Wafer storage device and detection method

Abstract

The application discloses a wafer storage device and a detection method. The wafer storage device comprises a storage rack and a first detection part. The storage rack comprises multiple groups of supports arranged at intervals in the up-down direction. Each group of supports comprises a first support and a second support. The first support and the second support form a placement position suitable for placing a wafer and suspend the wafer on both sides in the second horizontal direction. The first detection part is arranged on one side where the wafer is suspended. The first detection part comprises a transmitting sensor and a receiving sensor group. The receiving sensor group comprises multiple receiving ends I corresponding to the size and model of the wafer in the second horizontal direction. The intersection of the light rays emitted by the transmitting sensor to the multiple receiving ends I and the plane where the placement position is located is located between the first support and the second support.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor technology, in particular to a wafer storage device and a detection method. BACKGROUND

[0002] After the wafer is transmitted from the equipment front end module to the wafer processing module, the wafer handling system (such as a mechanical hand) in the wafer processing module will flow and process the wafer between multiple wafer processing units, and the processed wafer will be flowed out through the equipment front end module and enter the next equipment front end module and wafer processing module.

[0003] Generally, a wafer storage device is arranged in the equipment front end module or the wafer processing module to temporarily store the wafer. However, different batches of wafers need to be stored in the same wafer storage device at different time periods during the transmission process, and the mechanical hand in the wafer processing module may place the wafer of the wrong size in the wafer processing unit for processing, which will cause the wafer to be damaged. SUMMARY

[0004] In order to solve the above technical problems, the present application provides a wafer storage device which can accurately detect the size of different batches of wafers and whether the wafer exists when the wafer is placed left or right.

[0005] According to the wafer storage device provided by the embodiment of the present application, the storage rack includes a plurality of groups of supports arranged in an upper and lower interval, each group of supports includes a first support and a second support arranged opposite to each other in a first horizontal direction, and the first support and the second support form a placement position suitable for placing a wafer and suspend the wafer on both sides in a second horizontal direction.

[0006] The first detection part is arranged on one side of the wafer suspension, and the first detection part includes a transmitting sensor and a receiving sensor group, the receiving sensor group includes a plurality of receiving ends one arranged in the second horizontal direction and corresponding to the size and model of the wafer, the light ray tangent to the wafer passes through the intermediate region of the receiving end one corresponding to the wafer and the receiving end one adjacent to the wafer and away from the wafer, and the intersection point of the light ray emitted by the transmitting sensor to the plurality of receiving ends one and the plane where the placement position is located is located between the first support and the second support.

[0007] In some embodiments, the transmitting sensor is located between the adjacent two upper and lower placement positions, and the receiving sensor group of the first detection part has two groups, one group of the receiving sensor group is located on the upper side of the upper placement position, and the other group of the receiving sensor group is located on the lower side of the lower placement position.

[0008] In some embodiments, the first detection unit has multiple groups, and the emitting sensors of two adjacent groups of the first detection unit have a spacing in the up-down direction that is twice the spacing of two adjacent placement positions.

[0009] In some embodiments, two adjacent groups of the first detection unit are opposite in the first horizontal direction.

[0010] In some embodiments, the wafer storage device further comprises a second detection unit and a third detection unit, the second detection unit and the third detection unit are respectively arranged on both sides of the overhanging region of the wafer, and the second detection unit and the third detection unit respectively comprise a plurality of first protruding sensors and a plurality of second protruding sensors corresponding to different sizes of the wafer and suitable for detecting the protrusion of the wafer of different sizes in the second horizontal direction.

[0011] The application also provides a detection method of a wafer storage device, wherein if the second detection unit and the third detection unit do not detect the protrusion of the wafer, the result of the smallest wafer detected by the first detection unit or the result of no wafer is correct;

[0012] If the second detection unit and the third detection unit both detect the protrusion of the wafer, and the second detection unit detects the size of the wafer with the innermost protrusion, the third detection unit detects the size of the wafer with the innermost protrusion, and the sizes of the wafers detected by all the first detection units are consistent, the result of the size of the wafer detected by the first detection unit is correct, otherwise, the wafer stored on the storage rack is incorrect,

[0013] When all the receiving ends of the receiving sensor group receive light, the first detection unit detects no wafer; when one of the receiving ends is blocked, the size of the wafer corresponding to the outermost blocked receiving end of the receiving sensor group is the size of the wafer detected by the first detection unit.

[0014] In some embodiments, the method further comprises: if only one of the second detection unit and the third detection unit detects the wafer, and two of the receiving ends of the receiving sensor group are blocked, the wafer corresponding to the receiving sensor group is protruding towards the first detection unit.

[0015] In some embodiments, the method further includes: if only one of the second detection unit and the third detection unit detects the wafer, and all the receiving ends of the receiving sensor group are not blocked, the placement position corresponding to the unblocked receiving sensor group is compared with the empty placement position recorded by the wafer handling system; if they are inconsistent, the wafer placed at the placement position detected by all the unblocked receiving sensor groups except the empty placement position protrudes away from the first detection unit.

[0016] In some embodiments, the method further includes: when the second detection unit and the third detection unit detect that the wafer is exactly one size larger than the smallest model wafer, if all the receiving ends of the receiving sensor group are not blocked, the placement position detected by the unblocked receiving sensor group is compared with the empty placement position recorded by the wafer handling system. If they match, no wafer is placed at the placement position, and the result of the first detection unit detecting a wafer one size larger than the smallest model wafer is correct. If they do not match, the wafers placed at the placement positions detected by all the unblocked receiving sensor groups except the empty placement position protrude away from the first detection unit, and the wafer that the first detection unit judged to be one size larger than the smallest model wafer is changed to a smallest model wafer protruding backward.

[0017] In some embodiments, the method further includes: when the second detection unit and the third detection unit both determine that the wafer is at least two sizes larger than the smallest wafer size, if the wafer size detected by the receiving sensor group is smaller than the wafer size determined by the second detection unit and the third detection unit, then the wafer detected by the receiving sensor group is a wafer protruding away from the first detection unit, and there is a wafer that the first detection unit determined to be consistent with the wafer size determined by the second detection unit and the third detection unit is changed to a wafer protruding closer to the first detection unit. Attached Figure Description

[0018] Figure 1 This is a three-dimensional structural schematic diagram of a wafer storage device according to an embodiment of the present invention;

[0019] Figure 2 This is a three-dimensional structural schematic diagram of a wafer storage device according to another embodiment of the present invention;

[0020] Figure 3 This is a rear view schematic diagram of a wafer storage device according to an embodiment of the present invention;

[0021] Figure 4 for Figure 3 A schematic diagram of the cross-sectional structure from the perspective of the middle AA (analogous to ...

[0022] Figure 5 for Figure 3 A schematic diagram of the cross-sectional structure from the perspective of the middle BB (British Biological Building).

[0023] Figure 6 A rear view of the structure of the wafer storage device, which conceals the first mounting plate, the second mounting plate, and parts of the first and second supports.

[0024] Figure 7 This is a rear view schematic diagram of a wafer storage device according to an embodiment of the present invention;

[0025] Figure 8 for Figure 7 A schematic diagram of the cross-sectional structure from a mid-CC perspective;

[0026] Figure 9 Flowchart of a method for detecting the state of wafer storage Figure 1 ;

[0027] Figure 10 Flowchart of a method for detecting the state of wafer storage Figure 2 ;

[0028] Figure 11 Flowchart of a method for detecting the state of wafer storage Figure 3 . Detailed Implementation

[0029] 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.

[0030] Example 1:

[0031] See appendix Figures 1-8 As shown, this embodiment is a wafer storage device, in which a wafer transport system transports wafers located in the front-end module to the wafer storage device. The wafer storage device includes a storage rack 1 and a first detection unit 2.

[0032] The storage rack 1 includes multiple sets of supports arranged at vertical intervals. Each set of supports includes a first support 111 and a second support 112 arranged opposite each other along a first horizontal direction. The first support 111 and the second support 112 form a placement position 11 suitable for placing the wafer 5, suspending the wafer 5 on both sides in the second horizontal direction. The first horizontal direction and the second horizontal direction can be perpendicular or form an acute or obtuse angle. For example, the first horizontal direction can be... Figure 1 The left and right directions, and the second horizontal direction can be Figure 1 The front and back directions in the middle. "Suspended" means that wafer 5 is not supported by any structure in this area.

[0033] The first detection unit 2 of the application is arranged on the side of the wafer 5 which is suspended, and the first detection unit 2 comprises a transmitting sensor 211 and a receiving sensor group, the receiving sensor group comprises a plurality of receiving ends 212 which are arranged along the second horizontal direction and correspond to the size and model of the wafer 5 one by one, the light ray which is tangent to the wafer 5 passes through the middle area between the receiving end 212 corresponding to the wafer 5 and the receiving end 212 adjacent to the wafer 5 and far away from the wafer 5, and the intersection point of the light ray emitted by the transmitting sensor 211 to the plurality of receiving ends 212 and the plane on which the placing position 11 is located is between the first support 111 and the second support 112 (see FIG. 2). Figure 8

[0034] The working mode of the wafer storage device of the application is that the transmitting sensor 211 emits detection light to the receiving sensor group, since the intersection point of the light ray emitted by the transmitting sensor 211 to the plurality of receiving ends 212 and the plane on which the placing position 11 is located is between the first support 111 and the second support 112, that is, the light ray emitted by the transmitting sensor 211 to any one of the receiving ends 212 is not parallel to the placing position 11, thereby judging the size of the wafer placed on the placing position 11. When all the receiving ends 212 of the receiving sensor group receive the light ray, the first detection unit 2 detects that there is no wafer; when the receiving ends 212 of the receiving sensor group are just blocked, the size and model of the wafer corresponding to the receiving end 212 which is just blocked is the size and model of the wafer detected by the first detection unit 2.

[0035] For example, if there are three kinds of wafer sizes to be detected, and they are arranged in order from large to small as the first size wafer, the second size wafer and the third size wafer, if two receiving ends 212 receive the light ray, it means that only one group of wafers with the smallest diameter will be located in the receiving light path of the receiving end 212 closest to the center of the wafer and be blocked and sensed, and at this time it is determined that the wafer 5 is the third size wafer. By analogy, if p receiving ends 212 emit signals that the light ray is received, it is preliminarily judged that it is the (p+1)th size wafer, and p is an integer less than M. With the increase of the serial number of the wafer size, the size of the wafer gradually decreases. That is, the "first size wafer" is the wafer with the largest diameter in the storage rack 1, and by analogy, the "Mth size wafer" is the wafer with the smallest diameter in the storage rack 1. Therefore, the wafer storage device of the application can quickly judge the size of the wafer 5 located therein.

[0036] The application sets each group of supports as the first support 111 and the second support 112 which are oppositely arranged along the first horizontal direction, so that even if the wafer 5 is offset in the first horizontal direction, the size of the wafer can be accurately judged.

[0037] ​The application can avoid misjudgment of wafer size and model caused by errors (the errors can be the deviation between the real wafer position and the standard wafer position caused by wafer warping or slight deviation of wafer placement) by locating the intersection of the light emitted by the emitting sensor 211 towards the multiple receiving ends 212 and the plane on which the placement site 11 is located between the first support 111 and the second support 112.

[0038] In some embodiments, the emitting sensor 211 is located between two adjacent upper and lower placement sites 11, and the receiving sensor group of the first detection unit 2 has two groups, one group of receiving sensor group is located on the upper side of the upper wafer 5 placement site 11, and the other group of receiving sensor group is located on the lower side of the lower wafer 5 placement site 11. Thus, under the premise of ensuring that the first detection unit 2 fully plays a detection effect on the specification of the wafer, the use of the emitting sensor 211 is maximally reduced, and the cost is reduced.

[0039] Referring to FIGS. 1 to 5, Figure 4 and 5 As shown, the receiving sensor group located above the placement site 11 includes two upper receiving ends 2121, which are upper receiving end one 21211 and upper receiving end two 21212 and are sequentially arranged along the second horizontal direction; the receiving sensor group located below the placement site 11 includes two lower receiving ends 2122, which are lower receiving end one 21221 and lower receiving end two 21222 and are sequentially arranged along the second horizontal direction, and the upper receiving end two 21212 and the lower receiving end two 21222 are located on the side farther away from the center of the wafer 5. The upper and lower wafers 5 that can be detected by the first detection unit 2 are upper wafer 51 and lower wafer 52, respectively, and the height of the emitting sensor 211 is located between the upper wafer 51 and the lower wafer 52, the height of the two upper receiving ends 2121 is located above the upper wafer 51, and the height of the two lower receiving ends 2122 is located below the lower wafer 52.

[0040] In some embodiments, the first detection unit 2 has multiple groups, and the emitting sensor 211 of the adjacent two groups of first detection units 2 has a spacing in the up-down direction which is twice the spacing between the adjacent placement sites 11. Thus, the effect of arranging multiple groups of first detection units 2 on the storage rack 1 can be realized to meet the detection requirements of multiple layers of wafers.

[0041] In some embodiments, two adjacent groups of the first detection units 2 are opposite to each other in the first horizontal direction. For example, the transmission sensor 211 and the receiving end 212 can be staggered on the left and right sides of the storage rack 1, i.e., the transmission sensor 211 of one group of the first detection units 2 is arranged on the left side of the storage rack 1, and each receiving end 212 arranged in cooperation therewith is arranged on the right side of the storage rack 1; and the transmission sensor 211 of another group of the first detection units 2 adjacent to the one group is arranged on the right side of the storage rack 1, and each receiving end 212 arranged in cooperation therewith is arranged on the left side of the storage rack 1. In this way, the height of the adjacent placement positions 11 can be reduced to the greatest extent, and the signals emitted by the transmission sensors 211 of the two adjacent groups of the first detection units 2 can be prevented from interfering with each other while ensuring that the space of the wafer storage device is fully utilized.

[0042] In some embodiments, the transmission sensor 211 of one group of the first detection units 2 is arranged on the first mounting plate 13 on the left side of the wafer 5, and the corresponding receiving end 212 is arranged on the second mounting plate 14 on the right side of the wafer 5; and the transmission sensor 211 of another group of the first detection units 2 adjacent to the one group is arranged on the second mounting plate 14, and the corresponding receiving end 212 is arranged on the first mounting plate 13.

[0043] In some embodiments, the wafer storage device further comprises a second detection unit 3 and a third detection unit 4, the second detection unit 3 and the third detection unit 4 are arranged on both sides of the overhanging area of the wafer, and the second detection unit 3 and the third detection unit 4 each comprise a plurality of first protrusion sensors 31 and a plurality of second protrusion sensors 41 corresponding to wafers of different sizes and suitable for detecting the wafers 5 protruding outward in the second horizontal direction. Here, the outward protrusion refers to the deviation of the center of the wafer from the normal position. The second detection unit 3 is used to identify the wafer 5 protruding forward from the normal position, and the third detection unit 4 is used to identify the wafer 5 protruding backward from the normal position.

[0044] The specification of the wafer 5 to be stored is M, and M is an integer greater than or equal to 2, each first protruding sensor 31 or second protruding sensor 41 corresponds to detecting a wafer of one specification, the number of groups of the first protruding sensor 31 is also set to M groups, according to the size of the wafer 5 detected by the first protruding sensor 31, the order is sorted from large to small, then the serial number of the M groups of the first protruding sensor 31 is M11, M12…M1m, and is set from front to back to the direction close to the center of the wafer 5, according to the size of the wafer 5 detected by the second protruding sensor 41, the serial number of the M groups of the second protruding sensor 41 is M21, M22…M2m, and is set from back to front to the direction close to the center of the wafer 5. The first protruding sensor 31 and the second protruding sensor 41 of the present application along "from front to back" or "from back to front" does not mean strictly according to the direction parallel to the front-back direction in Figure 1 The direction can be the direction inclined to the left or right in Figure 1 The direction can be the direction inclined to the left or right in Figure 1 The direction can be the direction inclined to the left or right in

[0045] For example, the first protruding sensor 31 is M11, the second protruding sensor 41 is M21, the wafer 5 detected by M11 and M21 is the first specification wafer, M11 and M21 are set on the outer side close to the front and back direction of the first specification wafer, therefore, when the first specification wafer is placed in place, the sensing signal of M11 and M21 will not be blocked, but if the first specification wafer protrudes forward, the receiving end two 312 of M11 will not receive the signal of the transmitting end two 311; if the first specification wafer protrudes backward, the receiving end three 412 of M21 will not receive the signal of the transmitting end three 411. In turn, M12 and M22 correspond to detect the forward or backward protrusion of the second specification wafer…M1m and M2m correspond to detect the forward or backward protrusion of the Mth specification wafer.

[0046] The wafer storage device of the present application distinguishes the specification of the wafer located therein and the judgment method of whether there is a tab: the detection result obtained by detecting whether there is a tab by the second detection part 3 and the third detection part 4; and combining the judgment result of the wafer specification by the first detection part 2, thereby achieving the effect of determining which layer of wafer the tab occurs and the specification of the wafer 5 stored on the corresponding placement site 11. The present application only needs to set the sensor assembly with relatively low cost, without using expensive visual recognition components, and by cooperating the detection results of the second detection part 3 and the third detection part 4 with the first detection part 2, thereby quickly judging the specification of the wafer in the placement site 11.

[0047] Embodiment Two

[0048] The embodiment is a wafer storage state detection method based on the wafer storage device of embodiment one, which is used for detecting the wafer on the wafer storage device. When all the receiving ends 212 of the receiving sensor group receive light, the detection result of the first detection part 2 is determined as no wafer being placed; when the xth to Mth receiving ends 212 of the receiving sensor group are blocked, the detection result of the first detection part 2 is determined as the xth specification wafer, M is the number of wafer specifications, and the number of each group of receiving ends 212 is M, and x≤M.

[0049] If neither the second detection part 3 nor the third detection part 4 detects the wafer 5 protruding, the result of the smallest wafer detected by the first detection part 2 or the result of no wafer 5 is correct;

[0050] If both the second detection part 3 and the third detection part 4 detect the wafer 5 protruding, and the second detection part 3 detects the size of the wafer 5 that is just not protruding, the third detection part 4 detects the size of the wafer 5 that is just not protruding, and the size of the wafer 5 detected by all the first detection parts 2 is consistent, the result of the size of the wafer detected by the first detection part 2 is correct, otherwise, there is an error in the wafer 5 placed on the wafer storage rack. For example, the wafer to be detected is a large specification wafer, the receiving end two 312 and the receiving end three 412 corresponding to the large specification wafer of the second detection part 3 and the third detection part 4 are not blocked, the receiving end two 312 and the receiving end three 412 corresponding to the medium specification wafer and the small specification wafer are blocked, and the receiving end one 212 corresponding to the large specification wafer of the first detection part 2 is blocked, then the detection results of the first detection part 2, the second detection part 3 and the third detection part 4 are consistent with each other, and all are determined as large specification wafers, so it can be determined that the wafer to be detected is a large specification wafer.

[0051] In some embodiments, if only one group of the first protruding sensor 31 and the second protruding sensor 41 detects the wafer 5, and two receiving ends one 212 of the receiving sensor group are blocked, the wafer corresponding to the receiving sensor group detected protrudes towards the first detection part 2.

[0052] In some embodiments, if only one of the second detection part 3 and the third detection part 4 detects the wafer, and all the receiving ends one 212 of the receiving sensor group are not blocked, if the unblocked receiving sensor group corresponding placement site 11 is not consistent with the empty placement site recorded by the wafer handling system, then all the placement sites 11 corresponding to the unblocked receiving sensor group detected, except the empty placement site, place the wafers protruding away from the first detection part 2.

[0053] Referring to the accompanying drawings Figure 9As shown, only one group of the first and second protruding sensors 31 and 41 detects the wafer, so it can be determined that only the M-th size wafer is stored in the storage rack 1 and the wafer is protruding.

[0054] Meanwhile, the first detection unit 2 is used to determine the position of the wafer 5 in the storage rack 1. If two receiving ends 212 (for example, M-1 and M receiving ends 212) of the first detection unit 2 are blocked, it indicates that the M-th size wafer corresponding to the first detection unit 2 is protruding backward. If all the receiving ends 212 of the first detection unit 2 are not blocked, and compared with the empty placement position recorded by the wafer handling system, if they are consistent, it indicates that the placement position 11 is not placed with a wafer, and if they are inconsistent, it indicates that the M-th size wafer corresponding to the first detection unit 2 is protruding forward.

[0055] In some embodiments, referring to the accompanying drawings Figure 10 When the second and third detection units 3 and 4 determine that the wafer is the M-1-th size wafer, if all the receiving ends 212 of the first detection unit 2 are not blocked, and compared with the empty placement position recorded by the wafer handling system, if they are consistent, it indicates that the placement position 11 is not placed with a wafer, and if they are inconsistent, it indicates that all the wafers placed in the placement position 11 except the empty placement position are protruding away from the first detection unit 2, and the first detection unit 2 determines that the wafer is the smallest size wafer protruding backward.

[0056] When the wafer to be detected has three sizes, the receiving ends 312 and 412 of the second and third detection units 3 and 4 corresponding to the detection of the middle size wafer are not blocked, and the receiving ends 312 and 412 corresponding to the detection of the small size wafer are not blocked, so the second and third detection units 3 and 4 determine that the wafer is the middle size wafer. At this time, combined with the result of the first detection unit 2, if the first detection unit 2 determines that there is no wafer placed, compared with the empty placement position recorded by the wafer handling system, if they are consistent, it indicates that the placement position 11 is not placed with a wafer; if they are inconsistent, and all the receiving sensor groups of the first detection unit 2 are not blocked, it indicates that the wafer 5 in the placement position 11 is protruding away from the first detection unit 2 (the first detection unit 2 is arranged close to the rear side of the storage rack, and each receiving end 212 is arranged along the front and rear directions, so at this time, the wafer is protruding forward), and the wafer in the placement position 11 is the small size wafer, and the wafer determined by the first detection unit 2 as the middle size wafer is re-determined as the small size wafer protruding backward.

[0057] In some embodiments, referring to the accompanying drawingsFigure 11 As shown, when the second detection part 3 and the third detection part 4 detect that the wafer is at least two sizes larger than the minimum size wafer, if the wafer size detected by the receiving sensor group of the first detection part 2 is smaller than the wafer size detected by the second detection part 3 and the third detection part 4, then the wafer detected by the receiving sensor group of the first detection part 2 is a wafer protruding away from the first detection part 2, and the first detection part 2 judges that the wafer is consistent with the wafer size detected by the second detection part 3 and the third detection part 4, and the wafer protrudes towards the first detection part 2.

[0058] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. A wafer storage device, characterized in that, include: The storage rack includes multiple sets of supports arranged at intervals between the upper and lower parts. Each set of supports includes a first support and a second support arranged opposite to each other along a first horizontal direction. The first support and the second support form a placement position suitable for placing a wafer and suspend the wafer on both sides in the second horizontal direction. A first detection unit is located on the side of the wafer that is suspended. The first detection unit includes a transmitting sensor and a receiving sensor group. The receiving sensor group includes multiple receiving terminals arranged along the second horizontal direction and corresponding one-to-one with the size and model of the wafer. Light rays tangent to the wafer from the transmitting sensor pass through the area between the receiving terminal corresponding to the wafer and the adjacent receiving terminal that is farther from the wafer. The intersection point of the light rays from the transmitting sensor directed towards the multiple receiving terminals and the plane where the placement position is located is between the first support and the second support. The two adjacent groups of the first detection units are opposite each other in the first horizontal direction, and the transmitting sensor and the receiving end are staggered on the left and right sides of the storage rack.

2. The wafer storage device according to claim 1, characterized in that, The transmitting sensor is located between two adjacent upper and lower placement positions. The first detection unit has two sets of receiving sensors: one set of receiving sensors is located on the upper side of the upper placement position, and the other set of receiving sensors is located on the lower side of the lower placement position.

3. The wafer storage device according to claim 2, characterized in that, The first detection unit has multiple sets, and the distance between the emission sensors of two adjacent sets of the first detection units in the vertical direction is twice the distance between the adjacent placement positions.

4. The wafer storage device according to any one of claims 1-3, characterized in that, It also includes a second detection unit and a third detection unit, which are respectively located on both sides of the suspended area of ​​the wafer. The second detection unit and the third detection unit respectively include a plurality of first protrusion sensors and a plurality of second protrusion sensors that correspond one-to-one with wafers of different sizes and are suitable for detecting wafers of different sizes protruding outward along the second horizontal direction.

5. The detection method for the wafer storage device according to claim 4, characterized in that, If neither the second detection unit nor the third detection unit detects the wafer protrusion, then the result of the first detection unit detecting the smallest model wafer or the result of not having the wafer is correct; If both the second and third detection units detect a wafer protrusion, and the second detection unit and the third detection unit both indicate the same size for the innermost wafer without a protrusion, and all wafer sizes detected by the first detection unit are consistent, then the wafer size detected by the first detection unit is correct; otherwise, there is an error in the wafers stored on the storage rack. Wherein, when all the receiving ends of the receiving sensor group receive light, the first detection unit detects that there is no wafer; when one of the receiving ends is blocked, the size of the wafer corresponding to the outermost receiving end of the receiving sensor group that is blocked is the size of the wafer detected by the first detection unit.

6. The detection method for the wafer storage device according to claim 5, characterized in that, If only one of the second detection unit and the third detection unit detects the wafer, and one of the receiving ends of the receiving sensor group is blocked, then the wafer detected by the receiving sensor group protrudes towards the first detection unit.

7. The detection method for the wafer storage device according to claim 5, characterized in that, If only one of the second detection unit and the third detection unit detects the wafer, and all the receiving ends of the receiving sensor group are not blocked, the placement position corresponding to the unblocked receiving sensor group is compared with the empty placement position recorded by the wafer handling system. If they are inconsistent, the wafer placed in the placement position detected by all the unblocked receiving sensor groups except the empty placement position will protrude away from the first detection unit.

8. The detection method for the wafer storage device according to claim 5, characterized in that, When the second detection unit and the third detection unit detect that the wafer is exactly one size larger than the smallest wafer, if all the receiving ends of the receiving sensor group are not blocked, the placement position detected by the unblocked receiving sensor group is compared with the empty placement position recorded by the wafer handling system. If they match, no wafer is placed at the placement position, and the result of the first detection unit detecting a wafer one size larger than the smallest wafer is correct. If they do not match, the wafers placed at the placement positions detected by all the unblocked receiving sensor groups except the empty placement position protrude away from the first detection unit, and the wafer that the first detection unit judged as one size larger than the smallest wafer is changed to the smallest wafer protruding backward.

9. The detection method for the wafer storage device according to claim 5, characterized in that, When both the second detection unit and the third detection unit determine that the wafer is at least two sizes larger than the smallest wafer size, if the wafer size detected by the receiving sensor group is smaller than the wafer size determined by the second detection unit and the third detection unit, then the wafer detected by the receiving sensor group is a wafer protruding away from the first detection unit, and there is a wafer that the first detection unit determined to be the same size and model as the wafer determined by the second detection unit and the third detection unit, but it is changed to a wafer protruding closer to the first detection unit.

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