A method of machining the outer circle of a crystal ingot

Abstract

This invention discloses a method and equipment for processing the outer circle of a crystal ingot. On the end face of the ingot to be processed, the center of the end face is determined, and resistivity measurements are performed on measurement points distributed on the end face to obtain the resistivity of each measurement point. The radius of a circular region template is determined, and the center of the end face is used as the initial center of the circular region template. Based on preset movement parameters, the circular region template is moved multiple times to obtain multiple circular regions. The variance of the measurement points contained in each circular region is calculated, and the variances are compared. The circular region with the smallest variance is selected as the retained circular region. Based on the center and radius of the retained circular region, the ingot processing equipment is used to process the end face to be processed and the circumference of the ingot to obtain a cylindrical ingot with the retained circular region as the end face, thereby obtaining a cylindrical ingot with uniform resistivity in the retained region, thus improving the quality of ingot processing.

Description

Technical Field

[0001] This invention relates to the field of wafer processing technology, and in particular to a method for processing the outer diameter of a wafer ingot. Background Technology

[0002] In wafer processing, for the outer diameter processing of silicon carbide ingots or the reduction of the size of large crystals, it is required to remove defects such as burrs, holes, grooves, and impurities around the ingot by means of external cylindrical grinding machines, eccentric rolling, and rod-shaving machines, in order to retain a cylindrical ingot with a smooth outer perimeter, which is beneficial for the next step of processing.

[0003] Current processing methods generally only focus on avoiding drilling grooves, impurities, facets, etc. in the area of ​​the cylindrical ingot to be retained. There is no precise standard to determine the location of the retained area, which makes it difficult to guarantee the resistivity uniformity of the retained area.

[0004] Therefore, how to ensure the uniformity of resistivity in the retained region is a problem that urgently needs 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, the circular area corresponding to the smallest variance is selected as the retained circular area, thus ensuring that the resistivity of the retained area after the crystal ingot is uniform.

[0006] The present invention also provides an ingot processing apparatus that includes the above-described method for processing the outer diameter of an ingot.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for processing the outer diameter of a crystal ingot includes:

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

[0010] S2. Determine the radius of the circular region template, take the center of the end face as the initial center of the circular region template, move the circular region template multiple times based on the preset movement parameters to obtain multiple circular regions, calculate the variance of the measurement points contained in each circular region, compare the variances, and the circular region corresponding to the smallest variance is the retained circular region.

[0011] S3. Based on the center and radius of the reserved circular region, the end face to be processed and the peripheral surface of the crystal ingot are processed using a crystal ingot processing equipment to obtain a cylindrical crystal ingot with the reserved circular region as the end face.

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

[0013] Set the center of the end face circle as the origin of the coordinate system and construct the coordinate axis; among the multiple measurement points, make the center of one measurement point coincide with the origin of the coordinate system, divide the remaining measurement points into multiple groups, and the multiple groups of measurement points are concentrically distributed, with the measurement points in each group distributed around the origin of the coordinate system;

[0014] Using the origin of the coordinate system as the initial center of the circular region template, the first circular region is obtained;

[0015] According to the distance from the initial center of the circle, each group of measurement points is taken as the current processing group. For the current processing group, the center of the circular region is moved to the center of each of the measurement points in the current processing group to obtain multiple circular regions, all of which are within the ingot area.

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

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

[0018] The end face to be processed is then subjected to surface grinding.

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

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

[0021] The average resistivity ρ of each of the measured points is calculated based on the resistivity of the measured points within each circular region.

[0022] Based on the quantity n, the resistivity ρ, and the average value of the resistivity Calculate the variance of each of the circular regions.

[0023] Preferably, S3 includes:

[0024] Based on the center and radius of the reserved circular region, the reserved circular region is marked using the marking circle component of the ingot processing equipment;

[0025] Based on the marked circular area, the excess portion of the end face to be processed and the circumferential surface of the ingot is removed using the processing components of the ingot processing equipment to obtain a cylindrical ingot with the marked circular area as the end face.

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

[0027] Preferably, the outermost measuring point is tangent to the edge of the end face to be processed.

[0028] A crystal ingot processing apparatus includes: processing the crystal ingot using the above-described method for processing the outer diameter of the crystal ingot.

[0029] As can be seen from the above technical solution, the method for processing the outer circle of a crystal ingot provided by the present invention calculates the variance, and the circular area corresponding to the smallest variance is the retained circular area. The crystal ingot is processed based on the retained circular area, which can ensure that the resistivity of the retained area after crystal ingot processing is uniform (avoiding the problem that the resistivity uniformity of the selected area is difficult to guarantee due to the traditional random determination of the position of the retained area), thereby improving the quality of 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 crystal ingots is adopted, it has corresponding beneficial effects, which can be referred to the previous description and will not be repeated here. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic flowchart of a method for processing the outer diameter of a crystal ingot according to an embodiment of the present invention;

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

[0034] Figure 3 The motion trajectory diagram of the circular region provided in the embodiment of the present invention.

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

[0036] 20 represents the end face to be processed, and 30 represents the measurement point. Detailed Implementation

[0037] The technical terms involved in this solution are explained below;

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

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The method for processing the outer diameter of a crystal ingot provided in this embodiment of the invention, such as... Figure 1 and Figure 2 As shown, it includes:

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

[0042] S2. Determine the radius of the circular region template, using the center of the end face as the initial center of the circular region template. Move the circular region template multiple times based on preset movement parameters to obtain multiple circular regions. Calculate the variance of the measurement points 30 contained in each circular region. Compare the variances, and the circular region corresponding to the smallest variance is the retained circular region. The measurement points 30 contained in the circular region can be understood as including: measurement points 30 completely located within the circular region, and measurement points 30 with overlapping areas with the circular region. Preferably, the measurement points 30 contained in the circular region are measurement points 30 completely located within the circular region.

[0043] S3. Based on the center and radius of the retained circular region, the ingot processing equipment is used to process the end face 20 to be processed and the peripheral surface of the ingot to obtain a cylindrical ingot with the retained circular region as the end face.

[0044] In the above technical solution, by calculating the variance of each circular region, the circular region corresponding to the smallest variance is selected as the retained circular region. The ingot is then processed based on the retained circular region. This ensures that the resistivity of the retained region is uniform after the ingot is processed (avoiding the problem that the resistivity uniformity of the selected region is difficult to guarantee due to the traditional random determination of the location of the retained region), thereby improving the quality of ingot processing.

[0045] Optimize the above technical solutions, such as Figure 3 As shown in S2, the initial center of the circular region template is taken as the center of the end face circle. Based on preset movement parameters, the circular region template is moved multiple times to obtain multiple circular regions, including:

[0046] Set the center of the end face as the origin of the coordinate system and construct the coordinate axis. Among the multiple measurement points 30, make the center of one measurement point 30 coincide with the origin of the coordinate system, divide the remaining measurement points 30 into multiple groups, and distribute the multiple groups of measurement points 30 concentrically, with the measurement points 30 of each group distributed around the origin of the coordinate system.

[0047] Using the origin of the coordinate system as the initial center of the circular region template, we obtain the first circular region.

[0048] According to the distance from the initial center, each group of measurement points 30 is taken as the current processing group. For the current processing group, the center of the circular region is moved to the center of each measurement point 30 of the current processing group, resulting in multiple circular regions, all of which are within the ingot area.

[0049] In the above technical solution, after multiple movements, the resulting circular regions are stacked together to cover the entire end face 20 to be processed. The outer edge of the circular region is tangent to the edge of the end face 20 to be processed, thus further improving the uniformity of resistivity of the circular region.

[0050] Further optimization involves moving the center of the circular region counterclockwise to the center of each measurement point 30 in the current processing group, thus creating multiple circular regions.

[0051] In a specific technical solution, the center of the circular region moves from the inside out, and multiple sets of measurement points, namely the first set of measurement points 30, the second set of measurement points 30, the third set of measurement points 30, etc., are moved from the inside out. First, the center of the circular region is moved to the center of each measurement point 30 of the first set of measurement points 30, resulting in multiple circular regions. Then, the center of the circular region is moved to the center of each measurement point 30 of the second set of measurement points 30, resulting in multiple circular regions. Finally, the center of the circular region is moved to the center of each measurement point 30 of the third set of measurement points 30, resulting in multiple circular regions.

[0052] Further optimization of the above technical solution involves setting the center of the end face as the origin of the coordinate system and constructing a coordinate axis. This includes setting the center of the end face as the origin of the coordinate system, setting the distance between two adjacent scales of the horizontal axis to 2r, and setting the distance between two adjacent scales of the vertical axis to √3r, thus constructing the coordinate axis; where r is the radius of measurement point 30. In the above technical solution, if the coordinate values ​​of the retained circular area are (i m ,j m If ), then the corresponding actual coordinate value is (2ri). m ,√3rj m For example, if the coordinates of the circular region are (1,1), the corresponding actual coordinates are (2r,√3r), or if the coordinates of the circular region are (2,2), the corresponding actual coordinates are (4r,2√3r).

[0053] In an optional embodiment, prior to S1, the following is also included:

[0054] The end face 20 to be processed is ground flat, which improves the accuracy of the resistivity measured at each measuring point 30 on the end face 20 to be processed.

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

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

[0057] The average resistivity ρ of each measurement point 30 is calculated based on the resistivity of the measurement points 30 within each circular region.

[0058] The average resistivity is calculated based on the quantity n and resistivity ρ. Calculate the variance of each circular region.

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

[0060]

[0061] In the above formula, where σ 2 Ω represents the variance of each circular region. To distinguish between different measurement points 30, (i,j) in the resistivity value ρ(i,j) represents the coordinate values ​​of different measurement points 30. Preferably, only measurement points 30 that are completely located within the circular region are counted.

[0062] In an optional embodiment, S3 includes:

[0063] S31. Based on the center and radius of the retained circular area, mark the retained circular area using the standard circle component of the ingot processing equipment;

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

[0065] In the above technical solution, the use of the standard circle component and the processing component enables the rapid processing of 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 helps to improve the accuracy of the resistivity ρ detection.

[0067] In an optional embodiment, the outermost measurement point 30 is tangent to the edge of the end face 20 to be processed, thereby further improving the accuracy of preserving the variance of the circular region.

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

[0069] This invention also provides an ingot processing apparatus, comprising: processing the outer diameter of an ingot using the method described above. Since this solution employs the method described above for processing the outer diameter of an ingot, it possesses corresponding beneficial effects, as detailed in the preceding description, which will not be repeated here.

[0070] The technical features mentioned above, those to be mentioned below, and those shown individually in the accompanying drawings can be combined arbitrarily, provided that the combined technical features are not contradictory. All feasible combinations of features are the technical content explicitly described herein. Any one of the multiple sub-features contained in the same statement can be applied independently, without necessarily being applied together with other sub-features.

[0071] The following is a further description of this solution with reference to specific embodiments:

[0072] In one specific embodiment, the 8-inch silicon carbide ingot is replaced with a 6-inch ingot:

[0073] Step 1: The carbon and silicon end faces of the ingot are flat-ground, and the resistivity of the carbon end face is tested.

[0074] Step 2: Determine the diameter of the area to be retained as 150mm. Select a circular area with the best resistivity uniformity and a diameter of 150mm as the retained circular area. Determine the initial center of the circular area template. Using the origin of the coordinate system (i.e., the center of the end face of the ingot), obtain the first circular area. Move the circular area around the origin to obtain multiple circular areas (all within the ingot area), and calculate the variance σ of each circular area. 2 Choose the one with the smallest variance σ 2 The circular area is designated as the reserved circular area;

[0075] Step 3: Use a grinder or bar-removing 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, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0077] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those 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 invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for processing the outer diameter of a crystal ingot, characterized in that, include: S1. On the end face (20) to be processed of the crystal ingot, determine the center of the end face (20) to be processed, and measure the resistivity of the measurement points (30) distributed on the end face (20) to be processed, and obtain the resistivity of each measurement point (30); wherein, the measurement point (30) is circular, and adjacent measurement points (30) are tangent to each other; S2. Determine the radius of the circular area template, take the center of the end face as the initial center of the circular area template, move the circular area template multiple times based on the preset moving parameters to obtain multiple circular areas, calculate the variance of the measurement points (30) contained in each circular area, compare the variances, and the circular area corresponding to the smallest variance is the retained circular area. S3. Based on the center and radius of the reserved circular area, the ingot processing equipment is used to process the end face (20) to be processed and the circumferential surface of the ingot to obtain a cylindrical ingot with the reserved circular area as the end face. In step S2, the circular region template is moved multiple times based on preset movement parameters, using the center of the end face as the initial center, to obtain multiple circular regions, including: Set the center of the end face as the origin of the coordinate system and construct the coordinate axis; among the multiple measurement points (30), make the center of one measurement point (30) coincide with the origin of the coordinate system, divide the remaining measurement points (30) into multiple groups, and the multiple groups of measurement points (30) are concentrically distributed, with the measurement points (30) of each group distributed around the origin of the coordinate system; Using the origin of the coordinate system as the initial center of the circular region template, the first circular region is obtained; According to the order of distance from the initial center, each group of measurement points (30) is taken as the current processing group. For the current processing group, the center of the circular region is moved to the center of each of the measurement points (30) of the current processing group to obtain multiple circular regions, all of which are within the ingot.

2. The method for processing the outer diameter of a crystal ingot according to claim 1, characterized in that, The step of setting the center of the end face as the origin of the coordinate system and constructing the coordinate axis includes: setting the center of the end face as the origin of the coordinate system, setting the distance between two adjacent scales of the horizontal axis as 2r, and setting the distance between two adjacent scales of the vertical axis as √3r, and constructing the coordinate axis; where r is the radius of the measurement point (30).

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

4. The method for processing the outer diameter of a crystal ingot according to claim 1, characterized in that, The calculation of the variance of the measurement points (30) contained in each of the circular regions includes: Determine the number n of measurement points (30) contained in each of the circular regions and the resistivity ρ of each measurement point (30); The average resistivity ρ of each of the measurement points (30) is calculated based on the resistivity ρ of each of the circular regions. ; Based on the quantity n, the resistivity ρ, and the average value of the resistivity The variance of each of the circular regions is calculated.

5. The method for processing the outer diameter of a crystal ingot according to claim 1, characterized in that, S3 includes: Based on the center and radius of the reserved circular region, the reserved circular region is marked using the marking circle component of the ingot processing equipment; Based on the marked circular area, the processing components of the ingot processing equipment are used to remove the excess portion of the end face (20) to be processed and the circumferential surface of the ingot, so as to obtain a cylindrical ingot with the marked circular area as the end face.

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

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

8. A crystal ingot processing equipment, characterized in that, include: The crystal ingot is processed using the method for processing the outer circle of the crystal ingot as described in any one of claims 1-7.

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