JP2012195380A - Mark detection method and device, and exposure method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect position information of a mark to be detected provided in a rear surface of an object with high accuracy.SOLUTION: A mark detection method includes: a step 324 of measuring a first defocus amount of a surface of a wafer; a step 326 of detecting a mark on the surface of the wafer using an alignment light containing the light of a wavelength to be reflected on the surface of the wafer while focusing on the surface of the wafer based on the first defocus amount; a step 340 of measuring a second defocus amount of the surface of the wafer; and a step 342 of detecting a mark on a rear surface of the wafer using an alignment light containing the light of a wavelength which transmits the wafer while focusing on the rear surface of the wafer based on the defocus amount obtained by correcting the second defocus amount.

Description

  The present invention relates to a mark detection technique for detecting position information of a mark provided on an object such as a semiconductor wafer or a glass substrate, an exposure technique using the mark detection technique, and a device manufacturing technique using the exposure technique.

  Conventionally, for example, an exposure apparatus used in a lithography process for manufacturing a semiconductor device uses a plurality of alignment systems to maintain high overlay accuracy between a plurality of layers of a semiconductor wafer (hereinafter simply referred to as a wafer). The position of the mark (wafer mark) attached to the shot area (alignment shot) selected from the shot area is detected. Then, the detected mark position is statistically processed by, for example, the EGA method, the array coordinates of each shot area are obtained, and the wafer is driven based on the array coordinates, whereby the reticle pattern image is formed on each shot area of the wafer. Are overlaid with high precision.

  Recently, in order to perform wafer alignment efficiently, a multi-axis alignment system with three or more eyes is provided, the wafer is moved relative to these alignment systems in a predetermined direction, and the multi-axis alignment system and the wafer are aligned. And an exposure apparatus that repeatedly detects a position of a mark attached to an alignment shot in a row of a wafer with a multi-axis alignment system has been developed. 1 and Patent Document 2). In this exposure apparatus, the defocus amount with respect to the test mark (test surface) of the multi-axis alignment system is individually measured, and the test surface is focused on each alignment system based on the measured defocus amount. The detection mark was detected.

International Publication No. 2007/097379 Pamphlet International Publication No. 2008/029757 Pamphlet

  The conventional alignment system is based on the premise that the test mark is formed on the surface of the wafer. In contrast, recently, the structure of semiconductor devices has become three-dimensional, and depending on the process, the test mark on the back side of the substrate is detected, and based on the detection result, the substrate and the pattern to be transferred are aligned. May be required. However, in the conventional alignment system, it is difficult to focus on the back surface of the substrate and detect the position information of the test mark on the back surface.

  In view of such circumstances, it is an object of the present invention to detect position information of a test mark provided on the back surface of an object with high accuracy.

  According to the first aspect of the present invention, there is provided a mark detection method for detecting position information of a mark provided on a substrate. This mark detection method measures the first surface position information of the surface of the first substrate with respect to the mark detection system, and the surface of the first substrate with respect to the mark detection system based on the first surface position information. A first mark on the surface of the first substrate is irradiated by irradiating the first substrate with a first light beam including light of a first wavelength reflected from the surface of the first substrate from the mark detection system while focusing. , Detecting the second surface position information of the surface of the second substrate with respect to the mark detection system, and correcting the offset of the second surface position information based on the surface position information obtained The second substrate is irradiated with a second light flux including light of a second wavelength that passes through the second substrate from the mark detection system while focusing the back surface of the second substrate with respect to the mark detection system. Detect the second mark on the back of the second substrate It is intended to include a Rukoto, the.

  Moreover, according to the 2nd aspect, the exposure method which exposes an object through a pattern with exposure light is provided. This exposure method includes a step of detecting the first mark on the surface of the first substrate using the mark detection method of the present invention, and aligning the first substrate and the pattern to be transferred based on the detection result. A step of exposing the first substrate, a step of detecting a second mark on the back surface of the second substrate using the mark detection method, a pattern of the second substrate and a transfer target based on the detection result, And aligning the second substrate and exposing the second substrate.

  Moreover, according to the 3rd aspect, the mark detection apparatus which detects the positional information on the mark provided in the board | substrate is provided. The mark detection apparatus includes a first detection system that measures surface position information on the surface of the substrate, a first light beam that includes light of a first wavelength reflected on the surface of the substrate, and a second light that passes through the substrate. An irradiation system that switches and irradiates the substrate with a second light beam including light of a wavelength, and a second reflected light that includes light of the first wavelength or light of the second wavelength that is returned from the substrate. A second detection system that receives the reflected light and detects an image of the first mark on the front surface of the substrate or the second mark on the back surface of the substrate; and the second detection system in the optical axis direction of the second detection system; Obtained by correcting the offset of the surface position information measured by the first detection system when the substrate is irradiated with the second light flux from the irradiation system and the drive mechanism for adjusting the relative position with the substrate. The second detection system by controlling the drive mechanism based on the surface position information A focusing control device for focusing of the substrate that is intended with a.

Moreover, according to the 4th aspect, the exposure apparatus which exposes an object through a pattern with exposure light is provided. This exposure apparatus includes the mark detection apparatus of the present invention, and aligns the object and the pattern based on the detection results of a plurality of marks of the mark detection apparatus.
According to the fifth aspect, the method includes forming a photosensitive pattern on an object using the exposure method or exposure apparatus of the present invention, and processing the exposed object based on the photosensitive pattern. A device manufacturing method is provided.

  According to the present invention, the surface position information obtained by measuring the second surface position information of the surface of the second substrate relative to the mark detection system (second detection system) and correcting the offset of the second surface position information. Based on the above, it is possible to focus the back surface of the second substrate with respect to the mark detection system. In this state, the second substrate is irradiated with a second light beam containing light having a second wavelength that is transmitted through the second substrate from the mark detection system, and the second mark on the back surface of the second substrate is detected. Thus, the position information of the test mark provided on the back surface of the object can be detected with high accuracy.

It is a figure which shows schematic structure of the exposure apparatus which concerns on an example of embodiment. It is a figure which shows the wafer alignment apparatus of FIG. It is a figure which shows the state which is detecting the wafer mark of the back surface of a wafer with an alignment system. It is a flowchart which shows an example of the method of calculating | requiring the offset of the detection result of AF type | system | group. (A) is a figure which shows an example of an imaging signal, (B) is a figure which shows an example of a focus signal. It is a flowchart which shows an example of the alignment method and the exposure method. (A) is a figure which shows the alignment system which is detecting the mark on the surface of a board | substrate, (B) is a figure which shows the alignment system which is detecting the mark on the back surface of a board | substrate. It is a flowchart which shows an example of the manufacturing process of an electronic device.

  An exemplary embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of an exposure apparatus EX according to the present embodiment. The exposure apparatus EX is, for example, a scanning exposure type projection exposure apparatus (scanning type exposure apparatus) composed of a scanning stepper (scanner). As will be described later, in the present embodiment, the projection optical system PL is provided. In the following description, the Z-axis is taken in parallel to the optical axis AX of the projection optical system PL, and the reticle and wafer are aligned in a plane perpendicular to the Z-axis. The Y-axis is taken in the direction of relative scanning, the X-axis is taken in the direction perpendicular to the Z-axis and the Y-axis, and the rotation (tilt) directions around the X-axis, Y-axis, and Z-axis are respectively The description will be made with the θz direction.

  In FIG. 1, an exposure apparatus EX includes an illumination system 10 that illuminates a reticle R with exposure illumination light (exposure light) IL, a reticle stage RST that holds and moves the reticle R, and illumination light IL emitted from the reticle R. Is provided with a projection unit PU including a projection optical system PL that projects the projection onto the surface of the wafer W, a wafer stage WST that holds and moves the wafer W, and a control system thereof. Further, the exposure apparatus EX includes a main controller 20 (see FIG. 2) that is a computer that controls the overall operation of the apparatus, and a wafer that detects a wafer mark as an alignment mark provided on the surface of the wafer W. And an alignment device 48.

  The illumination system 10 includes a light source and an illumination optical system as disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-313250 (corresponding US Patent Application Publication No. 2003/0025890), and the illumination optical system. Includes, for example, a light amount distribution forming optical system including a diffractive optical element or a spatial light modulator, an optical integrator (such as a fly-eye lens or a rod integrator), and a reticle blind (not shown). The illumination system 10 illuminates the slit-shaped illumination area IAR on the pattern surface (reticle surface) of the reticle R defined by the reticle blind with illumination light IL with a substantially uniform illuminance distribution. As the illumination light IL, for example, ArF excimer laser light (wavelength 193 nm) is used. As illumination light, KrF excimer laser light (wavelength 248 nm), harmonic of a YAG laser, harmonic of a solid laser (such as a semiconductor laser), or a bright line (such as i-line) of a mercury lamp can be used.

  On the upper surface of reticle stage RST, reticle R on which a circuit pattern or the like is formed is held, for example, by vacuum suction. The reticle stage RST can be driven minutely in the XY plane and can be driven at a scanning speed specified in the scanning direction (Y direction). Position information (including the position in the X direction, the Y direction, and the rotation angle in the θz direction) within the moving surface of the reticle stage RST is, for example, 0. 0 through the moving mirror 15 by the reticle interferometer 116 including a laser interferometer. It is always detected with a resolution of about 5 to 0.1 nm. The measurement value of reticle interferometer 116 is sent to main controller 20 in FIG. Main controller 20 controls the position and speed of reticle stage RST by controlling stage drive system 124 based on the measurement value.

  In FIG. 1, the projection unit PU disposed below the reticle stage RST includes a lens barrel 40 and a projection optical system PL having a plurality of optical elements held in the lens barrel 40 in a predetermined positional relationship. . The projection optical system PL is, for example, telecentric on both sides (or one side on the wafer side) and has a predetermined projection magnification β (eg, 1/4 times, 1/5 times, etc.). An image of the circuit pattern of the reticle R in the illumination area IAR is formed in the exposure area IA (an area conjugate to the illumination area IAR) of one shot area of the wafer W via the projection optical system PL. Wafer W (semiconductor wafer) has a predetermined thickness (for example, several 10 to 10) of photoresist, which is a photosensitive agent (photosensitive layer), on the surface of a substrate made of, for example, disc-shaped silicon having a diameter of about 200 mm to 450 mm. (Approx. 200 nm). In each shot area of the wafer W of the present embodiment, a predetermined single layer or a plurality of layers of circuit patterns and corresponding wafer marks are formed by the pattern forming process so far. Some wafers to be exposed are formed by bonding a plurality of substrates, and a wafer mark is formed on the back surface of the uppermost substrate. The uppermost substrate is formed of a material that transmits near infrared light to such an extent that the wafer mark can be detected.

  In the exposure apparatus EX, in order to perform exposure using the liquid immersion method, the lower end of the lens barrel 40 that holds the tip lens 191 that is the optical element on the most image plane side (wafer W side) constituting the projection optical system PL. A nozzle unit 32 constituting a part of the local liquid immersion device 8 is provided so as to surround the part periphery. The nozzle unit 32 has a supply port that can supply the exposure liquid Lq and a recovery port that can recover the liquid Lq. The supply port is connected via a supply pipe 31A to a liquid supply device (not shown) capable of delivering the liquid Lq. The recovery port is connected to a liquid recovery apparatus (not shown) that can recover the liquid Lq via a recovery pipe 31B. As the local liquid immersion device, for example, a device disclosed in US Patent Application Publication No. 2007/242247 can be used.

  In FIG. 1, wafer stage WST is arranged on the upper surface of base board 12, and Y-axis interference for measuring position information (positions in X direction, Y direction, and angles in θx direction, θy direction, and θz direction) of wafer stage WST. A wafer interferometer 16 including a meter is provided. Wafer stage WST is provided in stage body 91 having stage body 91 having an XY stage moving in the X direction and the Y direction, wafer table WTB mounted on the upper surface of stage body 91, and to stage body 91. And a Z stage 125 (see FIG. 2) that relatively finely drives the wafer table WTB (wafer W) in the Z direction, θx direction, and θy direction. The measurement value of the wafer interferometer 16 is sent to the main controller 20 in FIG. Main controller 20 controls the operation of the XY stage via stage control system 124 based on the measured value. Main controller 20 controls the operation of stage 125.

  At the center of wafer table WTB, a wafer holder (not shown) for holding wafer W by vacuum suction or the like is provided. Further, the upper surface of wafer table WTB has a surface (liquid repellent surface) that is liquid repellent with respect to liquid Lq and has the same height as the surface of the wafer placed on the wafer holder, and has an outer shape ( A plate (liquid repellent plate) 28 having a low thermal expansion coefficient having a rectangular outline and a circular opening that is slightly larger than the wafer holder (wafer mounting region) is provided at the center thereof. A part of the plate 28 is provided with a reference member FM (see FIG. 2) in which a reference mark for baseline measurement is formed and a slit for measuring the position of the pattern image of the reticle R is formed. ing. On the bottom surface of the reference member FM, an aerial image measuring device 45 (see FIG. 5) that receives the light beam that has passed through the slit is provided.

In addition, an optical system of an alignment system 50 that detects position information of the wafer mark of the wafer W is disposed on the side surface of the projection optical system PL. The optical system of the alignment system 50 is supported by a frame (not shown). The alignment system 50 of the present embodiment is an image processing type FIA (Field Image Alignment) system.
FIG. 2 shows a configuration of the wafer alignment apparatus 48 including the alignment system 50 in FIG. In FIG. 2, the alignment system 50 detects an illumination system 49C that illuminates the wafer mark, a detection system 49A that detects an image of the wafer mark, and a defocus amount (surface position information) of the test surface with respect to the detection system 49A. And a surface position detection system (hereinafter referred to as AF system) 49B for autofocus. Furthermore, the alignment system 50 includes a detection signal processing system 127 and an offset correction system 129 (details will be described later).

  At the time of alignment, broadband light including a wavelength region from visible light to near infrared light is emitted from the light guide 51. The light emitted from the light guide 51 passes through the wavelength selection filter 52A, and the alignment light IL1 of visible light (wavelength of about 400 to 750 nm) is selected. The wavelength selection filter 52A can be exchanged with a wavelength selection filter 52B that selects near infrared light (wavelength of about 760 nm to 2.5 μm) by an exchange device 52D. In addition, when switching the wavelength of alignment light, you may switch light source itself.

  The alignment light IL1 enters the beam splitter 54A through the lens systems 53A and 53B. The alignment light IL1 reflected in the −Z direction by the beam splitter 54A is applied to the wafer mark WM1 on the surface of the wafer W via the beam splitter 54B and the first objective lens 55. Wafer mark WM1 is covered with a photoresist layer PR. The light guide 51, the wavelength selection filters 52A and 52B, the exchange device 52D, the lens systems 53A and 53B, the beam splitters 54A and 54B, and the first objective lens 55 constitute an illumination system 49C.

  The alignment light IL1 reflected by the wafer mark WM1 passes through the first objective lens 55, the beam splitters 54B and 54A, and the second objective lens 56 on the light receiving surface of the CCD or CMOS type two-dimensional image sensor 57. An image of the mark WM1 is formed. The first objective lens 55, the beam splitters 54B and 54A, the second objective lens 56, and the image sensor 57 constitute a detection system 49A. The optical axis of the detection system 49A is parallel to the Z axis. For example, a detection signal DS obtained by integrating the image pickup signals of the image pickup element 57 in the non-measurement direction is supplied to the detection signal processing system 127.

  The detection signal processing system 127 supplies the detection signal DS to the offset correction system 129 when obtaining the offset. During normal alignment, the detection signal processing system 127 converts the detection signal DS into a binary signal, for example, at a predetermined slice level, and the X direction of the wafer mark WM1 is based on a specific pixel of the image sensor 57 from the binary signal. , The amount of positional deviation in the Y direction is obtained, and the amount of positional deviation is supplied to the EGA computing unit 126 via the main controller 20. The EGA calculation unit 126 adds the coordinates (X, Y) of the wafer stage WST supplied from the main controller 20 to the amount of positional deviation, and a coordinate system (stage coordinate system) defined by the coordinates of the wafer stage WST. The coordinates of the wafer mark at are obtained.

  Further, in order to detect the defocus amount with respect to the detection system 49A, light in a wavelength region including visible light is emitted from the light guide 58. The light emitted from the light guide 58 passes through the wavelength selection filter 59 and the focus detection light AFL of visible light (wavelength of about 400 to 750 nm) is selected. The focus detection light AFL that has passed through the wavelength selection filter 59 illuminates the slit plate 61 on which the slit pattern is formed by the condenser lens 60. The focus detection light AFL emitted from the slit pattern is reflected by the beam splitter 62 and enters the beam splitter 53B via the lens system 63. The focus detection light AFL reflected by the beam splitter 53B is passed through the first objective lens 55 to form a detection region (here, a wafer mark WM1) of the detection system 49A on the front surface of the wafer W (the back surface of the photoresist layer PR). The image of the slit pattern is formed in the area). The focus detection light AFL reflected from the surface of the wafer W is incident on the pupil division mirror 65 via the first objective lens 55, the beam splitter 54B, the lens system 63, the beam splitter 62, and the lens system 64. The light beam divided and reflected by the mirror 65 in the X direction forms two slit pattern images separated in the X direction on the light receiving surface of the one-dimensional line sensor 67 via the lens system 66. A detection signal from the line sensor 67 is supplied to the focus signal processing system 128. Note that a two-dimensional image sensor can be used instead of the line sensor 67.

  An AF system 49B is configured including an optical member from the light guide 58 to the lens system 63, a beam splitter 54B, a first objective lens 55, an optical member from the lens system 64 to the line sensor 67, and a focus signal processing system 128. Yes. The focus signal processing system 128 generates a focus signal FS corresponding to the difference between the interval between the images of the two slit patterns and a predetermined reference interval from the detection signal of the line sensor 67, and offset-corrects the generated focus signal FS. Supply to system 129. The offset correction system 129 supplies the main controller 20 with a defocus amount obtained by correcting a defocus amount corresponding to the focus signal FS with a first offset described later. At the time of alignment, main controller 20 drives Z stage 125 based on the amount of defocus, and focuses test mark (surface to be detected) on alignment system 50 (detection system 49A). In this case, the initial value of the first offset, which is the difference in the Z direction between the best focus position of the detection system 49A when the alignment light IL1 is used and the best focus position detected by the AF system 49B, is zero. Actually, the correction amount δZ1 is added to the first offset by calibration described later.

  As shown in FIG. 3, when the wafer mark WM2 on the back surface of the wafer W is a detection target, near-infrared light (wavelengths from 760 nm to 2. Alignment light IL2 comprising about 5 μm) is selected, and alignment light IL2 passes through wafer W and is irradiated onto wafer mark WM2 on the back surface of wafer W. In this case, the base material of the wafer W has a transmittance such that at least the mark on the back surface can be observed with respect to near infrared light. Then, the alignment light IL2 reflected by the wafer mark WM2 forms an image of the wafer mark WM2 on the light receiving surface of the image sensor 57 via the first objective lens 55 and the like. By processing the detection signal of the image sensor 57 by the detection signal processing system 127 of FIG. 2, the amount of positional deviation of the wafer mark WM2 is obtained.

  In FIG. 3, visible focus detection light AFL is irradiated from the AF system 49B onto the surface of the wafer W, and reflected light of the focus detection light AFL from the surface of the wafer W is received by the line sensor 67 of the AF system 49B. Two slit pattern images are formed on the surface. A focus signal FS obtained by processing the detection signal of the line sensor 67 by the focus signal processing system 128 is supplied to the offset correction system 129, and a defocus amount corresponding to the focus signal FS is corrected by a second offset described later. The defocus amount is supplied to the main controller 20. At the time of alignment, main controller 20 drives Z stage 125 based on the defocus amount to focus the alignment system 50 (detection system 49A) of the test mark. In this case, the second offset, which is the difference in the Z direction between the best focus position of the detection system 49A when the alignment light IL2 is used and the best focus position detected by the AF system 49B, is Zof as an initial value. Actually, the correction amount δZ2 is added to the second offset by calibration described later. Since the alignment light IL1 and the alignment light IL2 have different wavelengths, the best focus position differs depending on the difference in longitudinal chromatic aberration in the detection system 49A.

  Returning to FIG. 1, the exposure apparatus EX of the present embodiment has an oblique incidence similar to that disclosed in, for example, Japanese Patent Laid-Open No. 6-283403 (corresponding US Pat. No. 5,448,332). A multi-point focus position detection system (hereinafter abbreviated as a multi-point AF system) (not shown). Based on the detection result of the multipoint AF system, each shot area of the wafer W is focused on the image plane of the projection optical system PL during exposure.

  At the time of exposure of wafer W, main controller 20 sets illumination conditions according to the pattern of reticle R. After the alignment of the reticle R and the alignment of the wafer W using the wafer alignment device 48, the wafer W is moved to the scanning start position by the movement (step movement) of the wafer stage WST. Thereafter, the illumination light IL starts to be emitted, and the reticle R and the wafer W are projected to be projected through the reticle stage RST and the wafer stage WST while exposing the wafer W with the image of the pattern of the reticle R by the projection optical system PL. By moving in synchronization with the speed ratio, the pattern image of the reticle R is scanned and exposed on one shot area of the wafer W. In this way, the image of the pattern of the reticle R is exposed on the entire shot area of the wafer W by the step-and-scan operation in which the step movement of the wafer W and the scanning exposure are repeated.

Next, an example of a method (calibration method) for obtaining an offset of the defocus amount detected by the AF system 49B of the alignment system 50 in the exposure apparatus EX of the present embodiment will be described with reference to the flowchart of FIG. This operation is controlled by the main controller 20.
First, in step 302 in FIG. 4, as shown in FIG. 2, a wafer (wafer W) having a wafer mark on its surface is loaded onto wafer stage WST, and wafer stage WST is driven to drive wafer W. The mark WM1 moves to the detection area of the detection system 49A. For example, rough alignment of the wafer W is performed by detecting a search alignment mark (not shown) or the like (hereinafter the same). In the next step 304, the illumination system 49C selects the visible alignment light IL1 and irradiates the wafer W, and the detection signal DS output from the image sensor 57 of the detection system 49A is output from the detection signal processing system 127 to the offset correction system. 129. In parallel with this, the focus signal FS detected by the AF system 49B is also supplied to the offset correction system 129. In this state, wafer W is moved in the Z direction via Z stage 125 of wafer stage WST.

  As a result, as shown in FIG. 5A, the contrast of the detection signal DS changes according to the Z position of the wafer W, and as shown in FIG. 5B, the focus signal FS becomes the Z position of the test surface. It changes according to. Therefore, as an example, the offset correction system 129 uses the Z position when the contrast of the detection signal DS is maximum as the best focus position of the detection system 49A, and uses the Z position obtained from the focus signal FS1 at this time as the first offset. Is the correction amount δZ1. This correction amount δZ1 is stored.

  In the next step 310, as shown in FIG. 3, a wafer (wafer W) having wafer mark WM2 provided on the back surface is loaded on wafer stage WST, and wafer mark WM2 of wafer W is moved by driving wafer stage WST. Move to the detection area of the detection system 49A. In the next step 312, the illumination system 49C selects the near-infrared alignment light IL2 to irradiate the wafer W, and the detection signal DS output from the image sensor 57 of the detection system 49A is offset from the detection signal processing system 127. The correction system 129 is supplied. In parallel with this, the focus signal FS detected by the AF system 49B is also supplied to the offset correction system 129. In this state, the Z stage 125 of the wafer stage WST is driven to move the wafer W in the Z direction.

  As an example, the offset correction system 129 uses the Z position when the contrast of the detection signal DS is maximum as the best focus position of the detection system 49A, and sets the Z position corresponding to the focus signal FS2 in FIG. The correction amount δZ2 for the second offset is used. This correction amount δZ2 is stored. As a result, the offset correction value of the defocus amount detection result by the AF system 49B of the alignment system 50 is obtained.

Next, an example of alignment and exposure operations in the exposure apparatus EX of the present embodiment will be described with reference to the flowchart of FIG. This operation is controlled by the main controller 20.
First, the reticle R1 is loaded onto the reticle stage RST in FIG. 1, and the main controller 20 reads information on the wafer to be exposed from an exposure data file (not shown). It recognizes whether it is formed on the front surface or the back surface of the upper layer (or single layer) substrate. Here, it is assumed that the test mark is on the surface of the single-layer substrate.

  Thereafter, in step 320 of FIG. 6, as shown in FIG. 7A, wafer W1 is loaded onto wafer stage WST. As an example, the wafer W1 has a wafer mark 71 attached to each shot region of the first surface B1 (front surface in this case) of the substrate 70 made of a silicon flat base material having a thickness d1 of about 780 μm, and the first surface. A photoresist layer PR1 having a predetermined thickness is formed on B1. In the next step 322, main controller 20 sets visible light alignment light IL1 in illumination system 49C of alignment system 50, and causes offset correction system 129 to set an offset for visible light. Here, the correction value δZ1 obtained in step 308 is set as the offset.

  In the next step 324, the wafer mark 71 is moved into the detection area of the detection system 49A, the focus detection light AFL is irradiated from the AF system 49B, and the defocus amount ΔF1 of the first surface B1 is measured. In the next step 326, the main controller 20 drives the Z stage 125 so as to cancel the defocus amount ΔF1, so that the first surface B1 is focused on the best focus position of the detection system 49A by the autofocus method. The In this state, the detection system 49A detects the amount of positional deviation of the image of the wafer mark 71 and supplies the detection result to the EGA computing unit 126. Actually, the position of a wafer mark attached to a plurality of predetermined alignment shots on the wafer W1 is detected. In the next step 328, the EGA calculation unit 126 calculates the array coordinates of the shot area of the wafer W1 by, for example, the EGA method using the measured coordinates of the plurality of wafer marks. In the next step 330, the wafer stage WST is driven based on the arrangement coordinates, whereby the pattern image of the reticle R1 is exposed to each shot area of the wafer W1. The exposed wafer W1 is developed by a coater / developer (not shown) (step 332). In the next step 334, the wafer W1 is patterned by an etching apparatus (not shown). Further, the wafer W2 is manufactured by thinning the back surface of the wafer W1 after pattern formation and then fixing the wafer support substrate with an adhesive on the front surface (first surface) of the wafer W1. In this case, the surface of the wafer W2 is the back surface of the thinly processed wafer W1, and a photoresist is applied to the surface (second surface) of the wafer W2.

At this time, on the exposure apparatus EX side, the reticle R2 is loaded onto the reticle stage RST of FIG. 1, and the main controller 20 determines that the wafer mark to be detected is the uppermost layer (or single layer) of the wafer from the exposure data file (not shown). ) Is recognized on the front surface or the back surface of the substrate. Here, it is assumed that the test mark is on the back surface of the uppermost substrate.
Thereafter, in step 336 of FIG. 6, as shown in FIG. 7B, wafer W2 is loaded onto wafer stage WST. As an example, the wafer W2 is a wafer support substrate 73 made of an insulator having a thickness d3 of about 780 μm on the first surface (here, the back surface) of a silicon substrate 70a having a thickness d2 of about 100 μm via an adhesive 72. Is fixed. Further, a photoresist layer PR2 is formed on the second surface B2 (here, the front surface) of the uppermost substrate 70a of the wafer W2, and is located at a position corresponding to each shot region on the first surface B1 (here, the back surface) of the substrate 70a. A wafer mark 71 is formed. Note that the wafer mark 71 in FIG. 7B may be different from the wafer mark 71 in FIG.

In the next step 338, main controller 20 sets near infrared light alignment light IL2 in illumination system 49C of alignment system 50, and causes offset correction system 129 to set an offset for near infrared light. Here, the correction value δZ2 obtained in step 316 is set as the offset.
In the next step 340, the wafer mark 71 of the wafer W2 is moved into the detection area of the detection system 49A, and the focus detection light AFL is irradiated from the AF system 49B to measure the defocus amount ΔF2 of the second surface B2. In the next step 342, the main controller 20 drives the Z stage 125 so as to cancel the defocus amount ΔF2, so that the first surface B1 is focused on the best focus position of the detection system 49A by the autofocus method. The In this state, the detection system 49A detects the amount of positional deviation of the image of the wafer mark 71 on the first surface B1 (here, the back surface) of the substrate 70a, and supplies the detection result to the EGA computing unit 126. Actually, the position of the wafer mark attached to a plurality of predetermined alignment shots of the wafer W2 is detected. In the next step 344, the EGA calculation unit 126 calculates the array coordinates of the shot area of the wafer W2 by, for example, the EGA method using the measured coordinates of the plurality of wafer marks. In the next step 346, the wafer stage WST is driven based on the arrangement coordinates, so that the pattern image of the reticle R2 is exposed on the second surface B2 (front surface) of each shot region of the wafer W2. The exposed wafer W2 is developed by a coater / developer (not shown) (step 348), and then patterned by an etching apparatus (not shown) or the like (step 350).

  As described above, according to the present embodiment, the position information of the wafer mark is accurately obtained by the autofocus method using the alignment system 50 regardless of the surface of the substrate (wafer). Can be detected. Therefore, since the pattern can be exposed on the surface of the substrate with high precision alignment with the pattern on the back surface of the substrate, an electronic device having a three-dimensional structure can be manufactured with high precision.

  As described above, the wafer alignment apparatus 48 according to the present embodiment includes the AF system 49B that measures the defocus amount of the surface of the wafer W, the alignment light IL1 of visible light reflected by the surface of the wafer W, and the wafer W (or the most An illumination system 49C that switches the near-infrared alignment light IL2 transmitted through the upper substrate) to irradiate the wafer W, and a second reflected light including the first reflected light or alignment light IL2 including the alignment light IL1 returned from the wafer W. And a detection system 49A that receives the reflected light and detects an image of the wafer mark WM1 on the front surface of the wafer W or the wafer mark WM2 on the back surface of the wafer W. Further, the wafer alignment apparatus 48 irradiates the wafer W with the alignment light IL2 from the illumination system 49C and the Z stage 125 that adjusts the relative position between the detection system 49A and the wafer W in the optical axis direction (Z direction) of the detection system 49A. In this case, the detection system 49A is controlled by controlling the Z stage 125 based on the defocus amount obtained by correcting the defocus amount measured by the AF system 49B using the offset corrected by the correction amount δZ2. And a main controller 20 for focusing the wafer W on the main body.

  In addition, the wafer mark detection method by the wafer alignment device 48 includes step 324 of measuring the defocus amount of the surface of the wafer W1, and focusing on the detection system 49A of the surface of the wafer W1 based on the defocus amount. The step 326 of detecting the wafer mark 71 on the surface of the wafer W1 using the alignment light IL1 including the light having the wavelength reflected on the surface of the wafer W1, and the step of measuring the defocus amount on the surface of the wafer W2 (substrate 70a) 340 and alignment light transmitted through the substrate 70a while focusing the back surface of the uppermost substrate 70a of the wafer W2 with respect to the detection system 49A based on the defocus amount obtained by correcting the defocus amount with an offset. Step 342 of detecting the wafer mark 71 on the back surface of the substrate 70a using IL2. It contains.

  According to this embodiment, the defocus amount of the surface of the wafer W2 (substrate 70a) with respect to the detection system 49A is measured, and the defocus amount obtained by correcting the defocus amount is used for the mark detection system. The back surface of the second substrate can be focused. In this state, the alignment light IL2 transmitted through the substrate 70a from the detection system 49A is irradiated onto the substrate 70a, and the wafer mark 71 on the back surface of the substrate 70a is detected, whereby the wafer mark 71 provided on the back surface of the substrate 70a is detected. Position information can be detected with high accuracy.

The substrate having the wafer mark on the surface to be detected by the wafer alignment device 48 and the substrate having the wafer mark on the back surface may be the same or different.
In addition, the exposure apparatus EX of the present embodiment is an exposure apparatus that exposes the wafer W through the pattern of the reticle R with the illumination light IL. The exposure apparatus EX includes the wafer alignment apparatus 48 and detects the alignment system 50 of the wafer alignment apparatus 48. Based on the result, wafer stage WST is driven to align the position of wafer W and reticle R pattern.

  The exposure method using the exposure apparatus EX uses the alignment method using the wafer alignment device 48 to detect position information of a plurality of wafer marks on the front surface or the back surface of the wafer (or the uppermost substrate), steps 326, 342, Steps 330 and 346 for exposing the wafer W while aligning the wafer W and the pattern of the reticle R based on the detection result are included.

According to the exposure apparatus EX and the exposure method, the position information of the wafer mark on the back surface of the wafer (substrate) can be detected with high accuracy as necessary. And the overlay accuracy can be improved.
In the present embodiment, the alignment system 50 is uniaxial, but the alignment system 50 may be a plurality of axes.

  Further, when an electronic device (microdevice) such as a semiconductor device is manufactured using the exposure apparatus (or exposure method) of the above-described embodiment, the electronic device has a function / performance design of the electronic device as shown in FIG. Step 221 is performed, Step 222 for fabricating a mask (reticle) based on this design step, Step 223 for fabricating a substrate (wafer) as a base material of the device, and the exposure apparatus EX (exposure method) of the above-described embodiment. A process for exposing a reticle pattern onto a substrate, a process for developing the exposed substrate, a substrate processing step 224 including heating (curing) and etching process for the developed substrate, a device assembly step (dicing process, bonding process, packaging process, etc.) 225) and inspection step 226, etc. It is manufactured Te.

In other words, this device manufacturing method includes exposing a substrate (object) using the exposure apparatus or exposure method of the above-described embodiment, and developing (processing) the exposed substrate. It is out. At this time, since the wafer mark on the back surface of the substrate can be detected with high accuracy, an electronic device having a three-dimensional structure can be manufactured with high accuracy.
In the above embodiment, a step-and-repeat type projection exposure apparatus (stepper or the like) can be used in addition to the above-described scanning exposure type exposure apparatus (scanner). Further, a dry exposure type exposure apparatus other than the immersion type exposure apparatus can be used in the same manner.

  In addition, the above embodiment is not limited to an exposure apparatus for manufacturing a semiconductor device, but is used for manufacturing a display including a liquid crystal display element, a plasma display, and the like. For exposure apparatuses that transfer device patterns used in the manufacture of ceramics onto ceramic wafers, as well as exposure apparatuses that are used in the manufacture of imaging devices (CCD, etc.), organic EL, micromachines, MEMS (Microelectromechanical Systems), and DNA chips Can also be applied. In addition to an electronic device (microdevice) such as a semiconductor element, an exposure apparatus that transfers a circuit pattern onto a glass substrate or a silicon wafer to manufacture a mask used in an optical exposure apparatus and an EUV exposure apparatus. The present invention can also be applied.

  Thus, the present invention is not limited to the above-described embodiments, and various configurations can be taken without departing from the gist of the present invention.

  EX ... exposure apparatus, R ... reticle, W ... wafer, WST ... wafer stage, WM1, WM2 ... wafer mark, 20 ... main controller 20, 48 ... wafer alignment apparatus, 49A ... detection system, 49B ... AF system, 49C ... Illumination system, 71 ... wafer mark, 125 ... Z stage

Claims (14)

A mark detection method for detecting position information of a mark provided on a substrate,
Measuring first surface position information of the surface of the first substrate relative to the mark detection system;
Including focusing on the surface of the first substrate with respect to the mark detection system based on the first surface position information, light having a first wavelength reflected from the surface of the first substrate from the mark detection system is included. Irradiating the first substrate with a first light flux to detect a first mark on the surface of the first substrate;
Measuring second surface position information of the surface of the second substrate relative to the mark detection system;
Based on the surface position information obtained by correcting the offset of the second surface position information, the second substrate is moved from the mark detection system while focusing on the back surface of the second substrate with respect to the mark detection system. Irradiating the second substrate with a second light flux containing light having a second wavelength to transmit, and detecting a second mark on the back surface of the second substrate;
The mark detection method characterized by including. When detecting the second mark on the back surface of the second substrate by the mark detection system, the relative position between the mark detection system and the second substrate is changed in the optical axis direction of the mark detection system, Correcting the offset based on a change in contrast of the image of the second mark;
The mark detection method according to claim 1, further comprising: When measuring surface position information of the surface of the first substrate or the second substrate with respect to the mark detection system, reflection from the mark detection system to the first substrate or the second substrate by the first substrate or the second substrate, respectively. The mark detection method according to claim 1, wherein a light beam including light having a third wavelength is irradiated.   4. The mark detection method according to claim 3, wherein the first and third wavelengths of light are visible light, and the second wavelength of light is near-infrared light.   The mark detection method according to claim 1, wherein a back surface of the second substrate on which the second mark is formed is fixed to a base substrate through an adhesive layer. . In an exposure method of exposing a substrate through a pattern with exposure light,
Detecting the first mark on the surface of the first substrate using the mark detection method according to claim 1;
Aligning the first substrate with a pattern to be transferred based on the detection result, and exposing the first substrate;
Detecting the second mark on the back surface of the second substrate using the mark detection method;
Aligning the second substrate with a pattern to be transferred based on the detection result, and exposing the second substrate;
An exposure method comprising: In a mark detection device that detects position information of a mark provided on a substrate,
A first detection system for measuring surface position information of the surface of the substrate;
An irradiation system for switching and irradiating the substrate with a first light beam including light having a first wavelength reflected by the surface of the substrate and a second light beam including light having a second wavelength transmitted through the substrate;
The first reflected light including the first wavelength light returned from the substrate or the second reflected light including the second wavelength light is received, and the first mark on the surface of the substrate or the back surface of the substrate is received. A second detection system for detecting an image of the second mark;
A drive mechanism for adjusting a relative position between the second detection system and the substrate in the optical axis direction of the second detection system;
When the substrate is irradiated with the second light flux from the irradiation system, the drive mechanism is controlled based on the surface position information obtained by correcting the offset of the surface position information measured by the first detection system. A focusing control device for focusing the substrate with respect to the second detection system;
A mark detection apparatus comprising: The focusing control device
When the second mark on the back surface of the substrate is detected by the second detection system, the relative position between the second detection system and the substrate is changed via the drive mechanism, and the image of the second mark is detected. The mark detection apparatus according to claim 7, wherein the offset is corrected based on a change in contrast.   The said 1st detection system irradiates the light beam containing the light of the 3rd wavelength reflected on the said board | substrate to the said board | substrate, and detects the reflected light from the surface of the said board | substrate, The mark detection apparatus described in 1.   The mark detection apparatus according to claim 9, wherein the light of the first wavelength and the third wavelength is visible light, and the light of the second wavelength is near infrared light.   The back surface of the substrate is fixed to the base substrate through an adhesive layer in a state where the second mark is formed on the back surface of the substrate. The mark detection apparatus described. In an exposure apparatus that exposes an object through a pattern with exposure light,
The mark detection device according to any one of claims 7 to 11, comprising:
An exposure apparatus characterized in that alignment of the object and the pattern is performed based on detection results of a plurality of marks by the mark detection apparatus. Forming a photosensitive pattern on a substrate using the exposure method according to claim 6;
Processing the exposed substrate based on the photosensitive pattern;
A device manufacturing method including: Forming a photosensitive pattern on a substrate using the exposure apparatus according to claim 12;
Processing the exposed substrate based on the photosensitive pattern;
A device manufacturing method including:

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