Pellicle surface inspection system having defect position correction function
The pellicle surface inspection system addresses the issue of sagging-induced defects by using diagonal line light and area cameras with correction algorithms to ensure comprehensive and precise defect detection and positioning.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- HIMS CO LTD
- Filing Date
- 2025-12-02
- Publication Date
- 2026-06-11
AI Technical Summary
Existing pellicle surface inspection systems fail to accurately detect defects due to sagging of the pellicle, leading to inspection omission areas and positional errors in the captured images, which can result in performance degradation of semiconductor chips.
A pellicle surface inspection system that irradiates line light in a diagonal direction and uses an area camera to capture images with a wider field of view, combined with a control unit to calculate and correct positional and shape errors based on bias information, ensuring complete defect detection and accurate defect positioning.
Prevents defect detection omission and corrects positional and shape errors in pellicle surface inspection images, providing accurate defect data and minimizing errors in defect size and shape readings.
Smart Images
Figure KR2025020470_11062026_PF_FP_ABST
Abstract
Description
Pellicle surface inspection system equipped with defect location correction function
[0001] The present invention relates to a pellicle surface inspection system equipped with a defect location correction function, and more specifically, to a pellicle surface inspection system equipped with a defect location correction function used to inspect whether defects such as scratches, holes, protrusions, foreign substances, and coating defects exist on the surface of a pellicle covering a pattern on a photomask.
[0002] Referring to FIG. 1, a pellicle (20) is generally a thin film made of a polymer light-transmitting material with high transmittance so that light can pass through, and is mounted to cover the pattern (11) of a photomask (10) used in semiconductor manufacturing to prevent the pattern (11) from being contaminated by foreign substances such as dust or moisture, or damaged by external impact and contact.
[0003] If there are defects such as scratches, holes, protrusions, foreign substances, and coating defects on the surface of the pellicle (20), they may be reflected directly onto the wafer during the photolithography process of semiconductor manufacturing, which can cause performance degradation or defects in the semiconductor chip, and since contamination of the pellicle (20) can damage the photolithography equipment, surface inspection of the pellicle (20) to detect defects is essential.
[0004] Conventionally, as shown in FIG. 1, a line-shaped light was irradiated onto the surface of a pellicle (20) using a line light device (31), and the part where the line light was irradiated was photographed by a line scan camera (32). The control unit (33) then analyzed the acquired inspection image to detect defects present on the surface of the pellicle (20).
[0005] In addition, as shown in FIG. 2, the line lighting device (31) irradiates a linearly extended line light in the Y-axis direction, and the line scan camera (32) generates an inspection image by capturing a shooting area (32a) having a width corresponding to the line width of the lighting area (31a) on the surface of the pellicle (20) where the line light of the line lighting device (31) is irradiated, and by capturing an image while moving horizontally in the X-axis direction together with the line lighting device (31), it was possible to obtain an inspection image of the entire surface of the pellicle (20).
[0006] However, while the photomask (10) typically has a large surface area of 6 inches to 14 inches or more, the pellicle is manufactured to be very thin with a thickness of 0.5 μm to 5 μm, and as shown in FIGS. 1 and 3, only the edge portion is fixed to the photomask (10), so a sagging phenomenon occurs in which the central portion of the pellicle (20) descends due to the load. As a result, the lighting area (31a) of the line lighting device (31) and the shooting area (32a) of the line scan camera (32) do not coincide and are misaligned with each other, so line lighting is not irradiated on the shooting area (32a), and an inspection omission area (B) may occur in which the surface image of the pellicle (20) is not displayed in the captured image. This inspection omission area (B) is not illuminated and is displayed as black on the image.
[0007] With reference to FIG. 3, the left end of the left portion (left-biased section) of the pellicle (20) is fixed to the photomask (10) and maintains a set height, but as it moves toward the right, it gradually descends, causing the lighting area (31a) to be biased to the left of the set reference line (L, e.g., center line) of the shooting area (32a), so that line lighting is not irradiated on the right edge of the shooting area (32a), and thus an inspection omission area (B) occurs in the right part of the captured inspection image.
[0008] Additionally, the right end of the right portion (right-biased section) of the pellicle (20) is fixed to the photomask (10) so that it maintains a set height, but as it moves toward the left, it gradually descends, causing the lighting area (31a) to be biased to the right of the set reference line (L, e.g., center line) of the shooting area (32a), so that line lighting is not irradiated on the left edge of the shooting area (32a), and thus an inspection omission area (B) occurs in the right portion of the captured inspection image.
[0009] In cases where a defect (A) exists in the inspection omission area (B), it may be omitted from surface inspection as it appears black due to a lack of illumination, and consequently, there was a problem in that defects or performance degradation occurred in semiconductor chips manufactured using the defective photomask.
[0010] Meanwhile, as shown in FIG. 4, when the central part of the pellicle (20) sags downward, the defect (A) located in the left part (left-biased section) of the pellicle (20) moves to a position (L2) to the left of its horizontal position (L1), and conversely, the defect (A) located in the right part (right-biased section) of the pellicle (20) moves to a position (L4) to the right of its horizontal position (L3), causing an error in the position data (coordinate value) of the defect (A) detected in the captured inspection image (I).
[0011] Additionally, since the pellicle (20) is formed of a transparent material, when the line scan camera (32) captures an image from directly below to directly above, the pattern (11) of the photomask (10) is included in the image, making it difficult to identify the defect (A), as shown in FIGS. 1 and 2, the line lighting device (31) illuminates the line light in a diagonal direction, and the line scan camera (32) captures an image in a diagonal direction toward the line lighting area from a position spaced apart from the line lighting device (31).
[0012] Therefore, even if the actual shape of the defect (A) is circular as in Fig. 5 (a), the shape of the detected defect (A) is distorted and displayed as in Fig. 5 (b) in the inspection image captured by the line scan camera (32) due to the downward convex shape caused by the sagging of the pellicle (20), resulting in a problem where errors occur in reading the size, shape, and location of the defect (A).
[0013] In the following, the portion of the surface image of the pellicle (20) that is not displayed in the inspection image because the lighting area (31a) and the shooting area (32a) are misaligned as described above, the portion where an error occurs in the position of the defect (A) relative to the horizontal state due to the sagging of the lower part of the pellicle (20), or the portion where the shape of the defect (A) is displayed in a distorted manner is referred to as the inspection omission area (B).
[0014] The present invention was created to solve the aforementioned problems, and the objective of the present invention is to provide a pellicle surface inspection system equipped with a defect position correction function that can prevent the omission of defect detection by ensuring that a portion of the pellicle's surface image is not displayed in the inspection image due to a mismatch between the lighting area and the shooting area, even if the central part of the pellicle sags downward due to its own weight, and can provide corrected position data that compensates for the positional error of the defect detected in the inspection image, or a corrected inspection image that compensates for the shape and size of the defect.
[0015] According to a feature of the present invention, in a pellicle surface inspection system for inspecting defects (A) of a pellicle (20) covering a pattern (11) on a photomask (10), the system comprises: an illumination unit (110) that irradiates a line light in a diagonal direction that extends in a straight line toward the surface of the pellicle (20); and an area camera (120) that generates an inspection image (I) by capturing an image in a diagonal direction centered on a line light area (111) on the surface of the pellicle (20) where the line light of the illumination unit (110) is irradiated, wherein the image is captured in a shooting area (121) having a width (W2) that is relatively wider than the width (W1) of the line light area (111). A pellicle surface inspection system is provided, comprising: a control unit (130) that detects a defect (A) placed on the surface of a pellicle (20) by image analysis of a generated inspection image (I), calculates bias information including the direction and value of the bias of the image of a line lighting area (111) centered on a reference line (L) set on the inspection image (I), and generates corrected position data (D) that corrects the position of the defect (A) by reflecting the calculated bias information, or generates a corrected inspection image (Ia) in which the position of the defect (A) is corrected.
[0016]
[0017] According to another feature of the present invention, a pellicle surface inspection system is provided, wherein the control unit (130) stores defect shape correction reference data for each bias information, reads out defect shape correction reference data that matches the bias information calculated from the currently captured inspection image (I), and generates a corrected inspection image (Ia) in which the shape of a defect (A) included in the inspection image (I) is corrected based on the read-out defect shape correction reference data.
[0018]
[0019] According to another feature of the present invention, the lighting unit (110) irradiates a line light that is linearly extended in the Y-axis direction, and the lighting unit (110) and the area camera (120) are fixedly mounted on a base unit (140); a horizontal movement driving unit (150) that moves the base unit (140) horizontally in the X-axis direction; and a vertical movement driving unit (160) that moves the base unit (140) vertically in the Z-axis direction. A pellicle surface inspection system is provided, further comprising: a distance measuring unit (170) fixedly mounted on the base unit (140) to measure the distance from the pellicle (20); wherein the control unit (130) controls the horizontal movement driving unit (150) so that the base unit (140) moves horizontally in the X-axis direction so that the area camera (120) takes a divided shot of the entire surface of the pellicle (20), and controls the vertical movement driving unit (160) so that the base unit (140) moves up and down according to the distance measuring unit (170) so that the area camera (120) takes an image while maintaining a set distance (d) from the pellicle (20).
[0020]
[0021] According to another feature of the present invention, a pellicle surface inspection system for inspecting defects (A) of a pellicle (20) covering a pattern (11) on a photomask (10) comprises: an illumination unit (210) that irradiates a line light in a diagonal direction that is linearly extended in the Y-axis direction toward the surface of the pellicle (20); a camera unit (220) that generates an inspection image (I) by capturing an image in a diagonal direction centered on the line light area where the line light of the illumination unit (210) is irradiated on the surface of the pellicle (20); a base unit (230) on which the illumination unit (210) and the camera unit (220) are fixedly mounted; a horizontal movement drive unit (240) that moves the base unit (230) horizontally in the X-axis direction; and a vertical movement drive unit (250) that moves the base unit (230) vertically in the Z-axis direction and measures the current vertically moved distance from a set reference position. A distance measuring unit (260) fixedly mounted on the base unit (230) to measure the distance from the pellicle (20); The control unit (270) detects a defect (A) by analyzing the generated inspection image (I) and controls the horizontal movement drive unit (240) so that the base unit (230) moves horizontally in the X-axis direction so that the camera unit (220) captures the entire surface of the pellicle (20) in segments, and controls the vertical movement drive unit (250) so that the base unit (230) moves up and down according to the distance measurement value of the distance measurement unit (260) so that the camera unit (220) captures an image while maintaining a set separation distance from the pellicle (20); wherein the control unit (270) calculates bias information including the direction and value of the defect (A) being deflected from the reference line (L) based on the movement distance measurement value measured by the vertical movement drive unit (250), and generates corrected position data (D) that corrects the position of the defect (A) by reflecting the calculated bias information, or generates a corrected inspection image (Ia) in which the position of the defect (A) is corrected. A pellicle surface inspection system characterized by the following is provided.
[0022]
[0023] According to another feature of the present invention, a pellicle surface inspection system is provided, wherein the control unit (270) stores defect shape correction reference data for each bias information, reads out defect shape correction reference data that matches the bias information calculated from the currently captured inspection image (I), and generates a corrected inspection image (Ia) in which the shape of a defect (A) included in the inspection image (I) is corrected based on the read-out defect shape correction reference data.
[0024] As described above, according to the present invention,
[0025] First, the lighting unit (110) irradiates a line light in a diagonal direction that extends in a straight line toward the surface of the pellicle (20), and the area camera (120) generates an inspection image (I) by capturing an image in a diagonal direction targeting a line lighting area (111) on the surface of the pellicle (20) where the line light of the lighting unit (110) is irradiated, and captures the image in a shooting area (121) having a width (W2) that is relatively wider than the width (W1) of the line lighting area (111); and the control unit (130) analyzes the generated inspection image (I) to detect a defect (A), calculates bias information including the direction and value of the bias of the image of the line lighting area (111) centered on a reference line (L) set on the inspection image (I), and generates corrected position data (D) that corrects the position of the defect (A) by reflecting the calculated bias information, or generates a corrected inspection image (Ia) in which the position of the defect (A) is corrected. Even if the central part of the pellicle (20) sags downward due to its own weight, it is possible to prevent the detection of defects (A) from being omitted because some surface images of the pellicle (20) are not displayed in the inspection image (I) due to the mismatch between the line lighting area (111) and the shooting area (121), and there is an advantage of being able to provide corrected position data (D) that compensates for the positional error of the defect (A) detected in the inspection image (I) or a corrected inspection image (Ia) that compensates for the shape and size of the defect (A).
[0026] Second, the control unit (130) stores defect shape correction reference data for each bias information, reads out defect shape correction reference data that matches the bias information calculated from the currently captured inspection image (I), and generates a corrected inspection image (Ia) in which the shape of the defect (A) included in the inspection image (I) is corrected based on the read-out defect shape correction reference data, thereby providing a shape that is identical or close to the actual defect (A) present in the pellicle (20), and thus can minimize errors in reading the shape and size of the defect (A).
[0027] Third, the lighting unit (110) emits a linearly extended line light in the Y-axis direction, and the base unit (140) is fixedly mounted with the lighting unit (110) and the area camera (120). The horizontal movement drive unit (150) moves the base unit (140) horizontally in the X-axis direction, and the vertical movement drive unit (160) moves the base unit (140) vertically in the Z-axis direction. The distance measuring unit (170) is fixedly mounted on the base unit (140) to measure the distance from the pellicle (20). The control unit (130) controls the horizontal movement drive unit (150) so that the base unit (140) moves horizontally in the X-axis direction so that the area camera (120) can divide and photograph the surface of the pellicle (20). As the base unit (140) moves up and down according to the distance measuring unit (170), the area camera (120) By driving and controlling the vertical movement drive unit (160) to capture an image while maintaining a set separation distance (d) from the pellicle (20), it is possible to prevent a difference in the image magnification of each image frame of the captured inspection image (I) or an error in reading the size of the detected defect (A) as the separation distance between the area camera (120) and the pellicle (20) changes, or to prevent the lighting focus of the line light and the shooting focus of the area camera (120) from being misaligned.
[0028] Fourth, the lighting unit (210) irradiates a line light in a linearly extended shape in the Y-axis direction toward the surface of the pellicle (20) from a diagonal direction, and the camera unit (220) generates an inspection image (I) by capturing an image from a diagonal direction targeting the line light area where the line light of the lighting unit (210) is irradiated on the surface of the pellicle (20); the base unit (230) is fixedly mounted with the lighting unit (210) and the camera unit (220); the horizontal movement driving unit (240) moves the base unit (230) horizontally in the X-axis direction, and the vertical movement driving unit (250) moves the base unit (230) vertically in the Z-axis direction and measures the currently vertically moved distance from a set reference position; the distance measuring unit (260) is fixedly mounted on the base unit (230) and measures the distance from the pellicle (20); and the control unit (270) performs image analysis on the generated inspection image (I). A defect (A) is detected, and a horizontal movement drive unit (240) is driven to control the base unit (230) to move horizontally in the X-axis direction so that the camera unit (220) captures a segmented image of the entire surface of the pellicle (20); a vertical movement drive unit (250) is driven to control the base unit (230) to move up and down according to the distance measurement value of the distance measurement unit (260) so that the camera unit (220) captures an image while maintaining a set distance from the pellicle (20); and based on the movement distance measurement value measured by the vertical movement drive unit (250), bias information including the direction and value of the deviation of the defect (A) from the reference line (L) is calculated, and a corrected position data (D) is generated to correct the position of the defect (A) by reflecting the calculated bias information, or a corrected inspection image (Ia) is generated to correct the position of the defect (A). Thus, even if the central part of the pellicle (20) sags downward due to its own weight, the captured inspection image (I) Since the inspection omission area (B) does not occur, it is possible to prevent the detection of defects (A) present in the inspection omission area (B), and there is an advantage of being able to provide corrected position data (D) or corrected inspection image (Ia) that compensates for the positional error of defects (A) detected in the inspection image (I).
[0029] Fifth, the control unit (270) stores defect shape correction reference data for each bias information, reads out defect shape correction reference data that matches the bias information calculated from the currently captured inspection image (I), and generates a corrected inspection image (Ia) in which the shape of the defect (A) included in the inspection image (I) is corrected based on the read-out defect shape correction reference data, thereby providing a shape that is identical or close to the actual defect (A) present in the pellicle (20), and thus can minimize errors in reading the shape and size of the defect (A).
[0030] FIG. 1 is a schematic diagram showing the configuration of a pellicle surface inspection system according to the prior art.
[0031] FIG. 2 is a perspective view showing the operation method of a line lighting device and a line scan camera according to the prior art.
[0032] FIG. 3 is a schematic diagram for explaining the operating principle of image damage occurring on an inspection image of a pellicle surface inspection system in the prior art.
[0033] FIG. 4 is a side view showing a phenomenon in which the location of detected defects changes as the central part of a typical pellicle sags downward.
[0034] FIG. 5 is a schematic diagram illustrating the phenomenon in which the shape of a defect detected in a pellicle surface inspection system according to the prior art is displayed in a distorted manner.
[0035] FIG. 6 is a schematic diagram showing the configuration of a pellicle surface inspection system according to a preferred first embodiment of the present invention.
[0036] FIG. 7 is a perspective view showing the operation method of a lighting unit and an area camera according to a preferred first embodiment of the present invention.
[0037] FIG. 8 is a schematic diagram showing each image frame of an inspection image captured by an area camera according to a preferred first embodiment of the present invention.
[0038] FIG. 9 is a schematic diagram showing the state in which each image frame captured by an area camera according to a preferred first embodiment of the present invention is combined to form an inspection image.
[0039] FIG. 10 is a schematic diagram illustrating the operating principle in which no image damage occurs on an inspection image in a pellicle surface inspection system according to a preferred first embodiment of the present invention,
[0040] FIG. 11 is a schematic diagram illustrating the operating principle of a control unit calculating bias information from an inspection image according to a preferred first embodiment of the present invention.
[0041] FIG. 12 is a schematic diagram showing correction position data and correction inspection image in which a control unit corrects the location of a defect according to a preferred first embodiment of the present invention,
[0042] FIG. 13 is a schematic diagram showing a correction inspection image generated by a control unit correcting the shape of a defect according to a preferred first embodiment of the present invention.
[0043] FIG. 14 is a schematic diagram of a state in which a base part moves horizontally while maintaining the same separation distance by a control unit according to a preferred first embodiment of the present invention.
[0044] FIG. 15 is a schematic diagram showing the configuration of a pellicle surface inspection system according to a preferred second embodiment of the present invention.
[0045] The objectives, features, and advantages of the present invention described above will become clearer through the following detailed description. Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings as follows.
[0046] A pellicle surface inspection system (100, 200) equipped with a defect location correction function according to a preferred embodiment of the present invention is an inspection system used to inspect whether defects (A), such as scratches, holes, protrusions, foreign substances, and coating defects, exist on the surface of a pellicle (20) that covers a pattern (11) on a photomask (10). Below, embodiments will be described by classifying them according to a method of calculating bias information used to correct the location of defects (A) detected on a captured inspection image (I).
[0047] First, a pellicle surface inspection system (100) according to a preferred first embodiment of the present invention is a system that generates correction position data (D) and correction inspection image (Ia) of a defect (A) based on the biased direction and numerical value of the image of a line lighting area (111) where line lighting is irradiated on a captured inspection image (I), and includes a lighting unit (110), an area camera (120), and a control unit (130) as shown in FIG. 6.
[0048] The lighting unit (110) is a means of providing lighting for shooting so that an inspection image (I) of clear quality can be captured by an area camera (120), and as shown in FIG. 7, it irradiates line lighting in a diagonal direction in a straight line extending toward the surface of the pellicle (20).
[0049] The area camera (120) is a shooting means that provides an inspection image (I) as basic data necessary for surface inspection of whether a defect (A) exists on the surface of the pellicle (20), and as shown in FIGS. 6 and 7, it generates an inspection image (I) by taking an image from a diagonal direction targeting a line lighting area (111) on which line lighting from the lighting unit (110) is irradiated on the surface of the pellicle (20).
[0050] Here, the area camera (120) is configured to capture an image in a shooting area (121) having a width (W2) that is relatively wider than the width (W1) of the line lighting area (111), so that even if the image of the line lighting area (111) is positioned at a location deviated from the reference line (L, see FIG. 10) of the inspection image (I) due to the sagging phenomenon of the pellicle (20), the image of the line lighting area (111) is included in the inspection image (I).
[0051] Accordingly, it is preferable that the width (W2) of the line lighting area (111) be set to be equal to or relatively larger than the size obtained by adding the maximum value to the width (W1) of the line lighting area (111) to which the image of the line lighting area (111) can be deflected.
[0052] Here, since the pellicle (20) is made of a light-transmitting material with high transmittance, if an image is taken at a position facing the line lighting area (111), which is the area where the line lighting of the lighting unit (110) is irradiated on the pellicle (20) (directly below based on the drawing), the pattern (11) of the photomask (10) covered by the pellicle (20) may be included in the inspection image (I) and act as noise in the detection of defects (A).
[0053] Accordingly, as shown in FIG. 7, it is preferable that the area camera (120) be equipped to capture an image by aiming at the line lighting area (111) of the lighting unit (110) from a diagonal direction so as to obtain only an image of the surface of the pellicle (20).
[0054] Additionally, although the drawing illustrates the lighting unit (110) and the area camera (120) illuminating line light or capturing images in diagonal directions from opposite directions, they may also illuminate line light or capture images in diagonal directions toward the surface of the pellicle (20) from the same position.
[0055] In addition, the area camera (120) moves horizontally in the X-axis direction from one end position to the other end position of the pellicle (20) together with the lighting unit (110) and sequentially captures images at regular intervals to generate a plurality of inspection images (I1 ~ In) as shown in FIG. 8.
[0056] Here, in each inspection image (I1 ~ In), the parts that do not include the image of the line lighting area (111) are images of the parts of the pellicle (20) where line lighting was not irradiated, so they can be removed as shown in the drawing and filtered so that only the parts where line lighting was irradiated remain.
[0057] The above control unit (130) is a means for determining whether a defect (A) exists on the surface of a pellicle (20) using an inspection image (I) captured by an area camera (120), and detects a defect (A) placed on the surface of the pellicle (20) by image analysis of the generated inspection image (I), calculates bias information including the direction and value of the bias of the image of the line lighting area (111) centered on the reference line (L) set on the inspection image (I), and generates corrected position data (D) that corrects the position of the defect (A) by reflecting the calculated bias information, or generates a corrected inspection image (Ia) in which the position of the defect (A) is corrected.
[0058] Here, the control unit (130) can detect a defect (A) on an inspection image (I) by performing image analysis on each inspection image (I1~In) taken at regular intervals to recognize the defect (A) as a detection object, and can also detect a defect (A) by performing image analysis on the entire inspection image (I) in which each inspection image (I1~In) is sequentially arranged and synthesized into a single image form as shown in FIG. 9.
[0059] Additionally, the reference line (L) may be an axis line indicating the central position of the inspection image (I, or shooting area (121)), and may also be an axis line arbitrarily selected to identify the bias state of the image of the line lighting area (111).
[0060] Referring to FIG. 10, due to the lower sagging phenomenon of the pellicle (20), in the left-biased section, the image of the line lighting area (111) is shown to be biased to the left from the reference line (L) of the inspection image (I), in the normal section, the image of the line lighting area (111) is shown to be roughly centered on the reference line (L) of the inspection image (I), and in the right-biased section, the image of the line lighting area (111) is shown to be biased to the right from the reference line (L) of the inspection image (I).
[0061] Accordingly, the control unit (130) can detect an image of a line lighting area (111) on an inspection image (I) through image analysis and calculate bias information including the direction in which the image of the line lighting area (111) is biased and the value of the bias from the reference line (L) of the inspection image (I).
[0062] Here, the biased value may be a value that measures the distance at which the image of the line lighting area (111) is biased on the pellicle (20), or a position coordinate value where the image of the line lighting area (111) is placed on the coordinates targeting the inspection image (I).
[0063] Additionally, as illustrated in FIG. 11, the control unit (130) can indicate the direction in which the image of the line lighting area (111) is biased on the inspection image (I) with an arrow or indicate the biased value.
[0064] In addition, an inspection image (I) containing a defect (A) can be provided as in (a) of FIG. 12, and in addition, a corrected position data (D) with the position of the defect (A) corrected can be generated and displayed as in (b) of FIG. 12, or a corrected inspection image (Ia) with the position of the defect (A) corrected can be generated and displayed.
[0065] Through the combined configuration of the lighting unit (110), camera unit (220), and control unit (130) as described above, even if the central part of the pellicle (20) sags downward due to its own weight, it is possible to prevent the detection of defects (A) from being omitted because some surface images of the pellicle (20) are not displayed in the inspection image due to the mismatch between the line lighting area (111) and the shooting area (121), and it is possible to provide corrected position data (D) that compensates for the positional error of the defect (A) detected in the inspection image (I), or a corrected inspection image (Ia) that compensates for the shape and size of the defect (A).
[0066] Meanwhile, as shown in FIG. 12, the control unit (130) stores defect shape correction reference data for each bias information and reads out defect shape correction reference data that matches the bias information calculated from the currently captured inspection image (I), and generates a corrected inspection image (Ia) that corrects the shape of the defect (A) included in the inspection image (I) based on the read-out defect shape correction reference data as shown in FIG. 13, thereby providing a shape that is identical or close to the actual defect (A) present in the pellicle (20), and thus can minimize errors in reading the shape and size of the defect (A).
[0067] Additionally, as illustrated in FIGS. 6 and FIGS. 14, the lighting unit (110) illuminates a linearly extended line light in the Y-axis direction, the base unit (140) is fixedly mounted with the lighting unit (110) and the area camera (120), the horizontal movement driving unit (150) moves the base unit (140) horizontally in the X-axis direction, and the vertical movement driving unit (160) moves the base unit (140) vertically in the Z-axis direction.
[0068] In addition, the distance measuring unit (170) is fixedly mounted on the base unit (140) to measure the distance from the pellicle (20), and the control unit (130) controls the horizontal movement driving unit (150) so that the base unit (140) moves horizontally in the X-axis direction so that the area camera (120) captures the entire surface of the pellicle (20) in segments, and controls the vertical movement driving unit (160) so that the base unit (140) moves up and down according to the distance measuring unit (170) so that the area camera (120) captures images while maintaining the set distance (d) from the pellicle (20).
[0069] Therefore, as the distance between the area camera (120) and the pellicle (20) changes, it is possible to prevent a difference in the image magnification of each image frame of the captured inspection image (I), an error in reading the size of the detected defect (A), or a mismatch between the lighting focus of the line light and the shooting focus of the area camera (120).
[0070]
[0071] Next, the configuration and function of a pellicle surface inspection system (200) according to a preferred second embodiment of the present invention will be described.
[0072] A pellicle surface inspection system (200) according to a preferred second embodiment of the present invention is a system that generates correction position data (D) and correction inspection image (Ia) of a defect (A) based on a measurement of the distance from the pellicle (20) measured when the base part (230) moves horizontally while rising and falling along the shape of the lower part of the pellicle (20), and includes a lighting part (210), a camera part (220), a base part (230), a horizontal movement driving part (240), a vertical movement driving part (250), a distance measuring part (260), and a control part (270) as shown in FIG. 15.
[0073] The lighting unit (210) irradiates a line light in a linearly extended Y-axis direction toward the surface of the pellicle (20) from a diagonal direction, and the camera unit (220) generates an inspection image (I) by capturing an image from a diagonal direction on the line light area where the line light of the lighting unit (210) is irradiated on the surface of the pellicle (20).
[0074] The base unit (230) has a lighting unit (210) and a camera unit (220) fixedly mounted thereon, the horizontal movement drive unit (240) moves the base unit (230) horizontally in the X-axis direction, and the vertical movement drive unit (250) moves the base unit (230) vertically in the Z-axis direction. In addition, the vertical movement drive unit (250) can measure the current vertical movement distance from a set reference position, and the measured vertical movement distance can be used as basic data necessary to precisely vertically move the base unit (230).
[0075] The distance measuring unit (260) is fixedly mounted on the base unit (230) to measure the distance from the pellicle (20), and the control unit (270) detects a defect (A) by image analysis of the generated inspection image (I), and controls the horizontal movement driving unit (240) so that the base unit (230) moves horizontally in the X-axis direction so that the camera unit (220) captures the entire surface of the pellicle (20) in segments, and controls the vertical movement driving unit (250) so that the base unit (230) moves up and down according to the distance measuring unit (260) and captures an image while maintaining the set distance from the pellicle (20).
[0076] Here, the lighting unit (210), camera unit (220), base unit (230), horizontal movement driving unit (240), vertical movement driving unit (250), and distance measuring unit (260) according to the second preferred embodiment of the present invention have the same configuration and function as the lighting unit (110), base unit (140), horizontal movement driving unit (150), vertical movement driving unit (160), and distance measuring unit (170) according to the first preferred embodiment of the present invention described above, so a redundant description is omitted.
[0077] However, the above camera unit (220) may use an area camera that captures a shooting area having a width relatively wider than the line lighting of the lighting unit (110), such as the area camera (120) according to the first preferred embodiment of the present invention, and may also use a line scan camera that captures a shooting area having a width equal to the line lighting of the lighting unit (110).
[0078] Additionally, the control unit (270) calculates bias information including the direction and value of the defect (A) being deflected from the reference line (L) based on the distance measured by the vertical movement drive unit (250), and generates corrected position data (D) that corrects the position of the defect (A) by reflecting the calculated bias information, or generates a corrected inspection image (Ia) in which the position of the defect (A) is corrected.
[0079] Therefore, even if the central part of the pellicle (20) sags downward due to its own weight, the inspection omission area (B) does not occur in the captured inspection image (I), so it is possible to prevent the detection of defects (A) present in the inspection omission area (B), and it is possible to provide corrected position data (D) or corrected inspection image (Ia) that compensates for the positional error of the defects (A) detected in the inspection image (I).
[0080] In addition, the control unit (270) stores defect shape correction reference data for each bias information, reads out defect shape correction reference data that matches the bias information calculated from the currently captured inspection image (I), and generates a corrected inspection image (Ia) in which the shape of the defect (A) included in the inspection image (I) is corrected based on the read-out defect shape correction reference data, thereby providing a shape that is identical or close to the actual defect (A) present in the pellicle (20), and thus can minimize errors in reading the shape and size of the defect (A).
[0081] The present invention described above is not limited by the aforementioned embodiments and attached drawings, and it will be obvious to those skilled in the art that various substitutions, modifications, and changes are possible within the scope of the technical concept of the present invention.
Claims
1. A pellicle surface inspection system for inspecting defects (A) of a pellicle (20) covering a pattern (11) on a photomask (10), A lighting unit (110) that illuminates a line light extending in a straight line toward the surface of the pellicle (20) from a diagonal direction; An area camera (120) that generates an inspection image (I) by capturing an image in a diagonal direction centered on a line lighting area (111) on the surface of the pellicle (20) where line lighting from the lighting unit (110) is irradiated, and captures the image in a shooting area (121) having a width (W2) that is relatively wider than the width (W1) of the line lighting area (111); and A pellicle surface inspection system comprising: a control unit (130) that detects a defect (A) present on the surface of a pellicle (20) by image analysis of a generated inspection image (I), calculates bias information including the direction and value of the bias of the image of a line lighting area (111) centered on a reference line (L) set on the inspection image (I), and generates corrected position data (D) that corrects the position of the defect (A) by reflecting the calculated bias information, or generates a corrected inspection image (Ia) in which the position of the defect (A) is corrected.
2. In Claim 1, The lighting unit (110) above irradiates a linearly extended line light in the Y-axis direction, and A base part (140) on which the lighting part (110) and area camera (120) are fixedly mounted; A horizontal movement driving unit (150) that moves the base part (140) horizontally in the X-axis direction; A vertical movement drive unit (160) that vertically moves the base unit (140) in the Z-axis direction; and It further includes a distance measuring unit (170) fixedly mounted on the base unit (140) to measure the distance from the pellicle (20), and The above control unit (130) is, A pellicle surface inspection system characterized by driving a horizontal movement drive unit (150) so that the base unit (140) moves horizontally in the X-axis direction so that the area camera (120) takes a divided shot of the entire surface of the pellicle (20), and driving a vertical movement drive unit (160) so that the base unit (140) moves up and down according to the distance measurement value of the distance measuring unit (170) so that the area camera (120) takes a shot while maintaining a set separation distance (d) from the pellicle (20).
3. A pellicle surface inspection system for inspecting defects (A) of a pellicle (20) covering a pattern (11) on a photomask (10), A lighting unit (210) that illuminates a line light in a diagonal direction, extending linearly in the Y-axis direction toward the surface of the pellicle (20); A camera unit (220) that generates an inspection image (I) by capturing an image from a diagonal direction centered on the line lighting area where the line lighting of the lighting unit (210) is irradiated on the surface of the pellicle (20); A base part (230) on which the lighting part (210) and camera part (220) are fixedly mounted; A horizontal movement driving unit (240) that moves the base unit (230) horizontally in the X-axis direction; A vertical movement drive unit (250) that moves the base unit (230) vertically in the Z-axis direction and measures the current vertical movement distance from a set reference position; A distance measuring unit (260) fixedly mounted on the base unit (230) to measure the distance from the pellicle (20); and The control unit (270) detects a defect (A) by analyzing the generated inspection image (I), controls the horizontal movement drive unit (240) so that the base unit (230) moves horizontally in the X-axis direction so that the camera unit (220) captures the entire surface of the pellicle (20) in segments, and controls the vertical movement drive unit (250) so that the base unit (230) moves up and down according to the distance measurement value of the distance measuring unit (260) so that the camera unit (220) captures an image while maintaining a set distance from the pellicle (20). The above control unit (270) is, A pellicle surface inspection system characterized by calculating bias information including the direction and value of the defect (A) being deflected from the reference line (L) based on the travel distance measurement measured by the vertical movement drive unit (250), and generating corrected position data (D) that corrects the position of the defect (A) by reflecting the calculated bias information, or generating a corrected inspection image (Ia) in which the position of the defect (A) is corrected.