JP7780993B2 - Exposure apparatus and exposure position measuring method - Google Patents

Description

The present invention relates to an exposure device that forms a pattern using an array of light modulation elements such as a DMD (Digital Micro-mirror Device), and in particular to detecting the exposure position.

In a maskless exposure device, a stage carrying a substrate is moved while a pattern of light is projected onto the substrate using a light modulation element array such as a DMD. During this type of exposure operation, the position of the substrate is detected in accordance with the movement of the stage, and light modulation elements such as micromirrors are controlled to project pattern light according to the position of the area to be projected (exposure area) of the pattern light.

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., or fluctuations in the fixed position of the exposure optical system caused by repeated exposure operations, deviations can occur in the projection position of the pattern light, resulting in errors in pattern formation.

To correct this exposure position deviation, a method is known in which multiple bar-shaped position detection pattern lights are scanned to detect the exposure position deviation (see Patent Document 1). In this method, a slit is formed next to the drawing surface, and multiple bar-shaped pattern lights with a width greater than the slit width are scanned in succession. The exposure position is then measured (calculated) based on the light intensity distribution output in time series from a photosensor that receives the pattern light that passes through the slit, and the exposure position deviation is corrected.

JP 2015-142036 A

In recent years, there has been a growing demand for finer patterns, even in maskless exposure equipment. 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.

Therefore, there is a need for exposure devices equipped with light modulation element arrays that are able to measure the exposure position with greater accuracy.

The exposure apparatus of the present invention comprises a mask for measuring the exposure position, which has multiple light-transmitting sections arranged one- or two-dimensionally by dividing it into a grid pattern; an exposure unit that projects one- or two-dimensional grid-like pattern light from a light modulation element array onto the mask to form a one- or two-dimensional moiré image; and a position measurement unit that measures the exposure position using the moiré method based on output signals from an imaging unit or photosensor that receives light that has passed through the multiple light-transmitting sections.

The exposure position measurement mask can form multiple light-transmitting areas arranged in a one- or two-dimensional matrix by forming grid-shaped light-blocking areas. A one- or two-dimensional grid-shaped pattern light is formed when the light (light beam) projected onto the exposure position measurement mask is a one- or two-dimensionally spaced pattern light. For example, a grid-shaped pattern light can be formed by regularly spaced multiple modulation element groups onto which the pattern light is projected, projecting rectangular light in one or two dimensions. By creating a difference in the pitch between the exposure position measurement mask and the grid-shaped pattern light, a moiré image can be formed. 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, etc., as long as the phase change, shift, etc. can be measured using the moiré method.

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

The position measurement unit can measure the exposure position while the exposure unit and mask are kept relatively stationary. The position measurement unit can calculate the exposure position based on, for example, a waveform-shaped brightness distribution in a moiré image or brightness values at multiple locations. The position measurement unit can also be configured to measure the exposure position based on image data obtained by the imaging unit that has been smoothed.

For example, the mask may have multiple 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. Alternatively, the exposure section may project a one-dimensional grid-like pattern of light onto the mask.

Another aspect of the present invention is a method for measuring an exposure position in a maskless exposure device. A one-dimensional or two-dimensional grid-like pattern of light is projected from a light modulation element array onto a mask for measuring the exposure position, which has a plurality of light-transmitting sections 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. The exposure position is measured 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 sections arranged one-dimensionally or two-dimensionally.

An exposure position measurement mask, one aspect of the present invention, can be installed in an exposure device equipped with a light modulation element array, and has multiple light-transmitting sections arranged one-dimensionally or two-dimensionally so as 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 light modulation element array.

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 was previously installed in the target exposure tool. Here, "pre-installed exposure position measurement mask" includes a mask that can form the above-mentioned moiré image, as well as 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.

According to the present invention, it is possible to measure the exposure position with greater accuracy in an exposure device equipped with a light modulation element array.

1 is a block diagram of an exposure apparatus according to a first embodiment. 1 is a diagram showing 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. 1A and 1B are diagrams illustrating moire images captured by an imaging unit. FIG. 4 is a diagram showing an image obtained by performing a smoothing process on a part of the moire image in FIG. 3 . 5 is a diagram showing the phase of the shift of the exposure position from the reference position for the moire image corresponding to FIG. 4. FIG. 10A and 10B are diagrams showing a mask and a mirror arrangement of a DMD that forms grid-shaped pattern light in a second embodiment. 10A and 10B are diagrams showing an example of a partial moire image formed on the light receiving surface of a photosensor;

The following describes an embodiment of the present invention with reference to the drawings.

Figure 1 is a block diagram of the exposure apparatus of the first embodiment.

The exposure apparatus 10 is a maskless exposure apparatus that forms a pattern by irradiating light onto a substrate W that has been coated or affixed with a photosensitive material such as photoresist, and the controller 30 controls the operation of the exposure apparatus 10.

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, laser diode, or discharge lamp, and is driven by a light source driver 21.

As CAD/CAM data composed of vector data and the like is input to the exposure device 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.

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

The stage 12 carrying the substrate W can be moved in the main scanning direction X and the 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) that measures the position of the stage 12 and moves the stage 12 in accordance with control signals from the controller 30.

During the exposure operation, as the stage 12 moves at a constant speed along the scanning direction X, the projection area of the entire DMD 22 (hereinafter referred to as the exposure area) 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 using multiple exposure heads.

Exposure methods include not only continuous movement, which moves at a constant speed, but also step-and-repeat, which moves intermittently. Multiple exposure (overlapping exposure), in which the projection areas during exposure shots partially overlap, is also possible. Meanwhile, highly accurate patterns can be formed by positioning multiple exposure heads relative to the stage 12 so that the exposure areas are tilted at a small angle relative to the main scanning direction X.

For example, before starting the exposure operation, such as when switching lots or after a certain amount of time has passed, a correction process is performed on the exposure start position to form a pattern in an accurate position. Specifically, the exposure head 18 projects pattern light for detecting the exposure position onto the position detection unit 28. The position calculation unit 27 then 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 on the exposure start position uses vector data or raster data for position detection.

Once the exposure position is determined by the position detection unit 28 and position calculation unit 27, which make up 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.

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 multiple 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 from the exposure head 18 onto the mask 29. The exposure position is then measured from image data of the moiré image acquired by the imaging unit 31. This is described in detail below.

Figure 2 shows the ON/OFF array of micromirrors (hereinafter referred to as the mirror array) used to form the pattern light for position measurement in the DMD 22, and the array of light-transmitting portions of the glass mask 29. First, we will briefly explain the moiré method, and then we will explain the method for generating moiré images in this embodiment.

A moiré image is an image in which interference fringes appear when regular periodic patterns are superimposed. For example, when a set of fine parallel gratings are superimposed, depending on the degree of superposition, dark fringes will appear where the light passage is blocked, and conversely, bright fringes will appear where the phase is in sync, and the phase shift will appear 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.

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, with the moiré method, it is possible to measure displacement and misalignment even with moiré images where interference fringes do not necessarily appear as stripes due to the method of measurement, etc. (In the following, moiré is said to occur in a broader sense, referring to a wide range of moiré images to which the moiré method can be applied).

Moiré patterns occur when there is a difference in the pitch of each of a set of gratings, and the period of the moiré pattern 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 a set of gratings, it is possible to adjust the period of the interference fringes.

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 hundred times) that is significantly greater than the actual amount of displacement.

In this embodiment, rather than superimposing a set of grids as in conventional moiré methods, a moiré image is formed by combining a two-dimensional periodic pattern of light (hereinafter referred to as grid pattern light) projected from the DMD 22 with a mask 29 having light-transmitting portions arranged in a two-dimensional periodic pattern. Here, to form a two-dimensional moiré image, a mask 29 having light-transmitting portions formed in a two-dimensional array (matrix) is arranged, and two-dimensional grid pattern light is formed by the DMD 22 and projected toward the light-transmitting portion-forming areas of the mask 29.

Figure 2 shows a partial arrangement of light-transmitting portions in the mask 29. The 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. The light-transmitting portions M of the mask 29 are rectangular in shape and have the same length in both the vertical and horizontal directions, forming a lattice structure in which multiple portions are regularly arranged at a set pitch P in the direction of movement of the stage 12 (X direction, Y direction).

The mask 29 is installed so that its surface position (height) is aligned with the position of the photosensitive material surface of the substrate W (Figure 1). The mask 29 is also 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 shielded from light with chrome or the like.

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

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 x P). To form two-dimensional moiré, 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 moiré of the moiré image, the magnification ratio, etc.

For example, the values of pitch P and coefficient K can be determined taking into account the need to detect the exposure position (deviation from the reference position) at a magnification of 10x to 100x or more. Pitch P can be set in the range of several micrometers to several hundred micrometers, depending on factors such as the size of the micromirror and the magnification of the imaging optical system 19.

When considering setting the magnification ratio 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 in the range K<2, K<1.5, or K<1.2. Here, K is set to a value greater than 1 (K>1), but it can also be less than 1 (K<1).

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.

The number of vertical and horizontal micromirrors that make up block B is then determined according to the size MS of block B. If 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 make up block B can be determined according to the magnification.

The position of the mask 29 relative to the DMD 22, i.e., the position of the stage 12, is determined so that a moiré image in which moiré appears two-dimensionally is formed on the light-receiving surface (field of view) of the imaging unit 31. The grid-like 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.

Figure 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.

Since 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, the period Tx of the two-dimensional moiré in the X direction and the period Ty in the Y direction are equal. The periods Tx and Ty of the two-dimensional moiré are known values determined from the design values.

Figure 4 shows an image obtained by smoothing a portion of the moiré image in Figure 3. This smoothing process allows the changes in brightness in both the X and Y directions to be represented as a waveform-shaped brightness distribution. This makes it possible to accurately detect the period of two-dimensional moiré. However, the position of the imaging surface of the imaging unit 31 may also be adjusted so that an out-of-focus moiré image such as that shown in Figure 4 can be obtained.

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. A variety of techniques can be applied as measurement methods 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 predetermined reference position (such as before shipping) and a characteristic position of the two-dimensional moiré that appears in the moiré image.

Figure 5 shows the deviation of the moiré image from the reference position, corresponding 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.

Specifically, the phase differences in the X and Y directions between a characteristic point of the two-dimensional moiré in the moiré image (for example, the pixel position with the highest brightness value) and a position determined in advance as a reference position (such as before shipping) (here, the center position of the light-receiving surface of the imaging unit 31) can be calculated as phases θx and θy from the reference position. Figure 5 shows that the exposure position in the moiré image 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.

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 deviation from the reference position on the stage 12, i.e., the exposure position, can be measured.

For example, when the phases θx and θy shown in FIG. 5 are obtained, the amount of deviation Dm in the moire image is calculated by the following equation (1).

Dm=((K×P)/(K-1))×(θ/2π)...(1)

As described above, the moiré image in which the two-dimensional moiré appears is an enlarged image of the actual exposure position deviation, so the actual exposure position deviation 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)

The exposure position can also be measured by methods other than the method described above, which uses the phase of the waveform brightness distribution in the X and Y directions. For example, multiple specific points (specific pixels) are defined along the X and Y directions in the moiré image captured by the imaging unit 31, and the brightness values of the specific points are detected.

Then, the phase of the two-dimensional moiré pattern, which represents the deviation of the exposure position in the moiré image, can be determined based on the correlation between the luminance value of a predetermined reference position and the luminance value of the detected specific point. Because two-dimensional moiré patterns are periodic in both the X and Y directions, i.e., they are images that produce wave-shaped changes in brightness, it is possible to determine the deviation of the two-dimensional moiré pattern from the reference point, as shown in Figure 5, by detecting the luminance values of an appropriate number of specific pixels.

According to this embodiment, a mask 29 for measuring the exposure position, which has a grid-shaped light-transmitting portion M, is installed in the exposure device 10, and grid-shaped pattern light is formed by controlling the DMD 22 and projected onto the mask 29. The exposure position is then measured using the moiré method based on the image data of the moiré image acquired by the imaging unit 31.

In the Moiré method, a two-dimensional lattice of light-transmitting portions M is formed on the mask 29, and a complementary lattice pattern of light is projected from the DMD 22. The lattice pitch (= K x P) of the lattice pattern of 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, making it possible to accurately measure exposure position deviations on the submicron order, even if they exceed the micron order level.

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

Alternatively, it is possible to form light-transmitting sections with different pitches P in different areas of a single mask 29, select an area where the light-transmitting sections are arranged at a pitch appropriate for the type of substrate being used and the required pattern accuracy, and then use the DMD 22 to form a grid-like pattern of light with a pitch (K x P) that matches this, and project it onto the mask 29.

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 x 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.

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

Figure 6 shows the mask 29' and the mirror arrangement of the DMD 22 that forms the grid pattern light in the second embodiment. In the second embodiment, instead of an imaging unit such as a CCD or CMOS that can acquire a moiré image as image data, a photosensor 31' that can detect 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'.

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

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). A partial moiré image can be considered a part of the moiré image in which two-dimensional moiré patterns of one period or more appear, as shown in the first embodiment.

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

Specifically, data switching (data shifting) is performed so that the exposure data for the micromirrors in block B that form the grid-like pattern light is converted into a partial moiré image that is shifted by a specified phase of the two-dimensional moiré. As a result, a partial moiré image that has been shifted by the amount of the shifted phase is formed on the light-receiving surface of photosensor 31'.

By shifting the exposure data (image shift) for the micromirrors that form this 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, just like in the first embodiment.

Figure 7 shows an example of a partial moiré image formed on the light-receiving surface of photosensor 31'. The partial moiré image shown in Figure 7 corresponds to the light intensity information of a portion of the moiré image shown in Figure 4, in which two-dimensional moiré of one or more periods appears. Because the area in which the light-transmitting portions M are formed is relatively small, moiré occurs in approximately the same position on the light-receiving surface of photosensor 31', while the light intensity changes sequentially in response to the relative movement of the grid-pattern light with respect to mask 29.

For example, if the partial moiré image shown in Figure 7 is formed by grid-pattern light transmitted through glass mask 29', the exposure mirror data can be shifted in both the X and Y directions to match the 1/4 period (π/2) of the two-dimensional moiré. By performing four mirror arrangement changes, it is possible to obtain light intensity information equivalent to the moiré image shown in Figure 4.

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

As described above, according to the second embodiment, a partial moiré image in which two-dimensional moiré of less than one period appears is formed, and partial moiré images that are sequentially phase-shifted in accordance with the phase (period) of the two-dimensional moiré are formed while the mirror arrangement is changed multiple times. This moiré method does not require the formation of a two-dimensional moiré image of one period or more, making it possible to form a moiré image with a larger magnification than in the first embodiment, and enabling the exposure position to be detected with even greater accuracy. In particular, because it relies on fixed-point observation, there is no burden on the takt time required for exposure position measurement.

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 a camera. This also simplifies the circuit configuration and improves processing speed.

In the second embodiment, the grid-like 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-forming area of the mask 29' based on the light-receiving surface size of the photosensor 31' and the moiré period. However, the reverse configuration is also possible.

That is, by providing a two-dimensional grid mask 29 with light-transmitting portions formed in the same manner as in the first embodiment, and limiting the area of the grid pattern light formed by the DMD 22, it is possible to form a partial moiré image in which the above-mentioned two-dimensional moiré of less than one period appears. Furthermore, the above-mentioned mask 29' may be disposed for the grid pattern light that forms such a partial moiré image.

Alternatively, an imaging unit 31 may be provided instead of the photosensor 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 the partial moiré image.

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. However, by performing the mirror arrangement change operation multiple times and calculating an average value, for example, it is possible to measure the exposure position with greater accuracy.

In other words, the moiré method described in the second embodiment can be applied not only to partial moiré images in which two-dimensional moiré patterns of less than one period appear, but also to moiré images in which two-dimensional moiré patterns of one period or more appear.

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 it is also possible to form a moiré image in which moiré appears only in the X or Y direction. In this case, it is possible to apply the moiré method separately to the X and Y directions and measure the exposure position.

For example, by projecting a one-dimensional grid pattern of 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 using the moiré method.

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 moiré method.

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 on which the two-dimensional grid-shaped light-transmitting portion M is formed, and one-dimensional grid pattern light for measuring the exposure position along the Y direction may be projected onto another portion.

On the other hand, 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 of light may be projected. Even in this case, by performing exposure data shifting as in the second embodiment, the exposure position in the X or Y direction can be detected with high accuracy.

In the first and second embodiments, it is assumed that masks 29 and 29' will be used as is once installed, but various masks may be installed in a detachable and interchangeable manner. This makes it possible to measure exposure positions using the moiré method even with conventional exposure equipment.

10 Exposure device 22 DMD (light modulation element array)
28 Position detection unit 29 29' Mask 31 Imaging unit 31' Photosensor

Claims (5)

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 pattern;
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 according to claim 1 , wherein a size of an area where the plurality of light transmitting portions are formed on the mask is narrower than a projection area of one-dimensional or two-dimensional grid pattern light projected from the light modulation element array. 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. 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. 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 mask into a grid-like pattern;
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 .