Control device and control method

Abstract

The present invention provides a control device and control method for improving the inspection accuracy of masks with pellicles. [Solution] A control device for an optical device equipped with a light detection means for detecting light from the pattern surface of a photomask illuminated by illumination light, comprising: an acquisition means for acquiring pellicle information including information indicating whether or not a pellicle is mounted on the photomask; and a setting means for setting the charge accumulation time in the light detection means when the optical device illuminates the pattern surface of a photomask on which a pellicle is mounted to be greater than the charge accumulation time in the light detection means when the optical device illuminates the pattern surface of a photomask on which a pellicle is not mounted.

Description

Technical Field

[0001] The present disclosure relates to a control device and a control method for an optical device including a light detection means.

Background Art

[0002] Techniques for inspecting defects in a patterned mask are known. In some cases, a pellicle is mounted on the mask to protect the pattern surface, and there is a need to inspect the pattern surface using illumination light that has passed through the pellicle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When inspecting a mask with a pellicle, there is a problem that the inspection accuracy decreases because part of the illumination light is reflected or absorbed by the pellicle.

[0005] The present disclosure has been made in view of such problems, and provides a control device and a control method for improving the inspection accuracy of a mask with a pellicle.

Means for Solving the Problems

[0006] A control device according to an aspect of the present embodiment is a control device for an optical device including a light detection means for detecting light from a pattern surface of a photomask illuminated with illumination light, an acquisition means for acquiring pellicle information including information indicating whether a pellicle is mounted on the photomask, A setting means for setting the charge accumulation time in the light detection means when the optical device illuminates the pattern surface of the photomask on which the pellicle is mounted to be greater than the charge accumulation time in the light detection means when the optical device illuminates the pattern surface of the photomask on which the pellicle is not mounted. It is equipped with.

[0007] A control device according to one aspect of this embodiment is: A control device for an optical device, comprising light detection means for detecting light from the patterned surface of a photomask on which a pellicle is mounted, illuminated by illumination light, An acquisition means for acquiring pellicle information, including the transmittance of the pellicle to the illumination light, The system includes a setting means for setting the charge accumulation time in the light detection means when illuminating the patterned surface, based on the transmittance. The setting means sets the charge accumulation time to be larger as the transmittance decreases, and to be smaller than an upper limit based on at least one of the illumination light intensity, the heat resistance performance of the pellicle, and the heat dissipation performance of the pellicle.

[0008] A control method according to one aspect of this embodiment is: A control method for an optical device comprising light detection means for detecting light from the patterned surface of a photomask illuminated by illumination light, A process for obtaining pellicle information, which includes information indicating whether or not a pellicle is mounted on the photomask, The process involves setting the charge accumulation time in the light detection means to be greater than the charge accumulation time in the light detection means when illuminating the pattern surface of the photomask on which the pellicle is mounted with the optical device, compared to the charge accumulation time in the light detection means when illuminating the pattern surface of the photomask on which the pellicle is not mounted with the optical device. Includes.

[0009] A control method according to one aspect of this embodiment is: A control method for an optical device comprising light detection means for detecting light from a patterned surface of a photomask on which a pellicle is mounted, illuminated by illumination light, A step of acquiring pellicle information, including the transmittance of the pellicle to the illumination light, The process includes setting the charge accumulation time in the light detection means when illuminating the patterned surface based on the transmittance, The step of setting the charge storage time involves setting the charge storage time to be larger as the transmittance decreases, and smaller than an upper limit based on at least one of the illumination light intensity, the heat resistance performance of the pellicle, and the heat dissipation performance of the pellicle. [Effects of the Invention]

[0010] According to this disclosure, a control device and control method can be provided for improving the inspection accuracy of masks with pellicles. [Brief explanation of the drawing]

[0011] [Figure 1] This is a diagram illustrating an inspection device according to Embodiment 1. [Figure 2] This is a diagram illustrating a control device according to Embodiment 1. [Figure 3] This diagram illustrates an example of appropriate imaging conditions for an inspection device. [Figure 4] This diagram illustrates an example of appropriate imaging conditions for an inspection device. [Figure 5] This diagram illustrates an example of appropriate imaging conditions for an inspection device. [Modes for carrying out the invention]

[0012] Embodiments of the present disclosure will be described below with reference to the drawings. The following description illustrates preferred embodiments of the present disclosure and does not limit the scope of the present disclosure to the following embodiments. In the following description, the same reference numerals indicate substantially the same thing.

[0013] Embodiment 1 FIG. 1 is a configuration diagram illustrating an inspection apparatus 1 as an optical apparatus according to Embodiment 1. The inspection apparatus 1 includes an illumination optical system 10, an imaging optical system 20, and a control device 40. The illumination optical system 10 illuminates a photomask 51 using illumination light L11. In FIG. 1, a pellicle 53 is mounted on the photomask 51, but there are cases where the pattern surface of the photomask 51 without the pellicle 53 mounted is inspected. Thus, the inspection apparatus 1 as an optical apparatus inspects the pattern surface based on the result of illuminating the photomask 51 with the illumination light L11. However, the optical apparatus is not limited to the inspection apparatus. It may function as a review apparatus or the like that reflects the state of reflected light or the like from the pattern surface when the photomask 51 is illuminated with the illumination light L11.

[0014] The illumination optical system 10 has, for example, a light source 11, an elliptical mirror 12, an elliptical mirror 13, and a reduction mirror 14. The imaging optical system 20 captures an imaging image of the pattern surface of the photomask 51 illuminated by the illumination light L11. The imaging optical system 20 has, for example, a perforated concave mirror 21, a convex mirror 22, and a photodetector 23. The perforated concave mirror 21 and the convex mirror 22 constitute a Schwarzschild magnification optical system. Note that the illumination optical system 10 and the imaging optical system 20 may further include optical members other than those described above, or any of the above optical members may be omitted.

[0015] The control device 40 controls the imaging optical system 20. Specifically, the control device 40 sets the charge accumulation time in the photodetector 23 of the imaging optical system 20. The control device 40 may be configured to be able to control the illumination optical system 10 so that the light intensity of the illumination light L11 can be adjusted. The control device 40 may perform control, for example, to insert a dimming filter into the optical path of the illumination light L11, perform control to adjust the angle of a mirror, or perform control to adjust the amount of energy input to the light source 11 or the luminous efficiency of the light source 11. The control device 40 will be described later.

[0016] Inspection device 1 is a device for inspecting defects, contamination, etc., of the photomask 51. The photomask 51 is, for example, an EUV (Extra Ultra Violet) mask that corresponds to EUV light. Note that the photomask 51 is not limited to an EUV mask; it may also be a photomask that corresponds to illumination light L11 having a different wavelength. Here, for the sake of convenience in explaining inspection device 1, we will introduce an XYZ Cartesian coordinate system. For example, the plane parallel to the stage surface of the stage 52 on which the photomask 51 is placed will be the XY plane, and the direction perpendicular to the stage surface will be the Z axis direction. For convenience, the direction of the +Z axis direction will be called upward.

[0017] The light source 11 generates illumination light L11. Illumination light L11 includes, for example, EUV light of 13.5 nm, which is the same as the exposure wavelength of the EUV mask, which is the photomask 51. However, illumination light L11 may also include light of other wavelengths.

[0018] The illumination light L11 generated from the light source 11 is reflected by the ellipsoidal mirror 12. The illumination light L11 reflected by the ellipsoidal mirror 12 travels while being focused. After the illumination light L11 reaches focus, it travels while spreading out.

[0019] The illumination light L11 then enters a reflecting mirror such as an ellipsoidal mirror 13. The illumination light L11 that enters the ellipsoidal mirror 13 is reflected by the ellipsoidal mirror 13, travels while being focused, and enters the recessed mirror 14. In other words, the ellipsoidal mirror 13 causes the illumination light L11 to enter the recessed mirror 14 as focused light. The recessed mirror 14 is positioned above the photomask 51. The illumination light L11 that enters the recessed mirror 14 and is reflected enters the photomask 51. That is, the recessed mirror 14 causes the illumination light L11 to enter the photomask 51.

[0020] Stage 52 is an XYZ driven stage. By moving Stage 52 in the X-axis and Y-axis directions, a desired area of ​​the photomask 51 can be illuminated. Furthermore, by moving Stage 52 in the Z-axis direction, focus adjustment can be performed. Stage 52 may also be rotated around the X-axis, Y-axis, and Z-axis as its rotation axes. Alternatively, instead of moving and rotating Stage 52 along the X-axis, Y-axis, and Z-axis directions, the illumination optical system 10 and the imaging optical system 20 may be moved and rotated.

[0021] Illumination light L11 from light source 11 illuminates the inspection area of ​​photomask 51. Reflected light L12 reflected by photomask 51 enters perforated concave mirror 21. A hole 21a is provided in the center of the perforated concave mirror 21.

[0022] Furthermore, if a pellicle 53 is mounted on the photomask 51, a portion of the illumination light L11 is reflected or absorbed by the pellicle 53, and the photomask 51 is illuminated by the illumination light L11 that has passed through the pellicle 53. Then, a portion of the reflected light L12 from the photomask 51 is reflected or absorbed by the pellicle 53, and the reflected light L12 that has passed through the pellicle 53 is incident on the perforated concave mirror 21.

[0023] The reflected light L12 reflected by the perforated concave mirror 21 is incident on the convex mirror 22. The convex mirror 22 reflects the reflected light L12 incident from the perforated concave mirror 21 toward the hole 21a of the perforated concave mirror 21. The reflected light L12 that has passed through the hole 21a is detected by the photodetector 23. The photodetector 23 may be a photodetector that includes a TDI (Time Delay Integration) sensor. The photodetector 23 includes a plurality of image sensors arranged in a line in one direction. The image sensors are, for example, CCDs (Charge Coupled Devices). However, the image sensors are not limited to CCDs.

[0024] In this manner, the imaging optical system 20 collects the reflected light L12 from the photomask 51 illuminated by the illumination light L11, and detects the collected reflected light L12 with the photodetector 23 to acquire image data of the photomask 51. The reflected light L12 contains information such as defects in the photomask 51. If defects exist in the photomask 51, the defects may be observed as dark images.

[0025] Figure 2 is a block diagram illustrating a control device 40. The control device 40 includes an acquisition unit 41 and a setting unit 42. The functions of the acquisition unit 41 and the setting unit 42 may be realized by a processor executing a program loaded into memory, or they may be realized by dedicated hardware.

[0026] The acquisition unit 41 acquires pellicle information, which includes information indicating whether or not the pellicle 53 is mounted on the photomask 51. The pellicle information may also include information on the transmittance of the pellicle 53 that transmits illumination light L11. If the pellicle 53 is not mounted on the photomask 51, the transmittance may be set to 100%.

[0027] The acquisition unit 41 may acquire pellicle information based on information entered by the user via an input device such as a keyboard, mouse, or touch panel. The acquisition unit 41 may acquire pellicle information of the photomask 51 to be illuminated from a database that stores pellicle information of each photomask. The acquisition unit 41 may acquire pellicle information of the photomask 51 by reading identification information written to each photomask. The acquisition unit 41 may acquire pellicle information of the photomask 51 based on a comparison of the result of illuminating the outer region of the photomask 51 (generally not covered by the pellicle) and the result of illuminating the central region of the photomask 51 (covered by the pellicle if a pellicle is mounted).

[0028] The acquisition unit 41 may acquire information on the intensity of the illumination light L11. The acquisition unit 41 may acquire information on the intensity of the illumination light L11 based, for example, on the detection result by the photodetector 23.

[0029] The setting unit 42 sets the charge accumulation time in the photodetector 23 based on the pellicle information. The setting unit 42 may also transmit a control signal to the photodetector 23 to set the charge accumulation time. The charge accumulation time may also be the exposure time. The charge accumulation time corresponds to the frame rate or line rate (e.g., the line rate of TDI), and the setting unit 42 may also set the frame rate or line rate in the photodetector 23. The setting unit 42 sets the charge accumulation time when the pellicle 53 is mounted on the photomask 51 to be longer than the charge accumulation time when the pellicle 53 is not mounted on the photomask 51. This prevents a decrease in the inspection accuracy of the photomask 51 with the pellicle 53 attached. Setting the charge accumulation time when the pellicle 53 is mounted on the photomask 51 to be longer than the charge accumulation time when the pellicle 53 is not mounted on the photomask 51 corresponds to setting the frame rate (line rate) when the pellicle 53 is mounted on the photomask 51 to be smaller or longer than the frame rate (line rate) when the pellicle 53 is not mounted on the photomask 51. Here, frame rate (line rate) may mean the number of images (lines) that can be acquired per second, or the period for acquiring one image (line).

[0030] The setting unit 42 may, for example, set the charge storage time so that the product of the charge storage time and the intensity of light detected by the photodetector 23 is constant. For example, if the transmittance of the pellicle 53 is 0.9, the illumination light L11 transmitted through the pellicle 53 illuminates the photomask 51, and the reflected light L12 transmitted through the pellicle 53 is detected by the photodetector 23. Therefore, the intensity of the detected light is 0.81 (=0.9 * 0.9) times the intensity of light detected when the pellicle 53 is not present. In this case, the setting unit 42 may set the charge storage time to approximately 1.23 (≒ 1 / 0.81) times. In other words, the setting unit 42 may set CATp to be CATn / T^2 or greater, where T is the transmittance, CATp is the charge storage time when illuminating the pattern surface of a photomask with a pellicle mounted, and CATn is the charge storage time when illuminating the pattern surface of a photomask without a pellicle mounted.

[0031] This allows for the inspection of images of a photomask 51 with a pellicle 53 mounted using the same standards and processes as when inspecting images of a photomask 51 without a pellicle 53 mounted. Furthermore, it allows for the inspection of images of a photomask 51 with a pellicle 53 mounted using the same standards and processes, regardless of the transmittance of the pellicle 53.

[0032] For example, when evaluating the image of the area to be inspected on the photomask 51 by the difference between it and a predetermined reference image, the threshold for the difference can be set to be the same regardless of the presence or absence of a pellicle or the transmittance of the pellicle, simplifying the processing. The control device 40 may also include an abnormality determination unit (not shown) that determines an abnormality on the pattern surface based on whether the image of the pattern surface and the reference image associated with the image differ by more than a predetermined threshold.

[0033] Furthermore, when generating a reference image by inputting information related to the pattern design data into an image generation model trained using machine learning, the internal coefficients of the image generation model can be made the same regardless of the presence or absence of a pellicle or the transmittance of the pellicle, thus simplifying the processing. The reference image may be an image generated by inputting information related to the pattern design data into an image generation model trained using machine learning, or it may be an image captured at different times of essentially the same die or photomask 51. The control device 40 may also include a reference image acquisition unit (not shown) that acquires the reference image by inputting information related to the pattern surface design data into a trained image generation model.

[0034] On the other hand, if the charge accumulation time is extended, the illumination light L11 will be irradiated onto the same area of ​​the pellicle 53 for a long period of time, which is expected to cause significant damage to the pellicle 53. Therefore, when the pellicle 53 is mounted on the photomask 51, the setting unit 42 needs to set the charge accumulation time so as not to exceed a predetermined upper limit. The upper limit may be determined based on at least one of the following: the intensity of the illumination light L11, the heat resistance performance of the pellicle 53, and the radiation performance of the pellicle 53.

[0035] Figure 3 shows how to set the intensity of the illumination light L11 (also called illumination light intensity) and the charge accumulation time when a pellicle 53 with a standard transmittance to the illumination light L11 is mounted on the photomask 51. In Figure 3, the horizontal direction represents the charge accumulation time, with longer charge accumulation times to the right. In Figure 3, the vertical direction represents the illumination light intensity, with higher illumination light intensity towards the bottom. Each grid cell shows imaging conditions that combine the charge accumulation time corresponding to the horizontal position of the grid cell and the illumination light intensity corresponding to the vertical position of the grid cell. The imaging condition that combines the i-th smallest illumination light intensity (where i is an integer from 1 to 5) and the j-th smallest charge accumulation time (where j is an integer from 1 to 5) is also called imaging condition Aij.

[0036] Under imaging conditions A15, A24-A25, A33-A35, A42-A45, and A51-A55, which are included in region NG1, there is a risk of damage to the pellicle 53. Under imaging condition A11, which is included in region NG2, the intensity of light detected by the photodetector 23 is low, which may result in low inspection accuracy. Therefore, the setting unit 42 needs to select an imaging condition from among appropriate imaging conditions A12-A14, A21-A23, A31-A32, and A41, which are not included in regions NG1 and NG2.

[0037] When the illumination light intensity is fixed, the setting unit 42 may select the imaging condition with the shortest charge accumulation time from among the appropriate imaging conditions. This can shorten the examination time. For example, the setting unit 42 may select imaging condition A12 from imaging conditions A12 to A14. Similarly, the setting unit 42 may select imaging condition A21 from appropriate imaging conditions A21 to A23, and imaging condition A31 from appropriate imaging conditions A31 to A32. "〇" indicates the imaging condition with the shortest charge accumulation time for each illumination light intensity. When the illumination light intensity is variable, the setting unit 42 may change the illumination light intensity to shorten the charge accumulation time. For example, the setting unit 42 may select imaging condition A21, which has a shorter charge accumulation time, from among imaging conditions A12 and A21. In this case, the setting unit 42 may perform control to change the illumination light intensity.

[0038] The setting unit 42 may select imaging conditions based on the illumination light intensity acquired by the acquisition unit 41.

[0039] Figure 4 shows appropriate imaging conditions A13-A14, A22-A23, and A31 when a pellicle 53 with a slightly lower transmittance to the illumination light L11 is mounted on the photomask 51. Comparing Figure 3 and Figure 4, imaging conditions A12, A21, A31, and A41 are added to region NG2 because the light intensity detected by the photodetector 23 is reduced. If the illumination light intensity is fixed, the setting unit 42 may select imaging condition A13 from imaging conditions A13-A14 to shorten the charge accumulation time. Similarly, the setting unit 42 may select imaging condition A22 from imaging conditions A22-A23. If no appropriate imaging condition exists at a certain illumination light intensity, the setting unit 42 can select an appropriate imaging condition by reducing the illumination light intensity. For example, imaging condition A42 is an inappropriate imaging condition, but imaging condition A32, obtained by reducing the illumination light intensity of imaging condition A42, is an appropriate imaging condition. The setting unit 42 may perform control to reduce the illumination light intensity.

[0040] Figure 5 shows appropriate imaging conditions A14 and A23 when a pellicle 53 with particularly low transmittance to illumination light L11 is mounted on the photomask 51. Comparing Figure 4 and Figure 5, imaging conditions A13, A22, A32, and A42 are added to region NG2. Imaging condition A42 is included in both region NG1 and region NG2.

[0041] Referring to Figures 3 to 5, the lower the transmittance of the pellicle 53, the greater the lower limit of the charge accumulation time included in the appropriate imaging conditions. Also, the greater the intensity of the illumination light, the smaller the upper limit of the charge accumulation time included in the appropriate imaging conditions.

[0042] The range of region NG1 may be determined according to the heat resistance and heat dissipation performance based on the thickness, material, and molecular structure of the pellicle 53. For example, when a pellicle 53 with low heat resistance or low heat dissipation performance is mounted on the photomask 51, the number of conditions that constitute region NG1 may increase compared to when a pellicle 53 with high heat resistance or high heat dissipation performance is mounted on the photomask 51. In this case, imaging conditions with higher illumination light intensity or longer charge storage time may be added to region NG1. The pellicle information may include information such as the thickness and material of the pellicle, and may also include information regarding the heat resistance and heat dissipation performance of the pellicle. The setting unit 42 can set the charge storage time, etc., using a map that shows appropriate imaging conditions according to the pellicle information.

[0043] The setting unit 42 may set a single charge accumulation time for the entire illumination area of ​​the pattern surface of the photomask 51. That is, the setting unit 42 uses the charge accumulation time selected and set from appropriate imaging conditions to inspect the entire illumination area (entire inspection area) of the pattern surface of the photomask 51 without changing the setting of the charge accumulation time. This makes it possible to inspect the captured image of the photomask 51 using the same standard across the entire illumination area (entire inspection area).

[0044] The control device according to Embodiment 1 can accurately inspect both a photomask 51 with a pellicle 53 mounted on it and a photomask 51 without a pellicle 53 mounted on it. Furthermore, the control device according to Embodiment 1 can reduce the damage accumulated on the pellicle 53 mounted on the photomask 51.

[0045] The vertical axis in Figures 3 to 5 represents illumination light intensity, but this is not the only option.

[0046] The vertical axis in Figures 3 to 5 may represent the heat resistance performance of the pellicle 53. In this case, the lower the axis, the lower the heat resistance performance. Therefore, the lower the heat resistance performance of the pellicle 53, the smaller the upper limit of the charge accumulation time included in the appropriate imaging conditions.

[0047] The vertical axis in Figures 3 to 5 may represent the heat dissipation performance of the pellicle 53. In this case, the lower the axis, the lower the heat dissipation performance. Therefore, the lower the heat dissipation performance of the pellicle 53, the smaller the upper limit of the charge accumulation time included in the appropriate imaging conditions.

[0048] The vertical axis in Figures 3 to 5 may represent an index based on the intensity of illumination light and the low heat resistance of the pellicle 53. In this case, the lower the axis, the larger the index. Therefore, the greater the illumination light intensity and the lower the heat resistance of the pellicle 53, the smaller the upper limit of the charge accumulation time included in the appropriate imaging conditions.

[0049] The vertical axis in Figures 3 to 5 may represent an index based on the intensity of the illumination light and the low heat dissipation performance of the pellicle 53. In this case, the lower the axis, the larger the index. Therefore, the greater the illumination light intensity and the lower the heat dissipation performance of the pellicle 53, the smaller the upper limit of the charge accumulation time included in the appropriate imaging conditions.

[0050] The vertical axis in Figures 3 to 5 may represent an index of the low heat resistance and low heat dissipation performance of the pellicle 53. In this case, the lower the axis, the larger the index. Therefore, the lower the heat resistance and heat dissipation performance of the pellicle 53, the smaller the upper limit of the charge accumulation time included in the appropriate imaging conditions.

[0051] The vertical axes in Figures 3 to 5 may represent indices based on the magnitude of illumination light intensity, the low heat resistance of the pellicle 53, and the low heat dissipation performance of the pellicle 53. In this case, the lower the axis, the larger the index. Therefore, the greater the illumination light intensity, the lower the heat resistance of the pellicle 53, and the lower the heat dissipation performance of the pellicle 53, the smaller the upper limit of the charge accumulation time included in the appropriate imaging conditions.

[0052] While embodiments of this disclosure have been described above, this disclosure includes appropriate modifications that do not impair its purpose and advantages, and is not limited by the embodiments described above. Furthermore, combinations of the configurations of Embodiments 1 and 2 also fall within the scope of the technical concept of this disclosure. [Explanation of symbols]

[0053] 1. Inspection device 10 Illumination optical system 11 Light source 12, 13 Ellipsoidal mirror 14. Recessed mirror 20 Imaging optical system 21. Perforated concave mirror 21a hole 22 Convex mirror 23 Photodetector 40 Control device 41 Acquisition Department 42 Setting section 51 Photomasks 52 stages 53 Pellicle L11 Illumination Light L12 reflected light

Claims

1. A control device for an optical device, comprising a light detection means for detecting light from the patterned surface of a photomask illuminated by illumination light, A means for acquiring pellicle information, which includes information indicating whether or not a pellicle is mounted on a photomask, A setting means for setting the charge accumulation time in the light detection means when the optical device illuminates the pattern surface of the photomask on which the pellicle is mounted to be greater than the charge accumulation time in the light detection means when the optical device illuminates the pattern surface of the photomask on which the pellicle is not mounted. A control device equipped with the following features.

2. The acquisition means acquires the pellicle information, including the transmittance of the pellicle to the illumination light, The setting means sets the charge accumulation time so as not to fall below a lower limit value based on the transmittance when the pellicle is mounted on the photomask. The control device according to claim 1.

3. The lower limit is larger as the transmittance decreases. The control device according to claim 2.

4. The setting means, when the pellicle is mounted on the photomask, sets the charge accumulation time to be less than an upper limit based on at least one of the illumination light intensity, the heat resistance performance of the pellicle, and the heat dissipation performance of the pellicle. The control device according to claim 1 or 2.

5. The upper limit is smaller as the intensity of the illumination light increases. The control device according to claim 4.

6. The aforementioned upper limit is smaller the lower the heat dissipation performance of the pellicle. The control device according to claim 4.

7. The system includes an anomaly determination means that determines an anomaly in the pattern surface based on whether the captured image of the pattern surface, obtained from the light detection result of the light detection means, and a reference image associated with the captured image differ by more than a predetermined threshold. The threshold value when the optical device illuminates the patterned surface of the photomask on which the pellicle is mounted is substantially the same as the threshold value when the optical device illuminates the patterned surface of the photomask on which the pellicle is not mounted. The control device according to claim 1 or 2.

8. The system includes a reference image acquisition means that obtains the aforementioned reference image by inputting information relating to the design data of the pattern surface to a trained image generation model, The coefficients of the image generation model when the optical device illuminates the patterned surface of the photomask on which the pellicle is mounted are substantially the same as the coefficients of the image generation model when the optical device illuminates the patterned surface of the photomask on which the pellicle is not mounted. The control device according to claim 7.

9. A control device for an optical device, comprising light detection means for detecting light from the patterned surface of a photomask on which a pellicle is mounted, illuminated by illumination light, An acquisition means for acquiring pellicle information, including the transmittance of the pellicle to the illumination light, The system includes a setting means for setting the charge accumulation time in the light detection means when illuminating the patterned surface, based on the transmittance. The setting means sets the charge accumulation time to be larger as the transmittance decreases, and to be smaller than an upper limit based on at least one of the illumination light intensity, the heat resistance performance of the pellicle, and the heat dissipation performance of the pellicle. Control device.

10. The upper limit is smaller as the intensity of the illumination light increases. The control device according to claim 9.

11. The aforementioned upper limit is smaller the lower the heat dissipation performance of the pellicle. The control device according to claim 9.

12. The system includes an anomaly determination means that determines an anomaly in the pattern surface based on whether the captured image of the pattern surface, obtained from the light detection result of the light detection means, differs from a reference image associated with the captured image by more than a predetermined threshold. The threshold value when the optical device illuminates the patterned surface of a photomask on which a pellicle having a first transmittance is mounted is substantially the same as the threshold value when the optical device illuminates the patterned surface of a photomask on which a pellicle having a second transmittance is mounted. The control device according to claim 9.

13. The system includes a reference image acquisition means that obtains the aforementioned reference image by inputting information relating to the design data of the pattern surface to a trained image generation model, The coefficients of the image generation model when the optical device illuminates the patterned surface of the photomask on which the pellicle is mounted are substantially the same as the coefficients of the image generation model when the optical device illuminates the patterned surface of the photomask on which the pellicle is not mounted. The control device according to claim 12.

14. The setting means sets a single charge accumulation time for the entire illumination area of ​​the pattern surface of the photomask. The control device according to claim 1 or 9.

15. The setting means sets CATp to be CATn / T^2 or greater, where T is the transmittance, CATp is the charge accumulation time when illuminating the pattern surface of the photomask on which the pellicle is mounted, and CATn is the charge accumulation time when illuminating the pattern surface of the photomask on which the pellicle is not mounted. The control device according to claim 2 or 9.

16. The setting means sets the charge storage time such that the product of the charge storage time and the intensity of the light detected by the photodetector is constant. The control device according to claim 1 or 9.

17. A control method for an optical device comprising light detection means for detecting light from the patterned surface of a photomask illuminated by illumination light, A process for obtaining pellicle information, which includes information indicating whether or not a pellicle is mounted on the photomask, The process involves setting the charge accumulation time in the light detection means to be greater than the charge accumulation time in the light detection means when illuminating the pattern surface of the photomask on which the pellicle is mounted with the optical device, compared to the charge accumulation time in the light detection means when illuminating the pattern surface of the photomask on which the pellicle is not mounted with the optical device. A control method including

18. A control method for an optical device comprising light detection means for detecting light from a patterned surface of a photomask on which a pellicle is mounted, illuminated by illumination light, A step of acquiring pellicle information, including the transmittance of the pellicle to the illumination light, The process includes setting the charge accumulation time in the light detection means when illuminating the patterned surface based on the transmittance, The step of setting the charge storage time involves setting the charge storage time to be larger as the transmittance decreases, and smaller than an upper limit based on at least one of the illumination light intensity, the heat resistance performance of the pellicle, and the heat dissipation performance of the pellicle. Control method.

Images