Pattern inspection device and pattern inspection method for photomask

Abstract

The invention provides a pattern inspection device and a pattern inspection method for a photomask, which can prevent detection (or recognition) of defects in a region corresponding to a pattern which is not guaranteed in manufacturing of the photomask. A pattern inspection apparatus of a photomask holds mask pattern data specifying a mask pattern generated by a non-secure pattern of the mask, performs pattern inspection of the mask to acquire defect data, and excludes a region corresponding to the mask pattern from a defect recognition region in which a defect is recognized from a defect signal.

Description

Technical Field

[0001] The present invention relates to a pattern inspection device and a pattern inspection method for a photomask. Background Art

[0002] Photomasks are used in the manufacturing process of products such as electronic devices such as displays. In order to manage and guarantee the quality of the photomasks, pattern inspection is performed during the manufacturing process of the photomasks to inspect the pattern formed on the photomasks.

[0003] However, among the defects detected by pattern inspection, in addition to true defects such as failures and malfunctions that may affect the product, pseudo defects (also called false defects) that will not affect the product are sometimes included. The operator needs to perform a confirmation operation (defect review) to confirm whether the output result of the defect inspection of the pattern inspection device is a true defect or a pseudo defect. In order to reduce the workload of the operator, a method for reducing the detection of pseudo defects by the pattern inspection device has been proposed. The previous method of preventing the detection of pseudo defects can prevent the detection of pseudo defects due to a specified size change (or shape change) relative to the designed pattern.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 5-198641

[0007] Patent Document 2: Japanese Patent Application Publication No. 2000-258352 Summary of the invention

[0008] Technical problem to be solved by the invention

[0009] The design patterns of the circuits constituting electronic devices may include non-guaranteed (unguaranteed) design patterns in the photomask manufacturing process. Such non-guaranteed design patterns in manufacturing may be mixed with resolved or unresolved states in the manufactured photomask, resulting in frequent defects detected by the pattern inspection device.

[0010] However, if such a specific pattern that is not guaranteed in manufacturing is corrected without affecting the performance and reliability of the device, the workload of the designer will increase. If such a non-guaranteed pattern is allowed in order to reduce the workload of the designer, the number of defects detected in the pattern inspection step of the photomask manufacturing process will increase, and the workload of classifying the defects caused by the non-guaranteed pattern as pseudo defects will increase.

[0011] In view of the above technical problems, the technical problem to be solved by the present invention is to provide a pattern inspection method and pattern inspection device for a photomask, which can prevent the area corresponding to the pattern that is not guaranteed in the manufacture of the photomask from being detected (or identified) as a defect.

[0012] Technical means for solving technical problems

[0013] The pattern inspection device of the present invention is used to inspect defects of a photomask, using mask pattern data of the photomask including a non-guaranteed design pattern, and defect data including the position and shape of defects obtained by pattern inspection of the photomask, and excluding the area corresponding to the non-guaranteed design pattern from the defect identification area identified as a true defect in the defect data.

[0014] By adopting such a pattern inspection apparatus, defects caused by non-guaranteed patterns in the manufacture of photomasks can be tolerated, and not only the workload of defect review in a photomask manufacturing factory can be reduced, but also the workload of pattern design by designers can be reduced.

[0015] Furthermore, in the above-mentioned configuration, the region corresponding to the non-guaranteed design pattern may be deleted from the defect recognition region, or may be classified as a pseudo defect in order to be distinguished from the true defect.

[0016] By using such a pattern inspection apparatus, defect data from conventional pattern inspections can be utilized.

[0017] Furthermore, in the above-mentioned configuration, it may be configured so that a region corresponding to the non-guaranteed design pattern is excluded from a region where the pattern inspection is performed.

[0018] By adopting such a pattern inspection device, the burden on the pattern inspection device can be reduced.

[0019] The pattern inspection method of the photomask of the present invention includes: a non-guaranteed pattern extraction step, which extracts the non-guaranteed design pattern of the photomask based on the design pattern of the pattern used to form the photomask; a mask pattern generation step, which generates a mask pattern including the non-guaranteed design pattern; and a pattern inspection step, which performs pattern inspection in order to detect true defects on the photomask, and excludes the area corresponding to the mask pattern from the defect identification area identified as the true defect.

[0020] By adopting such a photomask pattern inspection method, defects caused by non-guaranteed patterns during photomask manufacturing can be tolerated, and not only the workload of defect review in the manufacturing plant can be reduced, but also the workload of pattern design by designers can be reduced.

[0021] Furthermore, in the above aspect, the mask pattern may be generated by expanding the non-guaranteed design pattern by a predetermined amount.

[0022] By adopting such a pattern inspection method using a photomask, a pattern can be accurately generated.

[0023] Furthermore, in the above-mentioned aspect, the area corresponding to the mask pattern may be excluded from the defect recognition area by deleting the defect in the area corresponding to the mask pattern from the defect data acquired in the pattern inspection step or classifying the defect as a pseudo defect.

[0024] By adopting such a photomask pattern inspection method, defect data from conventional pattern inspections can be utilized.

[0025] Furthermore, in the above aspect, the region corresponding to the mask pattern may be excluded from the defect recognition region by excluding the region corresponding to the mask pattern from the inspection region in the pattern inspection step.

[0026] By adopting such a pattern inspection method using a photomask, it is possible to reduce the burden on a pattern inspection device.

[0027] Effects of the Invention

[0028] According to the present invention, it is possible to provide a pattern inspection apparatus and a pattern inspection method for a photomask that can prevent a region corresponding to a pattern not guaranteed for manufacturing of the photomask from being detected (or recognized) as a defect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 (A) is a top view (plan view) schematically showing an example of a design pattern (design data) of a mask pattern, Figure 1 (B) and (C) are schematic diagrams showing the use of Figure 1 (A) is a top view of an example of a pattern produced on a photomask 100 using a design pattern.

[0030] Figure 2 A top view for explaining a method of not detecting (or identifying) defects in a non-warranted area. Figure 2 (A) is a top view schematically showing a design pattern, Figure 2 (B) is a plan view schematically showing a non-guaranteed pattern below the resolution limit. Figure 2 (C) is a top view showing a mask pattern used to exclude an inspection object during pattern inspection. Figure 2 (D) is an enlarged plan view showing the positional relationship between the non-guaranteed pattern and the mask pattern.

[0031] Figure 3A top view schematically illustrating the defect selection process performed by a pattern inspection device. Figure 3 (A) Figure 3 (B) shows a top view of a photomask 100 having a first pattern 2 and a second pattern 3 on a transparent substrate 1. Figure 3 (C) is a top view schematically showing the positional relationship between the defect detected by the pattern inspection device and the mask pattern area MA, Figure 3 (D) represents a defect recognized by the pattern inspection device.

[0032] Figure 4 It is a plan view for explaining an example of a method of determining whether or not there is a non-guaranteed area for the design pattern PT1 and the design pattern PT2. Figure 4 (A) is a top view showing an example of a judgment pattern, Figure 4 (B) is a top view showing an example of a guaranteed pattern, Figure 4 (C) is a plan view showing an example of a guaranteed pattern and a non-guaranteed pattern.

[0033] Figure 5 1 is a top view showing examples of shapes of various non-guaranteed areas without limitation. Figure 5 (A) shows an example of a non-guaranteed area where the front end portion is a corner portion having an acute angle, Figure 5 (B) shows an example of a non-guaranteed area having a hole shape. Figure 5 (C) shows an example of a non-guaranteed area having a free shape (arbitrary shape).

[0034] Description of Reference Numerals

[0035] 100 Photomasks

[0036] 1Transparent substrate

[0037] 2First Pattern

[0038] 3 Second pattern

[0039] CT1, CT2, CT3 judgment pattern

[0040] D resolution limit

[0041] Df1 first pattern defect

[0042] Df2 second pattern defect

[0043] Df3 third pattern defect

[0044] MA mask pattern area

[0045] MT mask pattern

[0046] PT1 first design pattern

[0047] PT2 Second Design

[0048] PT3 third design (non-guaranteed design)

[0049] w Expansion width. DETAILED DESCRIPTION

[0050] Hereinafter, the embodiments of the present invention will be described with reference to the accompanying drawings. However, the following embodiments are not intended to limit the identification of the subject matter of the present invention. In addition, for the same or the same type of components, the same reference numerals may be assigned and the description thereof may be omitted.

[0051] Furthermore, terms such as "parallel", "orthogonal", "same", and numerical values ​​of lengths and angles used in this specification to define shape and geometric conditions and their degrees may be interpreted within a range that includes the degree to which the same function can be expected, and are not limited to a strict meaning.

[0052] (Implementation Method 1)

[0053] Hereinafter, a method for inspecting a pattern of the photomask 100 will be described with reference to the drawings.

[0054] Figure 1 (A) is a top view schematically showing an example of a design pattern (design data) for patterning (patterning) a pattern (pattern of various optical films) to be formed on the photomask 100. Figure 1 In (A), the area other than the first design pattern PT1 and the second design pattern PT2 is a blank area corresponding to the exposed area of ​​the transparent substrate 1.

[0055] The dotted line in the figure is the area A where the interval between the first design pattern PT1 and the second design pattern PT2 becomes the minimum value d. The width d of the area A is less than the resolution limit (resolution limit) D of the photolithography step used to form the pattern on the photomask 100 (d≤D). Because the pattern width d of the area A is less than the resolution limit, the resolution cannot be guaranteed in the photolithography step used to manufacture the photomask 100. Therefore, the pattern formation (patterning) in manufacturing of the pattern determined according to the area A cannot be guaranteed, so the formation of an opening cannot be guaranteed. Thus, for the sake of convenience, the pattern determined according to the area where the pattern formation cannot be guaranteed in manufacturing is referred to as a non-guaranteed pattern. Specifically, the non-guaranteed pattern is determined to be a non-guaranteed area in manufacturing based on a size that is less than the resolution limit of the photolithography step in the manufacturing process of the photomask. The non-guaranteed area, for example, Figure 1As in the example shown, depending on the arrangement of the two design patterns, it may occur in a partial region between the two design patterns, or may occur (or exist) in a part of the design pattern.

[0056] In addition, the design pattern is a pattern constituting a circuit diagram of a product (device) manufactured using the photomask 100, and is generally produced by a designer using a CAD (design aid). Hereinafter, the size of the design pattern is set to correspond to the photomask 100. For example, in the case of manufacturing a device by an exposure device of reduced projection, the size of the design pattern is set to a size that is converted to a value corresponding to the size of the pattern on the photomask 100 by appropriately considering the reduction ratio.

[0057] The design pattern is not limited to the design pattern for patterning the optical film formed on the transparent substrate 1, and may be a design pattern for patterning other optical films (e.g., light-shielding films, etc.) formed on the lower film formed on the transparent substrate 1, such as the semi-transparent film or the phase shift film. The pattern of the optical film on the photomask 100 and the structure of the lower layer of the pattern formed based on the design pattern are not limited. The same applies to the following.

[0058] Figure 1 (B) and (C) are top views schematically showing an example of the following pattern, which is based on Figure 1 The design pattern shown in (A) is obtained by exposing a photoresist film formed on a photomask 100 by a scanner or the like, and patterning an optical film on a transparent substrate 1 using the exposed photoresist film.

[0059] The inspection object of the pattern inspection device is not limited to the pattern of the formed optical film, but may also be a resist pattern.

[0060] like Figure 1 As shown in (B) and (C) of FIG. 1 , a first pattern 2 corresponding to the first design pattern PT1 and a second pattern 3 corresponding to the second design pattern PT2 are formed on the photomask 100 .

[0061] like Figure 1 (B) shows an example in which the photoresist film in the non-guaranteed area A is analyzed (developed) so that the optical film in the area B is opened.

[0062] On the other hand, Figure 1 (C) shows an example in which the photoresist film in the non-guaranteed area A is not resolved and the optical film in the area C is not opened. Thus, the pattern corresponding to the non-guaranteed area A may be resolved to form a pattern or not resolved to form a pattern.

[0063] The material of the optical film of the first pattern 2 and the second pattern 3 is not limited, and may be a material with light-shielding properties, a material with semi-transmissive properties, or a material with a phase shifting effect.

[0064] As described above, the non-guaranteed area A may be resolved or not resolved, so, for example, in the case of a die-to-die comparison pattern inspection device that compares images of different dies to perform pattern inspection, the positions and shapes of the areas B and C are detected as pattern defects. In addition, in a die-to-database comparison pattern inspection device that performs inspection based on a design pattern, the position and shape of the area C are also detected as pattern defects.

[0065] However, even if it is a non-guaranteed area in the photomask manufacturing process, in an actual product (electronic device, etc.) manufactured using the photomask, a defect corresponding to the non-guaranteed area A (see Figure 1 When the defect (region C) does not affect the performance and quality of the actual product, the burden of the designer to correct (re-produce) the design pattern can be reduced by allowing the defect (region C). That is, the designer can commission the manufacture of the photomask 100 without correcting the pattern of such a non-guaranteed region (non-guaranteed pattern).

[0066] Furthermore, since they are designers of the circuit of the actual product, they can determine whether the non-guaranteed area A will affect the performance of the actual product.

[0067] On the other hand, in the pattern inspection step included in the manufacturing process of the photomask 100, the pattern inspection device detects the area C corresponding to the non-guaranteed area A and outputs it as a defect (hereinafter referred to as a detected defect). The operator of the photomask 100 manufacturing plant determines (based on information from the circuit designer) that it is not necessary to correct the detected defect in the area C and classifies it as a pseudo defect rather than a defect (true defect). Such operations increase.

[0068] In addition, the so-called "pseudo-defects" in this specification are defined as follows: although they are detection defects detected by a pattern inspection device, they are different from "defects" (true defects) that may have adverse effects on the performance and reliability of the product, and will not affect the performance and reliability of actual products (electronic devices, etc.), and can be judged as detection defects that do not require correction or other processing.

[0069] Figure 2 A top view for explaining a method of not detecting (or identifying) defects in a non-warranted area. Figure 2 (A) is a top view schematically showing a design pattern, Figure 2(B) is a top view schematically showing a non-guaranteed pattern in a region below the resolution limit. Figure 2 (C) is a top view showing a mask pattern for specifying an area to be excluded from a defect inspection target area (or an area to be identified as a defect) during pattern inspection. Figure 2 (D) is an enlarged top view showing the positional relationship between the non-guaranteed pattern and the mask pattern. Therefore, the area outside the area determined by the mask pattern will become the area set as the target of defect recognition in the pattern inspection (hereinafter sometimes referred to as the defect recognition area).

[0070] Figure 2 (A) shows a plan view of a design pattern including a first design pattern PT1 and a second design pattern PT2. The design data specifying each design pattern constituting the circuit of the device includes data specifying the arrangement and shape of the first design pattern PT1 and the second design pattern PT2.

[0071] Figure 2 (B) is a plan view showing a non-guaranteed pattern PT3 (third design pattern PT3) corresponding to the non-guaranteed region.

[0072] exist Figure 2 In the example shown in (A), there is a portion where the interval between the first design pattern PT1 and the second design pattern PT2 is less than a predetermined value D (resolution limit of the photolithography step for pattern formation). Figure 2 As shown in (B), a non-guaranteed pattern PT3 with a width d (d≤D) is extracted between the first design pattern PT1 and the second design pattern PT2. The extraction (selection) of the non-guaranteed pattern PT3 can be performed by a processing device, for example, by using a design rule check (DRC) of a CAD (design support tool), etc., and the region where the interval d between the first design pattern PT1 and the second design pattern PT2 becomes less than a specified value D, i.e., the non-guaranteed pattern PT3 can be extracted. For example, as a design rule, the value D of the resolution limit can be specified as the minimum line width and the minimum space width.

[0073] In addition, non-guaranteed patterns are not limited to Figure 2 The extraction can be performed based on the data on the design pattern (including the layout data between the design patterns) by using a calculation processing device such as CAD, but the extraction can also be performed manually by the designer himself.

[0074] Figure 2(C) shows a top view of the mask pattern MT generated based on the extracted non-guaranteed pattern PT3. In each die on the photomask 100, the area specified by the mask pattern MT (mask pattern area MA) is excluded from the pattern inspection object (or defect recognition area for identifying defects).

[0075] like Figure 2 As shown in (D), the mask pattern MT has a shape that is expanded (enlarged) by a predetermined amount w (hereinafter, sometimes referred to as an expansion width) relative to the non-guaranteed pattern PT3.

[0076] The expansion width w can be determined by, for example, taking into account factors such as the overlap offset between the design pattern and the pattern of the optical film. In addition, the offset between the design pattern and the pattern of the optical film can be obtained by optical simulation, actual measurement, etc. In addition, the expansion width w can also be determined by taking into account the size difference between the design pattern and the pattern of the optical film.

[0077] Furthermore, when pattern inspection is performed after pattern formation of the optical film, the expansion width w may be determined by further considering pattern variation caused by etching.

[0078] For example, 1 to 5 pixels can be set as the expansion width w without limitation in the inspection image of the pattern inspection device.

[0079] The mask pattern MT can be defined as a region (mask pattern region MA) corresponding to the mask pattern MT in the inspection image of the pattern inspection device. The mask pattern region MA is substantially the same as the mask pattern MT, but is defined as a region of the inspection image of the pattern inspection device.

[0080] In this way, data specifying the configuration of the mask pattern MT can be generated based on the extracted non-guaranteed pattern PT3 and the specified expansion width w. The mask pattern MT can be automatically generated by the operation processing device, and the operation processing device can use a CAD tool. The operation processing device can perform the following operations: read the design pattern data from a storage device storing the design pattern data representing the configuration and area of ​​the design pattern, extract the non-guaranteed pattern, perform operation processing using the expansion width w, and generate data (mask pattern data) specifying the configuration and area (shape) of the mask pattern.

[0081] The generated mask pattern data is transmitted to the pattern inspection device and stored in the storage device of the pattern inspection device. The mask pattern data can be transmitted using wired communication or wireless communication, and can also be transmitted via a storage medium.

[0082] The pattern inspection device can read the mask pattern data from a storage device storing the mask pattern data, inspect the pattern formed on the photomask 100 , and output the inspection result.

[0083] Furthermore, the arithmetic processing device may be built in the pattern inspection device, may be a part of the pattern inspection device, or may be provided separately from the pattern inspection device without being built in the pattern inspection device.

[0084] Below, refer to Figure 3 A method of pattern inspection by the pattern inspection device will be described.

[0085] The pattern inspection device has a known pattern inspection mechanism, and can optically inspect the pattern on the photomask 100 to detect the presence or absence of defects, the position of the defects, and the like.

[0086] The pattern to be inspected may be a resist pattern or a pattern composed of an optical film.

[0087] As pattern inspection devices, there are known: a device that detects the difference between patterns by comparing a design pattern (specifically, a reference image generated based on the design pattern) with a pattern (captured image) detected by a pattern inspection device (die-to-database comparison inspection); and a device that compares patterns (captured images) of the same shape arranged at different locations on the photomask 100 (die-to-die comparison inspection). Either pattern inspection device may be used.

[0088] Figure 3 A top view schematically illustrating a defect extraction process performed by a pattern inspection device.

[0089] Figure 3 (A) Figure 3 (B) schematically shows a top view of a photomask 100 having a first pattern 2 and a second pattern 3 on a transparent substrate 1 .

[0090] Figure 3 (B) shows an example of a defect (detection defect) detected by the pattern inspection device.

[0091] Figure 3 (C) is a top view schematically showing the positional relationship between the defect detected by the pattern inspection device and the mask pattern area MA. Figure 3 (D) represents a defect recognized by the pattern inspection device.

[0092] In a pattern inspection device, Figure 3 The corresponding image is detected or photographed, and the obtained image (inspection image) is subjected to computational processing.

[0093] also, Figure 3 The pattern shown shows an example of a pattern of an optical film, but may be a resist pattern formed on the optical film.

[0094] exist Figure 3 There is no defect in the example shown in (A), but Figure 3 In the example shown in (B), a first pattern defect Df1 exists in the first pattern 2 , a second pattern defect Df2 exists in the second pattern 3 , and a third pattern defect Df3 exists between the first pattern 2 and the second pattern 3 .

[0095] Here, the third pattern defect Df3 is located in the non-guaranteed area (with the same Figure 1 The area A of (A) corresponds to the area

[0096] The pattern inspection device inspects the pattern on the photomask 100. Figure 3 In the example shown in (B), a first pattern defect Df1, a second pattern defect Df2, and a third pattern defect Df3 are detected. The pattern inspection device performs pattern inspection, obtains data about each defect (referred to as defect data or defect signal), such as information (data) about the position (coordinates) on the photomask 100 and the defect area (shape), and stores it in a storage device of the pattern inspection device.

[0097] like Figure 3 As shown in (C), the pattern inspection device compares the mask pattern data and identifies that the data (position and area) of the third pattern defect Df3 is located within the mask pattern area MA. On the other hand, because the first pattern defect Df1 and the second pattern defect Df2 are not located within the mask pattern area MA, the pattern inspection device identifies the first pattern defect Df1 and the second pattern defect Df2 as defects (true defects).

[0098] The pattern inspection device does not identify the defect (third pattern defect Df3) located in the mask pattern area MA in the defect signal as a defect (true defect) (does not identify it as a defect object), or deletes (ignores it). For example, the pattern inspection device identifies the first pattern defect Df1 and the second pattern defect Df2 as defects (true defects), and the third pattern defect Df3 is not identified as a defect or the data of the third pattern defect Df3 can be deleted from the defect signal.

[0099] In this way, the mask pattern area MA is constructed or deleted in a manner so that the detected defect is not identified as a defect (true defect), and is therefore excluded from the area where defects are identified, thereby preventing the third pattern defect Df3 in the non-guaranteed area from being identified as a defect.

[0100] In the defect review operation using the pattern inspection device, there is no need to review the mask pattern area MA in the non-guaranteed area, which can reduce the workload of operators and contribute to shortening the production period of the photomask 100 .

[0101] In addition, the pattern inspection device may also classify the third pattern defect Df3 as a detection defect in the mask pattern area MA as a pseudo defect (not a defect) and register it as a pseudo defect in the defect signal. In addition, the first pattern defect Df1 and the second pattern defect Df2 are maintained registered (identified) as defects in the defect signal.

[0102] Furthermore, if the mask pattern area MA is set too large relative to the non-guaranteed area (for example, if it is set to a rectangular area with a side of several mm relative to the non-guaranteed area with a width of d=1 μm or less), although the recognition of defects in the non-guaranteed area can be avoided (eliminated), defects near the non-guaranteed area (true defects) cannot be detected. As described above, by selecting the mask pattern area MA that matches the shape of the non-guaranteed area, the recognition of defects in the non-guaranteed area can be avoided, and the defects that need to be detected (the first pattern defect Df1 and the second pattern defect Df2) can be detected.

[0103] In order to avoid identifying defects in the mask pattern area MA, the pattern inspection device can perform a comparison between the detection data (inspection results) and the mask pattern area MA after completing the inspection of the entire area including the mask pattern area MA to avoid identifying defects in the mask pattern area MA.

[0104] In this case, the comparison (verification) between the mask pattern area MA and the defect signal (defect data) can be performed by the pattern inspection device itself (the operation processing device in the pattern inspection device), or by an inspection auxiliary device (or operation processing device) set independently of the pattern inspection device. The inspection auxiliary device can perform the following actions: input the inspection data of the photomask 100 from the pattern inspection device, compare the inspection data with the information of the mask pattern area MA in the mask pattern database, and not identify the detection defect located in the mask pattern area MA as a defect (ignore the detection defect), or identify (classify) it as a pseudo-defect, and store it together with other true defects as corrected detection data in the storage device of the inspection auxiliary device. The corrected detection data can be sent to the pattern inspection device and stored in the storage device of the pattern inspection device as a corrected defect signal (defect data).

[0105] The operator can perform a review of each defect using a pattern inspection device based on the corrected defect signal.

[0106] In addition, in order to avoid identifying defects in the mask pattern area MA, the pattern inspection device can exclude the mask pattern area MA from the inspection area (the target area of ​​pattern inspection) of the photomask 100. In this case, the pattern inspection device does not perform defect inspection on the mask pattern area MA on the photomask 100, so the first pattern defect Df1 and the second pattern defect Df2 can be detected, but the third pattern defect Df3 will not be detected. For example, it is configured so that image processing for defect detection is not performed in the mask pattern area MA, or image data of the mask pattern area MA is not obtained.

[0107] Since the mask pattern area MA is excluded from the area to be inspected for defects, it is excluded from the area to be identified for defects, and for example, it is possible to avoid identifying the third pattern defect Df3 in the non-guaranteed area as a defect.

[0108] The pattern inspection device is configured not to perform pattern inspection in the mask pattern area MA, so that the burden of image processing and the like on the pattern inspection device can be reduced.

[0109] like Figure 3 As shown in (D), the third pattern defect Df3 is not identified as a defect, while the pattern inspection device identifies the first pattern defect Df1 and the second pattern defect Df2 as defects. The position and area of ​​the identified pattern defects are registered as defects and stored in the pattern inspection device. During the defect review operation, the operator does not need to check the third pattern defect Df3, which can reduce the workload.

[0110] Furthermore, the above-mentioned method of not recognizing the mask pattern area MA as a defect can be adopted without depending on the inspection method of the pattern inspection device. For example, this method can be adopted in any pattern inspection device that adopts die-database comparison inspection or die-die comparison inspection.

[0111] Below, refer to Figure 4 , an example of a method for determining whether a design pattern or a part thereof is a non-guaranteed pattern is described.

[0112] exist Figure 4 In the figure, the area of ​​the design pattern PT1 and the area of ​​the design pattern PT2 are areas having design pattern data for pattern formation, and the areas other than these are blank areas, for example, areas where the transparent substrate 1 is exposed.

[0113] Here, “having design pattern data” means having data constituting the design pattern PT1 and the like, for example, having design pattern data in a region surrounded by the design pattern.

[0114] In addition, the blank area is not limited to the area where the transparent substrate 1 is exposed. For example, it can be an area where the lower film formed on the transparent substrate 1 is exposed, and the design pattern can be a pattern for patterning the upper film formed on the lower film.

[0115] like Figure 4 As shown by the dotted line in (A), a judgment pattern CT having a square shape with a side length equal to the resolution limit D (eg, 1 μm) is prepared.

[0116] The judgment pattern is not limited to a square, and may be, for example, a circular judgment pattern CT'. The judgment pattern may be appropriately set based on the design pattern.

[0117] exist Figure 4 In the example shown in (B), the judgment pattern CT1 can be surrounded by the design pattern PT1, and the judgment pattern CT1 has all the design pattern data. The judgment pattern CT1 that has all the design pattern data is judged to be not a non-guaranteed area. Among them, the area that is not a non-guaranteed area is an area that can be analyzed, which is sometimes referred to as a guaranteed area below.

[0118] Likewise, the determination pattern CT2 is determined to be a guaranteed area (not a non-guaranteed area).

[0119] Furthermore, the interior of the determination pattern CT3 is entirely blank, and in this case, it is also determined to be a guaranteed area.

[0120] exist Figure 4 In the example shown in (C), the determination pattern CT1 surrounded by the design pattern PT1 is a guaranteed area, and the design pattern PT1 is determined to be a guaranteed area.

[0121] However, the judgment pattern CT2 overlapping the design pattern PT2 only partially overlaps the design pattern PT2, and there are portions with the design pattern and blank portions, and it cannot be an area consisting of only the design pattern or an area consisting of only the blank. In this case, the design pattern is judged as a non-guaranteed area (an area that cannot be resolved) based on the judgment pattern CT2.

[0122] In addition, the judgment pattern CT3 overlapping the space area between the design pattern PT1 and the design pattern PT2 partially overlaps the design pattern PT1 and the design pattern PT2, and there are parts with design patterns and blank parts. Regarding the judgment pattern CT3, it is not possible to be a region with only design pattern data or a blank region. In this case, according to the judgment pattern CT3, the space area between the design pattern PT1 and the design pattern PT2 is judged as a non-guaranteed area (an area that cannot be resolved).

[0123] For these areas determined as non-guaranteed areas, mask pattern areas can be set separately. Figure 4 In the example shown in (C), the two mask pattern regions partially overlap, but the overlapping region can be excluded from the region where defects are to be identified.

[0124] Non-guaranteed areas have various shapes, not limited to Figure 4 The linear area shown. Figure 5 is a top view showing an example of the shape of other non-guaranteed areas without limitation, Figure 5 (A) shows an example of a non-guaranteed area of ​​a corner portion having an acute angle at the front end portion. Figure 5 (B) shows an example of a non-guaranteed area having a hole shape, Figure 5 (C) shows an example of a non-guaranteed area having a free shape (arbitrary shape). Figure 5 In FIG. 1 , (I) represents a design pattern, and (II) represents an extracted non-guaranteed area.

[0125] exist Figure 5 In the case of the example shown in (I) of (A), the interior of the judgment pattern CT1 and the judgment pattern CT2 are all blank areas, which are guaranteed areas. When the judgment area CT2 is offset in the X direction in the figure, as shown in the judgment pattern CT3, its interior becomes to include both the area with the design pattern data of the design pattern PT1 and the blank area, and it is judged to contain a non-guaranteed area. The judgment pattern CT2 determines the boundary between the guaranteed area and the non-guaranteed area in the X direction. By moving the judgment pattern CT, the boundary between the guaranteed area and the non-guaranteed area can be searched and determined. The following is the same.

[0126] Figure 5 (II) in (A) represents the extracted non-guaranteed pattern PT3.

[0127] In for Figure 5 In the example shown in (I) of (B), the interiors of judgment pattern CT1 and judgment pattern CT2 are all areas with design pattern data and are judged to be guaranteed areas, but the interior of judgment pattern CT3 contains areas with design pattern data and blank areas, and judgment pattern CT3 includes a non-guaranteed area.

[0128] Figure 5 (II) in (B) represents the extracted non-guaranteed pattern PT3.

[0129] exist Figure 5In the example shown in (I) of (C), the interiors of judgment patterns CT1 and CT2 are all blank areas and are judged to be guaranteed areas, but the interior of judgment pattern CT3 contains areas with design pattern data and blank areas, and judgment pattern CT3 includes a non-guaranteed area.

[0130] The determination pattern CT1 and the determination pattern CT2 determine the boundary between the guaranteed area and the non-guaranteed area in the direction parallel to the X direction.

[0131] Figure 5 (II) in (C) represents the extracted non-guaranteed pattern PT3.

[0132] Industrial Applicability

[0133] According to the present invention, a pattern inspection device can be configured to not identify defects caused by patterns that do not have adverse effects on product characteristics, etc. as defects for patterns below the resolution limit in the photomask manufacturing process, and can detect other defects. The burden of designers who design patterns can be reduced, and the workload of operators who inspect patterns in the photomask manufacturing process can be reduced, and the industrial applicability is high.

Claims

1. A pattern inspection device for inspecting defects of a photomask, wherein: Using mask pattern data of the photomask including a non-guaranteed design pattern and defect data including the position and shape of a defect acquired by pattern inspection of the photomask, an area corresponding to the non-guaranteed design pattern in the defect data is excluded from a defect identification area identified as a true defect.

2. The pattern inspection device according to claim 1, characterized in that: The area corresponding to the non-guaranteed design pattern is deleted from the defect recognition area, or is classified as a pseudo defect in a manner different from the true defect.

3. The pattern inspection device according to claim 1, wherein: An area corresponding to the non-guaranteed design pattern is excluded from an area where the pattern inspection is performed.

4. A method for inspecting a pattern of a photomask, characterized in that: include: a non-guaranteed pattern extraction step of extracting a non-guaranteed design pattern of the photomask based on a design pattern for forming a pattern of the photomask; a mask pattern generating step of generating a mask pattern including the non-guaranteed design pattern; and a pattern inspection step of performing pattern inspection in order to detect true defects on the photomask, An area corresponding to the mask pattern is excluded from a defect identification area identified as the true defect.

5. The pattern inspection method according to claim 4, wherein: The mask pattern is generated by expanding the non-guaranteed design pattern by a predetermined amount.

6. The pattern inspection method according to claim 4, wherein: The region corresponding to the mask pattern is excluded from the defect recognition region by deleting the defect in the region corresponding to the mask pattern from the defect data acquired in the pattern inspection step or classifying the defect as a pseudo defect.

7. The pattern inspection method according to claim 4, wherein: By excluding the region corresponding to the mask pattern from the inspection region in the pattern inspection step, the region corresponding to the mask pattern is excluded from the defect recognition region.

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