JP2020112419A - Spatial optical modulation element inspection device and inspection method - Google Patents

Abstract

To provide a spatial optical modulation element inspection device and inspection method that can highly accurately and effectively inspect unevenness in illuminance of the spatial optical modulation element.SOLUTION: An inspection method according to the present invention is configured to: prepare an inspection-purpose exposure image to be obtained by inputting to the spatial optical modulation element an inspection signal in which a ratio of the number of pixels of an ON pixel of each unit pixel block and the number of pixels of an OFF pixel thereof stays constant (S1 to S3); section the inspection-purpose exposure image to a plurality of unit cells of a size equal to or more than an exposure area corresponding to the unit pixel block, and measure a binary area ratio for each unit cell (S5); compare the binary area ratio for each unit cell or a prescribed physical value having correlationship with respect to the binary area ratio with a reference value; and determine presence or absence of unevenness in illuminance of the spatial optical modulation element on the basis of a comparison result (S6).SELECTED DRAWING: Figure 4

Description

The present invention relates to an inspection device and an inspection method for a spatial light modulator that inspects the illuminance unevenness of the spatial light modulator.

A digital micromirror device (DMD), which is a type of spatial light modulator (SLM), has 2 million or more micromirrors each having a side of dozens of μm arranged in an array and provided at the bottom. By driving the electrodes, the tilt of each micromirror is individually switched to either the ON state (+about 12 degrees) or the OFF state (−about 12 degrees), and the light from the internal light source is turned on. The desired output image is formed by reflecting the light at a high resolution. Since the resolution is high, it is possible to form a fine pattern.

Therefore, the DMD has become popular as an image forming element in recent years. As an example thereof, an exposure apparatus using a DMD as an exposure engine has already been put to practical use in the field of photolithography. This type of exposure apparatus is called a maskless exposure apparatus because it can directly form a circuit pattern of a semiconductor element, a liquid crystal display panel, a plasma display panel or the like on a photoresist without using a photomask. Further, in the photomask manufacturing process, pattern exposure is also performed by an exposure device.

On the other hand, it is said that DMD is likely to cause uneven illuminance. This is because, as described above, since the micromirror has a very small structure with a side of ten and several μm, variations in signal responsiveness and mechanical accuracy are likely to occur among the micromirrors, and as a result, variations in reflection characteristics occur among the micromirrors. Is likely to occur. Then, when the illuminance becomes uneven, the pattern width becomes large where the illuminance becomes strong (see FIG. 20(b)), while the pattern width becomes small where the illuminance becomes weak (see FIG. 20(c)). ), distortion and unevenness occur in the pattern (see FIG. 21A). Since this unevenness in illuminance is at an extremely minute level, it does not pose a problem when accuracy is not required so much, but it is a problem that cannot be ignored in photolithography in which highly precise pattern formation in micron units is required.

Therefore, when the illuminance unevenness is a problem, it is necessary to inspect the presence or absence and the degree of the illuminance unevenness, and digitally correct the illuminance unevenness if necessary. One of the inspection methods for uneven illuminance is to actually create an exposure image of an inspection pattern as shown in FIG. 21A, and to measure the pattern width of this exposure image at predetermined intervals using a line width measuring device or the like. This is a method of measuring and making the error of this pattern width the uneven illuminance. However, this method is not a proper inspection method because it is a one-dimensional inspection and not a uniform inspection of the entire surface of the DMD.

If it is a two-dimensional inspection and even inspection of the entire surface of the DMD, it is for inspection of a check pattern (checkered pattern) in which dots are formed every other pixel as shown in FIG. An inspection method is conceivable in which an exposure image of a pattern is created, and the widths of the upper and lower sides and the left and right sides of each dot are measured, and the error of these widths is taken as the uneven illuminance. However, there will be no line width measuring device for measuring the width of such a minute dot, and if it exists, it will be very expensive. Moreover, for each dot, which is half the number of pixels of the DMD (more than 2 million), it is necessary to measure the width at two locations. Since it is too large, there is a concern that the inspection will take a lot of time.

The inspection method described in Patent Document 1 is a method in which an illuminance sensor is arranged on a two-dimensionally movable stage, the stage is two-dimensionally moved, and the illuminance sensor detects an illuminance distribution in an exposure image of a DMD. It is said that the illuminance distribution of the DMD can be uniformly corrected by appropriately controlling the direction of each micromirror of the DMD based on the detection result. However, in the inspection method described in Patent Document 1, it is unknown how the illuminance sensor detects the illuminance distribution.

JP-A-8-313842

Therefore, the present invention has been made in view of such circumstances, and the spatial light capable of effectively inspecting the illuminance unevenness with high accuracy is not limited to the DMD and is effective for all spatial light modulators that have the problem of the illuminance unevenness. An object of the present invention is to provide an inspection device and an inspection method for a modulation element.

The inspection device for a spatial light modulation element according to the present invention,
A storage unit that stores an inspection exposure image obtained by inputting an inspection signal having a constant ratio of the number of ON pixels and the number of OFF pixels of each unit pixel block to the spatial light modulator.
A measurement unit that divides the inspection exposure image into a plurality of unit cells having a size equal to or larger than the exposure area corresponding to the unit pixel block, and measures a binary area ratio for each unit cell,
It is an apparatus provided with a computing unit that compares a binary area ratio or a predetermined physical value having a correlation with the binary area ratio for each unit cell with a predetermined reference value.

In addition, the inspection method of the spatial light modulation element according to the present invention,
An inspection exposure image obtained by inputting an inspection signal in which the ratio of the number of ON pixels and the number of OFF pixels of each unit pixel block is constant to the spatial light modulator is prepared,
The inspection exposure image is divided into a plurality of unit cells each having a size larger than the exposure area corresponding to the unit pixel block, and the binary area ratio is measured for each unit cell.
Comparing a predetermined physical value having a correlation with a binary area ratio or a binary area ratio for each unit cell with a predetermined reference value,
This is a method of determining the presence or absence of illuminance unevenness of the spatial light modulator based on the comparison result.

According to these aspects of the invention, when the binary area ratio or the predetermined physical value of each unit cell is the same or within a predetermined allowable range, it can be determined that the illuminance unevenness does not occur in the spatial light changing element. On the other hand, if the binary area ratio or the predetermined physical value of some unit cells is out of the predetermined allowable range, it is determined that the illuminance unevenness has occurred in (a part of the area of) the spatial light modulator. It is possible to suspect that illuminance unevenness may occur in (a part of the area of) the spatial light modulator. In this way, it is possible to judge the presence or absence of illuminance unevenness of the spatial light modulator based on the result of comparing the binary area ratio or the predetermined physical value with the predetermined reference value for each unit cell. Moreover, since it suffices to measure the binary area ratio for each unit cell, the inspection time is significantly longer than that of the inspection method that measures the width of each of the upper, lower, left, and right locations for each dot described in the Background Art section above. Can be shortened to

Here, as one aspect of the inspection device for the spatial light modulator according to the present invention,
The arithmetic unit may adopt a configuration in which the output correction data of the spatial light modulator for making the binary area ratio or the predetermined physical value constant for each unit cell is created based on the comparison result. it can.

Further, as another aspect of the inspection apparatus for a spatial light modulator according to the present invention,
The storage unit stores calibration curve data indicating the correlation between the binary area ratio and the illuminance of the spatial light modulator,
The calculation unit may employ a configuration in which the illuminance is referenced using a calibration curve for each unit cell and the illuminance is compared with a predetermined reference value.

Further, as another aspect of the inspection apparatus for a spatial light modulator according to the present invention,
The spatial light modulator can adopt a configuration of being a digital micromirror device (DMD) that reflects and outputs light emitted from a light source.

In addition, another method of inspecting a spatial light modulator according to the present invention is
An inspection exposure image obtained by inputting an inspection signal in which the ratio of the number of ON pixels and the number of OFF pixels of each unit pixel block is constant to the spatial light modulator is prepared,
The inspection exposure image is divided into a plurality of first unit cells each having a size equal to or larger than an exposure area corresponding to a unit pixel block, and a binary area ratio is measured for each first unit cell,
For each first unit cell, a binary area ratio or a predetermined physical value having a correlation with the binary area ratio is compared with a predetermined reference value,
Determine the presence or absence of illuminance unevenness of the spatial light modulator based on the comparison result,
If it is confirmed that the illuminance unevenness occurs in a part of the spatial light modulator, or if it is suspected that the illuminance unevenness occurs in a part of the spatial light modulator, one of the spatial light modulator The corresponding area of the exposure image for inspection corresponding to the partial area is divided into a plurality of second unit cells having a size smaller than the first unit cell, and a binary area ratio is measured for each second unit cell,
For each second unit cell, a binary area ratio or a predetermined physical value having a correlation with the binary area ratio is compared with a predetermined reference value,
This is a method of determining the presence or absence of uneven illuminance in a partial region of the spatial light modulator based on the comparison result.

According to this invention, the entire surface of the spatial light modulator is inspected by a large net called the first unit cell, and when the area is negative or suspected to be negative, the corresponding area is inspected by a small net called the second unit cell. As a result, the inspection time can be significantly shortened as compared with the case where the entire surface of the spatial light modulator is inspected from the beginning with a fine net.

As described above, according to the inspection device and the inspection method of the spatial light modulation element according to the present invention, the inspection time is short even though the entire surface of the spatial light modulation element is inspected uniformly. Can be effectively inspected with high accuracy.

FIG. 1 is a conceptual diagram of an inspection apparatus according to the first embodiment applied to a digital exposure apparatus. FIG. 2 is a block diagram of the inspection apparatus. FIG. 3 is a flowchart of a calibration curve creating process of the inspection method according to the first embodiment by the inspection device. FIG. 4 is a flowchart of the inspection process of the same inspection method. FIG. 5A is a partially enlarged view of the first reference image used in the calibration curve creating step of the inspection method, and FIG. 5B is the second reference image used in the calibration curve creating step of the inspection method. It is a partially expanded view of a reference image. FIG. 6A is an area ratio-illuminance calibration curve created in the calibration curve creation step of the inspection method, and FIG. 6B is an explanatory diagram of a procedure for obtaining illuminance from the calibration curve. .. FIG. 7A is a partially enlarged perspective view of the DMD to which an inspection signal is input in the inspection process of the inspection method, and FIG. 7B is an inspection exposure exposed based on the inspection signal. It is a partially enlarged view of an image. 8A to 8D are explanatory views of the unit cell area ratio measuring procedure in the inspection process of the same inspection method. FIG. 9 shows an illuminance table and an illuminance masking data structure created in the inspection process. FIG. 10 is a conceptual diagram of an inspection apparatus according to the second embodiment applied to the digital exposure apparatus. FIG. 11 is a block diagram of the inspection apparatus. FIG. 12 is a flowchart of a calibration curve creating process of the inspection method according to the second embodiment by the inspection device. FIG. 13 is a flowchart of the inspection process of the inspection method. FIG. 14A is a partially enlarged view of the first reference image used in the calibration curve creating step of the inspection method, and FIG. 14B is the second reference image used in the calibration curve creating step of the inspection method. It is a partially expanded view of a reference image. FIG. 15A is a calibration curve diagram of area ratio-illuminance created in the calibration curve creation step of the inspection method, and FIG. 15B is an explanatory diagram of a procedure for obtaining illuminance from the calibration curve. .. 16A is a partially enlarged perspective view of a DMD to which an inspection signal is input in the inspection process of the same inspection method, and FIG. 16B is a partially enlarged view of an output signal of the DMD. FIG. 16C is a partially enlarged view of the inspection exposure image exposed based on the inspection signal. 17A to 17D are explanatory views of the unit cell area ratio measurement procedure in the inspection process of the inspection method according to another embodiment. FIG. 18 is a flowchart of the inspection process of the inspection method according to another embodiment. FIG. 19 is an area ratio table and illuminance masking data structure created in the inspection process of the inspection method according to still another embodiment. FIGS. 20A to 20C are explanatory diagrams that the pattern is distorted due to the uneven illuminance. 21A is a partially enlarged view of an exposure image in which a pattern is distorted, and FIG. 21B is a partially enlarged view of an exposure image for distortion measurement.

<First Embodiment>
Hereinafter, a first embodiment of an inspection device and an inspection method for a spatial light modulator according to the present invention will be described with reference to FIGS. 1 to 9.

As shown in FIGS. 1 and 2, the inspection apparatus 1 according to this embodiment includes a main device 10 and an imaging device 20, and is mainly applied to the digital exposure apparatus 4. The digital exposure device 4 will be briefly described. The digital exposure device 4 projects a light source 40, a DMD 41 that reflects light emitted from the light source 40 to form an output image, and an output image (reflected light) of the DMD 41. Xy stage 42.

The main device 10 is configured by using a computer such as a personal computer, for example, a control unit 11 including a calculation unit 12, various software such as image analysis software described below, and image data such as an inspection exposure image and a reference image described below. A storage unit 13 for storing various data including data, I/F (interface) units 14 and 15, an image display unit 16 such as a monitor connected via the I/F unit 15, and a PD (pointing device) such as a mouse. ) 17 and.

The image pickup device 20 is mounted on the xy stage 42 of the digital exposure device 4 and picks up an output image output from the DMD 41 as an exposure image. The image pickup device 20 includes a control unit 21 including a CPU and a CCD image, for example. The imaging unit 22 including a sensor, the storage unit 23 that stores the captured exposure image, and the I/F unit 24 are provided.

The main device 10 and the imaging device 20 are separably connected via a communication cable 18 such as a USB cable connected to the I/F units 14 and 24. However, even if the main device 10 and the imaging device 20 are connected not by wired communication but by wireless communication such as wireless LAN, Bluetooth (registered trademark), IrDA, Zigbee (registered trademark), or specific low-power wireless communication. Alternatively, both may be integrally configured.

Next, an inspection method using the inspection device 1 will be described. The inspection method is roughly divided into a calibration curve preparation step, which is a preliminary preparation step, and an inspection step. The calibration curve creation process is a process for creating a calibration curve used in the inspection process.

In the calibration curve creating step, a digital exposure apparatus 4 different from the digital exposure apparatus 4 to be inspected, in which the illuminance of the DMD 41 is uniformly adjusted, is used. It is preferable that this digital exposure apparatus 4 has the same conditions as the digital exposure apparatus 4 to be inspected (same DMD mounted, same exposure condition, same device type, etc.).

As shown in FIG. 3, first, the source signal of the first reference image is input to the DMD 41 using the interface of the digital exposure device 4, the DMD 41 is output in this state, and the output image formed by the DMD 41 is output to the digital exposure device 4. It is projected on the xy table 42 (step 1). This is imaged by the imaging device 20 placed on the xy table 42 (step 2). At this time, the illuminance of the exposure is measured using an illuminance measuring means such as an illuminance sensor or an illuminance meter (not shown) (step 3). Then, the captured output image (first reference image) of the DMD 41 is stored in the storage unit 23 of the imaging device 20 (step 4). Here, the source signal of the first reference image is a signal in which the ratio of the number of ON pixels to the number of OFF pixels of each unit pixel block is constant, and the arrangement of ON pixels and OFF pixels is regular. In this embodiment, the unit pixel block is a 2×2 4-pixel block, and the ratio of the number of ON pixels to the number of OFF pixels is 3:1. As shown in FIG. 5A, the proportion of light (white, digital value 1) in each unit exposure region R corresponding to each unit pixel block is 75%, and the proportion of dark (black, digital value 0) is 25%. It is an exposure image.

Next, the source signal of the second reference image is input to the DMD 41 using the interface of the digital exposure device 4, the DMD 41 is output in this state, and the output image formed by the DMD 41 is displayed on the xy table 42 of the digital exposure device 4. Project (step 5). This is imaged by the imaging device 20 (step 6). At this time, the illuminance of the exposure is measured using the illuminance measuring means (step 7). Then, the captured output image of the DMD 41 (second reference image) is stored in the storage unit 23 of the imaging device 20 (step 8). Here, the source signal of the second reference image is a signal in which the ratio of the number of ON pixels to the number of OFF pixels in each unit pixel block is constant and the arrangement of ON pixels and OFF pixels is regular. In the present embodiment, the unit pixel block is a 2×2 4-pixel block, and the ratio of the number of ON pixels to the number of OFF pixels is 2:2. As shown in FIG. 5B, the ratio of light (white, digital value 1) in each unit exposure region R corresponding to each unit pixel block is 50%, and the ratio of dark (black, digital value 0) is 50%. It is an exposure image.

Next, the first reference image and the second reference image (image data) stored in the storage unit 23 are transferred from the imaging device 20 to the main device 10 and stored in the storage unit 13 of the main device 10 (step 9). .. Then, the calculation unit 12 measures the binary (1,0) area ratio of the first reference image using the above-described image analysis software (step 10). Since the illuminance of the DMD 41 of the digital exposure device 4 is adjusted uniformly, the binary area ratio is constant regardless of the exposure area of the first reference image. Therefore, the binary area ratio may be obtained from a predetermined exposure area of the first reference image or may be obtained from the entire first reference image. Similarly, the calculation unit 12 measures the binary (1,0) area ratio of the second reference image (step 11).

When the measurement of the binary area ratios of the first reference image and the second reference image is completed, the arithmetic unit 12 and the illuminance of the exposure of the first reference image measured in step 3, Based on the four measured values of the illuminance of the exposure of the second reference image measured in step 7, a calibration curve of the concept as shown in FIG. 6A is created (step 12), and the created calibration curve data (for example, It is stored in the storage unit 13 (in the form of a linear function) (step 13). This area ratio-illuminance calibration curve refers to (determines) the illuminance from a binary area ratio, as shown in FIG. 6B.

After completing these preparatory work, we will begin inspection work. The inspection process is started by switching from the master digital exposure device 4 used in the calibration curve creation process to the inspection target digital exposure device 4 and mounting the imaging device 20 on the xy stage 42 of the digital exposure device 4. ..

As shown in FIG. 4, first, an inspection signal is input to the DMD 41 using the interface of the digital exposure apparatus 4, the DMD 41 is output in this state, and the output image formed by the DMD 41 is displayed on the xy table 42 of the digital exposure apparatus 4. (Step 1). This is imaged by the imaging device 20 placed on the xy table 42 (step 2). Then, the captured output image (exposure image for inspection) of the DMD 41 is stored in the storage unit 23 of the imaging device 20 (step 3). Here, the inspection signal is a signal in which the ratio of the number of ON pixels and the number of OFF pixels in each unit pixel block is constant and the arrangement of ON pixels and OFF pixels is regular. In this embodiment, as shown in FIG. 7A, the unit pixel block is a 2×2 4-pixel block, and the ratio of the number of ON pixels to the number of OFF pixels is 3:1. As a result, in the inspection exposure image, as shown in FIG. 7B, the ratio of bright (white, digital value 1) in each unit exposure region R corresponding to each unit pixel block is 75%, and dark (black, digital). The ratio of the value 0) is an exposure image of 25%. That is, in the present embodiment, the inspection signal is the same as the source signal of the first reference image, and therefore, the inspection exposure image is the same as the first reference image unless illuminance unevenness occurs. Note that in FIG. 7A, ON pixels (the micro mirrors 33a that have transitioned to the ON state due to an ON signal) are shown in white, and OFF pixels (micro mirrors 33b that have transitioned to the OFF state due to an OFF signal) are shown in shade. ..

Next, the inspection exposure image (image data) stored in the storage unit 23 is transferred from the imaging device 20 to the main device 10 and stored in the storage unit 13 of the main device 10 (step 4). Then, the calculation unit 12 measures the binary (1,0) area ratio of the inspection exposure image using the image analysis software described above (step 5). Specifically, the exposure image for inspection is divided into a plurality of unit cells C having the same size as the unit exposure region R, and image analysis is performed for each unit cell C to analyze the total area of 1 and the value of 0. The total area of is calculated and the ratio is calculated. In FIG. 8, the unit cell C is moved by one pitch in one row (FIGS. 8A to 8C ), and the binary area ratio is calculated in each row. This is to explain that the same processing is performed (FIG. 8D).

Further, when the binary area ratio is measured for each unit cell C, the calculation unit 12 refers to the illuminance for each unit cell C using a calibration curve and creates an illuminance table of the concept as shown in FIG. 9. (Step 6). When the illuminance is uneven on the DMD 41, the area of 1 is large where the illuminance is strong and the binary area ratio is large, whereas the area of 1 is small when the illuminance is weak and the binary area is small. Area ratio becomes smaller. In the example of the illuminance table in FIG. 9, in the “error” column, it can be seen that the illuminance is strong in the unit cells C larger than 100 and the illuminance is weak in the unit cells C smaller than 100. In this embodiment, the DMD 41 having the number of pixels of 1080×1920 is used, and the unit cell C corresponds to a unit pixel block of 4 pixels of 2×2. There are up to 1080×1920/(2×2)=518,400 rows in the illuminance table.

Then, the calculation unit 12 creates the illuminance masking data based on the illuminance table as needed (step 7). The illuminance masking data is correction data for the output of the DMD 41 and is for uniformly correcting the illuminance distribution of the DMD 41. In the example of the illuminance table of FIG. 9, since the illuminance unevenness outside the predetermined allowable range occurs in the unit cells C of the numbers 223,358 to 223,360, 224,318 to 224,320, the “error” is 100 with respect to these unit cells C. Such masking data is created, and these data are used for the output correction of the DMD 41. The output correction of the DMD 41 is performed by increasing or decreasing the number of ON pixels or OFF pixels, or increasing or decreasing the ON time or OFF time in the unit pixel block corresponding to the corresponding unit cell C when the DMD 41 is output (during exposure). It is processed by the method.

As described above, according to the inspection device 1 and the inspection method of the DMD 41 according to the present embodiment, the illuminance (predetermined physical value) obtained from the binary area ratio of each unit cell C by using the calibration curve has a predetermined tolerance. When it is within the range, it can be determined that the DMD 41 has no unevenness in illuminance. On the other hand, when a part of the illuminance is out of the predetermined allowable range, the DMD 41 (a part of the area) has uneven illuminance. It is possible to determine that the illuminance is uneven, or it may be possible that the DMD 41 (a part of the area) has uneven illuminance. In this way, the result of comparing the illuminance with the predetermined reference value for each unit cell C (in the illuminance table of FIG. 9, the illuminance of the first reference image is used as the reference value, and “error” with respect to this reference value is displayed as the comparison result. It is possible to determine whether the DMD 41 has uneven illuminance. Moreover, since it suffices to measure the binary area ratio for each unit cell C, the inspection time can be shortened as compared with the inspection method described in the above-mentioned background art section, which measures the widths of the upper, lower, left and right portions for each dot. It can be greatly shortened.

Further, according to the inspection device 1 and the inspection method of the DMD 41 according to the present embodiment, it is possible to create the data necessary for the output correction of the DMD 41 based on the result of comparing the illuminance for each unit cell C with a predetermined reference value. it can. Moreover, since this data (masking data) is a unit of a predetermined pixel block of the DMD 41 and does not correct the output of each pixel of the DMD 41, the output correction control of the DMD 41 is simplified. As a result, the output correction control of the DMD 41 can be performed quickly, and the exposure process can be speeded up.

<Second Embodiment>
Hereinafter, a second embodiment of the inspection device and the inspection method for the spatial light modulator according to the present invention will be described with reference to FIGS. 10 to 16. In the inspection apparatus and the inspection method according to the first embodiment, the output image of the DMD 41 is used as the inspection medium, but in the inspection apparatus and the inspection method according to the second embodiment, the metal thin film layer is formed on the surface of the glass substrate, The difference is that the material S to be exposed having the photoresist layer laminated thereon is exposed by the DMD 41 and developed to be used as the inspection medium. In the second embodiment, the same or common configurations as those in the first embodiment are designated by the same reference numerals and the description thereof may be omitted.

As shown in FIGS. 10 and 11, the inspection apparatus 1 according to this embodiment includes a main device 10 and a measurement device 30, and is mainly applied to the digital exposure apparatus 4. The measurement device 30 includes a control unit 31 including a CPU, an xy stage 32 on which the exposed material S exposed and developed by the digital exposure device 4 is placed, and an xy stage 32 in the x direction and/or. an xy drive unit 33 that drives in the y direction; a measurement unit 34 that is located above the xy stage 32 and that measures the binary area ratio of the exposure image I of the exposed material S that is placed on the xy stage 32; A storage unit 35 that stores the measurement result of the unit 34 and the like, and an I/F unit 36 are provided. The measuring unit 34 is called a densitometer or a dot meter, and there are a transmission type and a reflection type. The structure is as described in JP-A-56-154604 and JP-A-2002-213933, and since it is a general measuring means, detailed description will be omitted.

The main device 10 and the measuring device 30 are separably connected via a communication cable 18 such as a USB cable connected to the I/F units 14 and 36. However, even if the main device 10 and the measuring device 30 are connected not by wired communication but by wireless communication such as wireless LAN, Bluetooth (registered trademark), IrDA, Zigbee (registered trademark), or specific low power wireless communication. Alternatively, both may be integrally configured.

Next, an inspection method using the inspection device 1 will be described. In the calibration curve creating step, a digital exposure apparatus 4 different from the digital exposure apparatus 4 to be inspected, in which the illuminance of the DMD 41 is uniformly adjusted, is used. It is preferable that this digital exposure apparatus 4 has the same conditions as the digital exposure apparatus 4 to be inspected (same DMD mounted, same exposure condition, same device type, etc.).

As shown in FIG. 12, first, the source signal of the first reference image is input to the DMD 41 using the interface of the digital exposure device 4, and in this state, the DMD 41 is output, and the output image formed by the DMD 41 is output to the digital exposure device 4. The material to be exposed S placed on the xy table 42 is projected (step 1). At this time, the illuminance of the exposure is measured using an illuminance measuring means such as an illuminance sensor or an illuminance meter (not shown) (step 2). Then, the exposed material S to be exposed is developed (step 3). The exposure image I formed on the surface of the material S to be exposed becomes the first reference image. Here, the source signal of the first reference image is a signal in which the ratio of the number of ON pixels to the number of OFF pixels of each unit pixel block is constant, and the arrangement of ON pixels and OFF pixels is regular. In the present embodiment, the unit pixel block is a 2×2 4-pixel block, and the ratio of the number of ON pixels to the number of OFF pixels is 1:3. As shown in FIG. 14A, the exposure image is such that the ratio of dots (non-etched thin film layer portion, digital value 1) in each unit exposure region R corresponding to each unit pixel block is 25%.

Next, the source signal of the second reference image is input to the DMD 41 using the interface of the digital exposure device 4, the DMD 41 is output in this state, and the output image formed by the DMD 41 is displayed on the xy table 42 of the digital exposure device 4. The image is projected on the new placed material S to be exposed (step 4). At this time, the illuminance of the exposure is measured using the illuminance measuring means (step 5). Then, the exposed material S to be exposed is developed (step 6). The exposure image I formed on the surface of the exposed material S becomes the second reference image. Here, the source signal of the second reference image is a signal in which the ratio of the number of ON pixels to the number of OFF pixels in each unit pixel block is constant and the arrangement of ON pixels and OFF pixels is regular. In the present embodiment, the unit pixel block is a 2×2 4-pixel block, and the ratio of the number of ON pixels to the number of OFF pixels is 2:2. As shown in FIG. 14B, the exposure image has a ratio of dots (non-etched thin film layer portion, digital value 1) in each unit exposure region R corresponding to each unit pixel block is 50%.

Next, after the exposed material S on which the first reference image is formed is placed on the xy table 32, the binary (1,0) area ratio of the first reference image is measured using the measuring device 30. (Step 7). Since the illuminance of the DMD 41 of the digital exposure device 4 is adjusted uniformly, the binary area ratio is constant regardless of the exposure area of the first reference image. Therefore, the binary area ratio may be obtained from a predetermined exposure area of the first reference image or may be obtained from the entire first reference image. Similarly, after the exposed material S on which the second reference image is formed is placed on the xy table 32, the binary (1,0) area ratio of the second reference image is measured using the measuring device 30. (Step 8).

The measurement data of the binary area ratios of the first reference image and the second reference image is transferred from the measuring device 30 to the main device 10 and stored in the storage unit 13, and the arithmetic unit 12 calculates the binary area ratio. Based on the four measurement values of the area ratio, the exposure illuminance of the first reference image measured in step 2 and the exposure illuminance of the second reference image measured in step 5, the concept as shown in FIG. Is prepared (step 9), and the prepared calibration curve data is stored in the storage unit 13 (for example, in the form of a linear function) (step 10). This area ratio-illuminance calibration curve refers to (determines) the illuminance from a binary area ratio, as shown in FIG.

After completing these preparatory work, we will begin inspection work. In the inspection process, the master digital exposure device 4 used in the calibration curve creation process is switched to the digital exposure device 4 to be inspected, and the material S to be exposed is placed on the xy stage 42 of the digital exposure device 4. Begins.

As shown in FIG. 13, first, an inspection signal is input to the DMD 41 using the interface of the digital exposure apparatus 4, the DMD 41 is output in this state, and the output image formed by the DMD 41 is displayed on the xy table 42 of the digital exposure apparatus 4. The material S to be exposed is projected onto the exposed material S (step 1). Then, the exposed material S to be exposed is developed (step 2). The exposure image I formed on the surface of the exposed material S becomes the inspection exposure image. Here, the inspection signal is a signal in which the ratio of the number of ON pixels and the number of OFF pixels in each unit pixel block is constant and the arrangement of ON pixels and OFF pixels is regular. In the present embodiment, as shown in FIGS. 16A and 16B, the unit pixel block is a 2×2 4-pixel block, and the ratio of the number of ON pixels to the number of OFF pixels is 1:. Since the inspection exposure image is 3, the ratio of dots (non-etched thin film layer portion, digital value 1) in each unit exposure region R corresponding to each unit pixel block in the inspection exposure image is as shown in FIG. It is a 25% exposure image. That is, in the present embodiment, the inspection signal is the same as the source signal of the first reference image, and therefore, the inspection exposure image is the same as the first reference image unless illuminance unevenness occurs. Note that in FIG. 16A, ON pixels (the micro mirrors 33a that have transitioned to the ON state due to the ON signal) are shown in white, and OFF pixels (micromirrors 33b that have transitioned to the OFF state due to the OFF signal) are shown in shade. ..

Next, after the exposed material S on which the inspection exposure image is formed is placed on the xy table 32, the binary area ratio (1,0) of the inspection exposure image is measured using the measuring device 30. (Step 3). Specifically, the exposure image for inspection is divided into a plurality of unit cells C having the same size as the unit exposure region R, and the total area of a value of 1 and a value of 0 is divided by the measuring unit 34 for each unit cell C. The total area of is calculated and the ratio is calculated.

The measurement data of the binary area ratio of each unit cell C of the inspection exposure image is transferred from the measurement device 30 to the main device 10 and stored in the storage unit 13, and the calculation unit 12 uses the calibration curve. By referring to the illuminance for each unit cell C, an illuminance table of the concept as shown in FIG. 9 is created (step 4). When the illuminance is uneven on the DMD 41, the area of 1 is large where the illuminance is strong and the binary area ratio is large, whereas the area of 1 is small when the illuminance is weak and the binary area is small. Area ratio becomes smaller.

Then, the calculation unit 12 creates the illuminance masking data based on the illuminance table as needed (step 5).

As described above, the inspection device 1 and the inspection method of the DMD 41 according to the present embodiment are different in the inspection medium and only the configuration for this, and substantially, the inspection device 1 and the inspection device according to the first embodiment. The method is the same. Therefore, the inspection device 1 and the inspection method of the DMD 41 according to the present embodiment also achieve the above-described operational effects of the inspection device 1 and the inspection method according to the first embodiment.

It should be noted that the inspection device and the inspection method for the spatial light modulation element according to the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

For example, in the first and second embodiments described above, exposure using the DMD, which is a reflective spatial light modulator and is a MEMS (Micro Electro Mechanical Systems) type spatial light modulator, as the spatial light modulator. Targeted the device. However, in the present invention, an exposure apparatus using a transmissive spatial light modulator may be used, and a reflective liquid crystal element, a transmissive liquid crystal element, and an optical element (PLZT) that modulates transmitted light by an electro-optical effect. The exposure apparatus may use a spatial light modulator other than the MEMS type, such as an element). Further, even the MEMS type may be an exposure apparatus using a reflection diffraction grating type (GLV) or an interference type spatial light modulation element in addition to the DMD.

Further, in the first and second embodiments, the inspection signal in which the ratio of the number of ON pixels to the number of OFF pixels of each unit pixel block is constant is used as a whole. However, the inspection signal is composed of a plurality of patterns in which the ratios are constant in some of them, and the ratios are constant in other parts of the other parts. It may be one.

In the first and second embodiments, the unit cell C is set to have the same size as the unit exposure region R corresponding to the unit pixel block. However, the size of the unit cell can be set appropriately. For example, the unit cell C shown in FIG. 17A is four times as large as the unit exposure area R, and the unit cell C shown in FIG. 17B is nine times as large as the unit exposure area R. Yes, the unit cell C shown in FIG. 17C is 2.25 times larger than the unit exposure region R, and the unit cell C shown in FIG. 17D is 12.25 times larger. .. Thus, as the size of the unit cell C increases, the number of times the binary area ratio is measured decreases, and the inspection time can be shortened. However, if the size of the unit cell C is too large, the inspection accuracy may be deteriorated. Therefore, the size of the unit cell C is set to an appropriate size.

In the first and second embodiments, the unit cell C is set to have the same binary area ratio of the first reference image. However, what type of unit cell having a binary area ratio (that is, how much the predetermined reference value is set) can be appropriately set. For example, the unit cell C shown in FIGS. 17C and 17D is different from the binary area ratio of the first reference image.

In addition, the fact that the size of the unit cell can be set appropriately enables the inspection method shown in FIG. 18 to be implemented. In this inspection method, the entire surface (effective surface) of the DMD 41 is inspected with a large mesh called the first unit cell, and if there is illuminance unevenness or illuminance unevenness is suspected, the corresponding area is made smaller than the first unit cell. This is a method of inspecting with a fine mesh of 2 unit cells. As a result, the inspection time can be significantly shortened as compared with the case where the entire surface of the DMD 41 is inspected from the beginning with a fine net. Each of the first unit cell and the second unit cell is independently independent as long as it has a size equal to or larger than the unit exposure region R corresponding to the unit pixel block, and the latter is smaller than the former. Any size, area ratio, etc. can be set. Note that this inspection method is applied after step 5 of the flowchart of FIG. 4, and steps 5 and 7, steps 6 and 8, and step 10 are the same as step 5, step 6, and step 7 of FIG. It is the content. When there are a plurality of relevant areas (YES in step 9), steps 7 and 8 are repeated by the number of the areas. It goes without saying that the present inspection method can be applied to step 3 and subsequent steps in the flowchart of FIG.

In addition, in the first and second embodiments, the illuminance is measured at the time of exposure, and the calibration curve is created using this. However, the illuminance may not be measured, and an appropriate illuminance value may be set for each of the first reference image and the second reference image, and the calibration curve may be created using this.

Moreover, in the said 1st and 2nd embodiment, the calibration curve preparation process was performed as a preparation process, and the calibration curve was created. However, the calibration curve data may be prepared as master data by the maker of the inspection device or the like and introduced into the inspection device from the beginning or by downloading. In this case, the calibration curve preparation step is unnecessary. Further, instead of providing the calibration curve data, the manufacturer or the like provides the first exposure image and the second exposure image (image data) or the first exposure image and the second exposure image (exposed material) as masters. You may do it.

Moreover, in the said 1st and 2nd embodiment, the comparison object was the illuminance calculated|required from the calibration curve. However, the comparison target may be a binary area ratio. In this case, the calibration curve creating step is unnecessary, and the area ratio table as shown in FIG. 19 is created (in the area ratio table of FIG. 19, the binary area ratio of the first reference image is used as the reference value, "Error" with respect to the reference value is displayed as the comparison result.)

In the first and second embodiments, the reference value for comparison is obtained from the reference image. This is a method similar to the Die To Database inspection in which a reference image is generated from a database image and the inspection is performed by comparing the reference image with the image of the inspection target. However, the reference value for comparison may be obtained from the inspection exposure image. Specifically, the binary area ratio or illuminance of any unit cell C may be used as the reference value, and for example, the maximum value of the binary area ratio or illuminance of each unit cell C (FIGS. 9 and 19). In the example of No. 47,172 or No. 518,399, the binary area ratio or illuminance of the unit cell C) or the binary area ratio or illuminance of any unit cell C that exceeds a predetermined threshold is used as the reference value. You can This is a method similar to the die-to-die inspection. Further, for example, the average value of the binary area ratio or the average value of the illuminance of each unit cell C is used as a reference value, or the value related to the distribution curve of the binary area ratio or the illuminance of each unit cell C (for example, the deviation The value) can also be used as the reference value.

Further, in the first and second embodiments, the spatial light modulation element incorporated in the exposure apparatus is inspected. However, the spatial light modulator alone may be inspected.

In addition, in the first and second embodiments, masking data is created and output correction is performed for “error” of the unit cell C that is out of the allowable range. The method of increasing or decreasing the number of ON pixels or OFF pixels or increasing or decreasing the ON time or OFF time was applied to the unit pixel block corresponding to the corresponding unit cell C. However, it is possible to appropriately set or select what kind of masking data is to be created in what kind of unit cell, and as the output correction method, various already known methods can be adopted. ..

In addition, the device configuration downsized and/or unitized in a state where at least the functions, characteristics, and effects of the detection device according to the present invention are maintained, for example, a DMD such as a maskless exposure device or a direct writing device is exposed. By incorporating it in an apparatus that uses an engine, it can be used as a self-diagnosis function when initializing the optical system of the apparatus, and can be expected to be used for regular maintenance of an apparatus that uses a DMD as an exposure engine. In that case, the exposure optical system and the inspection optical system may be independent or may be used together. The storage unit can be either independent or combined.

DESCRIPTION OF SYMBOLS 1... Inspection device, 10... Main device, 11... Control part, 12... Arithmetic part, 13... Storage part, 14, 15... I/F part, 16... Image display part, 17... PD, 18... Communication cable, 20 ... image pickup device, 21... control unit, 22... image pickup unit, 23... storage unit, 24... I/F unit, 30... measurement device, 31... control unit, 32... xy stage, 33... xy drive unit, 34... measurement Section, 35... storage section, 36... I/F section, 4... digital exposure apparatus, 40... light source, 41... DMD, 42... xy stage, C... unit cell, I... exposure image, R... unit exposure area, S … Exposed material

Claims (6)

A storage unit that stores an inspection exposure image obtained by inputting an inspection signal having a constant ratio of the number of ON pixels and the number of OFF pixels of each unit pixel block to the spatial light modulator.
A measurement unit that divides the inspection exposure image into a plurality of unit cells having a size equal to or larger than an exposure region corresponding to the unit pixel block, and measures a binary area ratio for each unit cell,
An inspection device for a spatial light modulation element, comprising: an arithmetic unit that compares the binary area ratio or a predetermined physical value having a correlation with the binary area ratio for each unit cell with a predetermined reference value. The calculation unit creates, based on the comparison result, output correction data of the spatial light modulator for making the binary area ratio or the predetermined physical value constant for each unit cell. Item 3. The inspection device for the spatial light modulator according to Item 1. The storage unit stores calibration curve data showing the correlation between the binary area ratio and the illuminance of the spatial light modulator,
The spatial light modulator inspection apparatus according to claim 1, wherein the arithmetic unit refers to the illuminance by using the calibration curve for each of the unit cells, and compares the illuminance with the predetermined reference value. The inspection device for a spatial light modulation element according to claim 1, wherein the spatial light modulation element is a digital micromirror device (DMD) that reflects and outputs light emitted from a light source. .. An inspection exposure image obtained by inputting an inspection signal in which the ratio of the number of ON pixels and the number of OFF pixels of each unit pixel block is constant to the spatial light modulator is prepared,
The inspection exposure image is divided into a plurality of unit cells having a size equal to or larger than the exposure region corresponding to the unit pixel block, and a binary area ratio is measured for each unit cell,
Comparing a predetermined physical value having a correlation with the binary area ratio or the binary area ratio for each unit cell with a predetermined reference value,
A method for inspecting a spatial light modulation element, wherein the presence or absence of illuminance unevenness of the spatial light modulation element is determined based on the comparison result. An inspection exposure image obtained by inputting an inspection signal in which the ratio of the number of ON pixels and the number of OFF pixels of each unit pixel block is constant to the spatial light modulator is prepared,
The inspection exposure image is divided into a plurality of first unit cells each having a size equal to or larger than an exposure region corresponding to the unit pixel block, and a binary area ratio is measured for each first unit cell,
For each of the first unit cells, the binary area ratio or a predetermined physical value having a correlation with the binary area ratio is compared with a predetermined reference value,
Based on the comparison result, the presence or absence of illuminance unevenness of the spatial light modulator is determined,
When it is recognized that unevenness of illuminance is generated in a partial area of the spatial light modulation element or when it is suspected that unevenness of illuminance is generated in the partial area of the spatial light modulation element, the spatial light A corresponding area of the inspection exposure image corresponding to the partial area of the modulation element is divided into a plurality of second unit cells having a size smaller than the first unit cell, and each second unit cell has a binary value. The area ratio of
For each of the second unit cells, the binary area ratio or a predetermined physical value having a correlation with the binary area ratio is compared with a predetermined reference value,
A method for inspecting a spatial light modulation element, wherein the presence or absence of illuminance unevenness in the partial area of the spatial light modulation element is determined based on the comparison result.

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