Method for machining outer circle of crystal ingot

Abstract

The invention discloses a method for machining an outer circle of a crystal ingot and crystal ingot machining equipment, and the method comprises the steps: determining the end face circle center of a to-be-machined end face on the to-be-machined end face of the crystal ingot, and carrying out the resistivity measurement of measurement points distributed on the to-be-machined end face, and obtaining the resistivity of each measurement point; determining the radius of the circular area template, taking the circle center of the end face as the initial circle center of the circular area template, moving the circular area template for multiple times based on preset movement parameters to obtain a plurality of circular areas, calculating the variance of the measurement points included in each circular area, and comparing the variances to obtain a plurality of measurement points; the circular area corresponding to the minimum variance is a reserved circular area; and based on the circle center and the radius of the reserved circular area, the to-be-machined end face and the circumferential face of the crystal ingot are machined through crystal ingot machining equipment, the cylindrical crystal ingot with the reserved circular area as the end face is obtained, then the cylindrical crystal ingot with the uniform resistivity in the reserved area is obtained, and the crystal ingot machining quality is improved.

Description

Technical Field

[0001] The invention relates to the technical field of wafer processing, and in particular to a method for processing the outer circle of a crystal ingot. Background Art

[0002] In wafer processing, for the outer circle processing of silicon carbide ingots or the reduction of large-sized crystals to smaller sizes, it is required to remove burrs, holes, grooves, and impurities around the ingot by means of eccentric rollers on cylindrical grinders and rod-pulling machines, so as to retain a cylindrical ingot with a smooth outer circumference, which is conducive to the next step of processing.

[0003] The processing methods currently used generally only focus on retaining the cylindrical ingot area to avoid drilling grooves, miscellaneous crystals, small faces, etc. There is no exact standard to determine the location of the retained area, which makes it difficult to ensure the resistivity uniformity of the retained area.

[0004] Therefore, how to ensure uniform resistivity of the reserved area is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0005] In view of this, the present invention provides a method for processing the outer circle of a crystal ingot, by calculating the variance and then retaining the circular area corresponding to the minimum variance, thereby ensuring that the resistivity of the retained area after the crystal ingot is uniform.

[0006] The present invention also provides a crystal ingot processing device comprising the method for processing the outer circle of the crystal ingot.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for processing an outer circle of a crystal ingot, comprising:

[0009] S1. On the end face to be processed of the ingot, determine the end face center of the end face to be processed, and measure the resistivity of the measuring points distributed on the end face to be processed to obtain the resistivity of each measuring point; wherein the measuring points are circular, and adjacent measuring points are tangent to each other;

[0010] S2, determining the radius of the circular area template, taking the center of the end face as the initial center of the circular area template, moving the circular area template multiple times based on preset movement parameters to obtain multiple circular areas, calculating the variance of the measurement points included in each circular area, comparing the variances, and the circular area corresponding to the smallest variance is the reserved circular area;

[0011] S3. Based on the center of the reserved circular area and its radius, use ingot processing equipment to process the end face to be processed and the circumferential surface of the ingot to obtain a cylindrical ingot with the reserved circular area as the end face.

[0012] Preferably, in S2, taking the end face center as the initial center of the circular area template, and moving the circular area template multiple times based on preset movement parameters to obtain multiple circular areas, includes:

[0013] The center of the end face circle is set as the coordinate origin to construct the coordinate axis; among the multiple measuring points, the center of one measuring point is made to coincide with the coordinate origin, and the remaining measuring points are divided into multiple groups, wherein the multiple groups of measuring points are concentrically distributed, and the measuring points of each group are distributed around the coordinate origin;

[0014] Taking the coordinate origin as the initial center of the circular area template, a first circular area is obtained;

[0015] Each group of the measuring points is used as the current processing group in order from near to far according to the distance from the initial center of the circle. For the current processing group, the center of the circular area is moved to the center of each measuring point of the current processing group to obtain multiple circular areas, and the multiple circular areas are all within the range of the ingot.

[0016] Preferably, setting the center of the end face circle as the coordinate origin and constructing the coordinate axis includes: setting the center of the end face circle as the coordinate origin, setting the distance between two adjacent scales of the horizontal axis to 2r, setting the distance between two adjacent scales of the vertical axis to √3r, and constructing the coordinate axis; wherein r is the radius of the measuring point.

[0017] Preferably, before S1, the method further includes:

[0018] The end surface to be processed is flat-ground.

[0019] Preferably, the calculating the variance of the measurement points contained in each circular area comprises:

[0020] Determine the number n of measurement points contained in each circular area and the resistivity ρ of each measurement point;

[0021] The average resistivity of the measuring points contained in each circular area is calculated based on the resistivity p of each measuring point.

[0022] Based on the number n, the resistivity ρ, the average value of the resistivity The variance of each of the circular areas is calculated.

[0023] Preferably, S3 includes:

[0024] Based on the center and radius of the reserved circular area, the reserved circular area is marked by using a circle marking component of an ingot processing device;

[0025] Based on the marked reserved circular area, the end face to be processed and the redundant part of the circumference of the ingot are removed by using the processing parts of the ingot processing equipment to obtain a cylindrical ingot with the reserved circular area as the end face.

[0026] Preferably, the end face to be processed is a carbon end face.

[0027] Preferably, the outermost measuring points are tangent to the edge of the end surface to be processed.

[0028] A crystal ingot processing device comprises: using the above-mentioned method for processing the outer circle of the crystal ingot to process the crystal ingot.

[0029] It can be seen from the above technical solution that the method for processing the outer circle of the crystal ingot provided by the present invention calculates the variance, and the circular area corresponding to the minimum variance is the retained circular area. The crystal ingot is processed based on the retained circular area. In this way, the resistivity of the retained area after the crystal ingot is ensured to be uniform (avoiding the traditional random determination of the position of the reserved area, which makes it difficult to ensure the resistivity uniformity of the selected area), so as to improve the quality of the crystal ingot processing.

[0030] The present invention also provides a crystal ingot processing device. Since the above-mentioned method for processing the outer circle of the crystal ingot is adopted, it also has corresponding beneficial effects. For details, please refer to the previous description, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic flow chart of a method for processing the outer circle of a crystal ingot provided in an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of an end face to be processed provided by an embodiment of the present invention;

[0034] Figure 3 A motion trajectory diagram of a circular area provided by an embodiment of the present invention.

[0035] The meanings of the reference numerals in the figures are as follows:

[0036] 20 is the end face to be processed, and 30 is the measuring point. DETAILED DESCRIPTION

[0037] First, the technical terms involved in this solution are explained as follows;

[0038] During the growth process of SiC single crystal, two regions with different growth modes are formed, namely facet regions and non-facet regions. It is known that the facet regions and non-facet regions have different physical properties such as resistivity and defect density due to the difference in their growth modes.

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The method for processing the outer circle of a crystal ingot provided by an embodiment of the present invention is as follows: Figure 1 and Figure 2 As shown, including:

[0041] S1. On the end face 20 of the ingot to be processed, determine the end face center of the end face 20 to be processed, and measure the resistivity of the measuring points 30 distributed on the end face 20 to be processed, so as to obtain the resistivity of each measuring point 30; wherein the measuring points 30 are circular, and adjacent measuring points 30 are tangent to each other;

[0042] S2. Determine the radius of the circular area template, take the end face center as the initial center of the circular area template, move the circular area template multiple times based on preset movement parameters to obtain multiple circular areas, calculate the variance of the measurement points 30 included in each circular area, compare the variances, and the circular area corresponding to the smallest variance is the retained circular area; the measurement points 30 included in the circular area can be understood as follows: including: measurement points 30 completely located in the circular area, and measurement points 30 with overlapping areas with the circular area; preferably, the measurement points 30 included in the circular area are measurement points 30 completely located in the circular area.

[0043] S3. Based on the center of the retained circular area and its radius, the end face 20 to be processed and the circumferential surface of the ingot are processed using an ingot processing device to obtain a cylindrical ingot with the retained circular area as the end face.

[0044] In the above technical solution, the variance of each circular area is calculated, and the circular area corresponding to the smallest variance is the retained circular area. The ingot is processed based on the retained circular area. This ensures that the resistivity of the retained area after the ingot is uniform (avoiding the traditional problem of randomly determining the position of the reserved area, which makes it difficult to ensure the resistivity uniformity of the selected area), so as to improve the quality of the ingot processing.

[0045] Optimize the above technical solutions, such as Figure 3 As shown, in S2, the end face center is used as the initial center of the circular area template, and the circular area template is moved multiple times based on preset movement parameters to obtain multiple circular areas, including:

[0046] The center of the end face circle is set as the coordinate origin to construct the coordinate axis; among the multiple measuring points 30, the center of one measuring point 30 is made to coincide with the coordinate origin, and the remaining measuring points 30 are divided into multiple groups, the multiple groups of measuring points 30 are concentrically distributed, and the measuring points 30 of each group are distributed around the coordinate origin;

[0047] The coordinate origin is used as the initial center of the circular area template to obtain the first circular area;

[0048] Each group of measuring points 30 is used as the current processing group in order from near to far in terms of the distance from the initial center of the circle. For the current processing group, the center of the circular area is moved to the center of each measuring point 30 of the current processing group to obtain multiple circular areas, all of which are within the range of the ingot.

[0049] In the above technical solution, after moving multiple times, the circular areas obtained by superposition can cover the entire end face 20 to be processed, and the outer edge of the circular area is tangent to the edge of the end face 20 to be processed, so that the resistivity uniformity of the circular area is further improved.

[0050] In a further optimization, for the current processing group, the center of the circular area is moved counterclockwise to the center of each measuring point 30 of the current processing group, thereby forming a plurality of circular areas.

[0051] In a specific technical solution, the center of the circular area moves from the inside to the outside, and the multiple groups of measurement points from the inside to the outside are respectively the first group of measurement points 30, the second group of measurement points 30, the third group of measurement points 30, etc. First, the center of the circular area is moved to the center of each measurement point 30 of the first group of measurement points 30 to obtain multiple circular areas, then the center of the circular area is moved to the center of each measurement point 30 of the second group of measurement points 30 to obtain multiple circular areas, and then the center of the circular area is moved to the center of each measurement point 30 of the third group of measurement points 30 to obtain multiple circular areas.

[0052] Further optimizing the above technical solution, setting the end face circle center as the coordinate origin, constructing the coordinate axis, including: setting the end face circle center as the coordinate origin, setting the distance between two adjacent scales of the horizontal coordinate to 2r, setting the distance between two adjacent scales of the vertical coordinate to √3r, and constructing the coordinate axis; wherein r is the radius of the measuring point 30. In the above technical solution, if the coordinate value of the retained circular area is (i m ,j m ), then the corresponding actual coordinate value is (2ri m ,√3rj m ), for example, if the coordinate value of the circular area is retained as (1,1), the corresponding actual coordinate value is (2r,√3r), or if the coordinate value of the circular area is retained as (2,2), the corresponding actual coordinate value is (4r,2√3r).

[0053] In an optional embodiment, before S1, the method further includes:

[0054] The end surface 20 to be processed is flat-ground, thereby improving the accuracy of the resistivity measured at each measuring point 30 on the end surface 20 to be processed.

[0055] In an optional embodiment, calculating the variance of the measurement points 30 included in each circular area includes:

[0056] Determine the number n of measurement points 30 contained in each circular area and the resistivity ρ of each measurement point 30;

[0057] Based on the resistivity ρ of each measuring point 30, the average resistivity of the measuring points 30 included in each circular area is calculated.

[0058] Based on the number n, the resistivity ρ, the average resistivity Calculate the variance of each circular area.

[0059] In the above scheme, the resistivity ρ of each measuring point 30 is detected by using an eddy current resistivity meter, and then the variance of each circular area is calculated using the following formula;

[0060]

[0061] In the above formula, where σ 2 Represents the variance of each circular area, Ω represents each circular area. In order to distinguish each measuring point 30, (i, j) in the resistivity value ρ(i, j) represents the coordinate values ​​of different measuring points 30. Preferably, only the measuring points 30 that are completely located in the circular area are counted.

[0062] In an optional embodiment, S3 includes:

[0063] S31, based on the center and radius of the reserved circular area, using a circle marking component of an ingot processing device to mark the reserved circular area;

[0064] S32. Based on the marked reserved circular area, the processing components of the ingot processing equipment are used to remove the end face 20 to be processed and the redundant parts of the circumference of the ingot, so as to obtain a cylindrical ingot with the reserved circular area as the end face.

[0065] In the above technical solution, the use of the rounding component and the processing component can quickly process the crystal ingot to obtain the required cylindrical crystal ingot.

[0066] In an optional embodiment, the end face 20 to be processed is a carbon end face, which is beneficial to improving the accuracy of detecting the resistivity ρ.

[0067] In an optional embodiment, the outermost measuring point 30 is tangent to the edge of the end surface 20 to be processed, thereby further improving the accuracy of retaining the circular area variance.

[0068] In an optional embodiment, the diameter of the reserved circular area is 150 mm. Of course, the diameter of the reserved circular area can also be determined according to actual needs, and is not specifically limited here.

[0069] The present invention also provides a crystal ingot processing device, including: using the above method for processing the outer circle of the crystal ingot. Since this solution adopts the above method for processing the outer circle of the crystal ingot, it also has corresponding beneficial effects, which can be specifically referred to the above description and will not be repeated here.

[0070] The technical features mentioned above, the technical features to be mentioned below, and the technical features shown separately in the drawings can be combined with each other arbitrarily, as long as the combined technical features are not contradictory. All feasible feature combinations are technical contents clearly recorded in this article. Any of the multiple sub-features contained in the same sentence can be applied independently, and does not have to be applied together with other sub-features.

[0071] The present invention is further described below in conjunction with specific embodiments:

[0072] In a specific embodiment, an 8-inch silicon carbide ingot is changed to a 6-inch ingot:

[0073] Step 1: Grind the carbon end face and silicon end face of the ingot flat, and test the resistivity of the carbon end face;

[0074] Step 2: Determine the diameter of the area to be retained as 150mm, and select a circular area with a diameter of 150mm and the best resistivity uniformity as the retained circular area. Determine the initial center of the circular area template, and use the coordinate origin (that is, the end face center of the ingot) to obtain the first circular area. Move the circular area again around the coordinate origin to obtain multiple circular areas (multiple circular areas are within the ingot range), and calculate the variance σ of each circular area 2 , choose the one with the smallest variance σ 2 The circular area is taken as the reserved circular area;

[0075] Step 3: Use a grinder or a rod-pulling machine to process along the marked circular area to obtain a 6-inch ingot with no small facets and good resistivity uniformity.

[0076] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0077] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for processing the outer circle of a crystal ingot, characterized in that: include: S1. On the end face (20) to be processed of the ingot, determine the end face center of the end face (20) to be processed, and measure the resistivity of the measuring points (30) distributed on the end face (20) to obtain the resistivity of each measuring point (30); wherein the measuring points (30) are circular, and adjacent measuring points (30) are tangent to each other; S2, determining the radius of the circular area template, taking the end face center as the initial center of the circular area template, moving the circular area template multiple times based on a preset movement parameter to obtain multiple circular areas, calculating the variance of the measurement points (30) contained in each circular area, comparing the variances, and the circular area corresponding to the smallest variance is the reserved circular area; S3. Based on the center and radius of the reserved circular area, the end face to be processed (20) and the circumferential surface of the ingot are processed using ingot processing equipment to obtain a cylindrical ingot with the reserved circular area as the end face.

2. The method for processing the outer circle of a crystal ingot according to claim 1, characterized in that: In S2, the end face center is used as the initial center of the circular area template, and the circular area template is moved multiple times based on preset movement parameters to obtain multiple circular areas, including: The center of the end face circle is set as the coordinate origin to construct a coordinate axis; among the plurality of measurement points (30), the center of one measurement point (30) is made to coincide with the coordinate origin, and the remaining measurement points (30) are divided into a plurality of groups, wherein the plurality of groups of measurement points (30) are concentrically distributed, and the measurement points (30) in each group are distributed around the coordinate origin; Taking the coordinate origin as the initial center of the circular area template, a first circular area is obtained; Each group of the measuring points (30) is used as a current processing group in order from near to far in terms of the distance from the initial center of the circle. For the current processing group, the center of the circular area is moved to the center of each measuring point (30) of the current processing group to obtain a plurality of circular areas, all of which are within the range of the ingot.

3. The method for processing the outer circle of a crystal ingot according to claim 2, characterized in that: The step of setting the center of the end face circle as the coordinate origin and constructing the coordinate axis comprises: setting the center of the end face circle as the coordinate origin, setting the distance between two adjacent scales of the horizontal coordinate to 2r, setting the distance between two adjacent scales of the vertical coordinate to √3r, and constructing the coordinate axis; wherein r is the radius of the measuring point (30).

4. The method for processing the outer circle of a crystal ingot according to claim 1, characterized in that: Before S1, it also includes: The end surface (20) to be processed is flat-ground.

5. The method for processing the outer circle of a crystal ingot according to claim 1, characterized in that: The calculating of the variance of the measurement points (30) contained in each circular area comprises: Determining the number n of measurement points (30) contained in each of the circular areas and the resistivity ρ of each of the measurement points (30); Based on the resistivity ρ of each of the measuring points (30), an average resistivity of the measuring points (30) included in each of the circular areas is calculated. Based on the number n, the resistivity ρ, the average value of the resistivity The variance of each of the circular areas is calculated.

6. The method for processing the outer circle of a crystal ingot according to claim 1, characterized in that: The S3 includes: Based on the center and radius of the reserved circular area, the reserved circular area is marked by using a circle marking component of an ingot processing device; Based on the marked reserved circular area, the processing components of the ingot processing equipment are used to remove the end face (20) to be processed and the redundant part of the circumference of the ingot, so as to obtain a cylindrical ingot with the reserved circular area as the end face.

7. The method for processing the outer circle of a crystal ingot according to claim 1, characterized in that: The end face (20) to be processed is a carbon end face.

8. The method for processing the outer circle of a crystal ingot according to claim 1, characterized in that: The outermost measuring point (30) is tangent to the edge of the end surface (20) to be processed.

9. A crystal ingot processing device, characterized in that: include: The ingot is processed by the method for processing the outer circle of the ingot as described in any one of claims 1 to 8.

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