Wafer storage device and detection method

Abstract

The invention 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 a plurality of sets of supports arranged at intervals up and down, each set of supports comprises a first support and a second support, and the first supports and the second supports form a placement position suitable for placing wafers and suspend the wafers on the two sides in the second horizontal direction; the first detection part is arranged on the suspended side of the wafer, the first detection part comprises a transmitting sensor and a receiving sensor group, and the receiving sensor group comprises a plurality of receiving ends I which are arranged along a second horizontal direction and are in one-to-one correspondence with the sizes and models of the wafers; the intersection point of the light emitted by the emission sensor to the plurality of receiving ends I and the plane where the placing position is located is located between the first support and the second support.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a wafer storage device and a detection method. Background Art

[0002] After the wafer is transferred from the equipment front-end module to the wafer processing module, the wafer handling system (such as a robot) in the wafer processing module transfers the wafer between multiple wafer processing units for processing. The processed wafer is then transferred out through the equipment front-end module and enters the next equipment front-end module and wafer processing module.

[0003] Typically, wafer storage devices are installed in the front-end module or wafer processing module of the equipment to temporarily store wafers. However, during the wafer transfer process, different batches of wafers at different time periods need to be stored in the same wafer storage device. The robot in the wafer processing module may place the wrong size wafer in the wafer processing unit for processing, which may cause wafer damage. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a wafer storage device, which can accurately detect the specifications and sizes of wafers of different batches and the presence or absence of wafers even when the wafer placement is shifted left or right.

[0005] A wafer storage device according to an embodiment of the present invention includes: a storage rack including a plurality of groups of supports spaced apart in an upper and lower arrangement, each group of supports including a first support and a second support disposed opposite to each other along a first horizontal direction, the first support and the second support forming a placement position suitable for placing a wafer and suspending the wafer on both sides in the second horizontal direction; The first detection part is arranged on the side where the wafer is suspended, and the first detection part includes a transmitting sensor and a receiving sensor group. The receiving sensor group includes multiple receiving ends one arranged along the second horizontal direction and corresponding to the size and model of the wafer. The light of the transmitting sensor tangent to the wafer passes through the middle area between the receiving end one corresponding to the wafer and the receiving end one adjacent to it and away from the wafer. The intersection of the light of the transmitting sensor to the multiple receiving ends one and the plane where the placement position is located is located between the first support and the second support.

[0006] In some embodiments, the transmitting sensor is located between two adjacent upper and lower placement positions, and there are two groups of receiving sensor groups in the first detection unit, one group of receiving sensor groups is located on the upper side of the upper placement position, and the other group of receiving sensor groups is located on the lower side of the lower placement position.

[0007] In some embodiments, there are multiple groups of the first detection parts, and the distance between the emission sensors of two adjacent groups of the first detection parts in the vertical direction is twice the distance between adjacent placement positions.

[0008] In some embodiments, two adjacent groups of the first detection parts are opposite to each other in the first horizontal direction.

[0009] In some embodiments, the wafer storage device also includes a second detection part and a third detection part, and the second detection part and the third detection part are respectively arranged on both sides of the suspended area of ​​the wafer, and the second detection part and the third detection part respectively include a plurality of first protrusion sensors and a plurality of second protrusion sensors that correspond one-to-one to the wafers of different sizes and are suitable for detecting the wafers of different sizes protruding outward along the second horizontal direction.

[0010] The present invention also provides a method for detecting a wafer storage device, the method comprising: if neither the second detection unit nor the third detection unit detects the wafer protrusion, then the result of the smallest wafer detected by the first detection unit or the result of the absence of the wafer is correct; If both the second detection unit and the third detection unit detect that the wafer has protrusions, and the detection result of the second detection unit is the size and model of the innermost wafer without protrusions, the detection result of the third detection unit is the size and model of the innermost wafer without protrusions, and the size and model of all the wafers detected by the first detection unit are consistent, then the size and model of the wafer detected by the first detection unit is correct; otherwise, there is an error in the wafers stored on the storage rack. Among them, 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 and model of the wafer corresponding to the outermost receiving end of the receiving sensor group that is blocked is the size and model of the wafer detected by the first detection unit.

[0011] In some embodiments, the method also includes: if only one of the second detection part and the third detection part detects the wafer, and one of the two receiving ends of the receiving sensor group is blocked, then the wafer detected by the receiving sensor group protrudes toward the direction close to the first detection part.

[0012] In some embodiments, the method also includes: if only one of the second detection part and the third detection part detects the wafer, and all the receiving ends of the receiving sensor group are not blocked, the placement positions corresponding to the unblocked receiving sensor groups are compared with the empty placement positions recorded by the wafer handling system. If they are inconsistent, the wafers placed at the placement positions detected by all the unblocked receiving sensor groups except the empty placement positions protrude away from the first detection part.

[0013] In some embodiments, the method also includes: when the second detection unit and the third detection unit detect that the wafer is exactly one size larger than the minimum 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 are consistent, there is no wafer placed at the placement position, and the result of the wafer that is one size larger than the minimum model wafer detected by the first detection unit is correct. If they are inconsistent, 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 judged by the first detection unit to be one size larger than the minimum model wafer is changed to the minimum model wafer protruding backward.

[0014] In some embodiments, the method also includes: when the second detection unit and the third detection unit detect that the wafer is at least two sizes larger than the smallest model wafer, if the wafer model detected by the receiving sensor group is smaller than the wafer model judged by the second detection unit and the third detection unit, then the wafer detected by the corresponding receiving sensor group is a wafer protruding in the direction away from the first detection unit, and the wafer judged by the first detection unit to be consistent with the wafer size model judged by the second detection unit and the third detection unit is changed to a wafer protruding in the direction close to the first detection unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the three-dimensional structure of a wafer storage device according to an embodiment of the present invention; Figure 2 A schematic diagram of the three-dimensional structure of a wafer storage device according to an embodiment of the present invention from another perspective; Figure 3 This is a schematic diagram of the rear structure of a wafer storage device according to one embodiment of the present invention; Figure 4 for Figure 3 Schematic diagram of the cross-sectional structure from the medium AA perspective; Figure 5 for Figure 3 Schematic diagram of the cross-sectional structure from the perspective of the middle BB; Figure 6 A schematic diagram of the rear structure of the wafer storage device with the first mounting plate, the second mounting plate, and parts of the first support and the second support hidden; Figure 7 This is a schematic diagram of the rear structure of a wafer storage device according to one embodiment of the present invention; Figure 8 for Figure 7 Schematic diagram of the cross-sectional structure from the CC perspective; Figure 9 Schematic diagram of the process of detecting the wafer storage status Figure 1 ; Figure 10 Schematic diagram of the process of detecting the wafer storage status Figure 2 ; Figure 11 Schematic diagram of the process of detecting the wafer storage status Figure 3 . DETAILED DESCRIPTION

[0016] The preferred embodiments of the present invention are described in detail below 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 making a clearer and more precise definition of the protection scope of the present invention.

[0017] Example 1: See attached Figure 1-8 As shown, this embodiment is a wafer storage device, which transports wafers located in a front-end module to the wafer storage device through a wafer transport system. The wafer storage device includes a storage rack 1 and a first detection unit 2.

[0018] The storage rack 1 includes multiple groups of supports arranged in an upper and lower interval, each group of supports includes a first support 111 and a second support 112 arranged opposite to 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, and the wafer 5 is suspended on both sides of the second horizontal direction. The first horizontal direction and the second horizontal direction can be vertical or at an acute or obtuse angle. For example, the first horizontal direction can be Figure 1 The left and right directions in the second horizontal direction can be Figure 1 “Overhanging” means that the wafer 5 is not supported by any structure in this area.

[0019] The first detection part 2 of the present invention is arranged on the side where the wafer 5 is suspended. The first detection part 2 includes a transmitting sensor 211 and a receiving sensor group. The receiving sensor group includes a plurality of receiving ends 212 arranged along the second horizontal direction and corresponding to the sizes of the wafers 5. The light tangent to the transmitting sensor 211 and the wafer 5 passes through the middle area between the receiving end 212 of the corresponding wafer 5 and the receiving end 212 adjacent to it and away from the wafer 5. The intersection of the light emitted by the transmitting sensor 211 to the plurality of receiving ends 212 and the plane where the placement position 11 is located is located between the first support 111 and the second support 112 (see Appendix 1). Figure 8 shown).

[0020] The wafer storage device of the present invention works as follows: a detection light is emitted from the transmitting sensor 211 to the receiving sensor group. Since the intersection of the light emitted by the transmitting sensor 211 to the multiple receiving terminals 212 and the plane where the placement position 11 is located is located between the first support 111 and the second support 112, that is, the light emitted by the transmitting sensor 211 to any receiving terminal 212 is not parallel to the placement position 11, the specifications of the wafer placed on the placement position 11 are judged. When all the receiving terminals 212 of the receiving sensor group receive light, the first detection unit 2 detects that there is no wafer; when the receiving terminal 212 of the receiving sensor group is just blocked, the size of the wafer corresponding to the blocked receiving terminal 212 is the size of the wafer detected by the first detection unit 2.

[0021] For example, if there are three wafer specifications to be detected, and they are the first specification wafer, the second specification wafer, and the third specification wafer arranged in order from large to small, then if there are two receiving ends 212 that receive light, 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 will be blocked and sensed, then at this time, wafer 5 is determined to be a third specification wafer. Similarly, if there are p receiving ends 212 that send out signals of receiving light, it is preliminarily determined to be a p+1th specification wafer, where p is an integer less than M, and the size of the wafer gradually decreases as the wafer specification serial number increases. That is, the "first specification wafer" is the wafer with the largest diameter in the storage rack 1, and by analogy, the "Mth specification wafer" is the wafer with the smallest diameter in the storage rack 1. Therefore, the wafer storage device of the present invention can be used to quickly determine the specifications of the wafer 5 located therein.

[0022] The present application sets each group of supports as a first support 111 and a second support 112 that are relatively arranged along the first horizontal direction. Therefore, even if the wafer 5 is offset in the first horizontal direction, the size and model of the wafer can be accurately determined.

[0023] The present application avoids misjudging the size and model of the wafer due to errors (the error may be the deviation between the actual wafer position and the standard wafer position caused by wafer warping or slight offset in wafer placement) by placing the intersection of the light emitted by the transmitting sensor 211 to multiple receiving ends 212 and the plane where the placement position 11 is located between the first support 111 and the second support 112.

[0024] In some embodiments, the transmitting sensor 211 is located between two adjacent upper and lower placement positions 11. The first detection unit 2 includes two receiving sensor groups: one receiving sensor group is located above the upper wafer 5 placement position 11, and the other receiving sensor group is located below the lower wafer 5 placement position 11. Thus, while ensuring that the first detection unit 2 fully detects wafer specifications, the use of transmitting sensors 211 is minimized, reducing costs.

[0025] See attached Figure 4 and 5 As shown, the receiving sensor group located above the placement position 11 includes two upper receiving ends 2121, namely upper receiving end 1 21211 and upper receiving end 2 21212, which are arranged sequentially along the second horizontal direction. The receiving sensor group located below the placement position 11 includes two lower receiving ends 2122, namely lower receiving end 1 21221 and lower receiving end 2 21222, which are arranged sequentially along the second horizontal direction. Upper receiving end 21212 and lower receiving end 21222 are located on the side further away from the center of the wafer 5. The upper and lower layers of wafers 5 that can be detected by the first detection unit 2 of this group are upper wafer 51 and lower wafer 52, respectively. The height of the transmitting 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.

[0026] In some embodiments, there are multiple groups of first detection units 2, and the vertical spacing between the emission sensors 211 of two adjacent groups of first detection units 2 is twice the spacing between adjacent placement positions 11. Therefore, the effect of providing multiple groups of first detection units 2 on the storage rack 1 can be achieved to meet the inspection requirements of multiple layers of wafers.

[0027] In some embodiments, two adjacent groups of first detection units 2 are opposite to each other in the first horizontal direction. For example, the transmitting sensors 211 and the receiving terminals 212 can be staggered on the left and right sides of the storage rack 1, that is, the transmitting sensors 211 of one group of first detection units 2 are set on the left side of the storage rack 1, and the receiving terminals 212 arranged in conjunction with them are set on the right side of the storage rack 1; while the transmitting sensors 211 of the adjacent group of first detection units 2 are set on the right side of the storage rack 1, and the receiving terminals 212 arranged in conjunction with them are set on the left side of the storage rack 1. With this arrangement, the setting height of adjacent placement positions 11 can be minimized to the greatest extent, and the mutual interference of the signals emitted by the transmitting sensors 211 of the first detection units 2 of the two adjacent groups can be reduced while ensuring that the space of the wafer storage device is fully utilized.

[0028] In some embodiments, a group of transmitting sensors 211 of the first detection unit 2 can be set on the first mounting plate 13 located on the left side of the wafer 5, and correspondingly, its receiving end 212 is set on the second mounting plate 14 located on the right side of the wafer 5; and correspondingly, another group of transmitting sensors 211 of the first detection unit 2 adjacent to the first detection unit 2 is set on the second mounting plate 14, and correspondingly, its receiving end 212 is set on the first mounting plate 13.

[0029] In some embodiments, the wafer storage device of the present invention further includes a second detection unit 3 and a third detection unit 4, which are respectively arranged on both sides of the suspended area of ​​the wafer. The second detection unit 3 and the third detection unit 4 respectively include a plurality of first protrusion sensors 31 and a plurality of second protrusion sensors 41 corresponding one-to-one to wafers of different sizes and suitable for detecting wafers 5 of different sizes protruding outward along the second horizontal direction. The outward protrusion here refers to the deviation from the center of the circle of the normally placed wafer. The second detection unit 3 is used to identify wafers 5 that protrude forward from the normal position, and the third detection unit 4 is used to identify wafers 5 that protrude backward from the normal position.

[0030] The specifications of the wafers 5 to be stored are M, and M is an integer greater than or equal to 2. Each first protrusion sensor 31 or second protrusion sensor 41 corresponds to detecting a wafer of one specification. The number of groups of first protrusion sensors 31 is also correspondingly set to M groups. According to the sizes of the wafers 5 corresponding to the first protrusion sensors 31, they are sorted from large to small. Then, the serial numbers of the M groups of first protrusion sensors 31 are M11, M12...M1m, and they are sequentially arranged from front to back toward the center of the wafer 5. According to the sizes of the wafers 5 corresponding to the second protrusion sensors 41, they are sorted from large to small. Then, the serial numbers of the M groups of second protrusion sensors 41 are M21, M22...M2m, and they are sequentially arranged from back to front toward the center of the wafer 5. The arrangement of the first protrusion sensors 31 and the second protrusion sensors 41 of the present invention from "front to back" or "back to front" does not mean strictly in accordance with the same arrangement. Figure 1 A direction parallel to the front-back direction in the Figure 1 To the left or right tilt direction, it is only necessary to ensure that the arrangement direction of the first protrusion sensor 31 and the second protrusion sensor 41 has Figure 1 The component direction of the "front and back direction" can be used.

[0031] For example, let the first protrusion sensor 31 be M11, the second protrusion sensor 41 be M21, and the wafer 5 correspondingly detected by M11 and M21 be a first-specification wafer. M11 and M21 are respectively positioned immediately outside the first-specification wafer in the front and rear directions. Therefore, when the first-specification wafer is in place, the sensing signals of M11 and M21 are not blocked. However, if the first-specification wafer protrudes forward, the second receiving end 312 of M11 will not be able to receive the signal from the second transmitting end 311; if the first-specification wafer protrudes backward, the third receiving end 412 of M21 will not be able to receive the signal from the third transmitting end 411. Similarly, M12 and M22 are used to detect the forward or backward protrusion of the second-specification wafer... and M1m and M2m are used to detect the forward or backward protrusion of the Mth-specification wafer.

[0032] The wafer storage device of the present invention determines the specifications of wafers within it and the presence of protrusions by utilizing the detection results of the second and third detection units 3 and 4 to detect the presence of protrusions. This is combined with the wafer specifications determination results from the first detection unit 2. This allows the specific wafer layer in which a protrusion occurs to be determined, as well as the specifications of the wafers 5 stored in the corresponding storage position 11. By utilizing only relatively low-cost sensor components, rather than expensive visual recognition components, the present invention utilizes the detection results of the second and third detection units 3 and 4 in conjunction with those of the first detection unit 2 to rapidly determine the specifications of the wafers in the storage position 11.

[0033] Example 2: This embodiment is a method for detecting the wafer storage status of a wafer storage device based on the first embodiment, and is used to detect wafers on the wafer storage device. When all receiving ends 212 of the receiving sensor group receive light, the first detection unit 2 determines that no wafer is placed. When the xth to Mth receiving ends 212 of the receiving sensor group are blocked, the first detection unit 2 determines that the wafer is of the xth specification, where M is the number of wafer specifications, and the number of receiving ends 212 in each group is M, and x≤M.

[0034] If neither the second detection unit 3 nor the third detection unit 4 detects that the wafer 5 is protruding, the result of the smallest wafer size detected by the first detection unit 2 or the result of no wafer 5 is correct; If both the second detection unit 3 and the third detection unit 4 detect that there is a protrusion of the wafer 5, and the size and model of the wafer 5 detected by the second detection unit 3 that just does not protrude, the size and model of the wafer 5 detected by the third detection unit 4 that just does not protrude, and the size and model of all the wafers 5 detected by the first detection unit 2 are consistent, then the result of the size and model of the wafer detected by the first detection unit 2 is correct; otherwise, there is an error in the wafer 5 stored on the wafer 5 storage rack. For example, if the wafer to be inspected is a large-sized wafer, the receiving end two 312 and the receiving end three 412 corresponding to the large-sized wafer of the second detection unit 3 and the third detection unit 4 are not blocked, the receiving end two 312 and the receiving end three 412 corresponding to the medium-sized wafer and the small-sized wafer are blocked, and the receiving end one 212 of the first detection unit 2 corresponding to the large-sized wafer is blocked, then the detection results of the first detection unit 2, the second detection unit 3, and the third detection unit 4 are consistent with each other and are all determined to be large-sized wafers, then it can be determined that the wafer to be inspected is a large-sized wafer.

[0035] In some embodiments, if only one group of all the first protrusion sensors 31 and the second protrusion sensors 41 detects the wafer 5 and two receiving ends 212 of the receiving sensor group are blocked, the wafer detected by the receiving sensor group protrudes toward the first detection part 2.

[0036] In some embodiments, if only one of the second detection unit 3 and the third detection unit 4 detects the wafer, and all receiving ends 212 of the receiving sensor group are not blocked, the placement position 11 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 wafers placed at the placement positions 11 detected by all unblocked receiving sensor groups except the empty placement positions protrude away from the first detection unit 2.

[0037] See attached Figure 9As shown, if only one set of all the first protrusion sensors 31 and the second protrusion sensors 41 detects a wafer, it can be determined that only wafers of the Mth specification are stored in the storage rack 1 and there are protrusions.

[0038] At the same time, the first detection part 2 is used to judge the situation of the wafer 5 located in the storage rack 1. If two receiving ends 212 (for example, M-1 and M receiving ends 212) in the first detection part 2 are blocked, it means that the M-th specification wafer detected by this group of first detection parts 2 protrudes backward, which means that the M-th specification wafer at this position protrudes backward; if all the receiving ends 212 of the first detection part 2 are not blocked and compared with the empty placement positions recorded by the wafer handling system, if they are consistent, it means that there is no wafer placed at the detected position; if they are inconsistent, it means that the M-th specification wafer detected by this group of first detection parts 2 protrudes forward.

[0039] In some embodiments, see Appendix Figure 10 When the detection results of the second detection unit 3 and the third detection unit 4 both judge that the wafer is an M-1 specification wafer, if all the receiving ends 212 of the receiving sensor group of the first detection unit 2 are not blocked, the placement position 11 detected by the unblocked receiving sensor group is compared with the empty placement position recorded by the wafer handling system. If they are consistent, it means that there is no wafer placed at the placement position 11, and the detection result of the first detection unit 2 is correct; if they are inconsistent, it means that the wafers placed at the placement position 11 detected by all the unblocked receiving sensor groups except the empty placement position protrude away from the first detection unit 2, and the wafer judged by the first detection unit 2 to be one size larger than the smallest model wafer is changed to the smallest model wafer protruding backward.

[0040] There are three types of wafer specifications to be inspected. The receiving end two 312 and the receiving end three 412 of the second inspection part 3 and the third inspection part 4 corresponding to the inspection of medium-specification wafers are just not blocked, and the receiving end two 312 and the receiving end three 412 corresponding to the inspection of small-specification wafers are just not blocked, so the second inspection part 3 and the third inspection part 4 determine that they are medium-specification wafers. At this time, combined with the result of the first detection part 2, if the first detection part 2 determines that there is no wafer placed, it is compared with the empty placement position recorded by the wafer handling system. If they are consistent, it means that there is no wafer placed in the placement position 11; if they are inconsistent, and the receiving sensor group of the first detection part 2 is not blocked, it means that the wafer 5 at the placement position 11 protrudes away from the first detection part 2 (the first detection part 2 is arranged close to the rear side of the storage rack, and each receiving end 212 is arranged along the front and rear direction, then correspondingly, the situation at this time is that the wafer protrudes forward), and the wafer at the placement position 11 is a small-size wafer. At the same time, the judgment result of the wafer judged as a medium-size wafer by the first detection part 2 is changed to a small-size wafer protruding backward.

[0041] In some embodiments, see Appendix Figure 11 As shown, when the detection results of the second detection part 3 and the third detection part 4 both judge that the wafer is at least two sizes larger than the smallest model wafer, if the wafer model detected by the receiving sensor group of the first detection part 2 is smaller than the wafer model judged by the second detection part 3 and the third detection part 4, then the wafer detected by the corresponding receiving sensor group of the first detection part 2 is a wafer protruding in the direction away from the first detection part 2, and the first detection part 2 judges that the wafer with the same size and model as the wafer judged by the second detection part 3 and the third detection part 4 is protruding in the direction close to the first detection part 2.

[0042] The above embodiments are only for illustrating the technical concept and features of the present invention. Its purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. It cannot be used to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A wafer storage device, characterized in that: include: A storage rack comprising a plurality of groups of supports spaced apart in an upper and lower direction, each group of supports comprising a first support and a second support disposed opposite to each other along a first horizontal direction, the first support and the second support forming a placement position suitable for placing a wafer and suspending the wafer on both sides in the second horizontal direction; The first detection part is arranged on the side where the wafer is suspended, and the first detection part includes a transmitting sensor and a receiving sensor group. The receiving sensor group includes multiple receiving ends one arranged along the second horizontal direction and corresponding to the size and model of the wafer. The light of the transmitting sensor tangent to the wafer passes through the middle area between the receiving end one corresponding to the wafer and the receiving end one adjacent to it and away from the wafer. The intersection of the light of the transmitting sensor to the multiple receiving ends one and the plane where the placement position is located is located between the first support and the second support.

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

3. The wafer storage device according to claim 2, characterized in that: There are multiple groups of the first detection parts, and the distance between the emission sensors of two adjacent groups of the first detection parts in the vertical direction is twice the distance between adjacent placement positions.

4. The wafer storage device according to claim 3, characterized in that: Two adjacent groups of the first detection parts are opposite to each other in the first horizontal direction.

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

6. The detection method of the wafer storage device according to claim 5, characterized in that: If neither the second detection unit nor the third detection unit detects the wafer protrusion, the result of the smallest wafer detected by the first detection unit or the result of the absence of the wafer is correct; If both the second detection unit and the third detection unit detect that the wafer has protrusions, and the detection result of the second detection unit is the size and model of the innermost wafer without protrusions, the detection result of the third detection unit is the size and model of the innermost wafer without protrusions, and the size and model of all the wafers detected by the first detection unit are consistent, then the size and model of the wafer detected by the first detection unit is correct; otherwise, there is an error in the wafers stored on the storage rack. Among them, 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 and model of the wafer corresponding to the outermost receiving end of the receiving sensor group that is blocked is the size and model of the wafer detected by the first detection unit.

7. The detection method of the wafer storage device according to claim 6, characterized in that: If only one of the second detection part and the third detection part detects the wafer, and one of the two receiving ends of the receiving sensor group is blocked, the wafer detected by the receiving sensor group protrudes toward the first detection part.

8. The detection method of the wafer storage device according to claim 6, characterized in that: If only one of the second detection part and the third detection part detects the wafer, and all the receiving ends of the receiving sensor group are not blocked, the placement positions corresponding to the unblocked receiving sensor groups are compared with the empty placement positions recorded by the wafer handling system. If they are inconsistent, the wafers placed at the placement positions detected by all the unblocked receiving sensor groups except the empty placement positions protrude away from the first detection part.

9. The method for detecting a wafer storage device according to claim 6, wherein: When the second detection unit and the third detection unit detect that the wafer is exactly one size larger than the minimum 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 are consistent, there is no wafer placed at the placement position, and the result of the wafer being one size larger than the minimum model wafer detected by the first detection unit is correct. If they are inconsistent, 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 judged by the first detection unit to be one size larger than the minimum model wafer is changed to the smallest model wafer protruding backward.

10. The detection method of the wafer storage device according to claim 6, characterized in that: When the second detection unit and the third detection unit detect that the wafer is at least two sizes larger than the smallest wafer, if the wafer model detected by the receiving sensor group is smaller than the wafer model judged 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 the wafer judged by the first detection unit to be consistent with the size and model of the wafer judged by the second detection unit and the third detection unit is changed to a wafer protruding toward the first detection unit.

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