Wafer state detection method and device and medium

Abstract

The invention discloses a wafer state detection method, device and medium, the method is used for wafer state detection in wafer cassettes of different specifications, and the method comprises the following steps: obtaining a target vacant spacing of the wafer cassettes and an interlayer spacing between crystal teeth of adjacent support wafers; obtaining an upper surface position and a lower surface position of a single wafer on a starting crystal tooth of the wafer box; calculating an upper clearance and a lower clearance corresponding to each crystal tooth according to the interlayer spacing, the target clearance spacing and the upper surface position and the lower surface position of the single wafer on the initial crystal tooth; scanning the wafer along the thickness direction of the wafer; judging whether a wafer is detected in the first area range or not; if yes, the wafers detected in the first area range are judged to be inclined wafers, for the wafers not detected in the first area range, the thickness of the wafers located in the second area range is calculated, and a function value with the wafer thickness as a parameter is compared with a target threshold value to judge whether lamination exists or not. The detection method can be compatible with wafers of various specifications, and the wafer state can be detected.

Description

[0001] This application is a divisional application of the invention patent application filed by Shanghai Gona Semiconductor Technology Co., Ltd. on June 11, 2025, with application number 202510776687.6 and invention title "A wafer state detection method, device and medium". Technical Field

[0002] This invention relates to the field of wafer inspection technology, and in particular to a wafer condition inspection method, device and medium. Background Technology

[0003] The integrated circuit manufacturing process requires multiple processing steps to move wafers between different processing machines. Wafer cassettes are needed to hold the wafers. Each time a wafer is processed on a different machine, it needs to be removed from the cassette. If the robotic fork accidentally picks up a stack of wafers, the upper wafers in the stack can be thrown out during rapid movement, resulting in a "flying wafer." If the robotic fork picks up a misaligned wafer, the misalignment can cause the wafer to break or damage the robotic fork itself.

[0004] Processing equipment handles wafers of different sizes and specifications, each with varying thicknesses. These wafers are then housed in wafer cassettes of corresponding sizes. A key challenge is determining the status of the wafers within these cassettes for each size. Summary of the Invention

[0005] To overcome the above-mentioned shortcomings, the present invention aims to provide a wafer condition detection method, device and medium that is compatible with wafers in various wafer cassettes and can detect the wafer condition.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a wafer state detection method for detecting the wafer state in wafer cassettes of different specifications, the method comprising: The target vacancy spacing of the wafer cassette and the interlayer spacing between adjacent supporting teeth of the wafer are obtained. The target vacancy spacing is the minimum value of the vacancy spacing when the wafer cassette of different specifications carries the corresponding wafer. The vacancy spacing is the distance between the upper vacancy corresponding to a tooth and the lower vacancy corresponding to the adjacent tooth located above it. The upper vacancy is the height position that does not coincide with the stacked wafers and is just away from the upper surface of the upper wafer in the stacked wafers. The lower vacancy is the height position that does not coincide with the single wafer or the stacked wafers and is just away from its lower surface. Obtain the upper and lower surface positions of a single wafer on the starting cleavage of the wafer cassette; The upper and lower vacancies corresponding to each crystal tooth are calculated based on the interlayer spacing, the target vacancies spacing, and the upper and lower surface positions of the single wafer on the starting crystal tooth. The wafer is scanned along its thickness direction; Determine whether the wafer is detected within a first region, wherein the first region is the area between the upper dummy position of a crystal tooth and the lower dummy position of the crystal tooth located above and adjacent to it; If so, the wafer detected in the first region is determined to be a slanted wafer; For wafers not detected in the first region, the thickness of the wafers located in the second region is calculated. The second region is the area between the upper dummy bit and the lower dummy bit corresponding to the same die. The function value with the thickness of the wafer as a parameter is compared with a target threshold to determine whether the wafer is a stack.

[0007] Furthermore, the function value is the absolute value of the thickness difference between the wafers in two adjacent die teeth, and the target threshold is the value at the intersection of different threshold ranges corresponding to the wafers in wafer cassettes of different specifications. The threshold range is the set of values ​​formed between the maximum value of the absolute thickness difference between two wafers in a wafer cassette of one specification and the minimum thickness value of the wafer. The function value is compared with the target threshold to determine whether the wafers are stacked. When the function value is greater than or equal to the threshold, the thickness of the wafers on the two die teeth is compared, and the wafer with the larger thickness is stacked.

[0008] Furthermore, once a wafer is determined to be a stacked wafer, wafers that were previously classified as single wafers because the function value obtained by subtracting the wafer from the stacked wafer value is less than the target threshold are reclassified as stacked wafers.

[0009] Furthermore, the target threshold is less than or equal to 140 micrometers and greater than or equal to 7 micrometers.

[0010] Furthermore, the function value is the ratio of the wafer thickness within two adjacent wafer teeth, the target threshold is the maximum and minimum value of the union of different threshold ranges corresponding to wafers of different specifications of wafer cassettes, and the threshold range is the set of values ​​formed between the maximum and minimum values ​​of the ratio of the thickness of two wafers of a wafer cassette of a certain specification. The function value is compared with the target threshold to determine whether the wafers are stacked. When the function value is less than the minimum value of the union of different threshold ranges, or when the function value is greater than the maximum value of the union of different threshold ranges, the thickness of the wafers on the two crystal teeth is compared, and the wafer with the larger thickness is a stacked wafer.

[0011] Furthermore, when a wafer is determined to be a stacked wafer, wafers that were previously classified as single wafers because the function values ​​obtained from comparing with the stacked wafers were within the union of different threshold ranges are now classified as stacked wafers.

[0012] Furthermore, the vacancy spacing of each type of wafer cell is calculated using the following formula: ; Where Z' is the dummy spacing, X is the layer spacing, tmax is the maximum thickness of the wafers allowed to be stacked within the wafer cassette, and t is the average thickness of the corresponding wafers within the wafer cassette.

[0013] Furthermore, the upper imaginary position corresponding to the nth crystal tooth ; The lower imaginary position corresponding to the nth crystal tooth ; Where P1 and P2 are the upper and lower surface positions of the single wafer on the starting crystal tooth, respectively, X is the interlayer spacing, Z is the target dummy spacing, a is a constant greater than 0 and less than or equal to 1, and n is an integer greater than or equal to 1.

[0014] The present invention also discloses a wafer condition inspection device, including a sensor, which can sequentially scan and inspect wafers in a wafer cassette in the thickness direction, and the inspection device adopts the wafer condition inspection method described above.

[0015] The present invention also discloses a storage medium storing instructions, which, when executed by a processor, are used to implement the above-described wafer state detection method. Attached Figure Description Figure 1 The process of an embodiment of the present invention Figure 1 ; Figure 2 The process of an embodiment of the present invention Figure 2 ; Figure 3 This is a scanning schematic diagram of a wafer cell according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the sensor position structure according to an embodiment of the present invention. Detailed Implementation

[0016] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0017] A wafer condition detection method is invented for detecting the condition of wafers in wafer cassettes of different sizes. See attached document. Figure 3 As shown, wafer states include monolithic, stacked, and skewed wafers. Different wafer cassettes contain wafers of different specifications, and the thickness of wafers of different specifications will vary.

[0018] The wafer box has multiple spaced-apart crystal teeth evenly distributed along the vertical direction, which are used to support the wafer.

[0019] See appendix Figure 1 As shown, the wafer condition detection method includes: S100: Obtain the target virtual spacing of the wafer cell and the interlayer spacing between the crystal teeth of adjacent supporting wafers.

[0020] The target vacancy spacing is the minimum vacancy spacing of wafer cassettes of different specifications when carrying the corresponding wafers. The vacancy spacing is the distance between the upper vacancy corresponding to a die tooth and the lower vacancy corresponding to the die tooth adjacent to and above it. For example, when the vacancy spacing of the first type of wafer cassette is set to Z1', the vacancy spacing of the second type of wafer cassette is Z2', and the vacancy spacing of the third type of wafer cassette is Z3', where Z1' > Z2' > Z3', then the target vacancy spacing is Z3'.

[0021] The upper virtual position is the height position that does not coincide with the stacked wafers and is just away from the upper surface of the upper wafer in the stacked wafers. The lower virtual position is the height position that does not coincide with the single wafer or the stacked wafers and is just away from its lower surface.

[0022] For example, when a sensor scans wafers in a wafer cassette of a certain size from bottom to top, the sensor signal jumps when it just scans a wafer. The position where the sensor signal is about to jump at this moment is the lower dummy position of the wafer corresponding to that dummy tooth. The sensor just detaches from the top surface of the stacked wafers, and the sensor signal jumps again. The position where the sensor signal jumps again at this moment is the upper dummy position of the stacked wafer corresponding to that dummy tooth. Similarly, when a sensor scans wafers in a wafer cassette of a certain size from top to bottom, the sensor signal jumps when it just scans a stacked wafer. The position where the sensor signal is about to jump at this moment is the upper dummy position of the stacked wafer corresponding to that dummy tooth. The sensor just detaches from the bottom surface of the wafer, and the sensor signal jumps again. The position where the sensor signal jumps again at this moment is the lower dummy position of the wafer corresponding to that dummy tooth.

[0023] In this embodiment, the target virtual spacing takes into account wafer cells of different specifications. The upper and lower virtual spacing calculated using this target virtual spacing is compatible with wafer cells of different specifications. That is, wafer cells of different specifications can calculate the corresponding upper and lower virtual spacing based on the target virtual spacing to achieve wafer status detection.

[0024] The interlayer spacing between the dies of adjacent supporting wafers is a property of the wafer cassette. This embodiment does not limit the method for obtaining the interlayer spacing; for example, it can be obtained by measuring with calipers or by photographing the wafer cassette in advance. The interlayer spacing between the dies is the height difference between the upper or lower surfaces of two adjacent dies. Alternatively, a sensor can scan individual wafers within the wafer cassette to obtain the height position of the upper or lower surfaces of two adjacent wafers; the interlayer spacing between the dies is then the height difference between the upper or lower surfaces of two adjacent wafers.

[0025] S200: Obtain the upper and lower surface positions of the single wafer on the starting die of the wafer cassette.

[0026] The starting wafer tooth is the first wafer tooth scanned by the sensor, typically the topmost or bottommost wafer tooth within the wafer cassette. The sensor can scan from bottom to top or top to bottom. Since the wafer has a certain thickness, when the sensor detects a wafer, it generates a first transition signal upon initial detection and a second transition signal upon removal from the wafer. Based on these signal transitions, the Z-axis encoder obtains the upper and lower surface positions of the single wafer on the starting wafer tooth detected by the sensor.

[0027] Here, a single wafer refers to a single wafer placed horizontally on the starting die; there is no stacking or tilting of the wafers.

[0028] S300. Calculate the upper and lower virtual positions corresponding to each crystal tooth based on the interlayer spacing, target virtual position spacing, and the upper and lower surface positions of the single wafer on the starting crystal tooth.

[0029] The specific values ​​for interlayer spacing, target vacancy spacing, and the upper and lower surface positions of the single wafer on the starting die have been obtained, and the upper and lower vacancy positions corresponding to each die can be calculated.

[0030] S400: Scan the wafer along its thickness direction.

[0031] The sensor moves vertically to scan each wafer to be inspected within the wafer cassette.

[0032] S500: Determine whether a wafer is detected within the first region.

[0033] S600, if so, then the wafer detected in the first region is judged as a skewed wafer.

[0034] See appendix Figure 3As shown, the first region is the area between the upper vacant position of a die and the lower vacant position of the die above and adjacent to it. The first region is a portion of the area between two adjacent vacant dies. When the wafer is a skewed wafer, at least a portion of it will be located within the first region. As long as a portion of the wafer is located within the first region, that is, a wafer is detected within the first region, this wafer is a skewed wafer.

[0035] For example, when the sensor detects a wafer, it generates a first transition signal immediately upon detection and a second transition signal upon leaving the wafer. Whether the transition signal is generated when the sensor moves within the first region, or whether the first transition signal occurs before entering the first region and the second transition signal occurs after leaving the first region, it indicates that a portion of the wafer is located within the first region, meaning the wafer was detected within that region.

[0036] Existing detection methods use a fixed threshold for wafer status detection, typically limiting their application to single-specification wafers. In this embodiment, when determining the target vacancy spacing, considering different wafer cassette sizes, the minimum vacancy spacing across different cassette sizes when carrying the corresponding wafer is taken as the target vacancy spacing. This is then used to calculate the upper and lower vacancy spacing for each die in the wafer cassette. The resulting first region is compatible with slant detection for wafers of various sizes. When performing status detection on wafers within wafer cassettes of different sizes, this target vacancy spacing is used to calculate the first region, ensuring that all wafers detected within this first region are slanted. This detection method is compatible with different wafer sizes, accurately identifies wafer slant, and eliminates the need to set different thresholds for different wafer cassette sizes.

[0037] When a new wafer cassette is available, the phantom pitch of this new wafer cassette is calculated, the target phantom pitch is obtained again, and the wafer status can also be detected in the wafer cassette of this new specification according to the above detection steps.

[0038] For a wafer cassette of a certain size, assume that the upper virtual space of the wafer corresponding to the nth die is F. n1 The lower imaginary position is F n2 ,in , S1 is the distance from the upper dummy position of the nth crystal tooth to the upper surface of the wafer, S2 is the distance from the lower dummy position of the nth crystal tooth to the lower surface of the wafer, P1 is the position of the upper surface of the single wafer on the starting crystal tooth, P2 is the position of the lower surface of the single wafer on the starting crystal tooth, t is the average thickness of the corresponding wafer in the wafer box, X is the interlayer spacing, and n is a positive integer greater than or equal to 1.

[0039] The vacancy pitch of this type of wafer cell is Z', and the formula for calculating the vacancy pitch Z' is as follows:

[0040] Because of the upper imaginary position F n1 To ensure that the upper virtual space F is sufficient when the thickest wafer is stacked on top of the first wafer, n1 It does not interfere with the thickest stacked wafer, and at this time the lower imaginary position F of the (n+1)th wafer is... (n+1)2 Since it does not interfere with the lower surface of the (n+1)th wafer, S2 is much smaller than the average wafer thickness t, therefore we can obtain:

[0041] Therefore, the vacancy pitch Z' for each wafer cell specification is set to be equal to X - 2tmax - t, where tmax is the maximum thickness of the wafers allowed to be stacked within the wafer cell. The interlayer spacing X, the maximum wafer thickness tmax, and the average wafer thickness t can be known in advance, so the vacancy pitch Z' for each wafer cell specification can be calculated.

[0042] The target virtual spacing is Z, which is the minimum value among these calculated virtual spacings Z'. The target virtual spacing Z can also be expressed as:

[0043] Where 0 < a ≤ 1, and a can be set; It can be obtained ; Then, the upper virtual position of the wafer corresponding to the nth wafer slot can be deduced:

[0044] The nth wafer slot corresponds to the lower virtual position of the wafer:

[0045] Calculate the imaginary F n1 and lower imaginary position F n2 There is no need to detect the average thickness t of the wafers in the wafer box, which makes it easy to calculate the upper and lower virtual positions corresponding to each crystal tooth, and thus obtain the range of the first region.

[0046] Through steps S100-S600, the skewed wafers have been identified, but the remaining wafers not located in the first region may still have the problem of stacking. Therefore, after judging the skewed wafers, it is necessary to detect the stacking and single wafers of the remaining wafers.

[0047] Therefore, the wafer state detection method also includes: determining whether other wafers are detected as single wafers or stacked wafers if they are not detected in the first region, see Appendix. Figure 2 As shown, it specifically includes: S800, Calculate the thickness of the wafer located within the second region.

[0048] The second region is the area between the upper and lower virtual positions corresponding to a single crystal tooth. The second region does not overlap with the first region. The first and second regions are alternately set in the vertical direction. Therefore, for wafers that are not detected in the first region, they will be completely located within the second region.

[0049] When scanning the wafers in the wafer cassette along the thickness direction of the wafer, a first height value when each wafer is detected and a second height value when it leaves the wafer can be obtained, and the wafer thickness is the absolute value of the difference between the first height value and the second height value.

[0050] The first and second transition signals can be combined with the Z-axis encoder to obtain the first and second height values ​​for each wafer.

[0051] S900, compare the function value with the wafer thickness as a parameter with a target threshold to determine whether the wafer is stacked, specifically including: S911, the function value is the absolute value of the thickness difference between two adjacent wafers in the wafer dies, the target threshold is the value in the intersection of different threshold ranges corresponding to wafers of different specifications, the threshold range is the set of values ​​formed between the maximum value of the absolute value of the thickness difference between two wafers in a wafer dies of a specification and the minimum thickness value of the wafer, the function value is compared with the target threshold to determine whether there is wafer stacking.

[0052] For example, the maximum absolute value of the thickness difference between two wafers in a wafer cassette of a certain specification is... The minimum thickness of a single wafer in this wafer cassette is h1, and the threshold range corresponding to the wafers in this wafer cassette is greater than... The set of values ​​less than h1. The maximum absolute value of the thickness difference between two wafers in another wafer cassette is... The minimum thickness of a single wafer in this wafer cassette is h2, and the threshold range corresponding to the wafers in this wafer cassette is greater than... The set of values ​​that are less than or equal to h2. Greater than If h1 is greater than h2, then the intersection of the threshold ranges of these two wafer cell specifications is greater than h1. The set of values ​​less than h2. Then, for the wafers in these two wafer cassettes, the target threshold is greater than... And less than any value within the range of h2.

[0053] S912. When the function value is greater than the target threshold, compare the thickness of the wafers on the two crystal teeth. The wafer with the larger thickness is the stacked wafer.

[0054] Since the absolute value of the thickness difference between two adjacent wafers within a single wafer dies is much smaller than the thickness of a single wafer, setting the target threshold as the value between the maximum absolute value of the thickness difference between two wafers and the minimum wafer thickness can be used as a threshold to determine whether the wafers in a corresponding wafer cassette are stacked. By taking the intersection of the maximum absolute value of the thickness difference between two wafers corresponding to wafers in different wafer cassettes and the minimum wafer thickness, the value within the intersection can be used as the target threshold to detect whether the wafers in different wafer cassettes are stacked. If the function value is larger than the target threshold, it indicates that the thickness difference between the two wafer dies is too large. In this case, one of the wafers in the two wafer dies is stacked, and the wafer with the larger thickness is also stacked.

[0055] When the function value is less than or equal to the target threshold, the wafer thicknesses subtracted correspond to single wafers.

[0056] However, if the wafers in two adjacent wafer teeth are both stacked, the absolute value of the difference in wafer thickness will be less than or equal to the target threshold, which will lead to a misjudgment. Therefore, step S900 also includes: S913, after determining that a wafer is stacked, the wafer that was previously judged as a single wafer because the absolute value of the difference in thickness between the wafer and the stack is less than the threshold is reclassified as a stacked wafer.

[0057] In another embodiment, S900, comparing a function value with the wafer thickness as a parameter with a target threshold to determine whether the wafer is a stacked wafer, specifically includes: S921, the function value is the ratio of the wafer thickness in two adjacent wafer teeth, the target threshold is the maximum and minimum values ​​of the union of different threshold ranges corresponding to wafers of different specifications of wafer boxes, and the threshold range is the set of values ​​formed between the maximum and minimum values ​​of the ratio of the thickness of two wafers of a certain specification of wafer box. The function value is compared with the target threshold to determine whether there is wafer stacking.

[0058] S922. When the function value is less than the minimum value of the union of different threshold ranges, or the function value is greater than the maximum value of the union of different threshold ranges, compare the thickness of the wafers on the two crystal teeth. The wafer with the larger thickness is a stacked wafer.

[0059] For example, if the maximum ratio of the thicknesses of the two wafers in a wafer cassette is γmax1 and the minimum ratio of the thicknesses of the two wafers is γmin1, then the threshold range corresponding to this wafer cassette is γmin1 and γmax1. A set of numerical ranges. For another wafer cassette specification, the maximum ratio of the thicknesses of the two wafers is γmax², and the minimum ratio is γmin². The threshold range corresponding to this wafer cassette specification is γmin² and γmax². The set of numerical ranges. If γmax1 is greater than γmax2 and γmin1 is greater than γmin2, the union of the threshold ranges of these two wafer cell specifications is greater than γmin2 and less than γmax1, and the target thresholds are γmax1 and γmin2.

[0060] When the function value is greater than γmax1 or less than γmin2, the wafers on the two crystal teeth corresponding to the function value are stacked, and the wafer with the larger thickness is a stack.

[0061] However, if the wafers in two adjacent wafer teeth are both stacked, the absolute values ​​of the wafer thicknesses compared will fall within the union of different threshold ranges, which can lead to misjudgment. Therefore, step S900 further includes: S923, after determining that a wafer is a stack, the wafer that was previously judged as a single wafer because the function value obtained from comparing it with the stack falls within the union of different threshold ranges is now judged as a stack.

[0062] The conventional method for determining whether wafers are stacked involves comparing the thickness of each wafer to a preset thickness. If the thickness exceeds the preset thickness, it is considered stacked. The preset thickness is typically slightly larger than the maximum wafer thickness. This method can only be used for wafers of a single size. To inspect wafers of multiple sizes, preset thicknesses for each size must be set. If the preset thickness does not match the wafer size to be inspected, stacking may be missed or incorrectly identified as stacking.

[0063] In this embodiment, when determining the stacking, the selected target dummy spacing is compatible with wafers of different specifications. The wafers within the determined second region are either stacked or single wafers. At this time, the determination of stacking and single wafers is made by comparing the threshold and the difference in wafer thickness. This threshold does not need to be changed when detecting wafers of different specifications. This detection method can accurately determine stacking and single wafers.

[0064] In one embodiment of the present invention, a wafer condition inspection device is disclosed, see attached document. Figure 4 As shown, the device includes a sensor, which comprises a sensor transmitter and a sensor receiver. The sensor can sequentially scan and detect the wafers in the wafer cassette in the thickness direction. The detection equipment uses the wafer state detection method described above.

[0065] The present invention also discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the above-described wafer state detection method.

[0066] Based on this understanding, the present invention can implement all or part of the processes in the above embodiments by instructing related hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable medium can include any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0067] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for detecting the state of a wafer, characterized in that: The method for detecting the state of wafers within wafer cassettes of different sizes includes: The target vacancy spacing of the wafer cassette and the interlayer spacing between adjacent support teeth of the wafer are obtained. The target vacancy spacing is the minimum value of the vacancy spacing of the wafer cassette of different specifications when carrying the corresponding wafer. The vacancy spacing is the distance between the upper vacancy corresponding to the support tooth and the lower vacancy corresponding to the adjacent support tooth located above it. The upper vacancy is the height position that does not coincide with the stacked wafers and is just away from the upper surface of the upper wafer in the stacked wafers. The lower vacancy is the height position that does not coincide with the single wafer or the stacked wafers and is just away from its lower surface. Obtain the upper and lower surface positions of a single wafer on the starting cleavage of the wafer cassette; The upper and lower vacancies corresponding to each crystal tooth are calculated based on the interlayer spacing, the target vacancies spacing, and the upper and lower surface positions of the single wafer on the starting crystal tooth. The wafer is scanned along its thickness direction; Determine whether the wafer is detected within a first region, wherein the first region is the area between the upper dummy position of a crystal tooth and the lower dummy position of the crystal tooth located above and adjacent to it; If so, the wafer detected in the first region is determined to be a slanted wafer; For wafers not detected within the first region, the thickness of wafers located within the second region is calculated. The second region is the area between the upper and lower dummy bits corresponding to the same die. The function value is compared with a target threshold to determine whether the wafer is a stack. The function value is the ratio of the wafer thickness within two adjacent dummy bits. The target threshold is the maximum and minimum values ​​of the union of different threshold ranges corresponding to wafers of different specifications in wafer cassettes. The threshold range is the set of values ​​between the maximum and minimum values ​​of the ratio of the thicknesses of two wafers of a wafer cassette of a certain specification. When the function value is less than the minimum value of the union of different threshold ranges, or when the function value is greater than the maximum value of the union of different threshold ranges, the thickness of the wafers on the two crystal teeth is compared, and the wafer with the larger thickness is a stacked wafer; Once a wafer is determined to be a stacked wafer, wafers that were previously classified as single wafers because the function values ​​obtained from comparing with the stacked wafers were within the union of different threshold ranges are now classified as stacked wafers.

2. The wafer condition detection method according to claim 1, characterized in that: The target threshold is less than or equal to 140 micrometers and greater than or equal to 7 micrometers.

3. The wafer condition detection method according to claim 1, characterized in that: The vacancy pitch for each type of wafer cell is calculated using the following formula: ； Where Z' is the dummy spacing, X is the layer spacing, tmax is the maximum thickness of the wafers allowed to be stacked within the wafer cassette, and t is the average thickness of the corresponding wafers within the wafer cassette.

4. The wafer condition detection method according to claim 1, characterized in that: The upper virtual position corresponding to the nth crystal tooth ; The lower imaginary position corresponding to the nth crystal tooth ; Where P1 and P2 are the upper and lower surface positions of the single wafer on the starting crystal tooth, respectively, X is the interlayer spacing, Z is the target dummy spacing, a is a constant greater than 0 and less than or equal to 1, and n is an integer greater than or equal to 1.

5. A wafer condition inspection device, characterized in that: The device includes a sensor capable of sequentially scanning and detecting wafers within a wafer cassette in the thickness direction, and the detection equipment employs the wafer state detection method according to any one of claims 1-8.

6. A storage medium, characterized in that: The device stores instructions, which, when executed by a processor, are used to implement the wafer state detection method according to any one of claims 1-4.

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