JP2007317862A - Aligner and exposure method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aligner capable of accurately and rapidly performing auto-focusing, while stabilizing and miniaturing the apparatus, and to provide an exposure method. <P>SOLUTION: The aligner 1 includes a projection optical system 3, including a DMD 9 and radiating a light-dark pattern for focusing onto the surface of a substrate 2; an FFT analyzer 28 for determining the focusing position of the projection optical system 3, based on the contrast of the light-dark pattern for focusing between the focus front side position anterior to a focusing surface, positioned at an optically conjugated position with the front surface of the substrate 2 and a focus rear side position posterior to the focusing surface; and a stage driver 26 for adjusting a distance between the projection optical system 3 and the substrate 2, so as to allow the focus of the projection optical system 3 to coincide to the focusing position. The projection optical system 3 generates the desired exposure pattern by the DMD 9 so as to expose the substrate 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exposure apparatus and an exposure method, and more particularly to an exposure apparatus and an exposure method using a spatial light modulator.

  Conventionally, in an inspection apparatus for inspecting surface defects such as semiconductor devices, even if the distance between the optical system and the substrate is slightly changed due to the higher magnification and higher NA of the optical system accompanying the miniaturization of the pattern. There was a problem that the image was blurred. In order to solve this problem, various autofocus techniques have been proposed.

  FIG. 7 shows the principle of height measurement based on triangulation that is generally widely used. The reflected light of the laser beam irradiated onto the substrate to be measured by the laser 29 forms an image on the photoelectric surface of a detector 31 such as a position detection element called PSD (Position Sensitive Detector), a split photodiode, or a CCD sensor. Is done. For example, if the height of the substrate is displaced from the position A to the position B, the irradiation position of the laser beam on the sensor moves from a to b, so that the displacement of the substrate can be detected.

  However, since the method shown in FIG. 7 is a method of detecting the height of only one point irradiated with laser light, there is a problem that it is easily affected by a complicated pattern or an edge. Further, when a thin film is attached on the substrate, there is a disadvantage that the amount of reflected light is lost due to interference at a specific incident angle and film thickness. Furthermore, in the case of a transparent substrate such as glass, both the reflected light from the front surface and the reflected light and scattered light from the back surface reach the detector 31 and the height measurement accuracy is significantly impaired. It cannot be applied to auto-focusing of substrates.

  Therefore, for example, in Non-Patent Document 1, a stripe pattern is irradiated on a pattern to be inspected, and the stripe pattern is shifted by an equal distance from the focal plane of the objective lens to the front and rear in the optical axis direction. A pattern inspection apparatus is described in which auto-focusing is performed by detecting each with an image sensor and detecting the defocus direction from the difference between these contrasts. In such a method for detecting the contrast of an image, height information of only one specific point is not detected, so that it is not easily affected by a pattern or an edge. Even in the case of a transparent substrate, the reflected light from the back side that is greatly deviated from the focal position of the objective lens has no contrast, so only the reflected light from the focused surface is used for contrast detection. .

On the other hand, even in an exposure apparatus that exposes a semiconductor device substrate, defocusing occurs due to variations in optical component characteristics, substrate warpage, thickness variations, etc., and a uniform pattern cannot be obtained on the substrate. There was a problem. For this reason, an exposure apparatus that provides a focusing optical system in addition to the exposure optical system and performs focus correction using the focusing optical system has been proposed.
Shunji Maeda and two others, “Development of Autofocus by Stripe Pattern Projection Contrast Detection Method”, Proceedings of the Spring Meeting of the 1993 Precision Engineering Society Spring Meeting, p. 977-978

  However, in the above exposure apparatus, since the exposure optical system and the focusing optical system are separately provided, the configuration of the apparatus becomes complicated, and it is difficult to stabilize and downsize the apparatus, and adjustment is troublesome. There was a problem of hanging.

  Accordingly, the present invention provides an exposure apparatus and an exposure method capable of performing autofocus accurately and at high speed even on a transparent substrate on which complicated patterns and edges are scattered while achieving stabilization and miniaturization of the apparatus. The challenge is to do.

  In order to solve the above-mentioned problem, the invention described in claim 1 is an exposure apparatus, comprising a spatial light modulation means for modulating the output light of the light source in accordance with pattern information, and a spatial light / dark pattern for focusing is generated by the spatial light modulation means. A projection optical system formed and projected onto the surface of the substrate; a focal front position ahead of the focal plane at a position optically conjugate with the substrate surface; and a focal back side behind the focal plane A focus position determining means for determining a focus position of the light projecting optical system based on the contrast of the focus light / dark pattern, and a focus of the light projecting optical system so as to coincide with the focus position. Adjusting means for adjusting the distance between the light projection optical system and the substrate, the light projection optical system forms a desired exposure pattern in the spatial light modulation means, and the surface of the substrate is formed by the exposure pattern. To be exposed And butterflies.

  A second aspect of the present invention is the exposure apparatus according to the first aspect, wherein the exposure apparatus includes a photoelectric conversion element that receives reflected light on the surface of the substrate and converts the reflected light into an electric signal so that the focal point is focused at the front focal position. And a second imaging unit that has the photoelectric conversion element and is placed so as to be in focus at the rear focal position, wherein the in-focus position determination unit is the first imaging unit. Focusing of the light projecting optical system is performed by obtaining a position where the contrast of the two matches based on the focus light / dark pattern imaged on the first image pickup means and the focus light / dark pattern imaged on the second image pickup means. The position is determined.

  A third aspect of the present invention is the exposure apparatus according to the second aspect, wherein the projection optical system includes an objective lens, and the objective lens forms an image of a focus light / dark pattern or an exposure pattern on the substrate, An imaging optical system for forming a focusing bright / dark pattern or an exposure pattern on one or both imaging surfaces of the first imaging unit and the second imaging unit is configured.

  Invention of Claim 4 is the exposure apparatus as described in any one of Claims 1-3, Comprising: The said light projection optical system is the light / dark pattern or exposure pattern for a focus formed by the said spatial light modulation means A relay lens for correcting the magnification of the lens is provided.

  The invention according to claim 5 is an exposure method, wherein a projection optical system including a spatial light modulation means for modulating output light of a light source according to pattern information is used, and the spatial light modulation means is used for focusing. A bright and dark pattern is formed and projected onto the surface of the substrate, and a front focal position on the front side of the focal plane that is optically conjugate with the surface of the substrate, and a rear focal position on the rear side of the focal plane, Between the light projecting optical system and the light projecting optical system so that a focus position of the light projecting optical system coincides with the focus position. After adjusting the distance from the substrate, the projection optical system is used, a desired exposure pattern is formed in the spatial light modulator, and the surface of the substrate is exposed by the exposure pattern.

  A sixth aspect of the present invention is the exposure method according to the fifth aspect, wherein the first imaging means having a photoelectric conversion element that receives reflected light on the surface of the substrate and converts it into an electrical signal is provided at the front focal position. And the second imaging means having the photoelectric conversion element is placed so as to be in focus at the rear focus position, and is focused on the first imaging means. The in-focus position of the light projecting optical system is determined by obtaining a position where the contrast of the two matches based on the pattern and the contrast bright / dark pattern imaged on the second image pickup means.

  A seventh aspect of the invention is the exposure method according to the sixth aspect of the invention, wherein an objective lens is used as the light projecting optical system, and a focusing light / dark pattern or an exposure pattern is formed on the substrate by the objective lens. The objective lens is used as an imaging optical system for forming a focus light / dark pattern or an exposure pattern on one or both imaging surfaces of the first imaging unit and the second imaging unit. And

  Invention of Claim 8 is the exposure method as described in any one of Claims 5-7, Comprising: The light-and-dark pattern or exposure pattern for a focus formed in the said light projection optical system by the said spatial light modulation means A relay lens for correcting the magnification is provided.

  According to the first or fifth aspect of the invention, it is possible to perform autofocus at high speed based on the contrast of the focus light / dark pattern between the focus front position and the focus back position. In addition, it is possible to form both the focus light / dark pattern and the exposure pattern in the spatial light modulation means, and since a common light projecting optical system is used during autofocus and during exposure, the stability of the apparatus is improved. And miniaturization can be achieved.

  According to the invention of claim 2 or claim 6, by determining the in-focus position of the light projecting optical system based on the contrast of the focus light / dark pattern of the first image pickup means and the second image pickup means, Since it is possible to obtain information on the shift amount and the shift direction of the focal position at the time of defocusing, it is possible to perform autofocus precisely and at high speed.

  According to the invention of claim 3 or claim 7, by using the objective lens of the light projecting optical system also as the image forming optical system, there is no deviation of the optical axis between the light projecting optical system and the image forming optical system. In either one or both of the first image pickup means and the second image pickup means, it is possible to accurately observe the focus light / dark pattern and the exposure pattern.

  According to the fourth or eighth aspect of the invention, by performing magnification correction with the relay lens of the light projecting optical system, it is possible to form the focus light / dark pattern or the exposure pattern on the substrate at a desired magnification. Become. Further, the distance between the relay lens and the substrate can be adjusted by correcting the magnification of the relay lens, and the degree of freedom in designing the light projecting optical system can be increased.

(overall structure)
As shown in FIG. 1, an exposure apparatus 1 according to the present embodiment projects a light projection optical system 3 that projects an exposure pattern onto a substrate 2 at the time of exposure, and projects a focus light / dark pattern onto the substrate 2 at the time of autofocus and reflects the reflected light. A focusing optical system 4 that forms an image of light, and the optical system for projecting the focus light / dark pattern on the substrate 2 in the focusing optical system 4 has the same configuration as the light projecting optical system 3. It has become.

(Detailed configuration)
The light projecting optical system 3 projects an exposure pattern onto the surface of the substrate 2. The substrate 2 of the present embodiment may be a transparent substrate having a thickness dimension of about 0.4 mm. The surface of the substrate 2 is coated with a photoresist that is sensitive to short-wavelength light such as blue light or ultraviolet light, and there is no problem even if the back surface is a sand surface. The substrate 2 is placed on a stage (not shown).

  As shown in FIG. 1, the projection optical system 3 includes an exposure light source 5, a collimator lens 6, mirrors 7 and 8, a DMD (Digital Micro-mirror Device) 9 as a spatial light modulation means, a mirror 10, and a relay lens. 11 and the objective lens 12, the output light of the exposure light source 5 is made incident on the DMD 9 via the collimator lens 6, and the reflected light from the DMD 9 is sent to the substrate 2 via the relay lens 11 and the objective lens 12. It is made to inject into.

  Among these, the exposure light source 5 is a light source that outputs short-wavelength light such as photosensitive blue light or ultraviolet light, and includes a laser, an LED, a lamp, and the like.

  The collimator lens 6 shapes the output light of the exposure light source 5 into parallel light, and the mirrors 7 and 8 allow the transmitted light of the collimator lens 6 to enter the DMD 9.

  In addition, the DMD 9 is formed as a single panel by laying fine mirror elements on a semiconductor element in a lattice pattern, and each mirror independently changes the tilt angle, so that the exposure light source 5 The projection of output light can be turned on / off. A controller 27 (see FIG. 2) is electrically connected to the DMD 9 so that light can be reflected from a mirror at a predetermined position in the DMD 9. Thereby, DMD9 which comprises the light projection optical system 3 can project and form a desired exposure pattern with a mirror.

  In this embodiment, the DMD 9 is used as the spatial light modulation means, but a liquid crystal panel, a light emitting diode array, a magneto-optical effect, or the like can be used as the spatial light modulation means.

  Further, the mirror 10 is adapted to make the reflected light from the DMD 9 enter the relay lens 11. The relay lens 11 corrects the magnification of the exposure pattern or the focus light / dark pattern formed by the DMD 9. For example, when a focus light / dark pattern or exposure pattern formed by the DMD 9 is projected onto the substrate 2, the mirror of the DMD 9 has a side of 13.68 μm and is projected by the projection optical system 3 at a size of 1/10. Then, the size of one side is 1.368 μm on the surface of the substrate 2, but by correcting the magnification with the relay lens 11, it becomes possible to perform reduction projection with a size of one side of 1.0 μm. In addition, the distance between the relay lens 11 and the substrate 2 can be adjusted by correcting the magnification of the relay lens 11, and the design flexibility of the light projecting optical system 3 can be increased.

  The objective lens 12 condenses the light transmitted through the relay lens 11 on the surface of the substrate 2.

  On the other hand, the focusing optical system 4 projects a focusing light / dark pattern on the surface of the substrate 2 and receives the reflected light.

  As shown in FIG. 1, the focus optical system 4 includes a focus light source 13, a collimator lens 14, a half mirror 15, mirrors 7 and 8, DMD 9, mirror 10, relay lens 11, objective lens 12, half mirror 16, and filter. 17, an imaging lens 18, a half mirror 19, and CCDs 20 and 21. Of these, the optical system for projecting the focus light / dark pattern onto the substrate 2, that is, the mirrors 7, 8, DMD 9, mirror 10, relay lens 11, and objective lens 12 have the same configuration as the light projecting optical system 3.

  With such a configuration, the focusing optical system 4 causes light to be incident on the DMD 9 from the focusing light source 13 via the collimator lens 14, and the reflected light from the DMD 9 is applied to the substrate 2 via the relay lens 11 and the objective lens 12. Incident light is reflected, and the reflected light from the substrate 2 is imaged on the CCD 20 or the CCD 21 via the filter 17 and the imaging lens 18.

  Among them, the focus light source 13 is a light source that outputs light having a long wavelength that is not exposed to light by the resist, and is configured by, for example, a red light emitting diode.

  The collimator lens 14 shapes the output light of the focus light source 13 into parallel light, and the half mirror 15 enters the mirrors 7 and 8 with the optical axis of the transmitted light of the collimator lens 14 being coaxial with the optical axis of the exposure light source 5. It is supposed to let you.

  The DMD 9 constituting the focusing optical system 4 forms a stripe pattern as a focusing light / dark pattern with a fine micromirror, and projects the reflected light from the mirrors 7 and 8 as a stripe pattern. It has become. The DMD 9 constituting the focusing optical system 4 may form a pattern similar to the exposure pattern as the focus light / dark pattern.

  The mirror 10 causes the reflected light from the DMD 9 to enter the relay lens 11, and the relay lens 11 corrects the magnification of the reflected light from the DMD 9. The objective lens 12 condenses the light transmitted through the relay lens 11 on the surface of the substrate 2.

  The objective lens 12 of the light projecting optical system 3 also serves as an imaging optical system that forms an image on the imaging surfaces of the CCD 20 and the CCD 21 using the reflected light of the substrate 2 as focusing light. The reflected light passes through the objective lens 12 again and enters the half mirror 16.

  Further, the half mirror 16 reflects the light incident from the objective lens 12 so as to enter the filter 17, and the filter 17 transmits only the light having a long wavelength among the reflected light and enters the imaging lens 18. ing.

  The CCD 20 and the CCD 21 are photoelectric conversion elements that receive light from the focusing optical system 4 and convert it into an electrical signal. The CCD 20 receives light that has passed through the half mirror 19 among the light transmitted through the imaging lens 18, and the CCD 21 receives light that has been reflected by the half mirror 19 among the light transmitted through the imaging lens 18. . The CCD 20 and the CCD 21 serve not only as a focus light / dark pattern but also as an image pickup means when observing an exposure pattern.

  Here, the CCD 20 and the CCD 21 are placed at positions shifted by an equal distance from the position (line b) conjugate with the focal position of the objective lens 12 in the optical axis direction. That is, as shown in FIG. 1, the CCD 20 is installed so that the photocathode is in focus at a focal front position (line a) that is in front of the focal plane that is optically conjugate with the surface of the substrate 2, The CCD 21 is installed so that the photocathode is in focus at a focus rear side position (line c) located behind the focal plane.

  Note that a control device 22 (see FIG. 2) such as a personal computer is connected to the exposure apparatus 1 via a network that can communicate with each other, and various instruction signals are transmitted to each component of the exposure apparatus 1. It has become.

(Control configuration)
Next, FIG. 2 shows a control block diagram of the exposure apparatus 1 according to the present embodiment.

  As shown in FIG. 2, the exposure apparatus 1 includes a control device 22. The control unit 23 included in the control device 22 includes a CPU (Central Processing Unit), a RAM (Random Access Memory) composed of a rewritable semiconductor element, and a ROM (Read Only Memory) composed of a nonvolatile semiconductor memory. The processing program recorded in the ROM is expanded in the RAM, and the processing program is executed by the CPU. Further, the control device 22 is provided with an input unit 24 and a storage unit 25 that are electrically connected to the control unit 23.

  The control device 22 is connected to a stage drive unit 26, a controller 27 for controlling the DMD 9, a CCD 20, a CCD 21, and an FFT analysis unit 28 as a focus position determining means.

  The input unit 24 includes a keyboard, a mouse, a touch panel, and the like, and is capable of inputting instructions by the user.

  The storage unit 25 is a recording memory made up of a semiconductor memory or the like, and has a recording area for recording information input from the input unit 24. The storage unit 25 may be, for example, a built-in memory such as a flash memory, a removable memory card or a memory stick, or a magnetic recording medium such as a hard disk or a floppy (registered trademark) disk. .

  The stage driving unit 26 adjusts the position of the substrate 2 by controlling the vertical movement and inclination of a stage (not shown) that supports the substrate 2. In particular, the stage drive unit 26 of the present embodiment moves the stage up and down so that the position of the substrate 2 coincides with the in-focus position (line B) of the objective lens 12 determined by the FFT analysis unit 28. It functions as an adjusting means for adjusting the distance between the optical system 4 and the substrate 2.

  In this embodiment, the position of the substrate 2 is moved by driving the stage. However, the distance between the focusing optical system 4 and the substrate 2 is adjusted by moving the focusing optical system 4. Is also possible.

  Further, the stage driving unit 26 sequentially moves the exposure area divided on the substrate by the movement of the stage to an area where pattern projection is possible.

  The controller 27 controls ON / OFF of the exposure light source 5 and the focus light source 13 and controls the tilt angle of the mirror included in the DMD 9 based on the instruction signal from the control unit 23. Thereby, a desired exposure pattern is formed in the DMD 9 as the light projecting optical system 3, and a stripe pattern as a focus light / dark pattern is formed in the DMD 9 as the focus optical system 4.

The CCD 20 and the CCD 21 receive reflected light from the surface of the substrate 2 at a predetermined timing under the control of the control unit 23 and convert it into an electrical signal, and transmit the electrical signal to the FFT analysis unit 28 as image data. Yes.

The FFT analysis unit 28 functions as a focus position determination unit, and is located in front of the focal plane at a position optically conjugate with the surface of the substrate 2, and behind the focal plane. The in-focus position of the light projecting optical system 3 is determined based on the contrast of the focus light / dark pattern with the rear focus side position. In the present embodiment, the following FFT analysis is performed on the stripe patterns received by the CCD 20 and the CCD 21 to obtain the in-focus position (line B) of the objective lens 12 and output it to the control unit 23. .

  Here, the FFT analysis performed by the FFT analyzer 28 will be described in detail. The FFT analysis unit 28 obtains a position where the contrasts of the CCD 20 and the CCD 21 are equal based on the received light intensity distribution of the stripe pattern received by the CCD 20 and the CCD 21, and thereby determines the focus position (line B) of the substrate 2. It has become.

  That is, in the exposure apparatus 1 according to the present embodiment, as shown in FIG. 1, the CCD 20 is installed so that the photocathode coincides with the line a, and the CCD 21 is arranged so that the photocathode coincides with the line c.

  FIG. 3 shows an example of the received light intensity distribution of the stripe pattern received by the CCD 20 and the CCD 21. As shown in FIG. 3, the line “a” on which the photocathode of the CCD 20 is placed is conjugate with the focal back position C of the objective lens 12, and the maximum contrast is obtained in the CCD 20 when the substrate 2 is at the position of the line C. As a result, the contrast gradually decreases as the position of the substrate 2 moves from C to A. On the other hand, the line c on which the photocathode of the CCD 21 is placed is conjugate with the pre-focus position A of the objective lens 12, and the maximum contrast is obtained when the substrate 2 is at the position of the line A. As it moves from A to C, the contrast gradually decreases.

  Therefore, it is possible to obtain the in-focus position (line B) of the objective lens 12 by searching for a position where the contrast of the CCD 20 and the CCD 21 becomes equal as shown in FIG. Become.

  FIG. 4 shows the contents of signal processing performed by the FFT analysis unit 28. Each stripe pattern received by the CCD 20 and the CCD 21 is converted into sinusoidal one-dimensional data by projection processing for integrating pixel values in the direction along the stripe. By applying FFT processing to this one-dimensional data, a signal intensity of a spectral component that matches the spatial frequency of the stripe pattern, that is, a direct current (DC) component corresponding to the average value of the amplitude and received light intensity of sinusoidal data is obtained. From these ratios, the contrast value of the received stripe pattern is calculated. The integration process by projection corresponds to obtaining the average value of the contrast over the entire image, and therefore has the effect of reducing the influence of the pattern and edge on the substrate 2. Also, unnecessary components such as scattered light can be effectively removed by combining the averaging process by projection and the FFT process.

Next, the in-focus position of the substrate 2 is obtained based on the respective contrasts of the stripe patterns received by the CCD 20 and the CCD 21. The horizontal axis of the graph shown in FIG. 5 is the position of the substrate 2, respectively the curve _{C 1} and curve _{C 2,} show the change in contrast values obtained by CCD 21, CCD 20. The curve C ₃ is a difference between the curve C ₂ and the curve C ₁ , and becomes a signal (error signal) that changes in an S shape in accordance with the positional deviation of the substrate 2.

Since the focal position (line B) of the objective lens 12 is positioned between the front focal position (line A) and the rear focal position (line C), the contrast between the CCD 20 and the CCD 21 when the substrate 2 comes to the in-focus position. The values are equal. Therefore, the in-focus position can be detected by searching for the position of the substrate 2 where the error signal becomes zero by the stage drive. Further, paying attention to the sign of the curve C _3, or the substrate 2 is in or after the focus position for understood instantaneously, can be realized high-speed auto focus control.

(Exposure method)
Next, an exposure method using the exposure apparatus 1 will be described with reference to FIG.

  First, the substrate 2 is placed on a stage (not shown). Subsequently, the substrate 2 is moved by stage driving so that the exposure pattern is projected from the DMD 9 to a desired position on the substrate 2 (step S1).

  Next, an autofocus process is performed (step S2). First, as shown in FIG. 1, the CCD 20 is installed so that the imaging plane coincides with the line a, and the CCD 21 is installed so that the imaging plane coincides with the line c.

  Subsequently, the controller 27 forms a stripe pattern as a focus light / dark pattern in the DMD 9 and turns on the focus light source 13. When the focus light source 13 outputs light having a long wavelength that the resist does not sensitize, the output light is shaped into parallel light by the collimator lens 14 and is made coaxial with the optical axis of the output light of the exposure light source 5 by the half mirror 15. Reflected by mirrors 7 and 8 and incident on DMD 9.

  Subsequently, when the stripe pattern is reflected by the mirror of the DMD 9, the stripe pattern is reflected by the mirror 10, corrected for magnification by the relay lens 11, and projected from the objective lens 12 onto the surface of the substrate 2.

  Subsequently, when a stripe pattern is projected onto the surface of the substrate 2, the reflected light of the substrate 2 is again transmitted through the objective lens 12 and enters the half mirror 16. Subsequently, the half mirror 16 causes the reflected light to enter the filter 17 as focusing light. Subsequently, the filter 17 transmits only the long-wavelength light out of the focusing light and makes it enter the imaging lens 18.

  Subsequently, the CCD 20 receives the light transmitted through the imaging lens 18, and the CCD 21 receives the light reflected by the half mirror 19 among the light transmitted through the imaging lens 18.

  Next, the FFT analysis unit 28 determines the in-focus position (line B) of the substrate 2 by performing the above-described FFT analysis on the stripe pattern received by the CCD 20 and the CCD 21, and sends the analysis result to the control unit 23. Output.

  Subsequently, the stage drive unit 26 moves the substrate 2 to the in-focus position determined by the FFT analysis unit 28 according to the instruction signal from the control unit 23.

  Next, the controller 27 forms a desired exposure pattern in the DMD 9 (step S3), and turns on the exposure light source 5 (step S4). When the exposure light source 5 outputs light having a short wavelength for exposure, the output light is shaped into parallel light by the collimator lens 14, passes through the half mirror 15, is reflected by the mirrors 7 and 8, and enters the DMD 9.

  Subsequently, when the exposure pattern is reflected by the mirror of the DMD 9, the exposure pattern is reflected by the mirror 10, corrected for magnification by the relay lens 11, and projected from the objective lens 12 onto the surface of the substrate 2. Thereby, the board | substrate 2 is exposed by a desired exposure pattern. In this way, by repeating the processing of step S1 to step S4, autofocus and exposure processing are performed.

  As described above, according to this embodiment, it is possible to perform autofocus at high speed based on the contrast of the focus light / dark pattern between the front focus position and the focus rear position. Further, it is possible to form both the focus light / dark pattern and the exposure pattern in the DMD 9, and since the common light projecting optical system 3 is used for the auto focus and the exposure, the apparatus can be stabilized. It is possible to reduce the size.

  Further, by determining the focus position of the light projecting optical system 3 based on the contrast of the focus light / dark pattern between the CCD 20 and the CCD 21, information on the shift amount and the shift direction of the focal position at the time of defocusing can be obtained. Therefore, it becomes possible to perform autofocus precisely and at high speed.

  Further, by using the objective lens 12 of the light projecting optical system 3 as an image forming optical system that forms an image of the reflected light of the substrate 2 on the image forming surfaces of the CCD 20 and the CCD 21, The optical axis shift from the optical system is eliminated, and it is possible to accurately observe the focus light / dark pattern and the exposure pattern in both the CCD 20 and the CCD 21.

  Further, by performing magnification correction with the relay lens 11 of the light projecting optical system 3, it becomes possible to form a focus light / dark pattern or an exposure pattern on the substrate 2 at a desired magnification. In addition, the distance between the relay lens 11 and the substrate 2 can be adjusted by correcting the magnification of the relay lens 11, and the design flexibility of the light projecting optical system 3 can be increased.

  The exposure apparatus 1 of the present embodiment has a configuration in which the exposure light source 5 and the focus light source 13 are separately provided. However, both the exposure light source 5 and the focus light source 13 may be incorporated in the bundle fiber. Is possible. In this case, blue light and red light are mixed and incident on the DMD 9. The blue light output from the exposure light source 5 is cut by the filter 17 in the focusing optical system 4.

  Further, in the exposure apparatus 1 of the present embodiment, the contrast of the entire field of view is observed. If the substrate 2 is tilted, the contrast value of the received image differs between the vicinity of the center of the field of view and the vicinity of the outer periphery. . Therefore, it is possible to correct the tilt of the substrate 2 by providing a tilt adjusting mechanism on the stage and performing tilt adjustment until the contrast value is uniform over the entire field of view.

  As described above in detail, according to the exposure apparatus and the exposure method of the present invention, it is possible to perform autofocus precisely and at high speed.

It is a schematic block diagram of the exposure apparatus which concerns on this embodiment. It is a block diagram which shows the functional structure of the exposure apparatus which concerns on this embodiment. It is a table | surface which shows the light reception intensity distribution of the stripe pattern in CCD which concerns on this embodiment. It is a graph which shows the spatial frequency spectrum of a stripe pattern. It is a graph which shows the contrast curve of a stripe pattern. It is a flowchart which shows the exposure apparatus which concerns on this embodiment. It is the figure which showed the autofocus by the conventional triangulation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exposure apparatus 2 Board | substrate 3 Light projection optical system 4 Optical system for focus 5 Light source for exposure 6 Collimator lens 7, 8 Mirror 9 DMD
DESCRIPTION OF SYMBOLS 10 Mirror 11 Relay lens 12 Objective lens 13 Focusing light source 14 Collimator lens 15, 16 Half mirror 17 Filter 18 Imaging lens 19 Half mirror 20, 21 CCD
22 control device 23 control unit 24 input unit 25 storage unit 26 stage drive unit 27 controller 28 FFT analysis unit

Claims (8)

A light projecting optical system comprising a spatial light modulation means for modulating the output light of the light source according to the pattern information, forming a bright and dark pattern for focusing by the spatial light modulation means, and projecting it on the surface of the substrate;
Based on the contrast of the focus light / dark pattern between the front focal position before the focal plane that is optically conjugate with the surface of the substrate and the rear focal position behind the focal plane. Focusing position determining means for determining a focusing position of the light projecting optical system;
Adjusting means for adjusting the distance between the projection optical system and the substrate so that the focal point of the projection optical system coincides with the in-focus position;
The light projection optical system forms a desired exposure pattern in the spatial light modulator and exposes the surface of the substrate with the exposure pattern. A first imaging means that has a photoelectric conversion element that receives reflected light from the surface of the substrate and converts it into an electrical signal, and is placed so as to be in focus at the front focal position; and the photoelectric conversion element, Second imaging means installed so as to be in focus at the back focal position,
The in-focus position determining means obtains a position where the contrast of the two matches based on the focus light / dark pattern imaged on the first image pickup means and the focus light / dark pattern imaged on the second image pickup means. The exposure apparatus according to claim 1, wherein an in-focus position of the light projecting optical system is determined by the step.   The projection optical system includes an objective lens, and the objective lens forms an image of a focus light / dark pattern or an exposure pattern on the substrate, and one or both of the first imaging unit and the second imaging unit. 3. An exposure apparatus according to claim 2, wherein an image forming optical system for forming a focus light / dark pattern or an exposure pattern on the image forming surface is formed.   4. The exposure according to claim 1, wherein the light projecting optical system includes a relay lens that corrects the magnification of a focus light / dark pattern or an exposure pattern formed by the spatial light modulator. 5. apparatus. Using a light projection optical system provided with spatial light modulation means for modulating the output light of the light source according to the pattern information, forming a bright and dark pattern for focusing by the spatial light modulation means and projecting it on the surface of the substrate,
Based on the contrast of the focus light / dark pattern between the front focal position before the focal plane that is optically conjugate with the surface of the substrate and the rear focal position behind the focal plane. Determining the in-focus position of the projection optical system;
After adjusting the distance between the projection optical system and the substrate so that the focal point of the projection optical system coincides with the in-focus position,
An exposure method using the projection optical system, forming a desired exposure pattern in the spatial light modulation means, and exposing the surface of the substrate with the exposure pattern. First imaging means having a photoelectric conversion element that receives reflected light on the surface of the substrate and converts it into an electrical signal is placed so as to be in focus at the front focal position, and a second imaging having the photoelectric conversion element. The means is installed so that it is in focus at the rear focus position,
Based on the focus light / dark pattern imaged on the first image pickup means and the focus light / dark pattern imaged on the second image pickup means, a position where both contrasts coincide with each other is obtained. 6. The exposure method according to claim 5, wherein a focusing position is determined.   An objective lens is used as the light projecting optical system, and a focus bright / dark pattern or an exposure pattern is formed on the substrate by the objective lens, and the objective lens is used for the first imaging means and the second imaging means. 7. The exposure method according to claim 6, wherein the exposure method is used as an imaging optical system for forming an image of a focus light / dark pattern or an exposure pattern on either or both imaging surfaces. 8. The exposure according to claim 5, wherein the projection optical system is provided with a relay lens for correcting a magnification of a focus light / dark pattern or an exposure pattern formed by the spatial light modulation unit. 9. Method.

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