Wafer loading system, rapid thermal annealing process machine and semiconductor equipment

Abstract

The utility model provides a wafer loading system, a rapid thermal annealing process machine and semiconductor equipment. According to the wafer loading system, before a wafer is placed or picked up, the horizontal position of the wafer relative to an edge ring can be detected through a positioning assembly. Wherein the positioning assembly comprises at least three position sensors. And the position sensors are distributed at intervals along the outer side of the edge of the target position, so that the position deviation of the wafer in the horizontal direction can be accurately detected from multiple points and multiple angles. And under the matching action of the mechanical arm, the position of the wafer can be efficiently adjusted according to the deviation condition of the wafer, so that the wafer can be quickly adjusted to the target position, the wafer can be placed on the bearing surface along the current horizontal position, accurate placement of the wafer is achieved, and the accuracy of the wafer placement is improved. The problem that the process effect is poor due to the deviation of the wafer placement position is effectively avoided, and the process effect and the product yield can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductor manufacturing, in particular to a wafer loading system, a rapid thermal annealing process machine and semiconductor equipment. Background Art

[0002] Rapid Thermal Processing (RTP) is one of the commonly used heat treatment processes in semiconductor technology. It heats the wafer in a very short time to adjust the internal structure of the wafer and improve the performance of semiconductor devices. The RTP machine is equipped with a robot to automatically transfer the wafer before and after the process. Figure 1 and Figure 2 As shown, before the process is executed, the robot arm will place the wafer W to be processed on the edge ring 10 in the chamber of the machine, and the standard placement position is that the center position of the wafer W is aligned with the center position of the edge ring 10 .

[0003] However, with the long-term use of the robot arm, its placement accuracy gradually decreases. Figure 3 and Figure 4 As shown, due to the placement deviation of the robot arm, the center position of the wafer W will deviate from the center position of the edge ring 10, which is called the Hand off phenomenon in the art. And when the center position of the wafer W deviates greatly from the center position of the edge ring 10, it is easy to cause the contact area between part of the edge of the wafer W and the edge ring 10 to be too large; and there is a gap between part of the edge and the edge ring 10, and the radiation beam will pass through the gap. Based on this, it is easy to cause uneven heating of the wafer W during the process implementation, which in turn leads to large differences in process parameters of different areas of the wafer W. Refer to Figure 3 and Figure 5 It can be seen that due to the placement deviation of the robot arm, the resistance of the light leakage side of the wafer W is greater than the resistance of the other opposite side, and the overall resistance distribution of the wafer W is quite different, which seriously affects the process stability and device performance.

[0004] Therefore, a new machine is needed to solve the above technical problems. Utility Model Content

[0005] The utility model aims to provide a wafer loading system, a rapid thermal annealing process machine, and a semiconductor device to solve at least one of the problems of how to improve the accuracy of wafer placement and how to improve the process effect.

[0006] In order to solve the above technical problems, the utility model provides a wafer loading system, comprising: an edge ring, a mechanical arm and a positioning component;

[0007] The edge ring has a bearing surface for bearing the wafer;

[0008] The robotic arm is used to clamp and transfer the wafer;

[0009] The positioning assembly is used to monitor the position information of the wafer, and the robot arm is also used to adjust the horizontal position of the wafer relative to the edge ring according to the position information until the wafer is located at the target position, and maintain the current horizontal position to place the wafer vertically on the carrying surface;

[0010] Wherein, the positioning component includes at least three position sensors; the at least three position sensors are located above the bearing surface and distributed along the edge of the target position.

[0011] Optionally, in the wafer loading system, the target position includes the horizontal position of the wafer when the center of the wafer coincides with the center of the inner ring of the edge ring; and the horizontal position of the wafer when the horizontal distance between the center of the wafer and the center of the inner ring of the edge ring is within a preset range.

[0012] Optionally, in the wafer loading system, the at least three position sensors are spaced apart around the outer side of the edge of the target position, and the detection signal emitted by each position sensor propagates vertically toward the carrying surface.

[0013] Optionally, in the wafer loading system, the at least three position sensors are distributed in an axisymmetric or rotationally symmetrical manner with respect to an orthographic projection of the plane where the carrying surface is located.

[0014] Optionally, in the wafer loading system, the at least three position sensors are spaced apart outside the edge of the target position and are located in the plane where the target position is located; and a propagation direction of a detection signal emitted by each of the position sensors is parallel to or coincides with the plane where the target position is located.

[0015] Optionally, in the wafer loading system, propagation directions of the detection signals emitted by any two of the position sensors are parallel or perpendicular to each other, and the distance between the position sensors corresponding to the two parallel detection signals is greater than the diameter of the wafer.

[0016] Optionally, in the wafer loading system, the minimum horizontal distance between the detection signal emitted by the position sensor and the edge of the target position is 0.

[0017] Optionally, in the wafer loading system, the edge ring has an outer ring and an inner ring that are nested and connected to each other; the top surface of the outer ring protrudes from the top surface of the inner ring, and the inner wall of the outer ring is set at an acute angle relative to the top surface of the inner ring; and the top surface of the inner ring is the bearing surface.

[0018] Based on the same concept, the utility model also provides a rapid thermal annealing process machine, including the wafer loading system.

[0019] Based on the same concept, the utility model also provides a semiconductor device, including the wafer loading system.

[0020] In summary, the utility model provides a wafer loading system, a rapid thermal annealing process machine, and a semiconductor device. The wafer loading system can detect the horizontal position of the wafer relative to the edge ring by using a positioning component before the wafer is placed or picked up. The positioning component includes at least three position sensors. Each of the position sensors is spaced apart along the outer side of the edge of the target position, and can accurately detect the horizontal position deviation of the wafer from multiple points and angles. In addition, with the cooperation of the robotic arm, the position of the wafer can be efficiently adjusted according to the deviation of the wafer, so that the wafer can be quickly adjusted to the target position, and the wafer can be placed on the carrying surface along the current horizontal position, so as to achieve accurate placement of the wafer, effectively avoid the problem of poor process effect due to the deviation of the wafer placement position, and help improve the process effect and product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Those skilled in the art will appreciate that the drawings are provided for a better understanding of the present invention, but do not constitute any limitation on the scope of the present invention.

[0022] Figure 1 It is a schematic diagram of a standard placement position of a wafer on an edge ring in the prior art.

[0023] Figure 2 yes Figure 1 Schematic diagram of the cross section along line A-A'.

[0024] Figure 3 It is a schematic diagram of a standard placement position of a wafer deviating from an edge ring in the prior art.

[0025] Figure 4 yes Figure 3 Schematic diagram of the cross section along line B-B'.

[0026] Figure 5 yes Figure 3 The corresponding resistance distribution diagram.

[0027] Figure 6It is a structural schematic diagram of a wafer loading system in an embodiment of the utility model.

[0028] Figure 7 It is a structural schematic diagram of another wafer loading system in an embodiment of the utility model.

[0029] Figure 8 It is a cross-sectional view of the edge ring in the embodiment of the utility model.

[0030] Fig. 9 It is a structural schematic diagram of the mechanical arm in the embodiment of the utility model.

[0031] Fig.10 In the present utility model embodiment Figure 6 Schematic diagram of the detection signals and target positions in the system.

[0032] Fig.11 In the present utility model embodiment Figure 6 A distribution diagram of the three position sensors in the system.

[0033] Fig.12 In the present utility model embodiment Figure 6 Another layout of the three position sensors in the system.

[0034] Fig.13 In the present utility model embodiment Figure 7 Distribution diagram of the four position sensors in the system.

[0035] And, in the attached drawings:

[0036] 10-Edge ring;

[0037] 20-edge ring; 201-outer ring; 202-inner ring;

[0038] 30-mechanical arm; 301-clamping part; 302-driving part;

[0039] 40-positioning assembly; 401-first position sensor; 402-second position sensor; 403-third position sensor; 404-fourth position sensor; 405-fifth position sensor; 406-sixth position sensor; 407-seventh position sensor;

[0040] W-wafer; C-target position; R-detection signal; M-carrying surface; α-angle. DETAILED DESCRIPTION

[0041] In order to make the purpose, advantages and features of the utility model clearer, the utility model is further described in detail in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the utility model. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis of each drawing is different, and sometimes different proportions are used. It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third", etc. in the specification are only used to distinguish between the various components, elements, steps, etc. in the specification, and are not used to represent the logical relationship or sequential relationship between the various components, elements, steps, etc.

[0042] In addition, the X-axis direction, Y-axis direction and Z-axis direction referred to in the present application specification and drawings are three directions perpendicular to each other in three-dimensional space; and the horizontal direction refers to the X-axis direction and the Y-axis direction, and the vertical direction refers to the Z-axis direction.

[0043] See also Figure 6 and Figure 7 The present embodiment provides a wafer loading system, comprising: an edge ring 20, a robot arm 30 and a positioning assembly 40; the edge ring 20 has a carrying surface M for carrying a wafer W; the robot arm 30 is used to clamp and transfer the wafer W; the positioning assembly 40 is used to monitor the position information of the wafer W, and the robot arm 30 is also used to adjust the horizontal position of the wafer W relative to the edge ring 20 according to the position information until the wafer W is located at a target position, and maintain the current horizontal position to place the wafer W vertically on the carrying surface M; wherein the positioning assembly 40 includes at least three position sensors; the at least three position sensors are located above the carrying surface M and distributed along the edge of the target position.

[0044] It can be seen that the wafer loading system provided in this embodiment uses at least three position sensors in the positioning assembly 40 to accurately detect the horizontal position deviation of the wafer W at multiple points and angles. In addition, with the cooperation of the robot arm 30, the wafer W is accurately placed, effectively avoiding the problem of poor process effect caused by the deviation of the placement position of the wafer W, which helps to improve the process effect and product yield.

[0045] The following is combined with Figure 6 to Figure 13 The wafer loading system provided in this embodiment is specifically described.

[0046] Please continue reading Figure 6 and Figure 7The wafer loading system provided in this embodiment is used to realize the automatic positioning and loading of the wafer W. Specifically, the wafer loading system includes: an edge ring 20, a robot arm 30 and a positioning assembly 40. The edge ring 20 is used to carry the wafer W; the robot arm 30 is used to clamp, place and move the wafer W along multiple degrees of freedom; the positioning assembly 40 is used to monitor the position information of the wafer W relative to the edge ring 20, and cooperate with the robot arm 30 to ensure that the wafer W is located at the target position on the edge ring 20.

[0047] See also Figure 6 , Figure 7 and Figure 8 , the edge ring 20 is an annular structure, and has an outer ring 201 and an inner ring 202 that are nested and connected. Preferably, the outer ring 201 and the inner ring 202 are both standard circular rings to match the morphology of the wafer W. Further, the inner diameter of the outer ring 201 is consistent with the outer diameter of the inner ring 202, so that the inner ring 202 can be embedded in the outer ring 201. And preferably, the outer ring 201 and the inner ring 202 are integrally formed. And, to ensure that the edge ring 20 can stably carry the wafer W, the top surface of the outer ring 201 protrudes from the top surface of the inner ring 202, so that the top surface of the inner ring 202 forms an annular groove surrounded by the inner ring wall of the outer ring 201, so that the wafer W can be stably accommodated. Based on this, the top surface of the inner ring 202 is the bearing surface M of the edge ring 20. Furthermore, the inner wall of the outer ring 201 is arranged at an acute angle relative to the top surface of the inner ring 202, that is, Figure 8 The angle α shown is an acute angle. It can be understood that, in view of the morphological feature that the inner wall of the outer ring 201 is inclined relative to the bearing surface M, even if the robotic arm 30 is slightly offset when placing the wafer W relative to the edge ring 20, the wafer W can slide down to the bearing surface M along the slope formed by the inner wall of the outer ring 201, which is conducive to improving the accuracy of the placement of the wafer W. It should be noted that this embodiment does not limit the specific dimensions (diameter, thickness) of the outer ring 201 and the inner ring 202, which can be determined according to the size of the wafer W to be carried.

[0048] See also Figure 6 , Figure 7 and Fig. 9 The robot arm 30 has a clamping part 301 and a driving part 302. The clamping part 301 is used to pick up and place the wafer W; the driving part 302 is used to drive the clamping part 301 according to instructions to drive the wafer W to move at least along the X-axis, Y-axis and Z-axis directions to achieve the transmission and position adjustment of the wafer W. Preferably, the robot arm 30 and the positioning assembly 40 are connected by wired or wireless communication.

[0049] See also Figure 6 and Figure 7 , the positioning assembly 40 includes at least three position sensors, which are used to detect the horizontal position of the wafer W relative to the edge ring 20 when the robot arm 30 places or picks up the wafer W, so as to ensure that the wafer W can be accurately placed and picked up. Preferably, the position sensor is a photoelectric sensor, which can detect the position of the wafer W by emitting a light signal toward the wafer W and the edge ring 20. In addition, the number of the position sensors in the positioning assembly 40 provided in this embodiment is greater than or equal to 3, and the projections of each position sensor on the plane where the carrying surface M is located are at least nonlinearly spaced, so as to at least be able to locate the projection surface of the wafer W toward the plane where the carrying surface M is located.

[0050] In order to further achieve accurate positioning of the wafer W, this embodiment provides two distribution examples of the positioning components 40. In one example, Figure 6 and Fig.10 As shown, each position sensor is arranged above the bearing surface M of the edge ring 20, and the detection signal R emitted by the position sensor propagates vertically toward the bearing surface M. For example, the positioning assembly 40 includes three position sensors, namely: a first position sensor 401, a second position sensor 402, and a third position sensor 403. The first position sensor 401, the second position sensor 402, and the third position sensor 403 are located above the top surface of the edge ring 20, and the signal transmitting end of each position sensor 402 is facing the top surface of the edge ring 20, so as to transmit the detection signal R vertically toward the edge ring 20. Optionally, the first position sensor 401, the second position sensor 402, and the third position sensor 403 can be installed on the same plane, for example, installed on the reflective plate B in the inner cavity of the rapid thermal annealing process machine; or installed on different planes, which is not specifically limited in this embodiment.

[0051] Further, the first position sensor 401, the second position sensor 402 and the third position sensor 403 are spaced apart around the outer edge of the target position C. It should be noted that the target position C includes the position of the wafer W when the center of the wafer W coincides with the center of the inner ring 202 of the edge ring 20, or the horizontal spacing (X-axis spacing and Y-axis spacing) between the center of the wafer W and the center of the inner ring 202 of the edge ring 20 is within a preset range. Among them, this embodiment does not limit the vertical (Z-axis direction) height of the target position C. In short, the target position C is the ideal placement position of the wafer W on the plane where the X-axis-Y-axis direction is located. Therefore, each of the position sensors is set around the edge of the ideal placement position of the wafer W, and on the plane where the X-axis-Y-axis direction is located, when the wafer W deviates from one side, at least one of the position sensors can detect the abnormal position of the wafer W. Among them, because the detection signal R emitted by the position sensor propagates along a straight line, and in order to accurately detect the position abnormality of the wafer W, the minimum horizontal distance between any detection signal R emitted by the position sensor and the edge of the target position C is 0. That is, any detection signal R intersects with the edge of the target position C. Figure 6 and Fig.10 As shown, on the plane where the X-axis-Y-axis direction is located, the detection signals R emitted by the first position sensor 401, the second position sensor 402 and the third position sensor 403 all vertically pass through the edge of the target position C. It can be understood that when the wafer W deviates from the target position C, the detection signal R emitted by at least one of the position sensors can be blocked by the wafer W, so that the position deviation information of the wafer W can be detected in time, which is beneficial for the robot arm 30 to accurately adjust the position of the wafer W until the wafer W is located within the target position C.

[0052] In order to further improve the accuracy of each position sensor in detecting the position of the wafer W, the orthographic projections of each position sensor relative to the surface where the bearing surface M of the edge ring 20 is located are axially symmetrically distributed or rotationally symmetrically distributed. Fig.11 As shown, the first position sensor 401, the second position sensor 402 and the third position sensor 403 are symmetrically distributed along the Y-axis direction relative to the projection position of the edge ring 20; or as shown Fig.12 As shown, the first position sensor 401, the second position sensor 402 and the third position sensor 403 are distributed in rotational symmetry along the center O of the edge ring 20. It can be understood that these two distribution modes can uniformly collect the peripheral position information of the wafer W, which is conducive to timely and accurate detection of the position information of the wafer W and its deviation.

[0053] In another example, if Figure 7 and Fig.13 As shown, the at least three position sensors are distributed at intervals outside the edge of the target position C and are located in the plane where the target position C is located. For example, the positioning component 40 includes a fourth position sensor 404, a fifth position sensor 405, a sixth position sensor 406 and a seventh position sensor 407. The fourth position sensor 404, the fifth position sensor 405, the sixth position sensor 406 and the seventh position sensor 407 are arranged in the same plane and are located on the plane where the X-axis-Y-axis direction is located, and are distributed around the periphery of the target position C. Its purpose is to be able to use the target position C as a detection reference and detect whether the wafer W is located at the target position C in the X-axis-Y-axis direction and its deviation along the edge limit of the target position C. Based on this, the propagation direction of the detection signal R emitted by each of the position sensors is parallel to or coincides with the plane where the target position C is located. That is, it can be appropriately adjusted in the Z-axis direction based on the thickness of the wafer W. However, since the thickness of the wafer W is relatively thin, the detection signal R can generally be set to coincide with the plane where the target position C is located.

[0054] Furthermore, the propagation directions of the detection signals R emitted by any two of the position sensors are parallel or perpendicular to each other, so as to detect and calculate the deviation of the wafer W from the target position C in the X-axis direction and the Y-axis direction, respectively. And preferably, the distance between the position sensors corresponding to the two parallel detection signals R is greater than the diameter of the wafer W, so as to ensure that the two parallel detection signals R can define the boundary of the target position C in the X-axis direction or the Y-axis direction. And, the minimum horizontal distance between the detection signal R emitted by any one of the position sensors and the edge of the target position C is 0. Assuming that the shape of the target position C is circular, any one of the detection signals R is tangent to the edge of the target position C, and its purpose is also to accurately detect the position information of the wafer W when it deviates from the target position C. Fig.13As shown, the fourth position sensor 404 and the fifth position sensor 405 are spaced apart along the X-axis direction, and the sixth position sensor 406 and the seventh position sensor 407 are spaced apart along the Y-axis direction. Among them, the propagation direction of the detection signal R emitted by the fourth position sensor 404 and the fifth position sensor 405 is parallel to the Y-axis direction, and is tangent to the edges on both sides of the X-axis of the target position C, so the position deviation of the wafer W along the X-axis direction can be detected in time by the fourth position sensor 404 or the fifth position sensor 405. The propagation direction of the detection signal R emitted by the sixth position sensor 406 and the seventh position sensor 407 is parallel to the X-axis direction, and is tangent to the edges on both sides of the Y-axis of the target position C, so the position deviation of the wafer W along the Y-axis direction can be detected in time by the sixth position sensor 406 or the seventh position sensor 407. Therefore, each of the position sensors is arranged according to Figure 7 and Fig.13 The distribution method shown is conducive to accurately defining the deviation of the wafer W relative to the target position C, thereby achieving effective positioning of the wafer W.

[0055] In summary, the wafer loading system provided in this embodiment uses the positioning assembly 40 to realize the pre-position detection of the wafer W, and can be used in conjunction with the robot arm 30 to realize real-time and accurate adjustment of the position of the wafer W, so as to facilitate adjusting the wafer W to the target position C and then vertically placing it on the carrying surface M. The process of placing the wafer W in the wafer loading system is as follows:

[0056] Step 1: The robot arm 30 clamps the wafer W and moves to the top of the edge ring 20. Preferably, the wafer W is placed close to the target position C and at least at the same vertical height as the target position C, so as to facilitate the subsequent position adjustment of the wafer W.

[0057] Step 2: Each position sensor in the positioning assembly 40 detects the deviation of the wafer W relative to the target position C in the X-axis direction and the Y-axis direction.

[0058] Among them, when the wafer W is located at the target position C, the detection signal R emitted by each position sensor is not blocked by the wafer W, and each position sensor cannot detect the wafer W signal, and the deviation is 0; when the wafer W deviates from the target position C, at least part of the detection signal R emitted by the position sensors is blocked by the wafer W, then the deviation of the wafer W relative to the target position C in the X-axis direction and / or Y-axis direction can be detected.

[0059] Step 3: When the deviation is not equal to 0, the robot arm 30 adjusts the position of the wafer W in the X-axis direction and the Y-axis direction according to the deviation, and repeats step 2 until the deviation is equal to 0, and then executes step 4; when the deviation is equal to 0, execute step 4;

[0060] It should be noted that when the deviation causes the robot arm 30 to reach the limit of movement, the wafer W is transferred back to the wafer box, the current placement operation of the wafer W is stopped, the machine is replaced, or the current machine fault is repaired.

[0061] And, preferably, when the deviation is equal to 0, the robot arm 30 records the current position and uses the current position as the initial placement position of the next wafer W relative to the edge ring 20 to reduce the adjustment of the position of the wafer W and improve the placement efficiency.

[0062] Step 4: The robot arm 30 keeps the current X-axis and Y-axis positions of the wafer W unchanged, and moves the wafer W along the negative half-axis direction of the Z-axis, so that the wafer W is located on the carrying surface M of the edge ring 20 .

[0063] Based on the same concept, this embodiment also provides a rapid thermal annealing process machine, including the above-mentioned wafer loading system, so as to accurately place the wafer W, thereby preventing the wafer W from being heated unevenly in different areas due to deviation in the placement position, thereby affecting the performance of the wafer W. Figure 6 In the distribution mode of the positioning components 40 shown in FIG. 1 , each of the position sensors can be arranged on the reflective plate B above the edge ring 20 . Figure 7 The distribution of the positioning components 40 shown in the figure, each of the position sensors can be set on the cavity wall in the reaction cavity of the rapid thermal annealing process machine. It should be noted that the wafer loading system provided in this embodiment is not limited to being set only in the rapid thermal annealing process machine, but can also be set in other semiconductor devices. Therefore, this embodiment also provides a semiconductor device, including the wafer loading system as described above.

[0064] In summary, the wafer loading system, rapid thermal annealing process machine, and semiconductor equipment provided in this embodiment can use the positioning component 40 to detect the horizontal position of the wafer W relative to the edge ring 20 before the wafer W is placed or picked up. Among them, the positioning component 40 includes at least three position sensors. Each of the position sensors is spaced apart along the outer side of the edge of the target position C, and can accurately detect the position deviation of the wafer W in the X-axis and / or Y-axis direction from multiple points and angles. In addition, with the cooperation of the robotic arm 30, the position of the wafer W can be efficiently adjusted according to the deviation of the wafer W, so that the wafer W can be quickly adjusted to the target position C, and the wafer W can be placed on the carrying surface M along the target position C to achieve accurate placement of the wafer W, thereby avoiding the problem of poor process effect caused by the deviation of the placement position of the wafer W, which helps to improve the process effect and product yield.

[0065] In addition, it should be recognized that although the present invention has been disclosed as a preferred embodiment, the above embodiment is not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the above disclosed technical content can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A wafer loading system, characterized in that: include: edge rings, robotic arms, and positioning components; The edge ring has a bearing surface for bearing the wafer; The robotic arm is used to clamp and transfer the wafer; The positioning assembly is used to monitor the position information of the wafer, and the robot arm is also used to adjust the horizontal position of the wafer relative to the edge ring according to the position information until the wafer is located at the target position, and maintain the current horizontal position to place the wafer vertically on the carrying surface; Wherein, the positioning component includes at least three position sensors; the at least three position sensors are located above the bearing surface and distributed along the edge of the target position.

2. The wafer loading system according to claim 1, characterized in that: The target position includes the horizontal position of the wafer when the center of the wafer coincides with the center of the inner ring of the edge ring; and the horizontal position of the wafer when the horizontal distance between the center of the wafer and the center of the inner ring of the edge ring is within a preset range.

3. The wafer loading system according to claim 1, characterized in that: The at least three position sensors are spaced apart and distributed around the outer side of the edge of the target position, and the detection signal emitted by each position sensor is vertically propagated toward the carrying surface.

4. The wafer loading system according to claim 3, characterized in that: The at least three position sensors are distributed in an axisymmetric manner or in a rotationally symmetrical manner relative to the orthographic projection of the plane where the bearing surface is located.

5. The wafer loading system according to claim 1, characterized in that: The at least three position sensors are spaced apart and distributed outside the edge of the target position and are located in the plane where the target position is located; and the propagation direction of the detection signal emitted by each of the position sensors is parallel to or coincides with the plane where the target position is located.

6. The wafer loading system according to claim 5, characterized in that: The propagation directions of the detection signals emitted by any two of the position sensors are parallel or perpendicular to each other, and the distance between the position sensors corresponding to the two parallel detection signals is greater than the diameter of the wafer.

7. The wafer loading system according to claim 1, 3 or 5, characterized in that: The minimum horizontal distance between the detection signal emitted by the position sensor and the edge of the target position is 0.

8. The wafer loading system according to claim 1, characterized in that: The edge ring comprises an outer ring and an inner ring which are nested and connected to each other; the top surface of the outer ring protrudes from the top surface of the inner ring, and the inner wall of the outer ring is arranged at an acute angle relative to the top surface of the inner ring; and the top surface of the inner ring is the bearing surface.

9. A rapid thermal annealing process machine, characterized in that: It comprises a wafer loading system as claimed in any one of claims 1 to 8.

10. A semiconductor device, characterized in that: It comprises a wafer loading system as claimed in any one of claims 1 to 8.

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