Silicon carbide wafer with low orientation deviation and method for non-destructively detecting crystal face deflection angle and orientation deviation of wafer

Abstract

The invention discloses a low-orientation-deviation silicon carbide wafer and a method for non-destructively detecting the crystal face deflection angle and orientation deviation of the wafer, and belongs to the technical field of silicon carbide wafer detection. The method is used for fixing a wafer and testing the wafer by using an X-ray diffractometer, and comprises the following steps of: (1) adjusting an incident angle scanning range to be (17.8 degrees-a preset deflection angle) + / -0.5 degrees to obtain a crystal face deflection angle A of the wafer, if a difference value between the crystal face deflection angle A and the preset deflection angle is within + / -0.1 degrees, continuing the next step of testing, otherwise, judging that the wafer is unqualified, and stopping testing; (2) adjusting the scanning range of the incident angle to be (17.8 degrees-A) + / -0.1 degrees, defining the Notch position of the wafer as 0 degree, and rotating the wafer in a plane by 360 degrees to obtain an in-plane deflection angle P of the wafer; and (3) testing to obtain a diffraction angle C, and calculating the orientation deviation angle omega of the wafer according to a formula. According to the method, an X-ray diffractometer is adopted to carry out nondestructive testing on the wafer, the testing accuracy is improved while the testing speed is increased, and industrial application detection is facilitated.

Description

Technical Field

[0001] The present application relates to a low-orientation-deviation silicon carbide wafer and a method for non-destructively testing the crystal plane angle and orientation deviation of the wafer, belonging to the technical field of silicon carbide wafer testing. Background Art

[0002] Silicon carbide materials are widely used in power devices and high-frequency devices, but at the same time, its growth and processing difficulty is much higher than conventional materials. Silicon carbide wafers face a variety of technical difficulties during processing, which mainly stems from their high hardness, high melting point and material properties. One of the difficulties includes the control and detection of crystal plane angle and orthogonal orientation deviation. The crystal plane angle and orthogonal orientation deviation of the wafer have a significant impact on the electrical and optical properties and process consistency of the chip. The following are the main effects of these two on chip performance and manufacturing:

[0003] Leakage current: Crystal plane angle and orientation deviation may lead to an increase in crystal defects, which in turn cause interface defects and increase leakage current, especially in ultra-low power and high-performance devices.

[0004] Alignment deviation: The photolithography process relies on the specific orientation of the wafer as an alignment reference. If the crystal plane angle or orientation deviation is not within the controllable range, it will cause device failure or performance degradation.

[0005] Etching and doping non-uniformity: Etching rate and doping distribution are related to crystal orientation. Orientation deviation will lead to uneven material removal rate or doping concentration during these processes, which in turn affects chip function and reliability.

[0006] Stress concentration: Crystal plane deflection and orientation deviation may cause uneven stress distribution inside the crystal. During high-temperature operation or packaging, this uneven stress can cause defects such as cracks and dislocations, affecting the long-term reliability of the chip.

[0007] Material defects: Crystal plane deviation is usually accompanied by more crystal defects, especially dislocation or vacancy defects. These defects will have a negative impact on the switching speed, voltage resistance and electrical consistency of semiconductor devices.

[0008] In power devices, crystal orientation has a significant impact on thermal conductivity and on-resistance. Orientation deviation will affect the chip's heat dissipation and current handling capabilities, thereby limiting its high-power applications.

[0009] Therefore, it can be seen that the crystal plane angle and orientation deviation of the wafer will have a significant impact on the performance, manufacturing process and reliability of the chip. These effects are particularly important for high-performance and advanced process node chips. Therefore, in semiconductor manufacturing, strict control of crystal plane angle and orientation deviation is the key to ensuring device consistency and yield.

[0010] At present, the testing of crystal plane angle and orientation deviation of silicon carbide wafers has the disadvantages of complicated steps (slow detection speed), low test accuracy, and difficulty in industrial application. Therefore, there is an urgent need for a non-destructive testing method with fast detection speed, high test accuracy and easy industrial application. Summary of the invention

[0011] In order to solve the above problems, a method for non-destructive detection of crystal plane angle and orientation deviation of wafer is provided. The method uses an X-ray diffractometer to perform non-destructive detection on the wafer. The crystal plane angle A is first obtained, and the difference between the crystal plane angle A and the preset angle is used as a test standard for whether the orientation deviation angle Ω can be performed. Then, the diffraction angle C is used to correct the orientation deviation angle Ω to improve the test accuracy. The method has simple steps and is convenient for industrial application detection.

[0012] According to one aspect of the present application, a method for non-destructively detecting the crystal plane angle and orientation deviation of a wafer is provided, wherein the wafer is fixed and tested using an X-ray diffractometer, comprising the steps of:

[0013] (1) Adjust the incident angle scanning range to (17.8°-preset deflection angle) ±0.5° to obtain the crystal plane deflection angle A of the wafer. If the difference between the crystal plane deflection angle A and the preset deflection angle is within ±0.1°, proceed to the next step of testing; otherwise, it is judged as unqualified and no further testing is performed;

[0014] (2) Adjust the incident angle scanning range to (17.8°-A)±0.1°, and determine the final incident angle. The wafer Notch position is defined as 0°, and the wafer is rotated 360° in the plane to obtain the wafer's in-plane deflection angle P;

[0015] (3) The diffraction angle C is obtained by testing, and the orientation deviation angle Ω of the wafer is calculated as follows:

[0016]

[0017] The above detection method uses an X-ray diffractometer to detect the wafer, so as to obtain the crystal plane angle and orientation deviation of the wafer, thereby achieving non-destructive detection while improving the detection speed and detection accuracy.

[0018] Wafers whose crystal plane deflection angle A differs from the preset deflection angle within ±0.1° are further subjected to step (2) because if the difference between the crystal plane deflection angle A and the preset deflection angle is greater than ±0.1°, it indicates that the wafer quality is poor and subsequent epitaxial growth is difficult, so there is no need to continue testing. The traditional method is to test within the (0001) plane, but since the actual crystal plane is not fixedly tilted in a certain direction, it is necessary to test the deviation of the actual crystal plane within the plane by testing the in-plane deflection angle P, and to test the deviation of the actual crystal plane between planes by testing the diffraction angle C, and comprehensively consider these two angles to characterize the orientation deviation angle. The present application uses the diffraction angle C and the in-plane deflection angle P to correct the orientation deviation angle Ω, which can achieve multi-dimensional characterization of the wafer within and between planes, thereby improving the accuracy of detection.

[0019] The range of the incident angle adjusted in step (1) refers to the incident angle within the range in which the incident angle is adjusted. A diffraction peak appears at only one angle within (17.8°-preset deflection angle) ±0.5°. The incident angle at which the diffraction peak appears is the true incident angle, and the crystal plane deflection angle A = 17.8°-true incident angle.

[0020] Optionally, in step (2), the incident angle range is adjusted to (17.8°-A)±0.1°. Compared with the scanning range in step (1), the smaller the scanning range is, the better the test accuracy can be, and the in-plane deflection angle P and diffraction angle C can be obtained more accurately, thereby improving the detection efficiency and accuracy.

[0021] Optionally, the preset deflection angle of step (1) is 0-8°.

[0022] The preset deflection angle in step (1) is for the needs of subsequent processing and production. Setting it within the range of 0-8° can facilitate epitaxy and improve the growth stability of the step flow of the epitaxial layer.

[0023] Optionally, in step (2), when A=0, the in-plane deflection angle

[0024] P = (|Peak1-60|+|(Peak2-120)|+|(Peak3-180)|+|(Peak4-240)|+|(Peak5-300)|) / 5. During the 360° rotation of the wafer, Peak1 is the angle of the peak that appears in the range of 60±1°, Peak2 is the angle of the peak that appears in the range of 120±1°, Peak3 is the angle of the peak that appears in the range of 180±1°, Peak4 is the angle of the peak that appears in the range of 240±1°, and Peak5 is the angle of the peak that appears in the range of 300±1°.

[0025] When A≠0, a peak appears when the wafer rotates 360°, and the in-plane deflection angle P is the angle of the peak obtained by the test.

[0026] Optionally, in step (3), the wafer is scanned in a normal direction of a plane formed by the incident light, the test point and the receiving point within a range of ±5°, and the strongest diffraction peak is obtained by testing. The angle at which the strongest diffraction peak is located is the diffraction angle C.

[0027] Under this setting, the diffraction angle C of the wafer can be accurately tested, otherwise the diffraction angle C cannot be obtained.

[0028] Optionally, the size of the wafer is at least 6 inches, and the number of test points for testing the wafer is at least 5.

[0029] Optionally, the size of the wafer is at least 8 inches, and the number of test points for testing the wafer is at least 9.

[0030] When the wafer is 6 inches, the test points are (40,0), (-40,0), (0,40), (0,-40), (0,0).

[0031] When the wafer is 8 inches, the test points are (90,0), (-90,0), (0,90), (0,-90), (0,45), (0,-45), (45,0), (-45,0), (0,0).

[0032] Optionally, the surface roughness Ra of the wafer is less than 10 nm.

[0033] The surface roughness setting of the wafer can reduce interference and further improve the detection accuracy.

[0034] According to another aspect of the present application, a method for non-destructively determining the quality of a wafer is provided, wherein the wafer is tested using any of the methods described above, and when the difference between the crystal plane deviation angle A and the preset deviation angle is within ±0.1° and the orientation deviation angle Ω is within ±1°, the wafer is determined to be qualified, otherwise the wafer is determined to be unqualified.

[0035] This determination method is based on the above-mentioned method for non-destructively detecting the crystal plane angle and orientation deviation of the wafer, and is based on the difference between the crystal plane angle A and the preset angle and the orientation deviation angle Ω. It can quickly and efficiently determine whether the wafer is qualified, improve the determination efficiency, save the determination cost, and improve the determination accuracy.

[0036] According to another aspect of the present application, a low-orientation deviation silicon carbide wafer is provided. The silicon carbide wafer is tested using any of the methods described above, and the difference between the crystal plane deviation angle A of the silicon carbide wafer and the preset deviation angle is within ±0.1°, and the orientation deviation angle Ω of the silicon carbide wafer is within ±1°.

[0037] Optionally, the difference between the crystal plane deviation angle A of the silicon carbide wafer and a preset deviation angle is within ±0.054°, and the orientation deviation angle Ω of the silicon carbide wafer is within ±0.961°.

[0038] The beneficial effects of this application include but are not limited to:

[0039] 1. The method of non-destructive testing of the crystal plane angle and orientation deviation of the wafer of the present application uses an X-ray diffractometer to test the wafer, which can improve the detection efficiency and reduce the detection cost. At the same time, it can also realize non-destructive testing of the wafer, which is convenient for industrial application.

[0040] 2. The method of non-destructive testing of the crystal plane angle and orientation deviation of the wafer of the present application uses the diffraction angle C and the in-plane angle P to correct the orientation deviation angle Ω, which can improve the test accuracy to better determine whether the wafer can be subsequently produced and processed, and avoid wasting production energy.

[0041] 3. The method of non-destructive testing of the crystal plane angle and orientation deviation of the wafer of the present application can quickly and accurately test the wafer, so as to feed back the test results to the production of the wafer to optimize the production process of the wafer and facilitate the acquisition of high-quality silicon carbide wafers and high-quality silicon carbide crystals.

[0042] 4. The non-destructive method for determining whether a wafer is qualified can be used to quickly and efficiently determine whether a wafer is qualified, thereby improving determination efficiency while saving determination costs and improving determination accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0044] Figure 1 This is a schematic diagram of the test of the wafer involved in Example 1 of the present application.

[0045] Figure 2 This is a test diagram of the in-plane deflection angle P under different conditions involved in Example 1 of the present application.

[0046] Figure 3 This is a test schematic diagram of the diffraction angle C involved in Example 1 of the present application.

[0047] Figure 4 Schematic diagram of the crystal plane tilt of the wafer.

[0048] List of parts and reference numerals:

[0049] 1. X-ray transmitter; 2. X-ray receiver; 3. Wafer; 4. Crystal plane. DETAILED DESCRIPTION

[0050] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0051] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0052] Unless otherwise specified, the methods used in the embodiments of the present application are conventional methods in the prior art. In the following embodiments, when an X-ray diffractometer is used to test a wafer, the rotation of the wafer in a plane or the scanning of the wafer along the normal direction of the plane formed by the incident light, the test point and the receiving point can be implemented in the prior art, such as adding a rotation unit or a tilting unit to the X-ray diffractometer to automatically control the wafer to adjust according to the above requirements, or it can also be adjusted manually. The above implementation does not limit the present application.

[0053] Example 1

[0054] This embodiment relates to a method for non-destructively detecting the angle and orientation deviation of the crystal plane 4 of the wafer 3. Figure 1 , first fix the wafer 3, and use an X-ray diffractometer to test the wafer 3. The surface roughness Ra of the wafer 3 is less than 10nm, including the steps of:

[0055] (1) The X-ray transmitter 1 emits X-rays, and the incident angle scanning range is adjusted to (17.8°-preset deflection angle) ±0.5°, and the preset deflection angle is 0-8°. The X-ray receiver 2 receives the reflected X-rays and obtains the deflection angle A of the crystal plane 4 of the wafer 3. If the difference between the deflection angle A of the crystal plane 4 and the preset deflection angle is within ±0.1°, the next step of testing is continued. Otherwise, it is judged as unqualified and no further testing is performed.

[0056] (2) Adjust the incident angle scanning range to (17.8°-A)±0.1°, define the Notch position of wafer 3 as 0°, rotate wafer 3 360° in the plane, and X-ray receiver 2 receives the reflected X-rays to obtain the in-plane deflection angle P of wafer 3:

[0057] refer to Figure 2 (a), when A≠0, wafer 3 rotates 360° and a peak appears. The in-plane deflection angle P is the angle of the peak obtained by the test;

[0058] refer to Figure 2(b), when A=0, wafer 3 rotates 360° and five peaks appear, the in-plane deflection angle P=(|Peak1-60|+|(Peak2-120)|+(Peak3-180)|+(Peak4-240)|+(Peak5-300)|, during the wafer rotation of 360°, Peak1 is the angle of the peak appearing in the range of 60±1°, Peak2 is the angle of the peak appearing in the range of 120±1°, Peak3 is the angle of the peak appearing in the range of 180±1°, Peak4 is the angle of the peak appearing in the range of 240±1°, and Peak5 is the angle of the peak appearing in the range of 300±1°;

[0059] (3)Reference Figure 3 , the wafer 3 is scanned in the normal direction of the plane formed by the incident light, the test point and the receiving point within a range of ±5°, that is, the in-plane scanning range in the X direction is ±5°, and the diffraction angle C is obtained by test. The orientation deviation angle Ω of the wafer 3 is calculated as follows:

[0060]

[0061] Figure 3 The middle wafer 3 is scanned in the X direction, and the scanning range can be 5° in the positive direction or 5° in the negative direction. As long as the scanning range is within ±5°, the diffraction angle C can be obtained within this range.

[0062] refer to Figure 4 The testing principle of the testing method of this embodiment is: the crystal plane actually tested may not be tilted to a specific crystal direction, so we must consider both the in-plane and inter-plane directions when testing. Because when the inclination direction of the crystal plane is unknown, there may be additional signals when testing the diffraction angles in the plane or between planes alone. There are inclinations both in the plane and between planes, so this application uses the in-plane deflection angle P to characterize the in-plane inclination degree of wafer 3, and uses the diffraction angle C to characterize the inter-plane inclination degree of wafer 3. Therefore, the calculation formula of the above-mentioned orientation deviation angle Ω can accurately know the orientation deviation degree of wafer 3, thereby improving the accuracy of the detection results.

[0063] Under the preset bias angle of 0°, the method of this embodiment is used to perform 5-point tests on a 6-inch wafer, and the test points are (40, 0), (-40, 0), (0, 40), (0, -40), and (0, 0). Five tests are performed in parallel on each test point to obtain the crystal plane bias angle A and orientation deviation angle Ω at different test points of the 6-inch wafer, and the average test time of the five tests at the test point, the difference between the maximum and minimum values ​​of the crystal plane bias angle A in the five tests, and the difference between the maximum and minimum values ​​of the orientation deviation angle Ω in the five tests are calculated. The specific data are shown in Table 1:

[0064] Table 1

[0065]

[0066]

[0067] Under the preset bias angle of 4°, the method of this embodiment is used to perform 9-point tests on the 8-inch wafer, and the test points are (90,0), (-90,0), (0,90), (0,-90), (0,45), (0,-45), (45,0), (-45,0), (0,0), and each test point is tested five times in parallel to obtain the crystal plane bias angle A and orientation deviation angle Ω at different test points of the 6-inch wafer, and the average test time of the five tests at the test point, the difference between the maximum and minimum values ​​of the crystal plane bias angle A in the five tests, and the difference between the maximum and minimum values ​​of the orientation deviation angle Ω in the five tests are calculated. The specific data are shown in Table 2:

[0068] Table 2

[0069]

[0070] Example 2

[0071] The present embodiment relates to a method for non-destructively judging the quality of a wafer, which adopts the method of Example 1 to test the wafer. When the difference between the crystal plane angle A and the preset angle is within ±0.1° and Ω is within ±1°, the wafer is judged to be qualified, otherwise the wafer is judged to be unqualified.

[0072] The above is only the embodiment of the present application, and the protection scope of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the technical ideas and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for non-destructive detection of crystal plane angle and orientation deviation of a wafer, characterized in that: Fix the wafer and use X-ray diffractometer to test the wafer, including the following steps: (1) Adjust the incident angle scanning range to (17.8°-preset deflection angle) ±0.5° to obtain the crystal plane deflection angle A of the wafer. If the difference between the crystal plane deflection angle A and the preset deflection angle is within ±0.1°, proceed to the next step of testing; otherwise, it is judged as unqualified and no further testing is performed; (2) Adjust the incident angle scanning range to (17.8°-A)±0.1°, define the wafer Notch position as 0°, rotate the wafer 360° in the plane, and obtain the wafer's in-plane deflection angle P; (3) The diffraction angle C is obtained by testing, and the orientation deviation angle Ω of the wafer is calculated as follows:

2. The method for non-destructive detection of wafer crystal plane angle and orientation deviation according to claim 1, characterized in that: The preset deflection angle of step (1) is 0-8°.

3. The method for non-destructive detection of wafer crystal plane angle and orientation deviation according to claim 1, characterized in that: In step (2), when A=0, the wafer rotates 360° and a peak appears, and the in-plane deflection angle P=(|Peak1-60|+|(Peak2-120)|+|(Peak3-180)|+|(Peak4-240)|+|(Peak5-300)|) / 5. During the 360° rotation of the wafer, Peak1 is the angle of the peak that appears within the range of 60±1°, Peak2 is the angle of the peak that appears within the range of 120±1°, Peak3 is the angle of the peak that appears within the range of 180±1°, Peak4 is the angle of the peak that appears within the range of 240±1°, and Peak5 is the angle of the peak that appears within the range of 300±1°. When A≠0, a peak appears when the wafer rotates 360°, and the in-plane deflection angle P is the angle of the peak obtained from the test.

4. The method for non-destructive testing of wafer crystal plane angle and orientation deviation according to claim 1, characterized in that: In step (3), the wafer is scanned in the normal direction of the plane formed by the incident light, the test point and the receiving point within a range of ±5°, and the strongest diffraction peak is obtained by testing. The angle at which the strongest diffraction peak is located is the diffraction angle C.

5. The method for non-destructive detection of wafer crystal plane angle and orientation deviation according to claim 1, characterized in that: The size of the wafer is at least 6 inches, and the number of test points for testing the wafer is at least 5.

6. The method for non-destructive detection of wafer crystal plane angle and orientation deviation according to claim 7, characterized in that: The size of the wafer is at least 8 inches, and the number of test points for testing the wafer is at least 9.

7. The method for nondestructive testing of wafer crystal plane angle and orientation deviation according to claim 1, characterized in that: The surface roughness Ra of the wafer is less than 10 nm.

8. A method for non-destructively judging whether a wafer is qualified, characterized in that: The wafer is tested using the method described in any one of claims 1 to 7. When the difference between the crystal plane deviation angle A and the preset deviation angle is within ±0.1° and the orientation deviation angle Ω is within ±1°, the wafer is judged to be qualified, otherwise the wafer is judged to be unqualified.

9. A low orientation deviation silicon carbide wafer, characterized in that: The silicon carbide wafer is tested using the method described in any one of claims 1 to 7, wherein the difference between the crystal plane deviation angle A of the silicon carbide wafer and the preset deviation angle is within ±0.1°, and the orientation deviation angle Ω of the silicon carbide wafer is within ±1°.

10. The low orientation deviation silicon carbide wafer according to claim 9, characterized in that: The difference between the crystal plane deviation angle A of the silicon carbide wafer and the preset deviation angle is within ±0.054°, and the orientation deviation angle Ω of the silicon carbide wafer is within ±0.961°.

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