appropriate, the pattern substantially to predicate) MP _H1 to MP _H5 are formed. The rectangular area IAR ′ has a size and a shape that substantially match the above-described illumination area. In this example, almost the entire pattern area PA is used as the light shielding part, but the pattern area PA may be used as the light transmitting part. In this case, both ends in the X-axis direction of the rectangular area IAR ′ are defined by the above-described light-shielding bands. Therefore, light-shielding portions having a predetermined width (for example, the same width as the light-shielding band) may be provided at both ends in the Y-axis direction. .

Each of the patterns MP _Hn (n = 1 to 5) has, for example, a predetermined line width, for example, 0.6 μm, and a predetermined length, for example, three (or five) line patterns of about 9 μm have a predetermined pitch, For example, it is constituted by a multi-bar pattern arranged in the X-axis direction at 2.0 μm. Hereinafter, the pattern MP _Hn is also referred to as an H line pattern for convenience.

  A pair of reticle alignment marks RM1 and RM2 are formed on both sides in the X-axis direction of the pattern area PA passing through the reticle center (see FIG. 2).

FIG. 3 shows another reticle R _TV . FIG. 3 is a plan view of reticle R _TV viewed from the pattern surface side (lower surface side in FIG. 1). As shown in FIG. 3, the reticle R _TV has a glass substrate 42 similar to the above-described reticle R _TH and has the same pattern area PA defined by a light shielding band (not shown) on its pattern surface. A pattern area PA ′ having a shape and size is formed, and almost the entire pattern area PA ′ is a light-shielding portion. However, in this example, measurement patterns (hereinafter abbreviated as patterns as appropriate) MP _V1 to MP _V5 are formed inside the opening patterns AP _{1 to} AP ₅ , respectively. Each of the patterns MP _{V1 to} MP _V5 is configured by a _multibar pattern similar to the pattern MP _Hn except that the arrangement direction (periodic direction) is the Y-axis direction. Hereinafter, the pattern MP _Vn is also referred to as a V-line pattern for convenience. Note that the entire surface of the pattern area PA ′ may be a light transmission portion.

Next, with respect to the method for measuring the optical characteristics of the projection optical system PL in the exposure apparatus 100 of the present embodiment, along with the flowchart of FIG. This will be described with reference to the drawings. In the following, for convenience of explanation, the term “measurement pattern (or pattern) MP _n ” is used, and unless otherwise specified, this means the pattern MP _Hn when the reticle R _TH is being used, and the reticle R _{When the TV} is in use, the pattern MP _Vn is meant. In addition, as an initial setting, it is assumed that a flag F, which will be described later, is turned off (F = 0).

First, in step 402 in FIG. 4, wafer exchange is performed. Specifically, after unloading the wafer from the wafer table 18 via a wafer unloader (not shown), the wafer W _T (see FIG. 5) is loaded onto the wafer table 18 via a wafer loader (not shown). It should be noted that, when there is no wafer on the wafer table 18 performs only the loading of the wafer W _T.

  Next, in step 404, predetermined preparatory work such as reticle replacement and alignment of the reticle with respect to the projection optical system PL is performed.

Specifically, replacing the reticle and the 1st reticle R _TH on the reticle stage RST via a reticle exchange mechanism (not shown). When there is no reticle on the reticle stage RST, simply loads the reticle R _TH.

Next, a pair of reference marks (not shown) on the reference plate FP provided on the wafer table 18 and a reticle on the reticle stage RST (in this case, reticle R _TH ) by the above-described reticle alignment detection system (not shown). The reticle stage RST and wafer stage WST are moved based on the measurement values of the laser interferometers 14 and 26, respectively, so that the pair of reticle alignment marks RM1 and RM2 are detected. Then, the position (including rotation) of reticle stage RST in the XY plane is adjusted based on the detection result of the above-described reticle alignment detection system. As a result, the rectangular area IAR ′ of the reticle in use (in this case, reticle R _TH ) is set in the illumination area, and the entire surface is irradiated with the illumination light IL. The position where the field of view (especially exposure area) the projected image of measurement pattern MP _n in the present embodiment via the projection optical system PL (pattern image) is generated, in a exposure area of the projection optical system PL This is an evaluation point for measuring the optical characteristic (for example, focus). Although the number of evaluation points is actually more than five, in this embodiment, for the sake of convenience of explanation, it is assumed that a total of five evaluation points are set for the center and four corners of the exposure area described above. Yes. However, the number of evaluation points (measurement pattern MP _n ) may be at least one.

  When the predetermined preparation work is completed in this way, the process proceeds to the next step 406 (exposure processing subroutine).

In this subroutine, first, as shown in FIG. 7, in step 502, the amount per unit area of illumination light IL irradiated on wafer W _T (exposure), ie, the target value of the dose (target dose referred to as) to initialize the _{P j.} That is, the initial value “1” is set to the counter j, and the target dose amount P _j is set to P ₁ (j ← 1). In the present embodiment, the counter j, together with the setting of the target dose, also used to set the movement target position in the row direction of the wafer W _T during exposure. In the present embodiment, about the optimum dose expected from the sensitivity characteristics of the example wafer W _T coated sensitive agent on the (resist), a target dose, as P _{N (an} example from P _1, N Change in increments of ΔP (P _j = P _{1 to} P ₂₃ ).

In the next step 504, the target value of the focus position of the wafer W _T (Z-axis direction position) (hereinafter, referred to as a target focus position) to initialize the Z _i. That is, by setting the initial value "1" to the counter i sets the target focus position Z _i of the wafer W _T to Z ₁ (i ← 1). In the present embodiment, the counter i, together with the setting of the target focus position of the wafer W _T, is also used to set the movement target position in the column direction of the wafer W _T during exposure. In this embodiment, for example, around the best known focus position for the projection optical system PL (including design value), and M = 13 the target focus position of the wafer W _T as Z _M (an example in ΔZ increments from Z ₁ (Z _i = Z _{1 to} Z ₁₃ ).

Accordingly, in the present embodiment, while changing the position and the dose of illumination light IL irradiated on wafer W _T of the wafer W _T to an optical axis of the projection optical system PL respectively, patterns MP _{n (n} = 1 for sequentially transferring 5) on the wafer _{W T,} so that the exposure of the 13 × 23 = 299) times as M × N (an example is performed. The projection optical system PL wafer W _T on a region (hereinafter referred to as "evaluation point corresponding region") DB ₁ to DB ₅ corresponding to each evaluation point in the visual field (see FIG. 5 and FIG. 6) is, M × N number The pattern MP _n is transferred.

The evaluation point corresponding area DB _n corresponds to a plurality of evaluation points whose optical characteristics are to be detected within the field of view of the projection optical system PL.

Here, description will be back and forth, for convenience, the exposure that will be described later, for each evaluation point corresponding area DB _n on wafer W _T that pattern MP _n is transferred will be described with reference to FIG. As shown in FIG. 6, in this embodiment, M × N (= 13 × 23 = 299) virtual partition areas DA _i arranged in a matrix of M rows and N columns (13 rows and 23 columns). _{, J} (i = 1 to M, j = 1 to N), the pattern MP _n is transferred respectively _, and the evaluation point corresponding area composed of M × N partition areas DA _{i, j} to which these patterns MP _n are transferred respectively. DB _n are formed on the wafer _{W T.} The virtual partition areas DA _{i, j} are arranged so that the + X direction is the row direction (increase direction of j) and the + Y direction is the column direction (increase direction of i), as shown in FIG. ing. Further, the subscripts i and j and M and N used in the following description have the same meaning as described above.

Returning to FIG. 4, in the next step 506, by moving the XY stage 20 via drive system 22 while monitoring the measurement values of laser interferometer 26, each evaluation point on wafer W _T corresponding area DB _n virtual (here _{DA 1, 1} (see FIG. 5)) of the divided area _{DA i, j} image of measurement pattern MP _n in is in a position to be transferred respectively to position the wafer _{W T.}

In the next step 508, the wafer table 18 while monitoring the measurement values from the focus sensor AFS and finely driven in the Z-axis direction and the tilt direction, the wafer W _T in the Z-axis direction position target focus position Z that is set to Set to _i (Z _{1 in} this case).

In the next step 510, exposure is performed. At this time, the target dose which dose is set on the wafer W _T such that (in this case P _1), performs the exposure control. The dose amount can be adjusted by changing at least one of the pulse energy amount of the illumination light IL and the number of pulses of the illumination light IL irradiated onto the wafer during exposure. Thus, as shown in FIG. 5, the image of the wafer W _T on each measurement pattern MP n the divided area DA _{1, 1} of each evaluation point corresponding area DB _{n (in} this case the pattern MP _Hn) is transferred .

In the next step 512, check the target focus position of the wafer W _T (count value of the counter i), the exposure of the predetermined range (namely from the target focus position Z ₁ Z _M) to determine whether the finished . Here, since only the exposure of the first target focus position Z ₁ is completed, the process proceeds to step 514, the counter i is incremented by one with (i ← i + 1), the ΔZ to the target value of the focus position of the wafer W _T Add (Z _i ← Z _{i + 1} = Z _i + ΔZ). Here, after changing the target value of the focus position to Z ₂ (= Z ₁ + ΔZ), the process returns to Step 506. Then, the processing (including judgment) in steps 506, 508, 510, 512, and 514 is repeated until the judgment in step 512 is affirmed. Here, in step 506, for each repetition, by moving the XY stage 20 in a predetermined step pitch predetermined direction in the XY plane (in this case the -Y direction), sequentially, each evaluation point corresponding area on wafer W _T the image of the measurement pattern MP _n the divided area DA _{i, 1} of the DB _n positions the wafer W _T to a position to be transferred respectively. Then, in step 508, the wafer WT is positioned at the target focus position Z _i , and in step 510, the measurement pattern MP is set in the partition area DA _{i, 1} of each evaluation point corresponding area DB _n on the wafer WT in the same manner as before. Transfer each image of _n . Thus, the wafer _W divided areas of each evaluation point corresponding area DB _n on _{T DA i, 1 (i =} 1~M) in measurement pattern MP _n (in this case the pattern MP _Hn) are transferred respectively.

On the other hand, when the exposure to the partition area DAM _{, 1} is completed and the determination in step 512 is affirmed, the process proceeds to step 516, where the target dose (count value of the counter j) is confirmed, and a predetermined range (ie, exposing the target dose P ₁ for P _N) of determining whether or not it is completed. Here, since the target dose amount set at that time is P ₁ , the determination in this step 516 is denied, and the routine proceeds to step 518.

In step 518, the counter j is incremented by one (j ← j + 1) with, you add the [Delta] P to the target dose _{P j (P j ← P j} + 1 = P j + ΔP). Here, after changing the target dose amount to P ₂ (= P ₁ + ΔP), the process returns to Step 504. Then, until the determination in step 516 is affirmed, the processing (including determination) of steps 504, (506, 508, 510, 512, 514), 516, 518 is repeated. Thus, all of the divided areas DA _i of each evaluation point corresponding area DB _n on wafer _{W T, j (i = 1~M} , j = 1~N) in measurement pattern MP _n (in this case, the pattern _{MP Hn} ) Image is transferred.

In this way, when the exposure for the target dose amount (P _{1 to} P _N ) within a predetermined range is completed, the determination in step 516 is affirmed, the processing of this subroutine is terminated, and FIG. 4 (main routine) is completed. The process proceeds to step 408 (returns). The process of step 406, as shown in FIG. 5, each evaluation point corresponding area DB _n on wafer _{W T,} exposure conditions (23 × 13 = 299 as an example) different N × M pieces of the pattern for measurement A transfer image (latent image) of MP _n (in this case, pattern MP _Hn ) is formed. In practice, as described above, pieces of divided areas (13 × 23 = 299 as an example) M × N to transfer image (latent image) is formed of a measurement pattern MP _n on wafer W _T is in the formed step, but than the evaluation point corresponding area DB _n are formed, if in the above description, for ease of explanation, evaluation point corresponding area DB _n is on the advance wafer W _T Such an explanation method is adopted.

In step 408, the wafer W _T, after unloaded from above the wafer table 18 via a wafer unloader (not shown), is transported to the coater developer (not shown) via the wafer transfer system (not shown). Here, the coater / developer (not shown) is connected to the exposure apparatus 100 in-line.

After transfer of the wafer W _T to the above coater developer, development of wafer W _T waits for the end proceeds to step 410. During the waiting time in step 410, development of the wafer W _T is performed by the coater developer. By the end of this development, wafer on wafer W _T, the resist image of evaluation points of the rectangular corresponding area DB _{n (n} = 1~5) as shown in FIG 5 is formed, the resist image is formed W _T is the sample for temporarily determining the optimum dose and the like at step 417 to be described later.

In the wait state of step 410, when confirming that the development of wafer W _T is completed by a notice from the control system of the coater developer (not shown), the process proceeds to step 412.

In step 412, instructs the wafer loader (not shown), similar to step 402 described above to load the developed wafer W _T on the wafer table 18.

In the next step 414, using the developed wafer W _T, in order to obtain basic data that can be used to determine the optimal dose, it performs predetermined image processing.

Specifically, the main controller 20, for each evaluation point corresponding areas _DB 1 to DB ₅ on wafer _{W T,} following a. ~ D. Perform the process.
a. First, the main controller 28, a resist image of evaluation point corresponding area DB _n on wafer W _T, and imaged using the alignment system AS (FIA system sensors of), it captures the captured data. The alignment system AS divides the resist image into pixel units of the image sensor (CCD or the like) and supplies the density of the resist image corresponding to each pixel to the main controller 28 as 8-bit digital data (pixel data), for example. That is, the imaging data is composed of a plurality of pixel data. In this case, it is assumed that the pixel data value increases as the density of the resist image increases (closer to black). In this case, the alignment system AS (the FIA sensor) can simultaneously (collectively) image an area including the N × M partition areas DA _{i, j} in the evaluation point corresponding area DB _n. To do.
b. Then, the main controller 28, for example, JP-A 2004-146702, JP-U.S. Patent by the methods disclosed in, for example, Application Publication No. 2004/0179190 Pat, evaluation point corresponding area DB _n by image processing the imaging data Detect the outer edge of.

c. Next, the main control device 28 uses the number M in the vertical direction and the number N in the horizontal direction of the known partition regions, using the outer edge of the evaluation point corresponding region DB _n detected above, that is, the inside of the rectangular frame line, By dividing equally, the divided areas DA _{1,1 to} DAM _{, N} are obtained. That is, each partition area DA _{i, j} (position information) is obtained using the outer edge as a reference.

d. Next, the main controller 28 calculates light and dark information for each resist image formed in each partition area DA _{i, j} (i = 1 to M, j = 1 to N), for example, contrast value E _{i, j} , The calculation result is stored in the memory. Here, the contrast value E _{i, j} is given by, for example, the variance (or standard deviation) of pixel data. Alternatively, the contrast value E _{i, j} may be given as E _{i, j} = (L _MAX −L _MIN ) / (L _MAX + L _MIN ) from the maximum L _MAX and the minimum L _MIN of the pixel data values.

When the above-described image processing is completed, the process proceeds to the next step 416, and it is determined whether or not the processing using the reticle R _TV has been completed. In this case, since the process using the reticle R _TV has not been performed yet, the determination in step 416 is denied and the process returns to step 402.

In step 402, the wafer is changed in the same manner as described above, and then in step 404, the reticle is changed. At this time, reticle R _TV is loaded on reticle stage RST instead of reticle R _TH . Further, preparatory work such as alignment of the reticle R _TV after the replacement with respect to the projection optical system PL is performed.

Thereafter, the processing using the reticle R _TV (the processing in steps 406 to 414) is performed in the same manner as described above.

In step 416, the main controller 28 determines again whether or not the processing using the reticle R _TV has been completed. In this case, since the process using the reticle R _TV has been completed, the determination here is affirmed and the routine proceeds to step 417.

In step 417, the following e. ~ G. According to the procedure, the optimal dose amount and the best focus position are provisionally determined.
e. First, for each evaluation point corresponding area DB _n , the main controller 28 calculates the contrast value E of each divided area DA _{i, j} calculated for each dose amount P _j and each type of measurement pattern (H line, V line). _{i, j} is plotted against the focus position Z _i as shown in FIG.

As can be seen from FIG. 8, the contrast value E _{i, j} is lower (higher) as the dose _Pj is higher (lower). Here, the contrast curve connecting the plot points with respect to the dose amount P _j within the optimum range (Opt. Dose) shows an ideal profile, that is, a mountain-shaped (convex) profile. Further, the optimum range (Opt. Dose) higher dose _{P j} (a dose _{P j} in the region Over Dose), the contrast curve indicates the profile of the mountain shape, the effective data is less. Further, the optimum range (dose _{P j} in the region Under Dose) low dose _{P j} from (Opt. Dose), the lower the dose _{P j,} collapsed peak profile of the contrast curve, there is a dose _{P j} When the value is lower than the value, a valley-shaped (concave) profile is shown.
f. Next, for each evaluation point corresponding area DB _n , the main control device 28 sets the contrast curve and / or each divided area DA _{i, j} (for each dose amount P _j and each type of measurement pattern (H line, V line)). The optimal dose amount P _optn is obtained using the data of the contrast value E _{i, j} of the resist image formed at i = 1 to M, j = j). Here, the optimum dose amount is a dose amount at which the contrast curve shows an ideal profile. Therefore, the main controller 28 gives, for example, an approximation function describing an ideal profile, performs least square fitting of the data of each contrast value E _{i, j} , and each contrast value from the curve (approximation function) after the fitting. The dose amount that minimizes the deviation of E _{i, j} is defined as the optimum dose amount P _optn . In addition, the main control device 28 determines the astigmatism (contrast for each of the V-line pattern and the H-line pattern, for example, when the deviation between the contrast curves for a plurality of doses is approximately the same. The dose amount P _j that minimizes the difference between the best focus positions obtained from the curve is the optimum dose amount P _optn .

g. Next, the main control device 28 uses, for example, a temporary optimum dose amount P _opt having a central size among the optimum dose amounts P _{opt1 to} P _opt5 obtained for the evaluation point corresponding regions DB _{1 to} DB ₅ . Obtain (temporarily determine the optimal dose amount P _opt ) and store it in the memory. Further, main controller 28 _{obtains a} temporary best focus position from the contrast data corresponding to the temporary optimal dose amount P _opt (temporarily determines the best focus position) and stores it in the memory.

After the optimum dose amount P _opt and the best focus position are tentatively determined in this way, the process proceeds to step 418.

  In step 418, the wafer is exchanged in the same manner as in the above-described step 402, and then the process proceeds to the next step 420, where it is determined whether or not the above-described flag F is in a state where the flag F is cleared (F = 0). In this case, since the flag F is set to 0 in the initial setting, the determination here is affirmed and the routine proceeds to step 424.

In step 424, the exposure process is performed in the same procedure as in step 406 described above. Thus, the reticle _{R TV} pattern _{PM Vn} is transferred onto the wafer _{W T,} an evaluation point corresponding areas _DB 1 to DB ₅ is formed on the wafer _{W T.} The detailed description of step 424 is omitted from the viewpoint of avoiding redundant description. However, in this step 424, the main controller 28 makes a dose pitch ΔP within a predetermined range centered on the previously determined provisional optimum dose amount P _opt (a range narrower than the previous range of P _{1 to} P _N ). Is set narrower than before, and the target dose is changed in N stages. In this case, it is desirable to change the target dose within the optimum range (Opt. Dose) shown in FIG. In step 424, the main controller 28 sets the focus pitch ΔZ within a predetermined range centered on the previously determined temporary best focus position (a range narrower than the previous range of Z _{1 to} Z _N ). The target focus position is changed in M steps by setting it narrower than before.

  Next, in steps 426 to 432, the same processing (including determination) as the above-described steps 408 to 414 is performed, and then the process proceeds to step 434.

In step 434, it is determined whether or not the processing using reticle R _TH has been completed. In this case, since the process using the reticle R _TH has not been performed yet, the determination in this step 434 is denied, the process proceeds to step 435, the flag F is set (F ← 1), and the process returns to step 418.

  In step 418, the wafer is exchanged in the same manner as described above.

  In the next step 420, it is determined again whether or not the flag F is lowered. In this case, since the flag F is set (F = 1), the process proceeds to step 422.

In step 422, reticle exchange is performed as in step 404. Here, instead of reticle R _TV , reticle R _TH is loaded onto reticle stage RST. Also, preparatory work such as alignment of the reticle _RTH after the replacement with respect to the projection optical system PL is performed.

In step 424, the exposure process is performed according to the above-described procedure. Thus, the pattern _{PM Hn} of the reticle _{R TH} is transferred onto the wafer _{W T,} an evaluation point corresponding areas _DB 1 to DB ₅ is formed on the wafer _{W T.}

  Next, in steps 426 to 432, the same processing (including determination) as the above-described steps 408 to 414 is performed, and then the process proceeds to step 434.

In step 434, it is determined whether or not the processing using reticle R _TH has been completed. In this case, since the process using the reticle R _TH is being performed, the determination in step 434 is affirmed, and the process proceeds to step 436.

At this point, more contrast data (contrast curve) for each dose amount is obtained within the optimum range (Opt. Dose) shown in FIG. Therefore, in step 436, the optimal dose amount P _opt is determined using the contrast data (contrast curve) in the same procedure as in step 417.

In the next step 438, the optical characteristic of the projection optical system PL, for example, the best focus position is calculated. Specifically, the main control device 28, for example, based on the contrast data (contrast curve) of each evaluation point corresponding region DB _n corresponding to the optimum dose amount P _opt determined in step 436, for example, the peak center of the contrast curve Thus, the best focus position is obtained for each evaluation point corresponding region DB _{n for} each of the H pattern and the V pattern. Next, main controller 28 calculates the average value of the best focus positions obtained for each of the H pattern and V pattern for each evaluation point corresponding area DB _n , and the best focus position at each evaluation point in the field of view of projection optical system PL. Calculate as Further, main controller 28 calculates the average value (or weighted average value) of the best focus positions at the evaluation points corresponding to evaluation point corresponding areas DB _{1 to} DB ₅ as the best focus position Z _best of projection optical system PL. .

Further, main controller 28 calculates the image plane shape based on the best focus position at each evaluation point within the field of view of projection optical system PL. Further, the main controller 28 evaluates the evaluation points corresponding to the evaluation point corresponding regions DB _{1 to} DB ₅ based on the difference in the best focus position obtained for each of the H pattern and the V pattern for each evaluation point corresponding region DB _n. Astigmatism at may be calculated.

  In place of step 438, the processing in steps 402 to 416 or steps 418 to 434 described above is performed again with the target dose amount fixed at the optimum dose amount determined in step 436, and contrast data (contrast data) (Curve) may be obtained, and based on the obtained contrast data, a step of obtaining optical characteristics of the projection optical system PL in the same procedure as described above may be provided.

  The main control device 28 corrects the optical characteristics of the projection optical system PL obtained as described above, through the imaging characteristic correction controller (not shown), and the optical characteristics (including the imaging characteristics) of the projection optical system PL. Adjust. Then, main controller 28 transfers the pattern formed on reticle R onto wafer W through projection optical system PL with adjusted optical characteristics. Further, the main control device 28 effectively suppresses the occurrence of color unevenness due to defocusing by performing focus control of the wafer W with reference to the best focus position using the focus sensor AFS during exposure. be able to. This makes it possible to transfer a fine pattern onto the wafer with high accuracy. The main controller 28 may calibrate the focus sensor with the best focus position as a reference prior to exposure.

As described above, according to this embodiment, in step 417, the exposure processing of step 406 by (step 502-518) the evaluation point corresponding area DB _n on wafer _{W T} M × N number of divided areas _{DA i,} Based on the detection result of the image formation state of the measurement pattern MP _n formed on _j , the optimum exposure dose (and the best focus position) using the measurement pattern MP _n for measuring the optical characteristics of the projection optical system PL ) Is temporarily determined.

Then, by the exposure processing in step 424, the target dose amount (and target focus position) is changed in a plurality of steps at a finer step pitch with the optimum dose amount (and best focus position) temporarily determined as a center. measurement patterns MP _n the same exposure and the exposure processing is sequentially transferred to the M × n region evaluation point corresponding area DB _n on wafer W _T via the projection optical system PL. Accordingly, a part of the exposure condition for measuring the optical characteristics of the projection optical system PL is finely adjusted.

Then, based on the detection result of the formation state of the fine-tuned image of the wafer W _T measurement pattern MP _n formed in each divided area on the exposure performed under the exposure condition, the projection optical system PL Are obtained (steps 436 and 438). Accordingly, the optical characteristics of the projection optical system can be obtained with high accuracy.

Further, according to the exposure apparatus 100 of the present embodiment, the optical characteristics of the projection optical system PL are accurately measured by the optical characteristic measurement method described above, and the optical characteristics of the projection optical system PL are taken into consideration in consideration of the measurement results of the optical characteristics. And the pattern formed on the reticle R is transferred onto the wafer W via the projection optical system PL whose optical characteristics are adjusted. At the time of exposure, focus control of the wafer W is performed using the focus sensor AFS with the best focus position as a reference. This
It becomes possible to transfer the fine pattern onto the wafer with high accuracy.

  In the above embodiment, contrast data (contrast curve) is obtained for each of the H-line pattern and the V-line pattern, and the optimal dose or the optical characteristics of the projection optical system is obtained based on the contrast data (contrast curve). However, the present invention is not limited to this, and contrast data (contrast curve) is obtained for one of the H-line pattern and V-line pattern, and an optimal dose or projection is performed based on the contrast data (contrast curve). The optical characteristics of the optical system may be calculated.

  In the above embodiment, the case where the H line pattern and the V line pattern are transferred onto separate wafers using two reticles each provided with the H line pattern and the V line pattern has been described. The present invention is not limited to this, and the H line pattern and the V line pattern may be transferred onto the same or different wafers using a single reticle provided with the H line pattern and the V line pattern.

Further, in the above embodiment, in order to obtain an ideal profile, when the above-mentioned least square fitting does not provide a sufficient approximate curve of the fitting degree, a lower-order approximation function is used to obtain the aforementioned least square. An approximate curve representing an ideal profile may be obtained by fitting. Similarly, from the viewpoint, the order of the approximation function (function for describing an ideal profile) for performing least square fitting of the data of the contrast value E _{i, j} may be different between Step 417 and Step 436. In this case, in step 436, it is desirable to perform least square fitting of the data of the contrast value E _{i, j} using a lower order approximation function. In addition, if a trapezoidal profile can be obtained by least square fitting, adjust the parameter for separating effective data and invalid data for least square fitting so that more data is valid. Also good.

In the above embodiment, the best focus position, field curvature, or astigmatism is obtained as the optical characteristics of the projection optical system. However, the optical characteristics are not limited to these, and other aberrations may be used. In the above embodiment, the surface of the wafer W _T by a positive resist was assumed that sensitive layer is formed, this is not limited, it may be formed sensitive layer by a negative resist.

  By the way, for example, when a line and space pattern (L / S pattern) having a width ratio (duty ratio) between the line portion and the space portion of 1 is adopted as the measurement pattern, the projection optical system is provided on the wafer. When the line width of the projected image (more precisely, the larger of the width of the line portion and the width of the space portion) is less than or equal to the resolution limit of the FIA sensor of the alignment system AS, It is known that a non-existent frame line appears around the pattern and causes measurement errors. In order to improve such inconvenience, an L / S pattern image (latent image) is formed by projecting an L / S pattern onto a wafer coated with a positive resist via a projection optical system in the first exposure. Thereafter, a second exposure (trim exposure) is performed to remove a part of the latent image, and as a result, a latent image having a pattern similar to an isolated line pattern having a duty ratio of 1/3 or less is obtained. A pattern image for measurement (resist image) formed on a wafer and developed to develop the wafer (however, this pattern image for measurement has the same characteristics (line width, etc.) as the image of the L / S pattern) The inventors previously proposed a method for measuring the optical characteristics of the projection optical system using the measurement pattern image (International Publication No. 2008/132799 and published US patent application corresponding thereto) 2008/0259353 Reference herein). By adopting trim exposure, after the development of the wafer, an image obtained by superimposing the image of FIG. 14A and the image of FIG. 14B, in other words, the image of FIG. 14A. And a resist image having a cross-sectional shape shown in FIG. 14C, which is a common part of the image of FIG. 14B.

  However, recently, it is necessary to set the exposure conditions for the above-described trim exposure, for example, the dose amount with higher accuracy. The second embodiment to be described next has been made in view of this point.

<< Second Embodiment >>
Next, 2nd Embodiment of this invention is described based on FIG. 9 (A)-FIG. 14 (C). The exposure apparatus according to the second embodiment is the same as that described above except that the processing algorithm of the main controller 28 in measuring the optical characteristics of the projection optical system is different from that of the first embodiment. The configuration is the same as that of the first embodiment and functions in the same manner. Therefore, in the following, from the viewpoint of avoiding redundant description, the description will be focused on the differences. For the same purpose, the same reference numerals are used for the same or equivalent components.

In the second embodiment, two reticles R1 and R2 are used to measure the optical characteristics of the projection optical system PL. Reticles R1, R2 are, basically, the preceding reticle _{R TH,} are configured similarly to the _{R TV,} each opening pattern (transparent regions) measurement pattern disposed inside AP ₁ ~AP ₅ different . Specifically, a measurement pattern (hereinafter referred to as a pattern as appropriate) having an L / S pattern as shown in FIG. 9A is provided in each opening pattern AP _n (n = 1 to 5) of the reticle R1. MP1 _n is arranged, and a measurement pattern (hereinafter referred to as a pattern as appropriate) having two line patterns as shown in FIG. 9B is provided inside each opening pattern AP _n of the reticle R2. MP2 _n is arranged.

The measurement pattern MP1 _n has a predetermined line width, for example, 0.6 μm, and a multi-line pattern in which eight line patterns having a predetermined length, for example, about 9 μm are arranged in the X-axis direction at a predetermined pitch, for example, 1.2 μm. It is composed of a bar pattern. The measurement pattern MP2 _n has a predetermined line width, for example, 1.2 μm, and two line patterns having a predetermined length, for example, about 9 μm, are arranged in parallel with a predetermined interval, for example, 4.8 μm. Pattern. The centers of the measurement patterns MP1 _n and MP2 _n coincide with the center of the opening pattern AP _n .

  Next, the optical characteristic measuring method according to the second embodiment will be described along the flowchart of FIG. 10 showing a simplified processing algorithm of the CPU in the main controller 28 and using other drawings as appropriate. In the second embodiment, the flag F1 is used for switching between a first exposure process and a second exposure process, which will be described later, and for switching between a third exposure process and a fourth exposure process. In the initial setting, the flag F1 is lowered (F1 = 0).

First, in step 602 in FIG. 10, wafer exchange is performed in the same manner as in step 402 described above. In this case, the sensitive layer on the surface by a positive type photoresist wafer W _T that has been formed is loaded on the wafer table 18.

  Next, in step 604, predetermined preparatory work such as reticle replacement and alignment of the reticle with respect to the projection optical system PL is performed. At this time, reticle R1 is loaded onto reticle stage RST. Further, as the preparation work, the same work as the above-described step 404 is performed.

In the next step 606, it is determined whether or not the flag F1 is lowered (F1 = 0). In this case, since F1 = 0 in the initial setting, the determination here is affirmed, and the routine proceeds to step 608 (first exposure processing subroutine). In this subroutine, main controller 28 performs the same processing as step 406 described above (steps 502 to 518 in FIG. 7). Accordingly, on wafer _{W T,} exposure conditions of different measurement patterns MP1 _n (13 × 23 = 299 as an example) M × N to transfer image (latent image) is formed of a number of divided areas, 5 Two evaluation point corresponding regions DB _{1 to} DB ₅ are formed (see FIG. 5).

  In the next step 612, it is determined whether or not the flag F1 is set (F1 = 1). In this case, since F1 = 0 in the initial setting, the determination here is denied, and the flag F1 is set in step 614 (F1 ← 1), and the process returns to step 604.

  In step 604, reticle exchange is performed. At this time, reticle R2 is loaded on reticle stage RST instead of reticle R1. Further, predetermined preparation work such as alignment of the reticle with respect to the projection optical system PL is performed.

  In the next step 606, it is determined whether or not F1 = 0. In this case, since F1 = 1, the determination here is denied, and the process proceeds to step 610 (second exposure processing subroutine).

In this subroutine, the main controller 28 performs processing according to the processing algorithm shown in the flowchart of FIG. That is, in this subroutine, the processing according to the procedure of step 702 to 718 is performed, the partitioned regions DA _i of each evaluation point corresponding area DB _n on wafer W _T in the same order and subroutines of the first exposure process described above _{, J} are exposed through the aperture pattern AP _n (including the pattern M2 _n ) of the reticle R2. As a result, multiple exposure for each of the divided areas DA _{i, j} , that is, the above-described exposure with the opening pattern AP _n of the reticle R1 is the first exposure, and the exposure with the opening pattern AP _n of the reticle R2 is the second exposure (trim exposure). ) Is performed. However, in the second exposure process, the main controller 28 performs exposure on each divided area while maintaining the target dose amount and the target focus position set in step 702 as the dose amount and the wafer focus position. Is called. That is, the counter i, j are each set moving target position of the row direction of the wafer _{W T} during exposure and is used only to set the movement target position in the column direction (see step 702,714,718).

Here, as the target dose amount, for example, an optimum value of the dose amount obtained in advance by simulation or the like is set. The target focus position, for example, a central value of the focus step in the first exposure process, is set to Z _7.

By the processing of this step 610 (second exposure processing subroutine), the image of the pattern MP2 _n is superimposed and transferred to each partitioned area DA _{i, j where} the latent image of the pattern MP1 _{n has} already been formed, and developed. Later, a part of the image of the pattern MP1 _n is removed. In the second embodiment, the line patterns other than the second line pattern from both ends of the measurement pattern MP1 _n are removed from the relationship between the sizes of the measurement patterns MP1 _n and MP2 _n and the intervals between the line patterns. A pattern image (resist image) having a cross-sectional shape as shown in FIG. 14C is obtained after development.

After the end of the second exposure process, the determination at step 612 is negative and the routine proceeds to step 616. Then, main controller 28 performs the same processing as in steps 408 to 414 in steps 616 to 622, and then in step 624 in the same procedure as in step 417 described above, the optimal dose amount P _opt 1 and The best focus position Z _best 1 is determined. Here, the optimum dose amount P _opt 1 is the optimum dose amount when transferring the pattern of the reticle R1 (measurement pattern MP1 _n ). This is because the second exposure described above is performed in a state where the dose amount is constant.

  Next, in step 626, the wafer is replaced, and in step 628, predetermined preparatory work such as reticle replacement and alignment of the reticle with respect to the projection optical system PL is performed. At this time, reticle R2 is loaded on reticle stage RST instead of reticle R1. Further, as the preparation work, the same work as the above-described step 404 is performed.

In the next step 630, it is determined whether or not the flag F1 is set (F1 = 1). In this case, since the flag F1 is set in step 614, the determination here is affirmed, and the routine proceeds to step 632 (third exposure processing subroutine). In this subroutine, the main control device 28 performs processing according to the processing algorithm shown in the flowchart of FIG. In other words, in this subroutine, processing similar to that of step 406 (steps 502 to 518 in FIG. 7) is performed according to the procedure of steps 802 to 818. However, in the third exposure process, the main controller 28 sets the target dose amount to the previously determined optimum dose amount P _opt 1 in step 802 and maintains this optimum dose amount P _opt 1 while maintaining the optimum dose amount P _opt 1. Exposure is performed on each partitioned area. That is, the counter j is used only for setting the movement target position in the column direction (see steps 802 and 818). Further, the target focus position is changed in M steps, for example, 13 steps within a predetermined width centered on the previously determined best focus position Z _best 1 (see step 814).

In step 632 (subroutine third exposure process), on the wafer _{W T,} the dose constant _{(P opt} 1) under transferred image transferred measurement patterns MP1 _n in the (latent image) is formed M row consisting number of divided areas (13 × 23 = 299 as an example) M × N arrayed in a matrix of N rows (13 rows 23 columns as an example), the five evaluation point corresponding areas _DB 1 to DB ₅ has Is formed (see FIG. 5).

  In the next step 636, it is determined whether or not the flag F1 is lowered (F1 = 0). In this case, since F1 = 1, the determination here is negative, the flag F1 is lowered at step 638 (F1 ← 0), and the process returns to step 628.

  In step 628, reticle exchange is performed. At this time, reticle R2 is loaded on reticle stage RST instead of reticle R1. Further, predetermined preparation work such as alignment of the reticle with respect to the projection optical system PL is performed.

  In the next step 630, it is determined whether or not F1 = 1. In this case, since F1 = 0, the determination here is denied and the routine proceeds to step 634 (fourth exposure processing subroutine).

In this subroutine, the main controller 28 performs processing according to the processing algorithm shown in the flowchart of FIG. That is, in this subroutine, the processing according to the procedure of step 902 to 918 is performed, the partitioned regions DA _i of each evaluation point corresponding area DB _n on wafer W _T in the same order and subroutines of the first exposure process described above _{, J} are exposed through the aperture pattern AP _n (including the pattern M2 _n ) of the reticle R2. As a result, double exposure is performed in which each divided area DA _{i, j is} subjected to multiple exposure, that is, exposure by the third exposure process is the first exposure, and exposure by the fourth exposure process is the second exposure (trim exposure). Is done. However, in the fourth exposure process, the main controller 28 sets the target focus position to, for example, the best focus position Z _best 1 previously determined in step 904, and maintains each focus section Z _best 1 while maintaining the focus position Z _best 1. The area is exposed. That is, the counter i is only used to set the movement target position in the row direction of the wafer _{W T} during exposure (see step 904,914). Further, the target value of the dose amount is changed in N stages, for example, 23 stages within a predetermined width centered on the target dose amount in the second exposure process described above (see step 918).

After completion of the fourth exposure process, the determination at step 636 is affirmed, and the routine proceeds to step 640. Then, main controller 28 performs the same processing as in steps 408 to 414 in steps 640 to 646, and then in step 648, calculates the optimal dose amount P _opt 2 in the same procedure as in step 417 described above. decide. Here, the optimum dose amount P _opt 2 is the optimum dose amount when transferring the pattern of the reticle R2 (measurement pattern MP2 _n ) by trim exposure. This is because the third exposure process described above is performed in a state where the dose amount is constant.

In step 650, the optical characteristics of the projection optical system PL, such as the best focus position, are calculated in the same manner as in step 438 described above. Specifically, the main controller 28 determines, for example, the peak of the contrast curve based on the contrast data (contrast curve) of each evaluation point corresponding region DB _n corresponding to the optimum dose amount P _opt 2 determined in step 648. From the center, the best focus position is obtained for each evaluation point corresponding area DB _n . Next, main controller 28 calculates the average value of the best focus positions obtained for each evaluation point corresponding area DB _n as the best focus position at each evaluation point in the field of view of projection optical system PL. Further, main controller 28 calculates the average value (or weighted average value) of the best focus positions at the evaluation points corresponding to evaluation point corresponding areas DB _{1 to} DB ₅ as the best focus position Z _best of projection optical system PL. .

  Further, main controller 28 calculates the image plane shape based on the best focus position at each evaluation point within the field of view of projection optical system PL.

In step 624, the optimum dose amount in the first exposure for transferring the pattern of the reticle R1 (measurement pattern MP1 _n ) is determined. In step 648, the pattern of the reticle R2 (measurement pattern MP2 _n ) is transferred by trim exposure. The optimal dose amount P _opt 2 for the second exposure is determined. Accordingly, thereafter, the main control device 28 performs the same processing as in Steps 626 to 646. However, the main controller 28 maintains the target dose amount at the optimum dose amount P _opt 1 instead of the third exposure process in step 632, and the image (latent image) of the pattern MP1 _n is obtained at a different target focus position. the evaluation point corresponding area DB _n consisting of the formed M-number of divided areas _DA i (i = 1~M) performing exposure for forming on the wafer _{W T.} In addition, in place of the fourth exposure process of step 634, main controller 28 maintains not only the target focus position but also the target dose amount constant (optimum dose amount P _opt 2), and each partition area DA. Exposure is performed to transfer the pattern MP2 _n so as to be superimposed on the image (latent image) of the pattern MP1 _n formed on _i . Thereafter, in step 650, the optical characteristics (such as the best focus position) of the projection optical system PL can be calculated based on the contrast data (contrast curve) obtained by the image processing in step 646.

  Also in the second embodiment, the main controller 28 corrects the optical characteristics of the projection optical system PL obtained as described above, via the imaging characteristic correction controller (not shown). Adjust optical characteristics (including imaging characteristics). Then, main controller 28 transfers the pattern formed on reticle R onto wafer W through projection optical system PL with adjusted optical characteristics. Further, the main controller 28 effectively suppresses the occurrence of color unevenness due to defocusing by performing focus control of the wafer W with reference to the best focus position using the focus sensor AFS during exposure. it can. This makes it possible to transfer a fine pattern onto the wafer with high accuracy.

As described above, according to the second embodiment, step 602 to step 624, from the particular process steps 608,610,622,624, using the reticle R1 (measurement patterns MP1 _n) on the wafer _{W T} The optimum dose amount (and the best focus position) for exposing the M × N partition areas DA _{i, j} in the evaluation point corresponding area DB _n (n = 1 to 5) is determined, and steps 626 to 648 are also performed. , in particular by the process of step 632,634,646,648, the wafer _W M × n number of divided areas of the evaluation point corresponding area DB _n on _{T DA i,} patterns for measurement are formed under different exposure conditions to _j The optimum dose amount when transferring the measurement pattern MP2 _n of the reticle R2 through the projection optical system PL while being superimposed on the image (latent image) of MP1 _n is determined. Therefore, the optimal dose for each pattern MP1 _n and MP2 _n when forming the measurement pattern onto the wafer _{W T} by a double exposure by using a pattern MP1 _n and pattern MP2 _n (a part of the exposure conditions) It becomes possible to decide.

According to the second embodiment, the pattern MP2 _n is superimposed on the image of the pattern MP1 _n according to the optimum dose amount for each of the patterns MP1 _n and MP2 _n determined as described above, and the projection optical system PL is transferred via the respective portion a plurality of divided areas DA _i on wafer W _T on which the image is formed in the pattern MP1 _n is exposed via the projection optical system PL. Thus, for example, an image of the pattern portion of the pattern MP1 _n is removed is formed into a plurality of divided areas DA _i respectively on wafer W _T. Then, based on the detection result of the state of formation of the plurality of divided areas DA _i image of a pattern formed on each of the wafer W _T after the transfer of the pattern MP2 _n, the optical characteristics of the projection optical system PL is calculated. Therefore, even if it is difficult to accurately calculate the optical characteristics of the projection optical system based on the detection result of the formation state of the image of the pattern MP1 _n, it can be accurately obtained the optical characteristics of the projection optical system It becomes.

  Also in the second embodiment, exposure is performed by adjusting the optical characteristics of the projection optical system PL in consideration of the measurement result of the optical characteristics by the main controller 28, and the measurement is performed at the time of exposure. The focus control of the wafer W is performed using the focus sensor AFS with reference to the best focus position. This makes it possible to transfer a fine pattern onto the wafer with high accuracy.

In the second embodiment, the reticle R1 and the reticle R2 are used to perform double exposure for producing the sample used for the above-described optical property measurement. It is not limited. For example, a pattern region where the opening pattern AP _n is arranged, including a pattern MP1 _n, and a pattern region where the opening pattern AP _n is arranged, including a pattern MP2 _n, formed in different portions of the same reticle, the reticle It is good also as performing the above-mentioned double exposure. Further, in the same manner as in the second embodiment, the reticle R2 is used to form a pattern MP2 _n image in each partition region while maintaining the wafer focus position constant, and then the reticle R1 is used to focus the position. It is also possible to perform overlay exposure on each partition area while changing the above.

Also in the second embodiment, as in the first embodiment, not only the H-line pattern but also the double sample for producing the sample used for the above-described optical characteristic measurement including the image of the V-line pattern is used. It is good also as performing exposure. In this case, for example, two or one reticle in which two types of measurement patterns MP3 _n or MP4 _n shown in FIGS. 9C and 9D are arranged in each opening pattern AP _n is used. it can.

In each of the first and second embodiments (hereinafter referred to as each embodiment), the entire evaluation point corresponding region is imaged simultaneously. For example, one evaluation point corresponding region is It is also possible to divide the images into a plurality of images. At this time, for example, the entire evaluation point corresponding region may be set in the detection region of the alignment system AS, and a plurality of portions of the evaluation point corresponding region may be imaged at different timings, or a plurality of portions of the evaluation point corresponding region May be sequentially set in the detection region of the alignment system AS and imaged. Furthermore, although the plurality of partition regions constituting one evaluation point corresponding region DB _n are formed adjacent to each other, for example, a part (at least one partition region) is formed as a detection region of the alignment system AS described above. You may form apart more than the distance corresponding to the magnitude | size. That is, the arrangement (layout) of a plurality of partition regions may be determined according to the size of the detection region of the alignment system AS so that the entire evaluation point corresponding region can be imaged simultaneously.

  In each of the above embodiments, the measurement pattern is transferred onto the wafer by still exposure. However, scanning exposure may be used instead of still exposure, and in this case, dynamic optical characteristics can be obtained. .

  In addition, the exposure apparatus of each of the above embodiments may be an immersion type disclosed in, for example, International Publication No. 99/49504 pamphlet, US Patent Application Publication No. 2005/0259234, and the like. By transferring the image of the measurement pattern onto the wafer through the optical characteristics of the projection optical system including the liquid can be measured.

  In the above embodiment, for example, the object to be imaged may be a latent image formed on a resist at the time of exposure. The wafer on which the image is formed is developed, and the wafer is further etched. An obtained image (etched image) or the like may be used. In addition, the photosensitive layer on which an image on an object such as a wafer is formed is not limited to a photoresist, and may be any layer that can form an image (a latent image and a visible image) by irradiation with light (energy). It may be an optical recording layer, a magneto-optical recording layer, or the like.

  Each of the above embodiments exemplifies a case where the present invention is applied to a method for obtaining the optical characteristics (such as the best focus position) of the projection optical system PL by contrast measurement disclosed in WO 02/091440. did. However, the present invention is not limited to this, and the present invention can also be applied to a method of measuring the line width of an image such as the CD / focus method and the SMP focus measurement method described above. Also in these cases, by applying the present invention, the exposure condition of the measurement pattern, for example, the energy dose (dose amount) per unit area given on the wafer can be set with higher accuracy. In the CD / focus method, the SMP focus measurement method, and the like, an LSA sensor of the alignment system AS can be used.

  In each of the above embodiments, the case where the resist image is picked up by the alignment type FIA sensor provided in the exposure apparatus is illustrated, but the present invention is not limited to this, and a dedicated image pickup apparatus (for example, an optical device) provided outside the exposure apparatus. A resist image may be taken with a microscope or the like. In the above-described embodiment, the pattern image on the wafer is detected using the imaging type FIA system. However, in this measurement apparatus, the light receiving element (sensor) is not limited to the imaging element such as a CCD. Therefore, the data (pattern image measurement result by the measurement device) used in the above-described contrast information calculation is not limited to the imaging data.

When the L / S pattern is used as the measurement pattern, the duty ratio and the period direction may be arbitrary. When a periodic pattern is used as the measurement pattern MP _n , the periodic pattern is not limited to the L / S pattern, but may be a pattern in which dot marks are periodically arranged, for example.

  In each of the above embodiments, the position information of wafer stage WST is measured using interferometer system 26. However, the present invention is not limited to this, and for example, a scale (diffraction grating) provided on the upper surface of wafer stage WST is detected. An encoder system may be used. In this case, it is preferable that a hybrid system including both the interferometer system and the encoder system is used, and the measurement result of the encoder system is calibrated using the measurement result of the interferometer system. Further, the position of the wafer stage may be controlled by switching between the interferometer system and the encoder system or using both.

  Further, in each of the above embodiments, the case where the present invention is applied to the scanner has been described. However, the exposure apparatus of the step and stitch system, the photo repeater, and the like as well as the stationary exposure type projection exposure apparatus such as a stepper. Can also be suitably applied.

Furthermore, the light source of the exposure apparatus to which the present invention is applied is not limited to a KrF excimer laser or an ArF excimer laser, but may be an F ₂ laser (wavelength 157 nm) or another pulsed laser light source in the vacuum ultraviolet region. In addition, as the illumination light for exposure, for example, a fiber doped with erbium (or both erbium and ytterbium), for example, an infrared or visible single wavelength laser beam oscillated from a DFB semiconductor laser or fiber laser. Harmonics that are amplified by an amplifier and wavelength-converted to ultraviolet light using a nonlinear optical crystal may be used. Further, an ultra-high pressure mercury lamp that outputs a bright line (g-line, i-line, etc.) in the ultraviolet region may be used.

  Further, the projection optical system PL may be any of a refraction system, a catadioptric system, and a reflection system, and may be any of a reduction system, a unit magnification system, and an enlargement system.

  Furthermore, the present invention relates to an exposure apparatus for transferring a device pattern onto a glass plate, a thin film magnetic head, which is used for manufacturing not only an exposure apparatus used for manufacturing a semiconductor element but also a display including a liquid crystal display element and a plasma display. It is also applied to exposure equipment used to manufacture device patterns, exposure equipment used to transfer device patterns onto ceramic wafers, imaging devices (CCD, etc.), micromachines, DNA chips, and masks or reticles. can do.

  A semiconductor device includes a step of designing a function / performance of a device, a step of manufacturing a reticle based on the design step, a step of manufacturing a wafer from a silicon material, and an image of a reticle pattern by the exposure apparatus of the above-described embodiment. The wafer is manufactured through a step of generating the wafer, a step of developing the wafer, a step of etching the developed wafer, a device assembly step (including a dicing process, a bonding process, and a package process), an inspection step, and the like. In this case, in the lithography step, the exposure method described above is executed using the exposure apparatus of each of the above embodiments, and a device pattern is formed on the wafer. Therefore, a highly integrated device can be manufactured with high productivity. .

  The optical property measurement method of the present invention is suitable for measuring the optical property of a projection optical system. The exposure condition determination method of the present invention is suitable for determining the exposure condition for preparing a sample for measuring the optical characteristics of the projection optical system. The exposure method of the present invention is suitable for transferring a pattern formed on a mask onto an object via a projection optical system. The device manufacturing method of the present invention is suitable for manufacturing an electronic device such as a semiconductor element or a liquid crystal display element.

It is a figure which shows schematically the structure of the exposure apparatus which concerns on 1st Embodiment. It is a figure which shows measurement reticle _RTH . It is a diagram illustrating a measurement reticle _{R TV.} It is a flowchart which simplifies and shows the process algorithm of CPU in the main controller regarding the measuring method of the optical characteristic of the projection optical system in the exposure apparatus which concerns on 1st Embodiment. It is a plan view showing a wafer W _T that evaluation point corresponding region is formed. It is a figure for demonstrating an evaluation score corresponding | compatible area | region. It is a flowchart which shows the specific example of step 406,424 of FIG. It is a figure which shows an example of the data for every dose amount which plotted the contrast value with respect to the focus position. FIG. 9A to FIG. 9D are diagrams for explaining a reticle used for measuring optical characteristics. It is a flowchart which simplifies and shows the process algorithm of CPU in the main controller regarding the measuring method of the optical characteristic of the projection optical system in the exposure apparatus which concerns on 2nd Embodiment. It is a flowchart which shows the specific example of step 610 of FIG. It is a flowchart which shows the specific example of step 632 of FIG. It is a flowchart which shows the specific example of step 634 of FIG. FIGS. 14A to 14C are diagrams for conceptually explaining trim exposure.

Explanation of symbols

28 ... main control unit, 100 ... exposure apparatus, AS ... alignment _{system, MP n, MP1 n, MP2} n ... measurement patterns, DB _n ... evaluation point corresponding area, DA _{i, j} ... divided region, PL ... projection optical system , W _T ... wafer.

Claims (9)

An optical property measurement method for measuring optical properties of a projection optical system that projects an image of a pattern on a first surface onto a second surface,
A part of a plurality of exposure conditions including a setting value of the position of the object with respect to the optical axis direction of the projection optical system and the energy amount of the energy beam irradiated on the object are stepwise within a predetermined first range. A first step of sequentially transferring the measurement pattern arranged on the first surface to the plurality of regions on the object arranged on the second surface side of the projection optical system via the projection optical system while changing When;
An image forming state of the measurement pattern in a plurality of areas on the object is detected, and at least a part of the partial exposure conditions for measuring the optical characteristics of the projection optical system is detected based on the detection result. A second step to be temporarily determined;
The at least a part of the exposure conditions is changed in a plurality of steps within a second range narrower than the first range with the provisionally determined exposure conditions as a center, and each of the plurality of different exposure conditions has the first A third step of sequentially transferring the measurement pattern arranged on one surface to a plurality of regions on the object arranged on the second surface side of the projection optical system via the projection optical system;
A fourth step of detecting a formation state of the image of the measurement pattern in a plurality of regions on the object, and determining an optical characteristic of the projection optical system based on the detection result.   In the second step, as a detection result of the image formation state of the measurement pattern, the setting value in a plurality of steps of the energy amount of the energy beam irradiated on the object is related to the optical axis direction of the projection optical system. The approximate curve which shows the relationship between the position of an object and the formation state of the image of the pattern for measurement is obtained, and at least a part of the partial exposure conditions is temporarily determined based on the shape of the approximate curve. The optical property measuring method described. The measurement pattern includes a first pattern and a second pattern in which the first axis and the second axis that are orthogonal to each other in the first surface are arranged in the respective directions,
In the second step, a first approximate curve indicating a relationship between the position of the object with respect to the optical axis direction of the projection optical system and the image formation state of the first pattern, and the optical axis direction of the projection optical system. A second approximate curve indicating a relationship between the position of the object and the image formation state of the second pattern is obtained, and at least a part of the partial exposure conditions is based on the first and second approximate curves. The optical property measuring method according to claim 2, in which   At least a part of the partial exposure conditions is when a measurement pattern arranged on the first surface is sequentially transferred to a plurality of regions on the object arranged on the second surface side of the projection optical system. 4. The optical characteristic measurement method according to claim 2, comprising at least one of a set value of an energy amount of an energy beam irradiated onto the object and a position of the object with respect to an optical axis direction of the projection optical system.   In the second step, in order to obtain the approximate curve, two-dimensional data determined from the position of the object in the optical axis direction of the projection optical system and the index value of the image formation state of the measurement pattern is obtained with a predetermined order. The least square fitting is performed on the approximate function, and when the approximate curve having a sufficient fitting degree is not obtained, the approximate curve is obtained by lowering the order of the approximate function and performing the fitting again. The optical property measuring method according to claim 1. An exposure condition determining method for determining an exposure condition for measuring an optical characteristic of a projection optical system that projects an image of a pattern on a first surface onto a second surface,
While changing a part of a plurality of exposure conditions including the set value of the position of the object with respect to the optical axis direction of the projection optical system and the energy amount of the energy beam irradiated on the object, the first A first step of sequentially transferring a first pattern arranged on a surface to a plurality of different regions on an object arranged on the second surface side of the projection optical system via the projection optical system;
A plurality of images on the object on which the first pattern image is formed by maintaining the same exposure condition and superimposing the second pattern on the first pattern image via the projection optical system. A second step of exposing a part of each of the regions through the projection optical system;
A third step of detecting an image formation state of a pattern formed in a plurality of regions on the object after the processing of the second step, and determining an exposure condition of the first pattern based on the detection result; ;
A fourth step of transferring the first pattern to a plurality of different areas on the object via the projection optical system according to the determined exposure condition;
A plurality of regions on the object on which the image of the first pattern is formed by changing the exposure condition and transferring the second pattern through the projection optical system so as to overlap the first pattern image A fifth step of exposing a part of the light through the projection optical system;
A sixth step of detecting an image formation state of a pattern formed in a plurality of regions on the object after the processing of the fifth step, and determining an exposure condition of the second pattern based on the detection result; A method for determining exposure conditions including; An optical property measurement method for measuring optical properties of a projection optical system that projects an image of a pattern on a first surface onto a second surface,
A determining step of determining an exposure condition for the first pattern and an exposure condition for the second pattern by the exposure condition determining method according to claim 6;
According to the determined exposure condition of the first pattern, the plurality of different first patterns arranged on the first surface on the object arranged on the second surface side of the projection optical system via the projection optical system. A first transfer step of sequentially transferring to the region of;
According to the determined exposure condition of the second pattern, the second pattern is transferred through the projection optical system so as to be superimposed on the image of the first pattern. A second transfer step of exposing a part of each of the plurality of regions through the projection optical system;
A calculation step of detecting a formation state of an image of a pattern formed in a plurality of regions on the object after the processing of the second transfer step, and calculating an optical characteristic of the projection optical system based on the detection result; An optical property measuring method including: Measuring optical characteristics of a projection optical system for projecting an image of a pattern on the first surface onto the second surface by the optical property measuring method according to any one of claims 1 to 5 and 7;
In consideration of the measurement result of the optical characteristic, at least one of the optical characteristic of the projection optical system and the position of the object with respect to the optical axis direction of the projection optical system is adjusted, and the image of the pattern is passed through the projection optical system. And exposing the object by projecting onto the object disposed on the second surface side. Forming a pattern on the object using the exposure method according to claim 8;
Treating the object on which the pattern has been formed.

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