A system for inspecting silicon wafers

Abstract

The embodiment of the present invention discloses a system for detecting silicon wafers, characterized in that the system includes: a plurality of carriers for carrying the silicon wafer by contacting with corresponding multiple parts of the silicon wafer; a detection device for detecting defects at different parts of the silicon wafer by moving relative to the silicon wafer; a sensing device for sensing the position of the detection device and generating a first command signal when sensing that the detection device is in a position for detecting the part of the silicon wafer in contact with the corresponding carrier; a driving device for moving the corresponding carrier from a contact position with the silicon wafer to a remote position without contact with the silicon wafer based on the first command signal, so that the silicon wafer is carried by other carriers among the plurality of carriers except the corresponding carrier. The above system realizes complete defect detection of the edge of the silicon wafer.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to a system for detecting silicon wafers. Background Art

[0002] In the field of semiconductor silicon wafer manufacturing, impurities may occur in the silicon wafers due to various reasons in the process steps of diffusion, thin film, etching and photolithography, resulting in defects. Due to the complex interaction between the above processes, defects are often more likely to occur in the edge area of ​​the silicon wafer, resulting in unstable film accumulation at the edge of the silicon wafer. In the subsequent process steps, some or all of these films may produce defects, and these defects will be transferred to the device area of ​​the silicon wafer. With the global development of informatization, the size of devices in the application field of silicon wafers continues to decrease, and the impact of the above defects has gradually become more significant. Therefore, the edge of the silicon wafer has become one of the main sources of yield limitation in semiconductor manufacturing. In the device manufacturing process, effectively removing these films accumulated at the edge of the silicon wafer can reduce defects and obtain a higher device yield.

[0003] The use of automatic inspection devices for silicon wafer appearance defects is now very common. It mainly photographs the surface of the silicon wafer, identifies defects such as particles, scratches, chemical contamination and edge damage on the silicon wafer surface through the obtained surface image, and then digitizes the results through the information processing module to evaluate the quality of the silicon wafer and determine whether it can meet the process quality requirements, thereby avoiding defective products from flowing into subsequent processing techniques, causing waste of production capacity and reduced yield.

[0004] In the prior art, commonly used detection methods for monitoring the appearance defects of silicon wafers include back contact detection and edge contact detection. When using the back contact defect detection method, the silicon wafer can be fixed by adsorbing the back of the silicon wafer, so as to accurately capture the defects on the edge and upper surface of the silicon wafer. However, the back adsorption device makes it impossible to obtain a complete image of the back of the silicon wafer. At the same time, the back contact will leave stains on the back of the silicon wafer, which will affect the product quality and increase the burden of the cleaning process in the subsequent steps. At the same time, it cannot be guaranteed that the above-mentioned residual stains will be completely removed in the subsequent cleaning process. When using the edge contact defect detection method, the silicon wafer is fixed by a silicon wafer edge clamping device, and the surface of the silicon wafer is photographed by a camera. Since the clamp used to clamp the silicon wafer will block a part of the silicon wafer when photographing the silicon wafer surface, in order to obtain a complete image of the silicon wafer edge, the clamp needs to be loosened after photographing the silicon wafer surface once, and the silicon wafer is rotated by a predetermined angle and then re-clamped to photograph the silicon wafer surface a second time. This makes the edge contact detection in the prior art low in efficiency, and the repeated clamping action will cause additional contamination to the edge of the silicon wafer. Summary of the invention

[0005] In order to solve the above technical problems, an embodiment of the present invention hopes to provide a system for detecting silicon wafers, which ensures the integrity of the edge defect detection of crystalline silicon wafers and avoids missed detection by controlling the configuration of the corresponding carrier to avoid the detection device when the detection device is in a position to detect the part of the silicon wafer that contacts any carrier.

[0006] The technical solution of the present invention is achieved in this way:

[0007] A system for inspecting silicon wafers, the system comprising: a plurality of carriers for carrying the silicon wafer by contacting corresponding portions of the silicon wafer; a detection device for detecting defects at different portions of the silicon wafer by moving relative to the silicon wafer; a sensing device for sensing the position of the detection device and generating a first command signal when it is sensed that the detection device is in a position for detecting portions of the silicon wafer in contact with corresponding carriers; and a driving device for moving the corresponding carrier from a contact position with the silicon wafer to a remote position without contact with the silicon wafer based on the first command signal, so that the silicon wafer is carried by other carriers among the plurality of carriers except the corresponding carrier.

[0008] An embodiment of the present invention provides a system for detecting silicon wafers, wherein the position of a detection device is sensed by a sensing device, and when the detection position is at a position for detecting a portion of the silicon wafer that is in contact with a corresponding carrier, the corresponding carrier is driven not to contact the silicon wafer, so that the detection device can obtain an image of the edge of the silicon wafer. At the same time, a configuration in which multiple carriers can independently switch between a contact position and a distance position ensures that when the corresponding carrier is not in contact with the silicon wafer, the silicon wafer can be stably held by other carriers. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram of a system for detecting silicon wafers according to an embodiment of the present invention;

[0010] Figure 2 This is a working diagram of a system for detecting silicon wafers according to an embodiment of the present invention;

[0011] Figure 3 is a schematic diagram of a system for inspecting silicon wafers according to another embodiment of the present invention;

[0012] Figure 4 This is a working diagram of a system for inspecting silicon wafers according to another embodiment of the present invention. DETAILED DESCRIPTION

[0013] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0014] The edge contact defect detection method in the prior art cannot obtain a complete image of the silicon wafer surface under the premise of only one detection, because the silicon wafer edge clamp used to fix the silicon wafer will block the part where the clamp contacts the edge of the silicon wafer, and there is a risk of missing edge defects. In order to avoid the above risks, in the prior art, after obtaining the upper and lower surfaces of the silicon wafer, the silicon wafer is rotated and then re-clamped for defect detection, but this method will increase the process time and reduce the overall efficiency. Based on this, the inventor proposed a system for detecting silicon wafers, through which the silicon wafer edge clamp can avoid blocking the silicon wafer edge during the silicon wafer detection process, so that the complete defect detection of the silicon wafer edge can be achieved through one detection, and the silicon wafer can be stably maintained throughout the process of detecting silicon wafer surface defects.

[0015] See attached Figure 1 The system for detecting silicon wafers comprises: a plurality of carriers G, wherein the plurality of carriers G cooperate with each other to stably hold the silicon wafer W, see the attached Figure 1 , preferably, there are 8 carriers G, and the multiple carriers G carry the silicon wafer W in a manner of contacting corresponding multiple positions of the silicon wafer W. The position where a single carrier G contacts the silicon wafer W is fixed, that is, the position where the single carrier G contacts the silicon wafer W remains unchanged during the entire silicon wafer detection process. The single carrier G can move from a contact position with the silicon wafer W to a distance position for releasing the silicon wafer W, that is, the single carrier G can move away from the silicon wafer W and not contact the silicon wafer W, wherein each carrier G can be moved from the contact position to the distance position individually. Preferably, the carrier G supports the silicon wafer W by contacting the periphery of the back side of the silicon wafer W, thereby reducing the area of ​​the silicon wafer W blocked by the carrier G during the detection process;

[0016] The detection device D is used to detect defects in the silicon wafer W. During the detection process, the detection device D moves relative to the silicon wafer W. During the movement, the detection device D can obtain a surface image of the silicon wafer W within the detection range of the detection device D, and the image processing unit analyzes the obtained image to detect defects existing in different parts of the surface of the silicon wafer W. Preferably, the detection device D is a camera for taking an image of the silicon wafer W, such as a CCD camera.

[0017] During the whole detection process, the multiple carriers G can cooperate with each other to always stably hold the silicon wafer W. In order to solve the above-mentioned technical problems, the system proposed by the inventor is that when the detection device D moves to the part of the silicon wafer W that contacts with any carrier G, the corresponding carrier G can move from the contact position to the remote position, so that the part of the silicon wafer W that contacts with the corresponding carrier G is exposed within the detection range of the detection device D without being blocked by the corresponding carrier G. The system for detecting the silicon wafer W includes a sensing device S, which is used to sense the position of the detection device D. When the detection device D detects the part of the silicon wafer W that contacts with any carrier G, the sensing device S can generate a first command signal, that is, when any carrier G appears within the detection range of the detection device D, the sensing device S can generate a first command signal.

[0018] At the same time, the system for detecting the silicon wafer W also includes a driving device M, which can receive the first command signal and drive the corresponding carrier G located within the detection range of the detection device D to move from the contact position to the distance position based on the first command signal, so that the portion of the silicon wafer W blocked by the corresponding carrier G is exposed within the detection range of the detection device D. The driving device M is preferably a stepping motor. At the same time, the silicon wafer W is still stably supported by a plurality of other carriers G that are not located within the detection range of the detection device D. Preferably, the corresponding carrier G moves along the radial direction of the supported silicon wafer W to avoid collision between the carrier G and other devices of the system during movement.

[0019] When the surface defect detection of different parts of the silicon wafer W is performed by the above-mentioned system for detecting silicon wafer W, when the detection device D moves to the part of the silicon wafer W that contacts any carrier G, the sensing device S sends a first command signal to the driving device M, and the driving device M drives the corresponding carrier G away from the silicon wafer W and exits the detection range of the detection device D, so that the part of the silicon wafer W blocked by the corresponding carrier G is completely exposed to the detection range of the detection device D, solving the technical problem of incomplete detection due to the carrier G blocking the edge of the silicon wafer W during the surface defect detection of the silicon wafer W. Preferably, the detection device D includes a front detector and a back detector that move on both sides of the carried silicon wafer W to detect the front and back of the silicon wafer W respectively. By arranging corresponding detectors on the front and back of the silicon wafer W, the detection device D can simultaneously detect the upper and lower surfaces of the same part of the silicon wafer W during the movement.

[0020] The above-mentioned sensing device S can also generate a second control signal when it senses that the detection device D is detecting a portion of the silicon wafer W that is not in contact with the corresponding carrier G. That is to say, in the process of detecting surface defects of the silicon wafer W, the detection device D continues to move relative to the silicon wafer W after completing the detection of the portion on the surface of the silicon wafer W that is blocked by any carrier G. When the surface of the silicon wafer W within the detection range no longer has a portion that can contact the corresponding carrier G, the sensing device S sends a second command signal to the driving device M. The driving device M drives the corresponding carrier G from the away position to the contact position based on the second command signal to clamp the edge portion of the silicon wafer W. At this time, since the detection device D has completed the detection of this portion, the corresponding carrier G will not block the surface of the silicon wafer W when carrying the silicon wafer W in the contact position. In another embodiment, the sensing device S includes a rangefinder for measuring the distance between the detection device D and a fixed position in its moving direction so as to obtain the position of the detection device D based on the distance, the rangefinder includes a laser transmitter arranged at the fixed position and a laser receiver arranged on the detection device D and moving with the detection device D, wherein the laser transmitter and the laser receiver are preferably arranged at the same horizontal height.

[0021] For details, please refer to the attached Figure 2Before the silicon wafer detection begins, multiple carriers G are in contact positions to carry silicon wafer W, and the detection device D moves from the initial position along the radial direction of the silicon wafer W. When the detection device D moves to the position Q1 where the part P1 of the silicon wafer W in contact with the carrier G1 is detected, since the contact point P1 of the carrier G1 with the silicon wafer W is fixed, when the detection device D is at the position Q1, it can be known that there is a part of the silicon wafer W in contact with the carrier G1 within the detection range of the detection device D. Therefore, when the sensing device S senses that the detection device D is at the detection position Q1, it generates a first command signal, and the driving device M drives the carrier G1 to move from the contact position to the away position based on the first command signal, so that the part P1 of the silicon wafer W is in contact with the carrier G1. The silicon wafer W is completely exposed within the detection range of the detection device D, and the detection device D obtains a complete image of the edge portion P1 of the silicon wafer W. At this time, multiple carriers G other than the carrier G1 are in contact position to stably carry the silicon wafer W; when the detection device D completes the detection of the portion P1 of the silicon wafer W and continues to move, the portion P1 of the silicon wafer W relatively leaves the detection range of the detection device D, that is, the detection device D is in the position Q2 for detecting the portion of the silicon wafer W that is not in contact with the carrier G1. At this time, the sensing device S generates a second command signal, and the driving device M drives the carrier G1 to move from the away position to the contact position based on the second command signal, and the carrier G1 contacts the edge portion P1 of the silicon wafer W to realize the carrying of the silicon wafer W. When the detection device D moves to the position for detecting the portion of the silicon wafer W in contact with the carrier G2, the above process is repeated.

[0022] In another embodiment, the detection device D moves along the radial direction of the silicon wafer W, and a plurality of carriers G are arranged in pairs, and the connecting lines between the two carriers G in each pair of carriers G are parallel to each other and perpendicular to the radial direction. Through the above configuration, the detection device D can simultaneously detect the parts of the silicon wafer W that are in contact with the two carriers G in each pair of carriers G. Furthermore, the carriers G located on the same side of the radial direction are evenly distributed in the circumferential direction of the supported silicon wafer W, see Appendix Figure 3 The carriers G located on the same radial side are arranged at equal intervals along the circumference of the silicon wafer W, and the two carriers G in each pair of carriers G can be switched between the contact position and the distance position at the same time, and the pairs of carriers G are configured so that when any pair of carriers G is in the distance position, the remaining pairs of carriers G are in the contact position to achieve stable support for the silicon wafer W.

[0023] For details, please refer to the attached Figure 4Before the silicon wafer detection begins, multiple carriers G are in contact position to carry the silicon wafer W, and the detection device D moves from the initial position along the radial direction of the silicon wafer W. When the detection device D moves to the position Q1 where the parts P1 and P1' of the silicon wafer W that are in contact with the pair of carriers G1 are detected, since the contact points of the pair of carriers G1 with the silicon wafer W are fixed, when the detection device D is at the position Q1, it can be known that there are parts P1 and P1' on the surface of the silicon wafer W within the detection range of the detection device D that are in contact with the pair of carriers G1. Therefore, when the sensing device S senses that the detection device D is at the detection position Q1, it generates a first command signal, and the driving device M drives the pair of carriers G1 from the contact position to the distance position based on the first command signal, so that the parts P1 and P1' of the silicon wafer W are The detection device D is completely exposed within the detection range of the detection device D, and the detection device D obtains a complete image of the edge parts P1 and P1' of the silicon wafer W. At this time, multiple pairs of carriers G other than a pair of carriers G1 are in contact position to stably carry the silicon wafer W. When the detection device D completes the detection of the parts P1 and P1' of the silicon wafer W and continues to move, the parts P1 and P1' of the silicon wafer W relatively leave the detection range of the detection device D, that is, the detection device D is in the position Q2 for detecting the parts of the silicon wafer W that are not in contact with the pair of carriers G1. At this time, the sensing device S generates a second command signal, and the driving device M drives the carrier G1 to move from the away position to the contact position based on the second command signal, and the pair of carriers G1 contacts the parts P1 and P1' of the silicon wafer W to realize the carrying of the silicon wafer W. When the detection device D moves to the position where it is in contact with another pair of carriers G2 to detect the parts of the silicon wafer W, the above process is repeated.

[0024] It should be noted that the technical solutions described in the embodiments of the present invention can be combined arbitrarily without conflict. The proportions between the components shown in the reference numerals are not fixed proportions, and their main purpose is to facilitate understanding of the solutions.

[0025] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A system for detecting silicon wafers, characterized in that: The system comprises: A plurality of carriers, used for carrying the silicon wafer by contacting with corresponding plurality of positions of the silicon wafer; A detection device, used for detecting defects at different parts of the silicon wafer by moving relative to the silicon wafer; A sensing device, used for sensing the position of the detection device and generating a first command signal when sensing that the detection device is in a position for detecting a portion of the silicon wafer in contact with a corresponding carrier; a driving device, configured to move the corresponding carrier from a contact position with the silicon wafer to a distance position without contact with the silicon wafer based on the first instruction signal, so that the silicon wafer is carried by other carriers among the plurality of carriers except the corresponding carrier, In which, the detection device moves along the radial direction of the silicon wafer being carried, the multiple carriers are arranged in pairs, and the connecting lines between the two carriers in each pair of carriers are parallel to each other and perpendicular to the radial direction, so that the detection device can simultaneously detect the parts of the silicon wafer that are in contact with the two carriers in each pair of carriers.

2. The system according to claim 1, characterized in that The sensing device is also used to generate a second command signal when it senses that the detection device is in a position to detect a portion of the silicon wafer that is not in contact with the corresponding carrier, and the driving device is also used to move the corresponding carrier from the away position to the contact position based on the second command signal.

3. The system according to claim 1, characterized in that The carriers located on the same side of the radial direction are evenly distributed in the circumferential direction of the supported silicon wafer.

4. The system according to claim 1, characterized in that The sensing device includes a distance meter for measuring the distance between the detection device and the fixed position in the radial direction, so as to obtain the position of the detection device according to the distance.

5. The system according to claim 4, characterized in that The rangefinder includes a laser transmitter disposed at the fixed position and a laser receiver disposed on the detection device to move with the detection device.

6. The system according to claim 1, characterized in that The plurality of carriers support the silicon wafer by contacting the periphery of the back side of the silicon wafer.

7. The system according to claim 6, characterized in that The corresponding carrier moves along the radial direction of the supported silicon wafer.

8. The system according to claim 1, characterized in that The detection device comprises a front detector and a back detector which move respectively on both sides of the carried silicon wafer to detect the front side and the back side of the silicon wafer respectively.

9. The system according to claim 1, characterized in that The detection device is a camera for taking an image of the silicon wafer.

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