Epitaxial wafer SFQR improvement analysis method and flatness measurement equipment

Abstract

The invention belongs to the field of epitaxial wafer improvement, and particularly relates to an epitaxial wafer SFQR improvement analysis method and flatness measurement equipment, and the method comprises the following steps: S1, generating an SFQR Map file and a Thickness Profile file after measuring an epitaxial wafer by using a flatness machine, S2, drawing the thickness Profile of 0-360 degrees of the epitaxial wafer by using the Thickness Profile file, S3, calculating the coordinate of each site by using the fixed size of each site in the SFQR Map, and calculating the flatness of the epitaxial wafer according to the coordinate of each site. The method comprises the following steps: S1, selecting a corresponding Thickness profile, then finding a range corresponding to the Thickness profile, and then intercepting a corresponding thickness profile, S4, adding a linear trend line to the intercepted thickness profile, and analyzing the intercepted thickness profile to adjust an epitaxial machine; the SFQR measured by the machine no longer only provides a single value, so that when the epitaxial machine performs process adjustment, how to change parameters such as lamp tube power and airflow can be guided to perform adjustment according to specific and regional information, the epitaxial machine is convenient to adjust corresponding parameters, and the SFQR capability of an epitaxial wafer is improved.

Description

Technical Field

[0001] This invention belongs to the field of epitaxial wafer improvement, specifically an analysis method and flatness measurement device for improving epitaxial wafer SFQR. Background Technology

[0002] An epitaxial wafer is a new single-crystal layer grown on a single-crystal substrate. This "epitaxy layer" can precisely control its thickness and doping concentration, and even achieve material crossover, such as growing gallium nitride on silicon. It is mainly divided into homoepitaxy (grown with the same material to repair substrate defects) and heteroepitaxy. It has lower defect density and oxygen content, and can precisely control doping concentration and type. It is widely used in the manufacturing of integrated circuits, power devices (such as IGBTs and MOSFETs), optoelectronic devices and sensors, and significantly optimizes key performance parameters such as device breakdown voltage and on-resistance. As Logic products gradually move from mature processes to advanced processes, the requirements for the flatness of their substrate-epitaxy wafers are becoming increasingly higher, and the SFQR parameter is one of the most critical parameters among the flatness parameters.

[0003] In the existing technology, the SFQR measured by the WS2 machine is only a single value. The epitaxial machine cannot make corresponding adjustments based solely on this value, which makes it difficult to improve the SFQR capability. At the same time, when using traditional flatness measurement equipment for inspection, it is often difficult to quickly remove the inspected wafer from the placement table, which makes the use of the device somewhat inconvenient.

[0004] Therefore, the present invention provides an analytical method and a flatness measurement device for improving the SFQR of epitaxial wafers. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0006] The technical solution adopted by this invention to solve its technical problem is: an analytical method for improving the SFQR of epitaxial wafers, comprising the following steps: S1: After measuring the epitaxial wafer using a flatness tester, generate the SFQR Map file and Thickness Profile file; S2: Using the Thickness Profile file, a thickness profile of the outer perimeter from 0-360° can be drawn; S3: Utilizing the fact that the size of each site in the SFQR map is fixed, calculate the coordinates of each site, then find the range of the corresponding Thickness Profile, and then extract the corresponding Thickness Profile; S4: Add a linear trend line to the thickness profile extracted above, and analyze the extracted thickness profile to adjust the epitaxy machine.

[0007] Preferably, the specific operation steps of step S4 are as follows: W1: Add a linear trend line to the extracted thickness profile, calculate the sum of the distances between the two points with the shortest vertical distance on both sides of this trend line, and this sum of distances is the SFQR data; W2: Analyze the SFQR value of this site. If improvement is needed, increase the edge thickness. This can be achieved by adjusting the lamp power and airflow at the corresponding position of the epitaxy machine.

[0008] An epitaxial wafer flatness measurement device is provided, which is applied to the above-mentioned epitaxial wafer SFQR improvement analysis method. The device is characterized in that: the flatness tester in step S includes a placement tray, a plurality of placement base bodies arranged in a equidistant ring inside the placement tray, and a wafer positioning and removal component that acts on the wafer placed inside the placement base body, thereby facilitating the fixing of the wafer and its rapid removal from the placement base body after the test is completed.

[0009] Preferably, the positioning and removal component includes an inner compartment formed inside the placement body, a second toothed ring inserted into the inner cavity of the inner compartment, a limiting component acting on the second toothed ring, and a plurality of clamping components arranged in a equidistant, circumferential manner on the inner wall of the inner peripheral surface of the placement body.

[0010] Preferably, the limiting component includes an annular groove communicating with the upper and lower ends of the inner cavity of the inner compartment and a limiting ring slidably inserted into the inner cavity of the annular groove, with one end of two adjacent limiting rings close to each other being fixed to the surfaces of the upper and lower ends of the second gear ring.

[0011] Preferably, the clamping component includes a sliding shaft slidably inserted into the inner wall of the inner peripheral surface of the placement base, a connecting shaft fixed to one end of the sliding shaft, a clamping plate fixed to one end of the connecting shaft, a connecting block fixed to the other end of the sliding shaft, and a plurality of abutment blocks fixed to the inner peripheral surface of the second gear ring and arranged in an equidistant ring.

[0012] Preferably, the clamping component further includes a collar fixedly sleeved on the outer circumferential surface of the sliding shaft and a spring fixed to one end of the collar, one end of the spring being fixed to the inner circumferential surface of the placement seat body.

[0013] Preferably, the positioning and removal assembly further includes a first gear ring rotatably connected to a position near the inner circumferential surface of the placement tray, a plurality of movable shafts rotatably connected to the inner wall of the placement tray near an adjacent position and arranged in a equidistant circular arrangement, and a gear fixedly sleeved on the outer circumferential surface of the movable shafts, wherein the gears are meshed with the adjacent second gear ring and the first gear ring.

[0014] Preferably, the positioning and removal assembly further includes an ejection assembly, which includes a support plate disposed at the bottom of the inner cavity of the placement seat body, a top rod slidably inserted into the inner wall of the placement seat body and the placement plate, a plurality of bottom rods disposed at the bottom of the placement plate, a rectangular groove opened inside the movable shaft, a sliding rod slidably inserted at the middle position of the movable shaft, a rectangular block slidably inserted into the inner cavity of the rectangular groove, a connecting strip fixed to the bottom of the rectangular block, a sleeve plate fixedly sleeved on the top rod extending to the bottom position of the placement plate, a support component acting on the bottom rod, and a connecting ring fixed between the plurality of top rods. The connecting strip is slidably inserted into and connected to the inner wall of the movable shaft and the inner wall of the placement plate. The bottom of the connecting strip is fixed to the surface of the top of the adjacent bottom rod. The support component includes a support groove opened on the inner wall of the sleeve plate near the bottom rod and a support ring inserted into the inner cavity of the support groove. The inner circumferential surface of the support ring is fixed to the outer circumferential surface of the bottom rod.

[0015] The beneficial effects of this invention are as follows: 1. The present invention, through the above method, can be used to analyze the causes of SFQR value deterioration and the direction of improvement. The SFQR measured by the epitaxial machine no longer provides only a single value, but can describe the details of thickness variation in different regions of the epitaxial wafer, and understand the specific pattern or trend of thickness variation in each site region, such as which regions have higher or lower thickness, and the gradient of thickness variation. As a result, when the epitaxial machine is adjusting the process, it can guide how to change parameters such as lamp power and airflow based on specific, regional information, thereby facilitating the adjustment of corresponding parameters by the epitaxial machine and improving the SFQR capability of the epitaxial wafer.

[0016] 2. The present invention, through the positioning and removal component, can facilitate the simultaneous fixation of multiple wafers and quickly release the fixation of multiple wafers after the test is completed. It can also simultaneously eject multiple wafers from the placement body, thereby facilitating the quick removal of the tested wafers from the placement base. This improves the ease of use of the device and shortens the time required for testing, thus improving the efficiency of the testing operation. Attached Figure Description

[0017] The invention will now be further described with reference to the accompanying drawings.

[0018] Figure 1This is a schematic diagram of the analytical method for improving the SFQR of epitaxial wafers according to the present invention; Figure 2 This is a schematic diagram of the specific process of S4 in this invention; Figure 3 This is a schematic diagram of the SFQR Map in this invention; Figure 4 This is a schematic diagram of the thickness profile of the epitaxial wafer from 0 to 360° in this invention; Figure 5 This is a schematic diagram of the coordinates of the Site in this invention; Figure 6 This is a schematic diagram of the total thickness profile x-axis of the epitaxial wafer in this invention; Figure 7 This is a schematic diagram of the AStie thickness range in this invention; Figure 8 This is a schematic diagram of the overall structure of the device of the present invention; Figure 9 In this invention Figure 8 Enlarged structural diagram at point A; Figure 10 This is a three-dimensional cross-sectional view of the structure of 03 in the front view direction in this invention; Figure 11 This is a three-dimensional structural cross-sectional view of 03 in the top view direction in this invention; Figure 12 This is a three-dimensional structural diagram of 03 in the upward view direction of this invention; Figure 13 This is a three-dimensional cross-sectional view of a local structure in this invention; Figure 14 In this invention Figure 13 Enlarged structural diagram at point B; Figure 15 In this invention Figure 13 Enlarged schematic diagram of the structure at point C.

[0019] In the diagram: 1. Placement plate; 2. First gear ring; 3. Placement seat body; 4. Inner compartment; 5. Second gear ring; 6. Ring groove; 7. Limiting ring; 8. Abutment block; 9. Connecting block; 10. Sliding shaft; 11. Clamping plate; 12. Collar; 13. Connecting shaft; 14. Spring; 15. Support plate; 16. Top rod; 17. Movable shaft; 18. Gear; 19. Bottom rod; 20. Sleeve plate; 21. Sliding rod; 22. Rectangular groove; 23. Rectangular block; 24. Connecting strip; 25. Support ring; 26. Support groove; 27. Connecting ring. Detailed Implementation

[0020] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0021] Example 1: like Figure 1 As shown, an analytical method for improving the SFQR of epitaxial wafers according to an embodiment of the present invention includes the following steps: S1: After measuring the epitaxial wafer using a flatness tester, generate the SFQR Map file and Thickness Profile file; S2: Using the Thickness Profile file, a thickness profile of the outer perimeter from 0-360° can be drawn; S3: Using the SFQR map, the size of each site is fixed. Calculate the coordinates of each site, find the range of the corresponding Thickness Profile, and then extract the corresponding Thickness Profile. S4: Add a linear trend line to the thickness profile extracted above, and analyze the extracted thickness profile to adjust the epitaxy machine.

[0022] like Figure 2 As shown, the specific operation steps of step S4 are as follows: W1: Add a linear trend line to the extracted thickness profile, calculate the sum of the distances between the two points with the shortest vertical distance on both sides of this trend line, and this sum of distances is the SFQR data; W2: Analyze the SFQR value of this site. If improvement is needed, increase the edge thickness. This can be achieved by adjusting the lamp power and airflow at the corresponding position of the epitaxy machine.

[0023] When an epitaxial wafer is measured using a flatness measuring machine, two files are generated: an SFQR Map and a Thickness Profile file. The SFQR Map file shows the SFQR values ​​for each region, but the reason for the different values ​​in different regions is unclear. Figure 3 This is an SFQR map, with each site measuring 26*33mm. Using the ThicknessProfile file, the epitaxial wafer's 0-360° area can be plotted. Figure 4 Thickness Profile Figure 5-7 For each site, there is a coordinate graph, a schematic diagram of the corresponding thickness profile, and a cropped thickness profile.

[0024] The above methods can be used to analyze the causes of SFQR value deterioration and identify areas for improvement. The SFQR measured by the WS2 machine no longer provides only a single value, but can describe the details of thickness variation in different regions of the epitaxial wafer, and understand the specific patterns or trends of thickness variation in each site region, such as which regions have excessively high or low thickness, and the gradient of thickness variation. This allows the epitaxial machine to adjust parameters such as lamp power and airflow based on specific, regional information when making process adjustments, thus facilitating the adjustment of corresponding parameters and improving the SFQR capability of the epitaxial wafer.

[0025] Example 2: like Figure 8-15 As shown, an epitaxial wafer flatness measurement device is used in the above-mentioned analysis method for improving epitaxial wafer SFQR. In step S1, the flatness machine includes a placement tray 1, multiple placement base bodies 3 fixed inside the placement tray 1 and arranged in a equidistant ring, and a wafer positioning and removal component that acts on the wafer placed inside the placement base body 3, so as to facilitate the fixing of the wafer and the quick removal from the placement base body 3 after the test is completed. The positioning and removal assembly includes an inner compartment 4 opened inside the placement body 3, a second toothed ring 5 inserted into the inner cavity of the inner compartment 4, a limiting component acting on the second toothed ring 5, and a plurality of clamping components arranged in a equidistant ring around the inner wall of the placement body 3 at a position on the inner circumferential surface.

[0026] When the second gear ring 5 rotates at a certain angle in the horizontal direction within the inner cavity of the inner chamber 4 under the limiting action of the limiting component, multiple clamping components can move towards the middle position of the placement body 3, thereby abutting against the outer surface of the wafer when the wafer is inserted into the inner cavity of the placement body 3, thus enabling rapid positioning of the wafer and improving the ease of use of the device.

[0027] like Figure 8-15 As shown, the limiting component includes an annular groove 6 that connects the upper and lower ends of the inner cavity of the inner compartment 4 and a limiting ring 7 that is slidably inserted into the inner cavity of the annular groove 6. The ends of two adjacent limiting rings 7 that are close to each other are fixed to the surfaces of the upper and lower ends of the second gear ring 5. Because the limiting ring 7 is resisted by the ring groove 6, it can only rotate in the horizontal direction within the inner cavity of the ring groove 6, thereby limiting the movement trajectory of the second gear ring 5 and making the second gear ring 5 rotate more smoothly in the horizontal direction.

[0028] like Figure 8-15As shown, the clamping component includes a sliding shaft 10 that is slidably inserted into the inner wall of the inner circumferential surface of the placement base body 3, a connecting shaft 13 fixed to one end of the sliding shaft 10, a clamping plate 11 fixed to one end of the connecting shaft 13, a connecting block 9 fixed to the other end of the sliding shaft 10, and a plurality of abutting blocks 8 that are equidistantly arranged around the inner circumferential surface of the second gear ring 5. When the second gear ring 5 rotates, it drives the abutment block 8 to make a circular motion, so that the abutment block 8 abuts against the adjacent connecting block 9, which drives the sliding shaft 10 to slide along a certain trajectory. This allows the connecting shaft 13 and the clamping plate 11 to move towards the middle position of the placement base body 3, until multiple clamping plates 11 simultaneously abut against the surface of the wafer extending into the placement base body 3, thereby clamping and limiting the wafer. Furthermore, since the abutment block 8 and the connecting block 9 have a certain curvature, they can clamp and limit wafers of various sizes, thus improving the ease of use of the device.

[0029] like Figure 8-15 As shown, the clamping component also includes a collar 12 fixedly sleeved on the outer circumferential surface of the sliding shaft 10 and a spring 14 fixed to one end of the collar 12. One end of the spring 14 is fixed to the inner circumferential surface of the placement seat body 3. When the abutting block 8 abuts the connecting block 9, the sliding shaft 10 drives the collar 12 to move towards the middle position of the placement base body 3, thereby stretching the adjacent spring 14 to deform it. When it is necessary to remove the wafer, the second toothed ring 5 continues to rotate so that the abutting block 8 moves away from the connecting block 9. Under the action of the spring 14's rebound force, the sliding shaft 10 is reset, so that the clamping plate 11 no longer abuts the surface of the wafer, thus facilitating the removal of the wafer.

[0030] like Figure 8-15 As shown, the positioning and removal assembly also includes a first gear ring 2 rotatably connected to a position near the inner circumferential surface of the placement plate 1, a plurality of movable shafts 17 rotatably connected to the inner wall of the placement plate 1 near the adjacent position of the placement seat body 3 and arranged in a equidistant ring, and a gear 18 fixedly sleeved on the outer circumferential surface of the movable shafts 17. The gear 18 is meshed with the adjacent second gear ring 5 and the first gear ring 2. By rotating one of the movable shafts 17, the adjacent gear 18 is driven to rotate, so that the gear 18 can move the first gear ring 2 in the horizontal direction under the meshing action between the gear 18 and the first gear ring 2. Thus, under the meshing action between the first gear ring 2 and the remaining gears 18, multiple gears 18 rotate synchronously. Thus, under the meshing action between the gear 18 and the adjacent second gear ring 5, multiple second gear rings 5 ​​can rotate synchronously in the same direction. This makes it easier for multiple sets of clamping components to clamp the wafers extending into the inner cavity of multiple placement base bodies 3 at the same time, thereby further improving the ease of use of the device.

[0031] like Figure 8-15 As shown, the positioning and removal assembly also includes an ejection assembly, which includes a support plate 15 disposed at the bottom of the inner cavity of the placement body 3, a top rod 16 slidably inserted into the inner wall of the placement body 3 and the placement plate 1, multiple bottom rods 19 disposed at the bottom of the placement plate 1, a rectangular groove 22 opened inside the movable shaft 17, a sliding rod 21 slidably inserted into the middle position of the movable shaft 17, a rectangular block 23 slidably inserted into the inner cavity of the rectangular groove 22, a connecting strip 24 fixed to the bottom of the rectangular block 23, a sleeve plate 20 fixedly sleeved on the top rod 16 extending to the bottom position of the placement plate 1, a support component acting on the bottom rod 19, and a connecting ring 27 fixed between the multiple top rods 16. The connecting strip 24 is slidably inserted into and connected to the inner wall of the movable shaft 17 and the inner wall of the placement plate 1, and the bottom of the connecting strip 24 is fixed to the surface of the top of the adjacent bottom rod 19. When the wafer needs to be removed, the sliding rod 21 is pulled upwards and rotated, allowing the bottom rod 19 to move vertically. The movable shaft 17 rotates due to the contact between the rectangular slot 22 and the rectangular block 23. This rotation of the movable shaft 17 moves the contact block 8 away from the adjacent connecting block 9, causing the clamping plate 11 to move away from the held wafer under the restoring force of the spring 14. The connecting strip 24 allows the bottom rod 19 to move vertically and rotate simultaneously. Under the support of the supporting components, the rotation of the bottom rod 19 does not affect the sleeve plate. 20, but it will drive the sleeve plate 20 to move in the vertical direction, thereby driving the push rod 16 and the support plate 15 to move in the vertical direction, so that the unclamped wafer can be pushed out by the support plate 15. After the sliding rod 21 is released, the support plate 15 will move vertically downward to the top of the inner cavity of the placement seat body 3, so as to clamp the next wafer. Under the connection of the connecting ring 27, when one of the push rods 16 slides in the vertical direction, it can drive the other push rod 16 to move in the vertical direction, thereby simultaneously pushing out multiple wafers, thus further improving the ease of use of the device.

[0032] like Figure 8-15 As shown, the support component includes a support groove 26 opened on the inner wall of the sleeve plate 20 near the bottom rod 19 and a support ring 25 inserted into the inner cavity of the support groove 26. The inner circumferential surface of the support ring 25 is fixed to the outer circumferential surface of the bottom rod 19. When the bottom rod 19 rotates, it can drive the inner cavity of the support ring 25 and the support groove 26 to rotate, thereby limiting the movement trajectory of the bottom rod 19 under the action of the resistance between the support ring 25 and the support groove 26. When the bottom rod 19 moves in the vertical direction, it can drive the sleeve 20 to move in the vertical direction under the action of the resistance between the support groove 26 and the support ring 25.

Claims

1. An analytical method for improving the SFQR of epitaxial wafers, characterized in that: Includes the following steps: S1: After measuring the epitaxial wafer using a flatness tester, generate the SFQR Map file and Thickness Profile file; S2: Using the Thickness Profile file, a thickness profile of the outer perimeter from 0-360° can be drawn; S3: Utilizing the fact that the size of each site in the SFQR map is fixed, calculate the coordinates of each site, then find the range of the corresponding Thickness Profile, and then extract the corresponding Thickness Profile; S4: Add a linear trend line to the thickness profile extracted above, and analyze the extracted thickness profile to adjust the epitaxy machine.

2. The analytical method for improving SFQR of epitaxial wafers according to claim 1, characterized in that: The specific steps for step S4 are as follows: W1: Add a linear trend line to the extracted thickness profile, calculate the sum of the distances between the two points with the shortest vertical distance on both sides of this trend line, and this sum of distances is the SFQR data; W2: Analyze the SFQR value of this site. If improvement is needed, increase the edge thickness. This can be achieved by adjusting the lamp power and airflow at the corresponding position of the epitaxy machine.

3. A flatness measurement device for epitaxial wafers, wherein the device is applied to the analytical method for improving the SFQR of epitaxial wafers as described in claim 1, characterized in that: The flatness tester in step S1 includes a placement tray (1), multiple placement base bodies (3) fixed inside the placement tray (1) and arranged in a equidistant ring, and a wafer positioning and removal component that acts on the wafer placed inside the placement base body (3), so as to facilitate the fixing of the wafer and quick removal from the placement base body (3) after the test is completed.

4. The flatness measuring device for an epitaxial wafer according to claim 3, characterized in that: The positioning and removal assembly includes an inner compartment (4) opened inside the placement body (3), a second toothed ring (5) inserted into the inner cavity of the inner compartment (4), a limiting component acting on the second toothed ring (5), and a plurality of clamping components arranged in a equidistant ring around the inner wall of the inner circumferential surface of the placement body (3).

5. The flatness measuring device for an epitaxial wafer according to claim 4, characterized in that: The limiting component includes an annular groove (6) connected to the upper and lower ends of the inner cavity of the inner compartment (4) and a limiting ring (7) slidably inserted into the inner cavity of the annular groove (6). The ends of two adjacent limiting rings (7) that are close to each other are fixed to the surfaces of the upper and lower ends of the second toothed ring (5).

6. The flatness measuring device for an epitaxial wafer according to claim 4, characterized in that: The clamping component includes a sliding shaft (10) slidably inserted into the inner wall of the inner circumferential surface of the placement base body (3), a connecting shaft (13) fixed to one end of the sliding shaft (10), a clamping plate (11) fixed to one end of the connecting shaft (13), a connecting block (9) fixed to the other end of the sliding shaft (10), and a plurality of abutting blocks (8) fixed to the inner circumferential surface of the second gear ring (5) and arranged in a equidistant ring.

7. The flatness measuring device for an epitaxial wafer according to claim 6, characterized in that: The clamping component also includes a collar (12) fixedly sleeved on the outer circumferential surface of the sliding shaft (10) and a spring (14) fixed to one end of the collar (12), one end of the spring (14) being fixed to the inner circumferential surface of the placement seat body (3).

8. The flatness measuring device for an epitaxial wafer according to claim 7, characterized in that: The positioning and removal assembly further includes a first gear ring (2) rotatably connected to the inner circumferential surface of the placement disk (1), a plurality of movable shafts (17) rotatably connected to the inner wall of the placement disk (1) near the adjacent placement seat body (3) and arranged in a equidistant arrangement, and a gear (18) fixedly sleeved on the outer circumferential surface of the movable shafts (17). The gear (18) is meshed with the adjacent second gear ring (5) and the first gear ring (2).

9. The flatness measuring device for an epitaxial wafer according to claim 8, characterized in that: The positioning and removal assembly further includes an ejection assembly, which includes a support plate (15) disposed at the bottom of the inner cavity of the placement body (3), a top rod (16) slidably inserted into the inner wall of the placement body (3) and the placement plate (1), a plurality of bottom rods (19) disposed at the bottom of the placement plate (1), a rectangular groove (22) opened inside the movable shaft (17), a sliding rod (21) slidably inserted at the middle position of the movable shaft (17), a rectangular block (23) slidably inserted into the inner cavity of the rectangular groove (22), a connecting strip (24) fixed to the bottom of the rectangular block (23), and a fixed sleeve on the top rod (16) extending to the placement plate. The plate (20) at the bottom of the plate (1), the support component acting on the bottom rod (19), and the connecting ring (27) fixed between the multiple top rods (16) are provided. The connecting strip (24) is slidably inserted into the inner wall of the movable shaft (17) and the inner wall of the plate (1). The bottom of the connecting strip (24) is fixed to the top surface of the adjacent bottom rod (19). The support component includes a support groove (26) opened on the inner wall of the plate (20) near the bottom rod (19) and a support ring (25) inserted into the cavity of the support groove (26). The inner circumferential surface of the support ring (25) is fixed to the outer circumferential surface of the bottom rod (19).

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