Substrate inspection apparatus, substrate inspection method and memory medium

Abstract

[Project] It can suppress the increase in startup time while performing defect inspection of substrate-based camera images with high accuracy. [Solution] A substrate inspection apparatus for inspecting substrates includes: a setting unit that defines a group of basic states independent of the presence or absence of substrate defects, and sets the defined group for each substrate to be inspected; an inspection unit that inspects for defects based on a photographic image of the substrate to be inspected and an inspection formula including a reference image corresponding to the group to which the substrate to be inspected belongs; a formula generation unit that generates the inspection formula for each group; and a determination unit that determines whether the substrates to be inspected, whose groups are defined by the setting unit, belong to a group defined by the setting unit; the determination unit determines whether the substrates to be inspected, whose groups are defined, belong to a group. The determination is made based on whether the processing performed on the substrate is consistent, and whether the basic state of the substrate of the set object, as estimated from the photographic image of the substrate of the set object in the above-mentioned group, is consistent with the basic state of the substrate belonging to the defined complete group. If the substrate of the set object is determined to belong to the defined complete group, the setting unit sets a matching group for the substrate of the set object. If the substrate of the set object is determined not to belong to the defined complete group, the setting unit defines a new group and sets a new group for the substrate of the set object. The formula making unit creates the inspection formula corresponding to the new group based on the photographic image of the substrate of the set object.

Description

[Technical Field]

[0001] This disclosure relates to a substrate inspection apparatus, a substrate inspection method, and a memory medium. [Previous Technology]

[0002] Patent Document 1 discloses a method for detecting defects by comparing an image pattern of an object to a reference image pattern. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2016-212008 [Summary of the Invention]

[0004] [The problem that the invention aims to solve]

[0005] The technology disclosed herein aims to suppress the increase in startup time while performing defect inspection of substrate-based camera images with high accuracy. [Means for solving the problem]

[0006] One aspect of this disclosure is a substrate inspection apparatus for inspecting substrates, comprising: a setting unit that defines a group of basic states, regardless of the presence or absence of substrate defects, for each substrate to be inspected; an inspection unit that inspects for defects based on a photographic image of the substrate to be inspected and an inspection formula including a reference image corresponding to the group to which the substrate to be inspected belongs; a formula creation unit that creates the inspection formula for each group; and a determination unit that determines whether the substrates to be inspected, which belong to the group defined by the setting unit, are part of the group defined by the setting unit; the determination unit determines whether the substrates to be inspected, which belong to the group defined by the setting unit, are part of the group defined by the setting unit. The determination is made based on whether the processing performed on the substrate is consistent, and whether the basic state of the substrate of the set object, as estimated from the photographic image of the substrate of the set object in the aforementioned group, is consistent with the basic state of the substrate belonging to the defined complete group. If the substrate of the set object is determined to belong to the defined complete group, the setting unit sets a matching group for the substrate of the set object. If the substrate of the set object is determined not to belong to the defined complete group, the setting unit defines a new group and sets a new group for the substrate of the set object. The formula creation unit creates a check formula corresponding to the new group based on the photographic image of the substrate of the set object. [Effects of the Invention]

[0007] By means of this disclosure, it is possible to suppress the increase in operation time during startup while performing defect inspection of substrate-based camera images with high accuracy.

Implementation Method

[0009] In the manufacturing process of semiconductor devices, a photoresist coating process is sequentially performed, which involves coating a photoresist solution onto a semiconductor wafer (hereinafter referred to as "wafer") to form a photoresist film, an exposure process for exposing the photoresist film, and a development process for developing the exposed photoresist film, thereby forming a photoresist pattern on the wafer. Furthermore, after the photoresist pattern formation process, an etching process is performed on an etching target layer that uses the photoresist pattern as a mask, thereby forming a pre-defined pattern on the etching target layer. Additionally, during the formation of the photoresist pattern, a film other than the photoresist film may also be formed on a layer below the photoresist film.

[0010] Furthermore, when forming a photoresist pattern as described above, or when etching using a photoresist pattern, there are instances where defects are inspected on wafers after various processing steps. In this defect inspection, checks are performed on, for example, whether the photoresist pattern was properly formed, or whether foreign matter adheres to the wafer. In recent years, there have been cases where this defect inspection uses a photographic image of the wafer to be inspected (specifically, the processed surface). In this case, defect inspection is performed by comparing the photographic image of the wafer to be inspected with a reference image that serves as the inspection benchmark (see Patent Document 1).

[0011] However, the condition of the wafer being inspected varies greatly depending on the type of processing performed on the wafer so far, regardless of whether there are defects. For example, the condition of the wafer is very different before the development process without forming a photoresist pattern, after the photoresist coating process, and after the development process with a photoresist pattern formed. Furthermore, even after the development process, the shape or spacing of the photoresist pattern will differ if the exposure conditions are different. Moreover, even after the photoresist coating process, the overall tone or the tone of each location in the photographic image of the wafer will differ if the condition of the base film or the coating conditions are different.

[0012] Therefore, if a reference image corresponding to the state of the wafer being inspected is used, defect inspection based on the photographic image of the wafer being inspected cannot be performed correctly. For example, if an appropriate reference image is used, there may be cases where the outline of a non-defective photoresist pattern is mistakenly detected as a defect. That is, there may be cases where suspected defects occur. Therefore, to correctly perform defect inspection based on the photographic image of each type of wafer, it is necessary to prepare multiple reference images. However, preparing multiple reference images is time-consuming when starting the inspection equipment for defect inspection.

[0013] Thus, the technology disclosed herein suppresses the increase in operation time during startup while performing defect inspection of substrate-based camera images with high accuracy.

[0014] Hereinafter, the substrate inspection apparatus and inspection method according to this embodiment will be described with reference to the drawings. In addition, in this specification and drawings, elements that have substantially the same functional configuration are indicated by the same symbols, and repeated descriptions are omitted.

[0015] [Wafer Processing System and Inspection Camera Device] FIG1 is a schematic diagram showing the general structure of a wafer inspection system having an overall control device as a substrate inspection device according to this embodiment. As shown in the figure, the wafer inspection system 1 includes a wafer processing system 10 and an overall control device 20.

[0016] The wafer processing system 10 processes wafers as substrates. In this example, it performs processes such as forming photoresist patterns on the wafer.

[0017] Figure 2 is a schematic top view showing the general structure of the wafer processing system 10. Figures 3 and 4 are schematic diagrams showing the internal structure of the front and back sides of the wafer processing system 10, respectively.

[0018] As shown in FIG2, the wafer processing system 10 includes a cassette station 100 for loading and unloading cassettes C containing a plurality of wafers W, and a processing station 101 for applying pre-set processing to the wafers W. The wafer processing system 10 is configured to connect the cassette station 100, the processing station 101, and an interface station 103 for receiving and accepting wafers W between an exposure apparatus 102 adjacent to the processing station 101.

[0019] A cartridge mounting stage 110 is provided in the cartridge station 100. A plurality of cartridge mounting plates 111 are provided in the cartridge mounting stage 110 for mounting cartridges C when they are loaded and unloaded from the outside of the wafer processing system 10.

[0020] A wafer transport device 113 that moves freely on a transport path 112 extending in the X direction is provided in the cassette station 100. The wafer transport device 113 is also freely movable in the vertical direction and around the vertical axis (θ direction), and can transport wafers W between the cassettes C on each cassette mounting plate 111 and the receiving and receiving device of the third block G3 of the processing station 101 described later.

[0021] The processing station 101 is provided with a plurality of blocks, for example, four blocks, namely blocks G1 to G4, each equipped with various devices. For example, block G1 is provided on the front side of the processing station 101 (the negative X-direction side in FIG2), and block G2 is provided on the back side of the processing station 101 (the positive X-direction side in FIG2). Furthermore, block G3 is provided on the cassette station 100 side of the processing station 101 (the negative Y-direction side in FIG2), and block G4 is provided on the interface station 103 side of the processing station 101 (the positive Y-direction side in FIG2).

[0022] A liquid processing apparatus is arranged in the first block G1 as a substrate processing apparatus for processing wafer W using a processing liquid. Specifically, in the first block G1, as shown in FIG3, for example, an imaging processing apparatus 120, a lower layer film forming apparatus 121, an intermediate layer film forming apparatus 122, and a photoresist coating apparatus 123 are arranged sequentially from below as a liquid processing apparatus.

[0023] The imaging processing apparatus 120 performs imaging processing on the wafer W. Specifically, the imaging processing apparatus 120 supplies developing solution to the photoresist film on the wafer W to form a photoresist pattern.

[0024] The lower layer film forming apparatus 121 forms a lower layer film as a substrate film of the photoresist film of the wafer W. Specifically, the lower layer film forming apparatus 121 forms a lower layer film by coating a lower layer film material, which is a material used to form the lower layer film, on the wafer W.

[0025] The intermediate layer film forming apparatus 122 forms an intermediate layer film on the lower layer film of the wafer W and below the photoresist film. Specifically, the intermediate layer film forming apparatus 122 forms an intermediate layer film by coating an intermediate layer film material, which is a material used to form the intermediate layer film, on the lower layer film of the wafer W.

[0026] The photoresist coating apparatus 123 is used to coat a photoresist liquid onto a wafer W to form a photoresist film. Specifically, the photoresist coating apparatus 123 coats a photoresist liquid onto an intermediate layer film on the wafer W to form a photoresist film.

[0027] For example, three of the imaging processing apparatus 120, the lower layer film forming apparatus 121, the intermediate layer film forming apparatus 122, and the photoresist coating apparatus 123 are arranged in a horizontal direction. In addition, the number or arrangement of these imaging processing apparatus 120, lower layer film forming apparatus 121, intermediate layer film forming apparatus 122, and photoresist coating apparatus 123 can be arbitrarily selected.

[0028] In these imaging processing apparatuses 120, lower layer film forming apparatus 121, intermediate layer film forming apparatus 122, and photoresist coating apparatus 123, a pre-set processing liquid is coated on the wafer W by, for example, spin coating. In spin coating, the processing liquid is ejected from, for example, a coating nozzle onto the wafer W while the wafer W is rotated, causing the processing liquid to diffuse on the surface of the wafer W.

[0029] In the second block G2, heat treatment apparatuses 130 are arranged in the vertical and horizontal directions. These heat treatment apparatuses 130 are substrate processing apparatuses that use a hot plate or a cold plate on which the wafer W is placed to perform heat treatment such as heating or cooling of the wafer W. The number or arrangement of these heat treatment apparatuses 130 can be arbitrarily selected. Furthermore, the heat treatment apparatuses 130 can each use known devices.

[0030] In block G3, a plurality of receiving and transmitting devices 140, 141, 142, 143, 144, 145, 146, and 147 are arranged sequentially from below. Furthermore, in block G4, a plurality of receiving and transmitting devices 150, 151, and 152 are arranged sequentially from below, and an inspection camera device 153 is arranged above them.

[0031] Hereinafter, the configuration of the inspection camera device 153 will be described. Figures 5 and 6 are schematic longitudinal and cross-sectional views of the configuration of the inspection camera device 153, respectively. The inspection camera device 153 has a housing 200 as shown in Figures 5 and 6. A stage 201 for mounting the wafer W is provided inside the housing 200. The stage 201 can rotate and stop freely by a rotation drive unit 202 such as a motor. A guide rail 203 is provided on the bottom surface of the housing 200, extending from one end side (the negative X direction side in Figure 6) to the other end side (the positive X direction side in Figure 6). The stage 201 and the rotation drive unit 202 are mounted on the guide rail 203 and can be moved along the guide rail 203 by a drive device 204.

[0032] A camera unit 210 is provided on the side of the other end (the positive X-direction side in FIG6) inside the housing 200. The camera unit 210 uses, for example, a wide-angle CCD camera.

[0033] A semi-transparent mirror 211 is provided near the center of the upper part of the housing 200. The semi-transparent mirror 211 is positioned facing the camera unit 210, tilted upwards at a 45-degree angle towards the camera unit 210 with its mirror surface facing vertically downwards. An illumination device 212 is provided above the semi-transparent mirror 211. The semi-transparent mirror 211 and the illumination device 212 are fixed inside the upper part of the housing 200. Illumination from the illumination device 212 is directed downwards through the semi-transparent mirror 211. Therefore, light reflected by an object located below the illumination device 212 is further reflected by the semi-transparent mirror 211 and captured by the camera unit 210. That is, the camera unit 210 can capture images of objects located in the illumination area caused by the illumination device 212. Furthermore, the imaging results caused by the camera unit 210 are input to the camera control device 251 described later.

[0034] Returning to the description of the wafer processing system 10 using Figures 2-4. As shown in Figure 2, a wafer transport region D is formed in the area surrounded by blocks 1-4 (G1-G4). A plurality of wafer transport devices 160, each having a transport arm 160a that can move freely in, for example, the Y, X, θ, and vertical directions, are disposed in the wafer transport region D. The wafer transport devices 160 move within the wafer transport region D and can transport the wafer W to a desired location within the surrounding blocks 1-G1, 2-G2, 3-G3, and 4-G4.

[0035] Furthermore, in the wafer transport area D, as shown in FIG4, a shuttle transport device 170 is provided for linearly transporting the wafer W between the third block G3 and the fourth block G4.

[0036] The shuttle transport device 170 can move freely in a linear manner in the Y direction, for example, as shown in FIG4. The shuttle transport device 170 moves in the Y direction while supporting the wafer W, and can transport the wafer W between the receiving and receiving device 142 of the third block G3 and the receiving and receiving device 152 of the fourth block G4.

[0037] As shown in Figure 2, a wafer transport mechanism 180 is provided next to the positive X-direction side of the third block G3. The wafer transport mechanism 180 has a transport arm 180a that can move freely in, for example, the X-direction, the θ-direction, and the vertical direction. The wafer transport mechanism 180 moves vertically while supporting the wafer W, and can transport the wafer W to the receiving devices within the third block G3.

[0038] A wafer transport device 190 and a receiving / receiving device 191 are provided at the interface station 103. The wafer transport device 190 has a transport arm 190a that can move freely in, for example, the Y direction, the θ direction, and the vertical direction. The wafer transport device 190 supports the wafer W, for example, on the transport arm 190a, and can transport the wafer W between the receiving / receiving devices, the receiving / receiving device 191, and the exposure device 102 within the fourth block G4.

[0039] Furthermore, a control device 250 is provided in the wafer processing system 10.

[0040] The control device 250 is a computer, such as one equipped with a CPU or memory, and has a program storage unit (not shown). This program storage unit stores programs for controlling the operation of the drive systems of the various processing devices or transport mechanisms described above to perform the wafer processing described later. Furthermore, the program storage unit also stores programs for controlling the operation of the camera unit or drive system of the inspection camera device 153 to control the image processing of the wafer W. Moreover, the aforementioned programs can be recorded on, for example, a computer-readable memory medium, and can be installed from that memory medium onto the control device 250. The memory medium can be temporary or non-temporary. Part or all of the program can be implemented using dedicated hardware (circuit board).

[0041] Furthermore, the control device 250 obtains an image of the wafer W based on the imaging results of the imaging unit 210 of the inspection imaging device 153. Specifically, the control device 250 applies the necessary image processing to the image captured by the imaging unit 210, thereby generating an image representing the overall state of the surface of the wafer W, which serves as the image of the wafer W. The image of the wafer W generated by the control device 250 is output to the overall control device 20.

[0042] Returning to the description of the wafer inspection system 1 using FIG1. ​​The wafer inspection system 1 has an overall control device 20 as described above. The overall control device 20 is composed of a computer, for example, equipped with a processor such as a CPU or memory, and has a memory unit 260 and a control unit 261.

[0043] The memory unit 260 stores various information and includes a memory such as RAM or a storage device such as an HDD. The memory unit 260 stores programs involved in the inspection of the image captured on the wafer W in the control unit 261. These programs can be recorded on a computer-readable memory medium H, or they can be installed from the memory medium H onto the overall control device 20. Furthermore, the memory medium H can be either temporary or non-temporary.

[0044] The control unit 261 controls the entire control device 20. The control unit 261 has a processor, such as a CPU.

[0045] [Wafer Processing] Next, wafer processing performed in the wafer processing system 10 configured as described above will be explained. Furthermore, the following processing is performed according to, for example, a processing formula set for each batch of wafers W, and the handling of wafers W during processing is performed according to a handling formula for wafers W corresponding to the aforementioned processing formula. The processing formula and handling formula are stored in a memory unit (not shown).

[0046] First, a cassette C containing a plurality of wafers W is moved into the cassette station 100. Then, under the control of the control device 250, the wafers W are transported to the underlayer film forming apparatus 121 in the first block G1, where an underlayer film is formed on the wafers W. Afterwards, the wafers W are transported to the underlayer film heat treatment apparatus 130 in the second block G2 for underlayer film heat treatment. Then, the wafers W are transported to the inspection camera device 153. And, under the control of the control device 250, an image of the wafers W after underlayer film formation is captured by the camera unit 210, obtaining an image of the wafers W after underlayer film formation. The acquired image of the wafers W is associated with the identification information of the wafers W and output to the overall control device 20. Furthermore, the image captured by the camera on wafer W is associated with identification information of the transport formula applicable to wafer W (specifically, the transport formula representing the path up to the inspection camera device 153) and is output to the overall control device 20. The image captured by the camera on wafer W that is output to the overall control device 20 is stored in the memory unit 260.

[0047] Next, under the control of the control device 250, the wafer W is transported to the intermediate layer film formation apparatus 122 of the first block G1, where an intermediate layer film is formed on the lower layer film of the wafer W. Then, the wafer W is transported to the intermediate layer heat treatment apparatus 130 of the second block G2 for heat treatment of the intermediate layer film. Afterwards, the wafer W is transported to the photoresist coating apparatus 123 of the first block G1, where a photoresist film is formed on the intermediate layer film of the wafer W. Next, the wafer W is transported to the PAB processing heat treatment apparatus 130 of the second block G2 for PAB processing.

[0048] Next, the wafer W is transferred to the exposure apparatus 102 and exposed to form the desired pattern. Then, the wafer W is transferred to the heat treatment apparatus 130 for PEB processing in the second block G2 for PEB processing. Next, the wafer is transferred to the imaging processing apparatus 120 in the first block G1 for imaging processing, forming a photoresist pattern on the wafer W.

[0049] Subsequently, wafer W is transferred to the heat treatment apparatus 130 for post-baking processing in block G2 for post-baking processing. Then, wafer W is returned to cassette C, completing a series of wafer processing steps. The aforementioned wafer processing is also performed on other wafers W.

[0050] Furthermore, when the processing formula and the transport formula are different, the imaging sequence caused by the inspection camera device 153 will also be different. For example, in the above example, although the wafer W is imaged by the inspection camera device 153 after the lower layer film is formed and before the intermediate layer film is formed, there are also cases where the wafer W is imaged by the inspection camera device 153 after the development process.

[0051] [Overall Control Device 20] Figure 7 is a functional block diagram of the control unit 261 of the overall control device 20 for wafer inspection based on the image captured by the wafer W. As shown in Figure 7, the control unit 261 includes a setting unit 301, an inspection unit 302, a recipe creation unit 303, and a determination unit 304, which are implemented by a processor such as a CPU reading and executing a program stored in the memory unit 260.

[0052] The setting unit 301 defines groups corresponding to the basic state (normal state) of the wafer W, and sets the defined groups for each wafer W. The basic state of the wafer W is a state unrelated to whether there are defects in the wafer W. The basic state of the wafer W varies depending on, for example, the thickness or type of the film on the outermost surface of the wafer W, the shape or spacing of the pattern caused by the film on the outermost surface, etc. Furthermore, the basic state of the wafer W also varies depending on the thickness or type of the base film relative to the film on the outermost surface, the shape or spacing of the pattern caused by the base film, etc. The setting unit 301 defines the above groups based on the pixel values ​​(pixel brightness values) in the image captured by the wafer W, which vary according to the stacking state of the films on the wafer W.

[0053] The inspection unit 302 inspects the wafer W for defects based on the photographic image of the wafer W to be inspected and an inspection formula corresponding to the group to which the wafer W belongs. The inspection formula includes at least a reference image, which serves as the basis for defect inspection, and is used as a comparison object of the photographic image of the wafer W to be inspected. Furthermore, the inspection formula includes defect conditions (i.e., defect inspection parameters) for detecting defects based on the comparison results between the photographic image of the wafer W to be inspected and the reference image.

[0054] The defect conditions include, for example, a combination of conditions regarding the pixel value that should be detected as a defect, conditions regarding the size (dimension) of the defect, and conditions regarding the location of the area where defects are not detected. The condition regarding the pixel value that should be detected as a defect is, for example, a critical value relating to the difference between the pixel values ​​of the photographic image of the wafer W to be inspected and the reference image; the portion where the difference in pixel values ​​exceeds the critical value is detected as a defect. The condition regarding the size of the defect is, for example, a critical value relating to the size of the portion detected as a defect based on the condition regarding the pixel value that should be detected as a defect; only those sizes exceeding the critical value are detected as defects. Specifically, the condition regarding the location of the area where defects are not detected is an adjustment amount for the size or location of the area where defects are not detected, i.e., the area suspected of being a defect.

[0055] Furthermore, the defect conditions may include, for example, conditions regarding the adjustment amount of the pixel values ​​of the entire wafer surface of the reference image, conditions regarding the size of the defect, and conditions regarding the adjustment amount of the pixel values ​​of each region after the reference image is radially divided on the wafer W.

[0056] In addition, the appropriate defect conditions are different for each baseline image.

[0057] The formulation creation unit 303 creates a check formulation for each group to which wafer W belongs.

[0058] The determination unit 304 determines whether the wafer W, which is an inspection object and belongs to the group defined by the setting unit 301, belongs to the group defined by the setting unit 301. Specifically, the determination unit 304 makes the above determination based on the following (1) and (2).

[0059] (1) Whether the processing performed on wafer W is consistent between the wafer W of the set object in the group and the wafer W of the group that has been defined above. (2) Whether the basic state of the set object wafer W, which is estimated from the image of the set object wafer W in the group, is consistent with the basic state of the wafer W of the group that has been defined above.

[0060] Specifically, (1) above refers to whether the transport formula is consistent between the wafer W of the set object of the group and the wafer W belonging to the group defined above. That is, whether the transport formula associated with the image of the wafer W of the set object of the group is consistent with the transport formula associated with the group defined above as described later.

[0061] Furthermore, specifically regarding (2) above, whether the image base feature quantity of the wafer W to which the group is defined is included within the range of the feature quantity (hereinafter referred to as the image base feature quantity) in the photographic image of the wafer W corresponding to the basic state of the wafer W belonging to the defined group. The image base feature quantity of the wafer W to which the group is defined is included within the range of the image base feature quantity of the wafer W to which the defined group should belong means that the wafer W to which the group is defined and the wafer W belonging to the defined group are consistent not only in terms of the transfer formula but also in terms of the processing performed before the processing according to the transfer formula. For example, if there are multiple image base feature quantities that serve as the basis for the range of the above image base feature quantities, the range of the above image base feature quantities is determined by the Mahalanobis' Distance from the distribution of the multiple image base feature quantities. In addition, the case where there is an odd number of image base feature quantities that serve as the basis for the range of the above image base feature quantities is not limited to this.

[0062] The basic feature quantity of the image is, for example, a feature quantity relating to the in-plane tendency of pixel values ​​in the image captured on wafer W. More specifically, the aforementioned in-plane tendency feature quantity is as follows: That is, as disclosed in International Publication No. 2020 / 246366, the planar distribution of pixel values ​​in the image captured on wafer W can be decomposed into in-plane tendency components of complex pixel values ​​using a Zernike polynomial, and the Zernike coefficient of each in-plane tendency component can be calculated. For example, the Zernike coefficient of each in-plane tendency component conforms to the feature quantity related to the aforementioned in-plane tendency.

[0063] Even if the basic image features include features of a unit area (e.g., exposure emission) of the image captured on wafer W. The unit area referred to here is an area when the surface of wafer W is divided at specific intervals, such as an exposure area unit when the object area is divided and exposed during the exposure process of the film on wafer W before being placed into the wafer processing system 10, which is equivalent to exposure emission. Specifically, the features of a unit area of ​​the image captured on wafer W can be, for example, the image value of that unit area or its average value, even if it is the difference in pixel values ​​when compared with the corresponding unit area in the reference image. Furthermore, even if the features of a unit area of ​​the image captured on wafer W include the distance between unit areas. Additionally, even if the aforementioned unit area is specified based on information about its position and size stored in the memory unit 260 beforehand, even if it is specified by analyzing the image captured.

[0064] Moreover, the determination unit 304 determines that the wafer W of the set object of the group does not belong to the defined group if at least one of the following conditions is met: (1) the processing of the wafer W of the set object in the group is inconsistent with that of the wafer W of the defined group; and (2) the basic state of the wafer W of the set object, which is inferred from the image of the wafer W of the set object in the group, is inconsistent with that of the wafer W of the defined group.

[0065] In particular, the determination unit 304 determines that the wafer W of the set object of the group does not belong to the defined group even under the following circumstances. That is, regarding the above (1), even if the processing of the wafer W of the set object of the group and the wafer W of the defined group are the same, that is, the transfer formula is the same, regarding the above (2), when the basic state of the set object wafer W estimated from the photographic image of the set object wafer W is inconsistent with the basic state of the wafer W of the defined group. It can also be said that the determination unit 304 determines from the photographic image of the wafer W whether the basic state caused by the thickness or type of the film formed on the set object wafer W, the pattern or spacing of various films is the same as the basic state corresponding to the defined group.

[0066] When the determination unit 304 determines that the wafer W to be set as a group belongs to a defined group, the setting unit 301 sets a matching group for the wafer W to be set. If, after setting, an inspection formula corresponding to the matching group is completed, the inspection unit 302 inspects the wafer W with the set group for defects based on the image of the wafer W and the inspection formula corresponding to the set group.

[0067] On the other hand, if the determination unit 304 determines that the wafer W to be set as a group does not belong to a defined group, the setting unit 301 defines a new group and sets the wafer W to be set. Furthermore, the setting unit 301 establishes a correlation between the new group and the conditions of the wafer W that should belong to that new group. Specifically, it establishes a correlation between the transport formula of the wafer W that should belong to the new group and the range of the basic image feature quantities of that wafer W.

[0068] Furthermore, when the setting unit 301 sets the aforementioned new group on the wafer W to which the group is set, the recipe creation unit 303 creates an inspection recipe corresponding to the aforementioned new group based on the photographic image of the wafer W to which the group is set, which is the photographic image of the wafer W to which the new group is set. Specifically, the recipe creation unit 303 creates an inspection recipe corresponding to the aforementioned new group based on the photographic images of multiple wafers W to which the new group is set.

[0069] A method for generating a reference image for defect inspection included in an inspection formula from photographic images of multiple wafers W can use well-known methods (e.g., the method disclosed in Japanese Patent Application Publication No. 2014-115140). In the method disclosed in Japanese Patent Application Publication No. 2014-115140, it is presumed that there are no defects from photographs of multiple wafers W, and photographic images of wafers W that meet specific conditions are extracted. The reference image is generated based on the extracted photographic images of wafers W.

[0070] Furthermore, when determining the aforementioned defect conditions in the inspection formula based on images from multiple wafers, for example, the formula creation unit 303 adjusts the defect conditions for each of the extracted wafer W images generated using the reference image, in a way that defects are not detected when inspecting according to the generated reference image. For example, from the extracted wafer W images, the pixel value of the image with the largest difference in pixel value compared to the reference image is selected and set as the reference for the critical value within the range of defect conditions. It is acceptable to set its pixel value as is, or to set the value multiplied by a pre-set coefficient as the critical value. When determining defect conditions for a certain position or region (detection area unit) within a certain number of wafer W surfaces, for each detection area unit, the pixel value of the image with the largest difference in pixel value is selected and set as the critical value within the defect conditions. In addition, when a region containing multiple pixels is set as the detection region unit, the defect condition is determined using the same method as described above, which uses the average pixel value within the region as the benchmark.

[0071] According to the setting unit 301, the formula is checked and prepared as follows. First, a coefficient is set relative to the overall pixel value distribution within the plane of the wafer W (an example of the condition for adjusting the overall pixel value within the plane of the wafer W). This coefficient is a constant of 1 or more, and is multiplied by the pixel value at each position in the above-mentioned brightness distribution. The product of the pixel value at each position of the extracted camera pixel of the wafer W and this coefficient is set to be outside the range of defect conditions (i.e., non-defect). Next, the bias values ​​of the inner region, which is narrower in the radial direction than the range covered by the above-mentioned coefficient, and the outer region, which is located further outward than the inner region, are determined. The aforementioned bias value is an example of the condition regarding the adjustment amount of pixel values ​​in each region after radial division of wafer W. Specifically, the maximum value that can be obtained in each of the inner and outer regions, provided that the value of the sum of the pixel values ​​at each location and the aforementioned coefficients is not within the range of defect conditions, is set, for example, by verification results for specific complex post-complementary values.

[0072] Even when the wafer W of the object to be inspected has a pattern, the inspection formula containing the above-mentioned defect conditions is determined and made without using the design data (specifically, CAD data) about the pattern.

[0073] When a new inspection formula is prepared corresponding to the new group mentioned above, the inspection unit 302 inspects the wafer W belonging to the new group that has not been inspected, based on the photographic image of the wafer W and the new inspection formula mentioned above, for defects.

[0074] [Inspection Processing and Pre-Inspection Processing] Next, the inspection processing and pre-inspection processing for the entire control device 20 will be explained. First, the pre-inspection processing will be explained.

[0075] Figure 8 is a flowchart illustrating an example of the pre-inspection process for the inspection caused by the entire control device 20.

[0076] In the pre-inspection process, for example, as shown in FIG8, firstly, the control unit 261 obtains camera images of multiple wafers W that should belong to the same group, and the camera images of wafers W that have been normally processed (i.e., without defects) (step S1). Here, the camera images obtained by the control unit 261 are obtained by, for example, by the user being selected.

[0077] Next, the control unit 261 defines the group of wafer W after obtaining the camera image as group 1 (step S2).

[0078] Furthermore, the control unit 261 determines the transport formula of wafer W belonging to group 1 and the range of image basic feature quantities of wafer W belonging to group 1 as conditions for belonging to group 1, and establishes an association with these groups (step S3). In the transport formula of wafer W belonging to group 1, a transport formula, for example, associated with the image obtained in step S1 is used. Furthermore, the range of image basic feature quantities of wafer W belonging to group 1 is determined from the image obtained in step S1.

[0079] Furthermore, the recipe creation unit 303 determines the inspection recipe corresponding to group 1 based on the photographic images of the plurality of wafers W obtained in step S1 (step S4). Here, the pre-processing of a series of inspections ends. Alternatively, the pre-processing can be omitted.

[0080] Next, the inspection process caused by the overall control device 20 will be explained. Figure 9 is a flowchart showing an example of the inspection process caused by the overall control device 20. First, the determination unit 304 obtains the image of the wafer W to be inspected from the memory unit 260 (step S11).

[0081] Next, the determination unit 304 shall set a group for the wafer W of the inspection object and determine whether the transport recipe associated with the image of the wafer W of the inspection object is consistent with the transport recipe associated with any one of the defined groups (step S12).

[0082] In the case of consistency (step S12, YES case), the determination unit 304 determines whether the image basic feature quantity of the wafer W to be inspected is within the range of the image basic feature quantity of the wafer W that should belong to the group for each of the groups with consistent transport formulas (step S13).

[0083] For any group with the same transport formula, if the image basic feature quantity of the wafer W to be inspected is within the range of the image basic feature quantity of the wafer W to be inspected (step S14, YES case), the setting unit 301 sets the wafer W to be inspected to a corresponding group (step S15).

[0084] Furthermore, if an inspection formula has been prepared for the group set for the wafer W to be inspected (step S16, YES case), the inspection unit 302 inspects for defects based on the photographic image of the wafer W to be inspected and the prepared inspection formula (step S17). Afterwards, the control unit 261 returns the process to step S1 of the next wafer W.

[0085] In the case where no inspection recipe is created for the group set for the wafer W to be inspected (step S16, NO case), the recipe creation unit 303 determines whether the number of wafers W to be inspected that are set to the same group exceeds the threshold (step S18).

[0086] If the threshold value is not exceeded (NO case), the control unit 261 returns the process to step S1. If the threshold value is exceeded (YES case), the recipe creation unit 303 creates an inspection recipe corresponding to the matching group based on the photographic images of the wafers W to which the number of inspected objects exceeds the threshold value (step S19). Next, the inspection unit 302 inspects each wafer W belonging to the group after the inspection recipe is created for defects based on the photographic images of that wafer W and the created inspection recipe (step S20). Afterward, the control unit 261 returns the process to step S1 for the next wafer W.

[0087] Furthermore, in step S12, if either the transport formula associated with the image of the wafer W to be inspected is inconsistent with the transport formula associated with the defined group (NO case), the setting unit 301 defines a new group and sets it for the wafer W to be inspected (step S21). Furthermore, the setting unit 301 establishes an association between the new group and the range of transport formulas and image basic feature quantities of the wafer W to which the new group should belong (step S22). Afterwards, the control unit 261 returns the process to step S1 for the next wafer W. In step S14, even if the image basic feature quantity of the wafer W to be inspected is not within the range of image basic feature quantities of the wafer W to which the group should belong (NO case), it is the same as the NO case in step S12.

[0088] [Specific Example] Here, we consider the case where the inspection is performed for the first time after the pre-inspection process described above, according to the flowchart shown in FIG9, that is, the wafer W to be inspected is as follows (A), (B), (C).

[0089] (A) If the wafer W to be inspected has the same transport formula and the wafer W used for imaging in the pre-inspection process has the same basic image features (i.e., it should belong to the wafer W1 of group 1 defined in the pre-inspection process), the inspection process proceeds in the order of steps S11 → S12 → S13 → S14 → S15 → S16 → S17. Moreover, the wafer W1 to be inspected is set to group 1 defined in the pre-inspection process and is inspected according to the inspection formula corresponding to group 1 created in the pre-inspection process.

[0090] (B) In cases where the transport formulation of the wafer W to be inspected differs from that of the wafer W used for imaging during the pre-inspection process (i.e., the wafer W to be inspected is a wafer W2 for which a transport formulation R2, different from the transport formulation R1 of the aforementioned wafer W1, is used), the inspection process proceeds in the order of step S11 → step S12 → step S21 → step S22. Furthermore, a new group 2 is defined and set as the wafer W2 to be inspected, and a correlation is established between the new group 2 and the range A2 of the transport formulation R2 and the basic image feature quantity of the wafer W belonging to that group 2.

[0091] For wafers W2 that are to be inspected after the second wafer and up to the threshold value in step S18, the inspection process proceeds in the order of steps S11 → S12 → S13 → S14 → S15 → S16 → S18 → S1. Accordingly, for each wafer W2, a defined group 2 is set according to the wafer W2 that was to be inspected in the first wafer. However, the inspection is not performed at this point.

[0092] Furthermore, for the wafer W2 that exceeds the threshold value in step S18, the process proceeds in the order of S11 → S12 → S13 → S14 → S15 → S16 → S18 → S19 → S20. Accordingly, the wafers W2 to be inspected after the second wafer are set to group 2 defined based on the first wafer W2, and an inspection formula corresponding to group 2 is created based on the photographic images of the plurality of wafers W2. Furthermore, each of the wafers W2 for which group 2 has been set is inspected according to the created inspection formula.

[0093] For the wafer W2 to be inspected after the inspection formula is made, the inspection process proceeds in the order of steps S11 → S12 → S13 → S14 → S15 → S16 → S17. Moreover, the wafer W2 to be inspected is set to group 2 and is inspected according to the inspection formula corresponding to group 2 as described above.

[0094] (C) In the case where the wafer W to be inspected and the wafer W to which the image is captured during the pre-inspection process have the same transport formula but different image basic feature quantities (i.e., the wafer W to be inspected uses the same transport formula R1 as the wafer W1 mentioned above, but the image basic feature quantities of wafer W3 are different), the inspection process proceeds according to steps S11 → S12 → S13 → S14 → S21 → S22. Furthermore, a new group 3 is defined and set as the wafer W3 to be inspected, and a correlation is established between the new group 3 and the transport formula R3 and the range A3 of the image basic feature quantities of the wafer W to which it belongs.

[0095] For wafers W3 that are to be inspected after the second wafer and up to the threshold value in step S18, the inspection process proceeds in the order of steps S11 → S12 → S13 → S14 → S15 → S16 → S18 → S1. Accordingly, for each wafer W3, a defined group 3 is set according to the wafer W2 that was to be inspected in the first wafer. However, the inspection is not performed at this point.

[0096] Furthermore, for the wafer W2 that has exceeded the threshold in step S18, the process proceeds in the order of S11 → S12 → S13 → S14 → S15 → S16 → S18 → S19 → S20. Accordingly, the wafers W3 to be inspected after the second wafer are set to group 3 defined based on the first wafer W3, and an inspection formula corresponding to group 3 is created based on the photographic images of the plurality of wafers W3. Furthermore, each of the wafers W2 for which group 3 has been set is inspected according to the created inspection formula.

[0097] For the wafer W3 to be inspected after the inspection formula is made, the inspection process proceeds in the order of steps S11 → S12 → S13 → S14 → S15 → S16 → S17. Moreover, the wafer W3 to be inspected is set to group 3 and is inspected according to the inspection formula corresponding to group 3 as described above.

[0098] [Main Effects of the Technology Disclosed Herein] As described above, the inspection method involved in this embodiment includes: defining groups corresponding to the basic state of wafer W, and setting defined groups for each wafer W to be inspected; inspecting defects based on the photographic image of the wafer W to be inspected and an inspection formula containing a reference image corresponding to the group to which the wafer W to be inspected belongs; creating an inspection formula for each group; and determining whether the wafer W to which the group is set belongs to the defined group. Furthermore, the determination process involves determining whether the processing performed on the wafer W to which the group is set is consistent with that of the wafer W to which the group is set, and whether the basic state of the wafer W to which the group is set, as inferred from the photographic image of the wafer W to which the group is set, is consistent with the reference state of the wafer W to which the group is defined, and performing the above determination. If the wafer W to be set belongs to a defined group, then in the above-mentioned setting process, the wafer W is assigned a matching group. Conversely, if the wafer W is determined not to belong to a defined group, then in the above-mentioned setting process, a new group is defined and set for the wafer W. In the recipe creation process, a check recipe corresponding to the new group is created based on the photographic image of the wafer W.

[0099] Therefore, in this embodiment, when there is no inspection formula suitable for the wafer W to be inspected, an inspection formula suitable for the wafer W to be inspected is created based on the photographic image of the wafer W to be inspected. Therefore, it is not necessary to create an inspection formula in advance, or the number of inspection formulas created in advance can be minimized. In this way, the operation time at startup of the wafer inspection system 1 can be reduced. Furthermore, in this embodiment, since each wafer W to be inspected uses an inspection formula suitable for that wafer W, a well-designed defect inspection can be performed. That is, with this embodiment, the increase in operation time at startup can be reduced while the defect inspection based on the photographic image of the wafer can be performed with high accuracy.

[0100] Furthermore, in this embodiment, since it is not necessary to use design data (CAD data) regarding the pattern formed on the wafer W for checking the formulation, the time-consuming process of inputting design data for teaching purposes in advance can be saved. That is, with this embodiment, even when various wafers W are being processed, autonomous processing can be performed without prior data input, such as determining whether an existing group is a new group and checking whether the determination result matches. In addition, design data is not required for adjusting the conditions of coating or heat treatment in the wafer processing system 10.

[0101] Furthermore, in this embodiment, a group is set for the wafer W to be inspected, and defects in the wafer W are inspected according to the inspection formula corresponding to that group. Moreover, the group setting for the wafer W to be inspected is based on the handling formula of the wafer W to be inspected or the basic characteristic parameters of the image of the wafer W to be inspected. That is, the group setting for the wafer W to be inspected does not require user operation; the setting unit 301 can perform it automatically. Therefore, user time can be saved.

[0102] Furthermore, with this embodiment, even when transporting wafers W with the same inspection formula, different inspection formulas can be used if the basic image feature quantities are different. Therefore, defect inspection can be performed more accurately.

[0103] (Modification) Even if the image of multiple wafers W belonging to the same group is used as a photographic image, an inspection formula corresponding to each group can be created again at a specific time sequence. The specific time sequence is each batch, each processing of a specific number of wafers W, and each time a specific period of time has elapsed. In this way, defect inspection based on the inspection formula can be performed with better accuracy. In addition, in the case of creating an inspection formula again, even for wafers W that were inspected according to the old inspection formula, defects can be inspected according to the newly created inspection formula. [Simplified Explanation of the Diagram]

[0008] [Figure 1] is a schematic diagram showing the general structure of a wafer inspection system equipped with an overall control device as a substrate inspection apparatus according to this embodiment. [Figure 2] is a schematic top view showing the general structure of a wafer processing system. [Figure 3] is a schematic diagram showing the general internal structure of the front side of the wafer processing system. [Figure 4] is a schematic diagram showing the general internal structure of the back side of the wafer processing system. [Figure 5] is a longitudinal sectional view showing the general structure of the inspection camera device. [Figure 6] is a cross sectional view showing the general structure of the inspection camera device. [Figure 7] is a functional block diagram of the control unit of the overall control device for inspecting wafers based on the image captured by the camera on wafer W. [Figure 8] is a flowchart showing an example of the pre-inspection processing caused by the overall control device. [Figure 9] is a flowchart showing an example of the inspection processing caused by the overall control device.

Claims

1. A substrate inspection apparatus, comprising: a setting unit that defines a group of basic states, independent of the presence or absence of substrate defects, for each substrate to be inspected; an inspection unit that inspects for defects based on a photographic image of the substrate to be inspected and an inspection formula including a reference image corresponding to the group to which the substrate to be inspected belongs; a formula generation unit that generates the inspection formula for each group; and a determination unit that determines whether the substrates to be inspected in the group defined by the setting unit belong to a group defined by the setting unit; the determination unit performs the determination on the substrates to be inspected in the group and the substrates belonging to the defined group based on whether the processing performed on the substrates is consistent and whether the basic state of the substrates to be inspected, as inferred from the photographic image of the substrates to be inspected in the group, is consistent with the basic state of the substrates belonging to the defined group. When the substrate of the aforementioned target is determined to belong to the group defined above, the setting unit sets a matching group for the substrate of the aforementioned target. When the substrate of the aforementioned target is determined not to belong to the group defined above, the setting unit defines a new group and sets a new group for the substrate of the aforementioned target. The formula creation unit creates the aforementioned inspection formula corresponding to the new group based on the photographic image of the substrate of the aforementioned target.

2. The substrate inspection apparatus of claim 1, wherein if at least one of the following conditions is met—that the substrate of the set object in the aforementioned group and the substrate belonging to the aforementioned defined completion group have inconsistent processing on the substrate, and that the basic state of the set object substrate estimated from the photographic image of the set object substrate in the aforementioned group is inconsistent with the basic state of the substrate belonging to the aforementioned defined completion group—the determination unit determines that the substrate of the set object does not belong to the aforementioned defined completion group.

3. In the substrate inspection apparatus of claim 2, if the processing of the substrate being inspected in the aforementioned group and the substrate belonging to the aforementioned defined completion group are the same, but the basic state of the substrate being inspected, as inferred from the photographic image of the substrate being inspected in the aforementioned group, is inconsistent with the basic state of the substrate belonging to the aforementioned defined completion group, the determination unit determines that the substrate being inspected does not belong to the aforementioned defined completion group.

4. The substrate inspection apparatus of claim 1, wherein the inspection formula includes defect conditions for detecting defects based on a comparison result of a photographic image of the substrate to be inspected and a reference image.

5. The substrate inspection apparatus of claim 4, wherein the aforementioned defect conditions include conditions regarding the pixel value of the defect to be detected, conditions regarding the size of the defect, and conditions regarding the location of the area where the defect is not detected.

6. The substrate inspection apparatus of claim 5, wherein the defect conditions include conditions regarding the adjustment amount of the pixel value of the entire substrate surface, conditions regarding the size of the defect, and conditions regarding the adjustment amount of the pixel value of each region after the substrate is radially divided.

7. A substrate inspection apparatus according to any one of claims 1 to 6, wherein a pattern is formed on the substrate to be inspected, and the formulation making unit makes the inspection formula without using design data about the pattern.

8. The substrate inspection apparatus of any of claims 1 to 6, wherein whether the basic state of the substrate of the set object, which is estimated from the photographic image of the substrate of the set object of the above group, is consistent with the basic state of the substrate of the group to which the definition is completed, is determined by whether the feature quantity in the photographic image of the basic state of the substrate of the set object corresponding to the above group is within the range of the feature quantity in the photographic image of the basic state of the substrate of the set object corresponding to the above group to which the definition is completed.

9. The substrate inspection apparatus of claim 8, wherein the feature quantity in the photographed image is a feature quantity of in-plane tendency with respect to the pixel value in the photographed image.

10. The substrate inspection apparatus of any one of claims 1 to 6, wherein when the substrate of the set object is determined not to belong to the group defined above, the formula generation unit generates the inspection formula corresponding to the new group based on the photographic images of the plurality of substrates of the set object.

11. The substrate inspection apparatus of any one of claims 1 to 6, wherein the above-mentioned formula generation unit generates the above-mentioned inspection formula corresponding to the above-mentioned group again at a specific time sequence based on the photographic images of a plurality of substrates belonging to the group.

12. A substrate inspection method, comprising: defining a group of basic states independent of the presence or absence of substrate defects for each substrate to be inspected; inspecting for defects based on a photographic image of the substrate to be inspected and an inspection formula including a reference image corresponding to the group to which the substrate to be inspected belongs; creating an inspection formula for each group; determining whether a substrate belonging to the defined group belongs to a defined group; the determination being performed on substrates belonging to the defined group and substrates belonging to the defined group based on whether the processing performed on the substrates belonging to the defined group is consistent, and whether the basic state of the substrate belonging to the defined group, as inferred from the photographic image of the substrate belonging to the defined group, is consistent with the basic state of the substrate belonging to the defined group; when a substrate belonging to the defined group is determined to belong to the defined group, in the setting process, a corresponding group is set for the substrate belonging to the defined group. If the substrate of the above-mentioned target is determined not to belong to the group defined above, in the above-mentioned setting process, a new group is defined and the substrate of the above-mentioned target is set. In the process of creating the above-mentioned inspection formula, the above-mentioned inspection formula corresponding to the above-mentioned new group is created based on the photographic image of the substrate of the above-mentioned target.

13. A computer-readable memory medium that stores a program on a computer that controls the operation of a control unit of the substrate inspection apparatus for performing the substrate inspection method as described in claim 12 by means of a substrate inspection apparatus.

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