Exposure apparatus and exposure position measuring method

Abstract

To provide an exposure apparatus in which, in an exposure apparatus equipped with a light modulation element array, the exposure position can be measured with higher accuracy.SOLUTION: A mask 29 for measuring exposure position provided with a lattice-shaped light transmission section M is installed in the exposure apparatus 10, and a lattice-shaped pattern light is formed by control for the DMD 22 and projected onto the mask 29. Then, based on the image data of the moire image acquired in the imaging unit 31, the exposure position is measured by the moire method.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an exposure apparatus that forms a pattern using a light modulation element array such as a DMD (Digital Micro-mirror Device), and in particular to detection of an exposure position. [Background technology]

[0002] In a maskless exposure system, a pattern of light is projected onto the substrate using a light modulation element array such as a DMD while the stage carrying the substrate is moved. During this type of exposure operation, the position of the substrate is detected according to the movement of the stage, and light modulation elements such as micromirrors are controlled to project the pattern of light according to the position of the projection target area (exposure area) of the pattern of light.

[0003] For example, when forming a micron-order fine pattern on a substrate, it is necessary to accurately detect the position of the substrate. However, due to temperature changes in the DMD, etc., and fluctuations in the fixed position of the exposure optical system caused by repeated exposure operations, deviations in the projection position of the pattern light can occur, resulting in errors in pattern formation.

[0004] To correct such exposure position deviation, a method is known in which a plurality of bar-shaped patterned light beams for position detection are scanned to detect the exposure position deviation (see Patent Document 1). In this method, a slit is formed near the image plane, and a series of bar-shaped patterned light beams each with a width greater than the slit width are scanned. Then, the exposure position is measured (calculated) based on the light intensity distribution output in time series from a photosensor that receives the patterned light beams that pass through the slit, and the exposure position deviation is corrected. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-142036 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, there has been a growing demand for finer patterns in maskless exposure devices. However, there are limits to the accuracy of the exposure position measured by scanning the pattern light due to factors such as the sensitivity characteristics of the photosensor and the accuracy of the stage feed.

[0007] Therefore, in an exposure apparatus equipped with a light modulation element array, it is required to be able to measure the exposure position with higher accuracy. [Means for solving the problem]

[0008] The exposure apparatus of the present invention comprises a mask for measuring the exposure position having a plurality of light-transmitting portions arranged one-dimensionally or two-dimensionally by dividing the mask into a grid pattern, an exposure unit that projects one-dimensional or two-dimensional grid-like pattern light from an optical modulation element array onto the mask to form a one-dimensional or two-dimensional moiré image, and a position measurement unit that measures the exposure position by the moiré method based on an output signal from an imaging unit or photosensor that receives light that has passed through the plurality of light-transmitting portions.

[0009] The exposure position measurement mask can have multiple light-transmitting portions arranged in a one- or two-dimensional matrix by forming grid-shaped light-blocking portions. The one- or two-dimensional grid-shaped pattern light is formed by projecting light (light beams) onto the exposure position measurement mask in a one- or two-dimensionally spaced pattern. For example, a grid-shaped pattern light can be formed by projecting rectangular light beams one- or two-dimensionally onto a group of modulation elements at regular intervals. A moiré image can be formed by varying the pitch of the exposure position measurement mask and the grid-shaped pattern light. Note that the term "moiré image" does not only refer to an image in which one- or two-dimensional interference fringes (moiré) are at least recognizable as fringes, but also includes images that are out of focus or blurred due to smoothing processing, as long as the phase change or shift can be measured using the moiré method.

[0010] The exposure unit can project onto the mask one- or two-dimensional grid-like pattern light that forms a moiré image in which one- or two-dimensional interference fringes with less than one period appear, or the exposure unit can project onto the mask one- or two-dimensional grid-like pattern light that forms a moiré image in which interference fringes with one period or more appear.

[0011] The position measurement unit can measure the exposure position while the exposure unit and the mask are kept relatively stationary. The position measurement unit can calculate the exposure position based on, for example, a waveform-shaped luminance distribution in a moiré image or luminance values ​​at multiple locations. The position measurement unit can also be configured to measure the exposure position based on image data obtained by smoothing the image data acquired by the imaging unit.

[0012] For example, the mask may have a plurality of light-transmitting sections arranged in a two-dimensional matrix, and the exposure section may project a two-dimensional grid-like pattern of light onto the mask, or the exposure section may project a one-dimensional grid-like pattern of light onto the mask.

[0013] Another aspect of the present invention is a method for measuring an exposure position in a maskless exposure device, which projects one-dimensional or two-dimensional grid-like pattern light from an optical modulation element array onto a mask for measuring the exposure position, which has a plurality of light-transmitting portions arranged one-dimensionally or two-dimensionally by dividing the light into a grid-like pattern, thereby forming a one-dimensional or two-dimensional moiré image, and measures the exposure position by the moiré method based on the output signal from an imaging unit or photosensor that receives light that has passed through the plurality of light-transmitting portions arranged one-dimensionally or two-dimensionally.

[0014] An exposure position measurement mask, which is one aspect of the present invention, can be installed in an exposure device equipped with an optical modulation element array, and has a plurality of light-transmitting portions arranged one-dimensionally or two-dimensionally so as to be able to form a moiré image that appears one-dimensionally or two-dimensionally in response to the one-dimensional or two-dimensional grid-like pattern light formed by the optical modulation element array.

[0015] As a method for replacing such an exposure position measurement mask, it is possible to provide a method for replacing it with an exposure position measurement mask that has been installed in advance in the target exposure tool. Here, the "preset exposure position measurement mask" includes a mask that can form the above-mentioned moiré image, and an exposure position measurement mask that does not form a moiré image and has slits or the like formed in a glass mask or the like. [Effects of the Invention]

[0016] According to the present invention, in an exposure apparatus equipped with a light modulation element array, it is possible to measure the exposure position with higher accuracy. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a block diagram of an exposure apparatus according to a first embodiment. [Figure 2] FIG. 1 shows the arrangement of micromirrors that form a pattern light for position measurement in a DMD and the arrangement of light-transmitting portions of a glass mask. [Figure 3] 1A and 1B are diagrams illustrating moire images captured by an imaging unit. [Figure 4] FIG. 4 is a diagram showing an image obtained by performing a smoothing process on a part of the moire image in FIG. 3. [Figure 5] 5 is a diagram showing the phase of the shift of the exposure position from the reference position for a moiré image corresponding to FIG. 4. FIG. [Figure 6] 10 is a diagram showing a mask and a mirror arrangement of a DMD that forms grid-shaped pattern light in a second embodiment. FIG. [Figure 7] 10A and 10B are diagrams showing an example of a partial moire image formed on the light receiving surface of a photosensor; DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] FIG. 1 is a block diagram of an exposure apparatus according to the first embodiment.

[0020] The exposure apparatus 10 is a maskless exposure apparatus that forms a pattern by irradiating light onto a substrate W on which a photosensitive material such as photoresist is applied or attached, and the controller 30 controls the operation of the exposure apparatus 10.

[0021] The exposure device 10 is equipped with multiple exposure heads that project pattern light (only one exposure head 18 is shown here). The exposure head 18 comprises an illumination optical system 17, a DMD 22, and an imaging optical system 19, and constitutes an exposure unit. The light source 20 that emits the illumination light can be composed of, for example, an LED, a laser diode, a discharge lamp, etc., and is driven by a light source driver 21.

[0022] As CAD / CAM data composed of vector data and the like is input to the exposure apparatus 10, the raster conversion circuit 26 converts the vector data into raster data. The generated raster data is temporarily stored in a buffer memory (not shown) and then sent to the DMD drive circuit 24.

[0023] The DMD 22 is configured as a light modulation element array in which minute micromirrors are arranged two-dimensionally, and each micromirror selectively switches the direction of light reflection by changing its posture. The posture of each mirror is controlled in accordance with exposure data (ON / OFF data) from the DMD drive circuit 24, and light according to the pattern is projected onto the surface of the substrate W through the imaging optical system 19.

[0024] The stage 12 on which the substrate W is mounted can be moved in a main scanning direction X and a sub-scanning direction Y (hereinafter also referred to as the X direction and Y direction) by a stage driving mechanism 15. The stage driving mechanism 15 is equipped with a linear encoder (not shown) and measures the position of the stage 12, and moves the stage 12 in accordance with a control signal from a controller 30.

[0025] During the exposure operation, as the stage 12 moves at a constant speed along the scanning direction X, the projection area (hereinafter referred to as the exposure area) of the entire DMD 22 moves relatively on the substrate W in accordance with the movement of the substrate W. Each micromirror of the DMD 22 is controlled to turn on / off according to the relative position of the exposure area, and a pattern of light corresponding to the position of the exposure area is projected. The exposure operation is performed according to a predetermined exposure pitch, and the entire substrate W is imaged by the multiple exposure heads.

[0026] The exposure method can be a continuous movement method in which the head moves at a constant speed, or a step-and-repeat method in which the head moves intermittently. Multiple exposure (overlapping exposure) is also possible, in which the projection areas during exposure shots partially overlap. Meanwhile, by positioning multiple exposure heads relative to the stage 12 so that the exposure areas are tilted at a small angle with respect to the main scanning direction X, it is possible to form highly accurate patterns.

[0027] For example, before starting the exposure operation, when switching lots or a certain amount of time has passed, a correction process for the exposure start position is performed to form a pattern at an accurate position. Specifically, the exposure head 18 projects pattern light for detecting the exposure position onto the position detection unit 28. Then, the position calculation unit 27 calculates the exposure position, i.e., the relative position of the substrate W (stage 12) with respect to the exposure head 18, based on the output signal from the position detection unit 28. Note that the correction process for the exposure start position uses vector data or raster data for position detection.

[0028] When the exposure position is determined by the position detection unit 28 and the position calculation unit 27 that constitute the position measurement unit, the controller 30 corrects the exposure start position based on the exposure position information sent from the position calculation unit 27. For example, correction processing is performed on vector data. Correction processing may also be performed on raster data.

[0029] The position detection unit 28 includes a mask 29 and an imaging unit 31, and is installed and positioned at a predetermined position on the stage 12. The mask 29 has a plurality of light-transmitting sections formed by providing grid-like divisions, and an image in which interference fringes appear (hereinafter referred to as a moiré image) is formed by projecting patterned light that generates moiré onto the mask 29 from the exposure head 18. The exposure position is then measured from image data of the moiré image acquired by the imaging unit 31. This will be described in detail below.

[0030] 2 is a diagram showing the ON / OFF array of micromirrors (hereinafter referred to as the mirror array) for forming a pattern light for position measurement in the DMD 22, and the array of light-transmitting portions of the glass mask 29. First, the moiré method will be briefly explained, and then the method for generating a moiré image in this embodiment will be explained.

[0031] A moiré image is an image that shows interference fringes when regular periodic patterns are superimposed. For example, when a pair of fine parallel gratings are superimposed, depending on the degree of superposition, dark fringes appear where the light passage is blocked, and conversely, bright fringes appear where the phase is in sync, and the phase shift appears as light and dark fringes. Visually, the ratio between transparent and opaque areas resulting from the phase shift is identified as light and dark fringes, and the beat caused by the phase difference is perceived rather than individual waveforms.

[0032] By utilizing such moiré images, it is possible to measure displacement and misalignment, a process known as the moiré method. Interference fringes (moiré) are generated due to geometric interference, and the equivalent of the scale markings on a moiré image when measuring displacement is the period of the interference fringes. This is larger than the order of wavelengths (nanometers) and depends on the pitch of the periodic pattern. Furthermore, the moiré method can measure displacement and misalignment even when the moiré image does not necessarily show interference fringes as a striped pattern due to factors such as the measurement method (hereinafter, moiré is said to occur in a broader sense, covering a wide range of moiré images to which the moiré method can be applied).

[0033] Moiré patterns are generated by creating a difference in the pitch of each pair of gratings, and the period of the moiré patterns is uniquely determined by the magnitude of this difference, i.e., the difference in the number of gratings per unit distance. Therefore, by adjusting the difference in the pitch of each pair of gratings, it is possible to adjust the period of the interference fringes.

[0034] By minimizing the difference in the number of gratings per unit distance, it is possible to generate a moiré pattern with a period greater than the grating pitch. This means that the amount of displacement can be displayed and measured in the moiré image at a magnification (for example, several tens to several hundreds of times) that is significantly greater than the actual amount of displacement.

[0035] In this embodiment, instead of a configuration in which a set of gratings is superimposed as in the conventional moiré method, a moiré image is formed by combining light having a two-dimensional periodic pattern (hereinafter referred to as grating pattern light) projected from DMD 22 with mask 29 having light-transmitting portions arranged in a two-dimensional periodic pattern. Here, to form a two-dimensional moiré image, mask 29 having light-transmitting portions formed in a two-dimensional array (matrix) is arranged, and two-dimensional grating pattern light is formed by DMD 22 and projected toward the light-transmitting portion-forming areas of mask 29.

[0036] 2 shows a partial arrangement of light-transmitting portions in mask 29. Mask 29 is configured as a two-dimensional lattice that generates a moiré image in which moiré appears in two dimensions along two mutually perpendicular directions. In this case, light-transmitting portions M of mask 29 are rectangular and have the same length in both the vertical and horizontal directions, forming a lattice structure in which multiple light-transmitting portions M are regularly arranged at a predetermined pitch P in the movement directions (X direction and Y direction) of stage 12.

[0037] The mask 29 is installed so that the position (height) of its surface is aligned with the position of the photosensitive material surface of the substrate W (FIG. 1). The mask 29 is configured so that light does not pass through the gaps between adjacent light-transmitting portions M, or so that the transmittance is relatively low compared to the light-transmitting portions M. For example, the mask 29 can be configured as a glass mask with the periphery of the light-transmitting portions M being light-shielded with chrome or the like.

[0038] On the other hand, the grid-like pattern light projected from DMD 22 onto mask 29 becomes a pattern light in which the projected image is arranged in a grid pattern at a pitch (K × P) along the stage movement directions (X direction, Y direction). Each micromirror is rectangular, and the image of the grid-like pattern light becomes a pattern in which rectangular grid images are arranged regularly in the X and Y directions, similar to the arrangement of light-transmitting portions M of mask 29, but are arranged in the X and Y directions at a pitch different from that of mask 29.

[0039] The pitch of the grid pattern light image is calculated by multiplying the pitch P of the light-transmitting portions by a coefficient K (K×P). To form a two-dimensional moire pattern, the coefficient K is set to a value other than 1 (K≠1). The value of the coefficient K is determined taking into consideration the field of view of the imaging unit 31, the period of the two-dimensional moire pattern of the moire image, the magnification ratio, etc.

[0040] For example, the values ​​of the pitch P and coefficient K can be determined in consideration of detecting the exposure position (deviation from the reference position) at a magnification of 10 to 100 times or more. The pitch P can be set in the range of several μm to several hundred μm depending on the size of the micromirror, the magnification of the imaging optical system 19, etc.

[0041] Considering that the enlargement ratio should be set to as large a value as possible, the coefficient K should be set to a value relatively close to 1. For example, it can be set to a range of K<2, K<1.5, or K<1.2. Here, K is set to a value greater than 1 (K>1), but it may also be less than 1 (K<1).

[0042] Here, the magnification of the imaging optical system 19 is set to 1, and the size MS of the micromirror block B that is set to the ON state to form the light of each grating in the DMD 22 is set to match the size S of the light-transmitting portion M.

[0043] The number of vertical and horizontal micromirrors that form block B is determined according to the size MS of block B. When the magnification of the imaging optical system 19 is set to a value other than 1 (enlargement or reduction magnification), the number of micromirrors that form block B can be determined according to the magnification.

[0044] The position of the mask 29 relative to the DMD 22, i.e., the position of the stage 12, is determined to be a position where a moiré image in which moiré appears two-dimensionally is formed on the light receiving surface (field of view) of the imaging unit 31. Then, the grid pattern light from the DMD 22 is projected onto the mask 29 so that a moiré image in which moiré appears with one or more periods in both the X and Y directions can be formed on the light receiving surface of the imaging unit 31.

[0045] 3 is a diagram illustrating a moiré image captured by the imaging unit 31. Here, a moiré image of two-dimensional interference fringes is formed, with a dark area in the center of the light-receiving surface (field of view) of the imaging unit 31 and bright areas near the four corners. Note that since the grid-like pattern light is imaged on the surface of the mask 29 (=drawing surface), it is out of focus on the light-receiving surface of the imaging unit 31, but this does not substantially affect the detection of the exposure position.

[0046] The pitch P of the mask 29 and the pitch K×P of the blocks B that turn the micromirrors ON are the same in both the X and Y directions, so the period Tx of the 2D moiré in the X direction and the period Ty in the Y direction are equal. The periods Tx and Ty of the 2D moiré are known values ​​determined from the design values.

[0047] FIG. 4 shows an image obtained by smoothing a portion of the moiré image in FIG. 3. This smoothing process allows the brightness variations in both the X and Y directions to be expressed as a waveform-like brightness distribution. This makes it possible to accurately detect the period of the two-dimensional moiré. However, the position of the imaging plane of the imaging unit 31 may be adjusted so that an out-of-focus moiré image such as that shown in FIG. 4 can be obtained.

[0048] From the moiré images shown in Figures 3 and 4, the exposure position (deviation from the exposure start position) in the X and Y directions on the stage 12 can be measured using the moiré method. Various methods can be applied as measurement techniques using the moiré method. For example, it is possible to measure the exposure position by finding the correlation between the distance or phase between a reference position determined in advance (before shipping, for example) and a characteristic position of the two-dimensional moiré that appears in the moiré image.

[0049] Figure 5 shows the deviation of the moiré image from the reference position, which corresponds to Figure 4. By performing a smoothing process on the image data of the moiré image described above, the brightness changes in the X and Y directions of the two-dimensional moiré appear as a waveform (accumulated waveform). Then, by calculating the phase between the reference position and the characteristic points of the two-dimensional moiré from the waveform, the deviation from the reference position can be determined.

[0050] Specifically, the phase differences in the X and Y directions between a feature point of the two-dimensional moiré in the moiré image (for example, the pixel position with the highest brightness value) and a position (here, the center position of the light receiving surface of the imaging unit 31) that is determined in advance as a reference position (before shipping, etc.) can be found as phases θx and θy from the reference position. Figure 5 shows that the exposure position is shifted by phases θx and θy from the reference position, which is the center position of the imaging area of ​​the imaging unit 31, in the moiré image.

[0051] By determining the phases θx and θy from a reference position along the X and Y directions, the exposure position (exposure position deviation) can be calculated. Specifically, the amount of deviation from the reference position in the moiré image is calculated based on the moiré phases θx and θy. Then, from the calculated amount of deviation from the reference position, the actual amount of deviation from the reference position on the stage 12, i.e., the exposure position, can be measured.

[0052] For example, when the phases θx and θy shown in FIG. 5 are obtained, the amount of deviation Dm in the moiré image is calculated by the following equation (1). Dm=((K×P) / (K-1))×(θ / 2π) ····(1)

[0053] As mentioned above, the moiré image in which the two-dimensional moiré appears is an enlarged image of the deviation of the actual exposure position, so the deviation of the actual exposure position is calculated using the following equation (2). Then, the exposure start position is corrected based on the calculated Dm. d=-Dm(K-1)=-KP(θ / 2π) ····(2)

[0054] The exposure position can be measured by a method other than the method described above that determines it from the phase of the waveform luminance distribution in the X and Y directions. For example, a plurality of specific points (specific pixels) are determined along the X and Y directions in the moiré image captured by the imaging unit 31, and the luminance values ​​of the specific points are detected.

[0055] Then, the phase of the two-dimensional moiré, which indicates the deviation of the exposure position in the moiré image, may be determined based on the correlation between the luminance value of a predetermined reference position and the luminance value of the detected specific point. Since the two-dimensional moiré is an image that has periodicity in both the X and Y directions, i.e., produces wave-like changes in brightness, it is possible to determine the deviation of the two-dimensional moiré from the reference point as shown in Figure 5 by detecting the luminance values ​​of an appropriate number of specific pixels.

[0056] As described above, according to this embodiment, the mask 29 for measuring the exposure position, which is provided with the lattice-shaped light-transmitting portion M, is installed in the exposure apparatus 10, and the lattice-shaped pattern light is formed by controlling the DMD 22 and projected onto the mask 29. Then, based on the image data of the moiré image acquired by the imaging unit 31, the exposure position is measured by the moiré method.

[0057] In the Moiré method, a two-dimensional lattice light-transmitting portion M is formed on the mask 29, and a complementary lattice pattern light is projected from the DMD 22. The lattice pitch (= K × P) of the lattice pattern light is determined based on the lattice pitch P of the mask, and the actual exposure position deviation can be expressed in a Moiré image at the desired magnification ratio. Therefore, even if the exposure position deviation is on the submicron order, exceeding the micron order level, it can be measured with high accuracy.

[0058] In particular, the size and position of block B, which is made up of micromirrors in the ON state, can be set arbitrarily in the DMD 22. Therefore, it is possible to prepare and install multiple masks with light-transmitting sections of different pitches and project grid-like pattern light from the DMD 22 in accordance with them.

[0059] Alternatively, it is possible to form light-transmitting portions with different pitches P in different areas of a single mask 29, select an area where the light-transmitting portions are arranged at a pitch suitable for the type of substrate being used and the required pattern accuracy, etc., and form a grid-like pattern light according to the corresponding pitch (K×P) using DMD 22 and project it onto mask 29.

[0060] The imaging unit 31 captures within its field of view a moiré image in which at least one cycle of moiré appears in the X and Y directions. Therefore, it is possible to simultaneously determine the exposure position shift in both the X and Y directions from a single image data. The pitch P of the light-transmitting portions M of the mask 29 and the pitch (K × P) of the grid-like pattern light can be determined so that a moiré image in which at least one cycle of two-dimensional moiré appears can be captured.

[0061] Next, a second embodiment will be described with reference to Figures 6 and 7. In the second embodiment, the image of the two-dimensional interference fringes is moved by converting exposure data for the micromirrors that form the grid-like pattern light and moving the grid-like pattern light relative to the mask 29. Then, by fixed-point observation, image data of a phase-shifted moiré image, i.e., a moiré image in which the image is shifted by the amount of movement, is acquired multiple times to measure the exposure position.

[0062] 6 is a diagram showing a mask 29' and the mirror arrangement of a DMD 22 that forms a grid-like pattern light in the second embodiment. In the second embodiment, instead of an imaging unit capable of acquiring a moiré image as image data, such as a CCD or CMOS, a photosensor 31' capable of detecting the amount of light or illuminance as a brightness value is provided and installed below the mask 29'. In the mask 29', the formation area of ​​the light-transmitting portion M is determined to match the size of the light-receiving surface of the photosensor 31'.

[0063] In the DMD 22, a grid pattern that forms a moiré image in which two-dimensional moiré appears (for example, the moiré image shown in FIG. 5) is projected onto the mask 29′ in the same manner as in the first embodiment. Meanwhile, the formation region (see symbol R) of the light-transmitting portion M on the mask 29′ is determined according to the size of the light-receiving surface of the photosensor 31′ and the moiré period, and the size of the formation region R is narrower than the projection region of the grid pattern light projected from the DMD 22.

[0064] Therefore, the moiré image formed on the light receiving surface of the photosensor 31' is a moiré image in which two-dimensional moiré patterns of less than one period appear in both the X and Y directions (hereinafter referred to as a partial moiré image). The partial moiré image can be regarded as a part of the moiré image in which two-dimensional moiré patterns of one period or more appear, as shown in the first embodiment.

[0065] Since the partial moiré image only shows two-dimensional moiré patterns with less than one period, it is not possible to determine the exposure position deviation from that image alone. However, by performing an exposure operation (referred to here as a mirror array changing operation) that moves the two-dimensional moiré patterns relative to the light receiving surface (mask 29') of photosensor 31', image information of two-dimensional moiré patterns with more than one period can be obtained by photosensor 31'.

[0066] Specifically, data switching (data shift) is performed so that the exposure data for the micromirrors of block B that form the grid pattern light is converted into a partial moiré image shifted by a predetermined phase of the two-dimensional moiré. As a result, a partial moiré image shifted by the shifted phase is formed on the light receiving surface of photosensor 31'.

[0067] By shifting the exposure data (image shift) for the micromirror that forms such grid-like pattern light a predetermined number of times in each of the X and Y directions and performing fixed-point observation using the photosensor 31', it is possible to obtain image information of a two-dimensional moiré image with one or more periods, as in the first embodiment.

[0068] 7 is a diagram showing an example of a partial moiré image formed on the light receiving surface of photosensor 31'. The partial moiré image shown in FIG. 7 corresponds to the light intensity information of a portion of the moiré image in which two-dimensional moiré of one period or more appears, as shown in FIG. 4. Because the area in which light transmitting portion M is formed is relatively small, moiré occurs at approximately the same position on the light receiving surface of photosensor 31', while the light intensity changes sequentially in accordance with the relative movement of the grid pattern light with respect to mask 29.

[0069] For example, when the partial moiré image shown in Fig. 7 is formed by the grid-like pattern light transmitted through the glass mask 29', the exposure mirror data can be shifted in the X and Y directions in accordance with 1 / 4 period (π / 2) of the two-dimensional moiré. By changing the mirror arrangement four times, it is possible to obtain light intensity information equivalent to the moiré image shown in Fig. 4.

[0070] The photosensor 31' does not have an imaging function, but detects brightness values ​​instead of acquiring image data. Therefore, the exposure position can be measured by determining the above-mentioned multiple specific points (pixel positions) and projecting the grid-like pattern light while shifting the exposure data so that the specific points are located at the center of the light-receiving surface of the photosensor 31'. The deviation of the moiré image from the reference position can be calculated from the brightness values ​​detected by the photosensor 31' during each mirror arrangement change operation.

[0071] As described above, according to the second embodiment, a partial moiré image in which a two-dimensional moiré pattern of less than one period appears is formed, and partial moiré images are sequentially phase-shifted in accordance with the phase (period) of the two-dimensional moiré pattern while performing a mirror arrangement change operation multiple times. Since this moiré method does not require the formation of a two-dimensional moiré pattern of more than one period, it is possible to form a moiré image with a larger magnification than in the first embodiment, and the exposure position can be detected with even greater accuracy. In particular, since the method relies on fixed-point observation, there is no burden on the tact time required for exposure position measurement.

[0072] Furthermore, by installing a photosensor 31' that detects brightness values, it is possible to measure the exposure position without relying on the resolution limitations of cameras.Furthermore, the circuit configuration is simplified and processing speed can be improved.

[0073] In the second embodiment, the grid pattern light formed by the DMD 22 forms a moiré image in which two-dimensional moiré appears, as in the first embodiment, and a partial moiré image is formed by setting the grid formation area of ​​the mask 29' based on the light-receiving surface size of the photosensor 31' and the moiré period. However, the reverse configuration may also be used.

[0074] That is, it is possible to form a partial moiré image in which the above-mentioned two-dimensional moiré of less than one period appears by providing a two-dimensional grid mask 29 having light-transmitting portions formed thereon as in the first embodiment, while restricting the area of ​​the grid pattern light formed by the DMD 22. Furthermore, the above-mentioned mask 29' may be disposed for the grid pattern light that forms such a partial moiré image.

[0075] Alternatively, the photo sensor 31' may be replaced with an imaging unit 31. By performing multiple mirror arrangement changes accompanied by exposure data shifts and detecting the brightness value at the center of the light receiving surface of the imaging unit 31, it is possible to measure the exposure position from a partial moiré image.

[0076] Furthermore, it is also possible to shift the exposure data to the micromirror while capturing a moiré image in which two-dimensional moiré patterns of one or more periods appear using the imaging unit 31. In this case, the moiré image in which two-dimensional moiré patterns of one or more periods appear is moved on the exposure data light-receiving surface, and it is possible to measure the exposure position with higher accuracy by, for example, performing the mirror arrangement change operation multiple times and calculating an average value.

[0077] That is, the moiré method described in the second embodiment can be applied not only to partial moiré images in which two-dimensional moiré of less than one period appears, but also to moiré images in which two-dimensional moiré of one period or more appears.

[0078] In the first and second embodiments, a moiré image is formed in which two-dimensional moiré appears along both the X and Y directions, but a moiré image in which moiré appears only in the X or Y direction may be formed. In this case, the moiré method can be applied separately to the X and Y directions to measure the exposure position.

[0079] For example, by projecting a one-dimensional grid pattern light in which bar-shaped light extending in the X direction is arranged in the Y direction at a pitch KP onto the mask 29 or mask 29' used in the first or second embodiment, the exposure position along the Y direction can be measured by the moiré method.

[0080] Similarly, by projecting a one-dimensional grid pattern of light, in which bar-shaped light extending in the Y direction is arranged in the X direction at a pitch KP, onto mask 29 or mask 29', the exposure position along the Y direction can be measured using the moire method.

[0081] Alternatively, one-dimensional grid pattern light for measuring the exposure position along the X direction may be projected onto a portion of the glass mask 29 having the two-dimensional grid-shaped light-transmitting portion M formed thereon, and one-dimensional grid pattern light for measuring the exposure position along the Y direction may be projected onto another portion of the glass mask 29.

[0082] Alternatively, a one-dimensional grid mask (or a mask formed in different regions of a single mask) with light-transmitting portions aligned along the X or Y direction may be arranged, and a two-dimensional grid pattern light may be projected. In this case, too, the exposure position in the X or Y direction can be detected with high accuracy by performing exposure data shifting as in the second embodiment.

[0083] In the first and second embodiments, it is assumed that the masks 29 and 29' are used as they are once installed, but various masks may be installed so that they are detachable and replaceable. This makes it possible to measure the exposure position using the moire method even for conventional exposure apparatuses. [Explanation of symbols]

[0084] 10 Exposure equipment 22 DMD (Digital Modulator Array) 28 Position detection unit 29 29' Mask 31 Imaging unit 31' Photo Sensor

Claims

1. a mask for measuring exposure positions, the mask having a plurality of light transmitting portions arranged one-dimensionally or two-dimensionally by dividing the mask into a grid; an exposure unit that projects one-dimensional or two-dimensional grid pattern light from a light modulation element array onto the mask to form a one-dimensional or two-dimensional moire image; a position measurement unit that measures an exposure position by a moire method based on an output signal from an imaging unit or a photosensor that receives light that has passed through the plurality of light transmitting units, an exposure device characterized in that the exposure unit shifts exposure data for a light modulation element that forms a one-dimensional or two-dimensional grid pattern light in accordance with the phase of the one-dimensional or two-dimensional moiré image, and moves the one-dimensional or two-dimensional moiré relative to the light-receiving surface of the imaging unit or photosensor.

2. An exposure apparatus as described in Claim 1, characterized in that the size of the formation area of ​​the multiple light-transmitting portions in the mask is narrower than the projection area of ​​the one-dimensional or two-dimensional grid pattern light projected from the light modulation element array.

3. the mask has a plurality of light transmitting portions arranged in a two-dimensional matrix, 3. The exposure apparatus according to claim 1, wherein the exposure unit projects a two-dimensional grid pattern of light onto the mask.

4. the mask has a plurality of light transmitting portions arranged in a two-dimensional matrix, 3. The exposure apparatus according to claim 1, wherein the exposure unit projects a one-dimensional grid pattern of light onto the mask.

5. A one-dimensional or two-dimensional moiré image is formed by projecting one-dimensional or two-dimensional grid-like pattern light from a light modulation element array onto a mask for exposure position measurement having a plurality of light-transmitting portions arranged one-dimensionally or two-dimensionally by dividing the light into grid-like sections; An exposure position measurement method for a maskless exposure apparatus, which measures the exposure position by a moiré method based on an output signal from an imaging unit or a photosensor that receives light that has passed through the one-dimensionally or two-dimensionally arranged plurality of light-transmitting units, An exposure position measurement method for a maskless exposure apparatus, characterized in that exposure data for a light modulation element that forms one-dimensional or two-dimensional grid pattern light is shifted according to the phase of the one-dimensional or two-dimensional moiré image, and the one-dimensional or two-dimensional moiré is moved relative to the light receiving surface of the imaging unit or photosensor.

Images