Sample wafer preparation method for distinguishing primary defect areas of crystal bar

Abstract

The invention provides a sample wafer preparation method for distinguishing a primary defect area of a crystal bar, and relates to the technical field of silicon wafer defect detection.The method comprises the steps that the crystal bar is cut off according to the length to obtain a first crystal ingot with the diameter as the end face, and then the first crystal ingot with the diameter as the end face is longitudinally cut in the length direction to obtain a rectangular block; preparing for obtaining a circular sample wafer in the length direction, and then performing circle sleeving on the rectangular block to obtain a second crystal ingot of which the end surface is a section with different lengths of the crystal bar; slicing the second crystal ingot of which the end face is a section with different lengths of the crystal bar to obtain a circular sample wafer; the round sample wafer is subjected to post-treatment to obtain the sample wafer to be detected, the obtained sample wafer to be detected is a wafer in different length section directions of the crystal bar, the conditions of different areas in the length direction of the crystal bar can be detected, the size of a perfect single crystal area and the position of an original defect area can be known, and the crystal pulling process or the structure of a thermal field can be adjusted according to the detection result; and corresponding defects are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicon wafer defect detection, and in particular relates to a sample preparation method for distinguishing native defect areas of a crystal rod. Background Art

[0002] At present, there are many items that need to be evaluated for the pulled single crystal ingot. The pulled single crystal ingot is mainly cut, rolled, sliced ​​along the diameter of the ingot, and polished to prepare samples for relevant performance evaluation. However, the existing samples can only detect the local resistivity and other properties of the crystal ingot, and cannot detect the particle defects (LPD), flow pattern defects (FPD), oxidation induced stacking fault (OSF) density in the length direction of the crystal ingot. As a result, the original defect area of ​​the crystal ingot cannot be known, and the actual defect area of ​​the crystal ingot cannot be understood, so as to make improvements based on the actual defect area of ​​the crystal ingot. Summary of the invention

[0003] In view of this, the present invention provides a sample preparation method capable of distinguishing the native defect areas of a crystal rod.

[0004] The technical solution adopted by the present invention to solve the technical problem is:

[0005] A method for preparing a sample for distinguishing native defect areas of a crystal rod comprises the following steps:

[0006] S1: cutting the crystal rod to obtain a first crystal ingot with an end face having a diameter;

[0007] S2: Cutting the first crystal ingot with the end face being the diameter longitudinally along the length direction to obtain a rectangular block, so as to prepare for obtaining a circular sample in the length direction;

[0008] S3: performing rounding on the rectangular block to obtain a second crystal ingot with end faces of different lengths of the crystal rod;

[0009] S4: Slicing the second crystal ingot whose end faces are different length segments of the crystal rod to obtain circular samples;

[0010] S5: Post-process the circular sample to obtain a sample to be tested.

[0011] Preferably, in the step S1, the length of the first crystal ingot with the end face being the diameter is equal to the diameter of the crystal rod.

[0012] Preferably, in step S2, the length and width of the rectangular block are equal.

[0013] Preferably, in step S2, the length of the rectangular block is obtained by the following steps:

[0014] S21: Obtaining the thickness of the rectangular block according to the predetermined number of slices;

[0015] S22: Obtaining the length of the rectangular block according to the thickness of the rectangular block.

[0016] Preferably, the length L of the rectangular block is:

[0017]

[0018] Where: L is the length of the rectangular block, in mm;

[0019] r is the radius of the crystal rod, in mm;

[0020] d is the thickness of the rectangular block, in mm.

[0021] Preferably, in the step S3, the difference between the diameter of the second crystal ingot whose end faces are different length segments of the crystal rod and the length of the rectangular block is 0-20 mm.

[0022] Preferably, in the step S4, before slicing, it is necessary to first groove the lower part of the second crystal ingot whose end faces are different length segments of the crystal rod for head and tail identification.

[0023] Preferably, in the step S5, the post-processing is to chamfer, grind and polish the circular sample.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention provides a method for preparing samples to distinguish native defect areas of a crystal rod, which comprises the following steps: firstly cutting the crystal rod according to length to obtain a first crystal ingot with an end face as a diameter, and then longitudinally cutting the first crystal ingot with an end face as a diameter along the length direction to obtain a rectangular block, so as to prepare for obtaining a circular sample in the length direction, and then performing rounding on the rectangular block to obtain a second crystal ingot with end faces of different length segments of the crystal rod; slicing the second crystal ingot with end faces of different length segments of the crystal rod to obtain a circular sample; post-processing the circular sample to obtain a sample to be tested, and the obtained sample to be tested is a circular piece in the direction of different length segments of the crystal rod, which can detect the conditions of different areas in the length direction of the crystal rod, understand the size of the perfect single crystal area and the position of the native defect area, so as to adjust the crystal pulling process or the structure of the thermal field according to the detection results, and improve the corresponding defects; and the sample to be tested prepared by the present invention is still circular, which meets the existing sample preparation production line and detection equipment, and there is no need to purchase new detection equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of single crystal axial crystal data.

[0027] Figure 2 Schematic diagram of the preparation. DETAILED DESCRIPTION

[0028] The technical solutions and technical effects of the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings of the present invention.

[0029] Please see Figure 2 A method for preparing a sample for distinguishing native defect areas of a crystal rod comprises the following steps:

[0030] S1: cutting the crystal rod to obtain a first crystal ingot with an end face having a diameter;

[0031] Specifically, the crystal rod can be cut into required length segments according to the needs, or the crystal rod can be cut into equidistant segments.

[0032] S2: Cutting the first crystal ingot with the end face of the diameter longitudinally along the length direction to obtain a rectangular block;

[0033] Specifically, the first crystal ingot is expanded to a certain width on both sides along the center position of the end surface, and then cut along the length direction to obtain a rectangular block;

[0034] S3: performing rounding on the rectangular block to obtain a second crystal ingot with end faces of different lengths of the crystal rod;

[0035] S4: Slicing the second crystal ingot whose end faces are different length segments of the crystal rod to obtain circular samples;

[0036] S5: Post-process the circular sample to obtain a sample to be tested.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention provides a method for preparing a sample for distinguishing the native defect area of ​​a crystal rod, which comprises the following steps: firstly cutting the crystal rod according to the length to obtain a first crystal ingot with an end face of a diameter, then longitudinally cutting the first crystal ingot with an end face of a diameter along the length direction to obtain a rectangular block, so as to prepare for obtaining a circular sample in the length direction, and then performing a rounding on the rectangular block to obtain a second crystal ingot with an end face of different length segments of the crystal rod; slicing the second crystal ingot with an end face of different length segments of the crystal rod to obtain a circular sample; post-processing the circular sample to obtain a sample to be tested, and the obtained sample to be tested is a circular piece in the direction of different length segments of the crystal rod, which can detect the conditions of different regions in the length direction of the crystal rod, understand the size of the perfect single crystal region and the position of the native defect region, so as to adjust the crystal pulling process or the structure of the thermal field according to the detection results, and improve the corresponding defects, such as Figure 1 As shown; and the sample to be tested prepared by the present invention is still circular, which meets the requirements of the existing sample preparation production line and testing equipment, and there is no need to purchase new testing equipment.

[0039] Please see Figure 2Furthermore, in the step S1, the length of the first crystal ingot with the end face being the diameter is equal to the diameter of the crystal rod, so as to obtain a circle with the maximum length of the crystal rod, so as to obtain a specific defect area or the position of a perfect single crystal in the length direction of the crystal rod.

[0040] Specifically, the crystal rod is rolled and ground, and the rolled crystal rod is cut to obtain a first crystal ingot with an end face having a diameter.

[0041] For example, in one embodiment, the diameters of the crystal rods of various sizes, the diameters of the crystal rods after rolling and the cut lengths are shown in Tables 1 and 2.

[0042] Table 1

[0043]

[0044]

[0045] Table 2

[0046] size 4 inches 5 inches 6 inches 8 inches 12 inches Cutting length(mm) 106 131 156 206 306

[0047] Through the above processing, the sizes of the first crystal ingots of various sizes are shown in Table 3.

[0048] Table 3

[0049] size 4 inches 5 inches 6 inches 8 inches 12 inches First ingot (diameter*length mm) 106*106 131*131 156*156 206*206 306*306

[0050] Furthermore, in step S2, the length and width of the rectangular block are equal.

[0051] Furthermore, in step S2, the length of the rectangular block is obtained by the following steps:

[0052] S21: Obtaining the thickness of the rectangular block according to the predetermined number of slices;

[0053] S22: Obtaining the length of the rectangular block according to the thickness of the rectangular block.

[0054] Furthermore, the length L of the rectangular block is:

[0055]

[0056] Where: L is the length of the rectangular block, in mm;

[0057] r is the radius of the crystal rod, in mm;

[0058] d is the thickness of the rectangular block, in mm; in order to obtain the size that can intercept the largest circle, it is convenient to obtain the required disc.

[0059] Specifically, a cutter is used to perform longitudinal cutting along the length direction of the first crystal ingot to obtain a rectangular block.

[0060] For example, in one embodiment, a rectangular block with a thickness of 30 mm is obtained, and the sizes of the rectangular blocks obtained from crystal rods of various sizes are shown in Table 4.

[0061] Table 4

[0062]

[0063] Furthermore, in the step S3, the difference between the diameter of the second crystal ingot whose end faces are different length segments of the crystal rod and the length of the rectangular block is 0-20 mm.

[0064] Specifically, in the step S3, a second crystal ingot of a predetermined thickness is formed by a sleeve machine with the center of the widest surface of the rectangular block as the center of the circle, and a chamfering machine is used to grind and clean the burrs on the edges of both ends of the second crystal ingot to prevent cutting of operators and cutting of the slicer steel wire in subsequent processing.

[0065] For example, in one embodiment, a sleeve machine is used to sleeve a rectangular block with a thickness of 30 mm with its center as the center of the circle to produce a second crystal ingot with a thickness of 30 mm. The sizes of the second crystal ingots obtained from crystal rods of various sizes are shown in Table 5.

[0066] Table 5

[0067]

[0068] Only by cutting the crystal rod into the first crystal ingot of relevant size, and then gluing the first crystal ingot to the cutting machine tooling, longitudinally cutting the first crystal ingot into a rectangular block of relevant size along the center of the first crystal ingot, and then using a circular cutting machine to process the second crystal ingot of relevant size.

[0069] Furthermore, in the S4 step, before slicing, it is necessary to first groove the lower part of the second crystal ingot whose end face is a crystal rod of different length segments for head and tail marking, and the marking direction is the tail or head of the processed second crystal ingot, so that the detection data and graphics can correspond one by one to the detection sample. If it is not marked, after cutting into circular samples, the head and tail cannot be identified, and the silicon wafer LTmap cannot correspond to the circular sample after being scanned.

[0070] For example, in one embodiment, a manual roller grinder is used to make a notch mark at the tail end of the second ingot. After notching and solidification, it is sliced ​​by a steel wire slicer. After slicing, about 20 circular samples can be obtained. The groove depth and circular sample size of the second ingot obtained from crystal rods of various sizes are shown in Table 6.

[0071] Table 6

[0072]

[0073] Furthermore, in the step S5, the post-processing is to chamfer, grind and polish the circular sample.

[0074] For example, in one embodiment, the sizes of the samples to be tested in each step after post-processing are shown in Table 7.

[0075] Table 7

[0076]

[0077] What is disclosed above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for preparing a sample for distinguishing the native defect area of ​​a crystal rod, characterized in that: The following steps are involved: S1: cutting the crystal rod to obtain a first crystal ingot with an end face having a diameter; S2: Cutting the first crystal ingot with the end face of the diameter longitudinally along the length direction to obtain a rectangular block; S3: performing rounding on the rectangular block to obtain a second crystal ingot with end faces of different lengths of the crystal rod; S4: Slicing the second crystal ingot whose end faces are different length segments of the crystal rod to obtain circular samples; S5: Post-process the circular sample to obtain a sample to be tested.

2. The method for preparing a sample for distinguishing native defect areas of a crystal ingot according to claim 1, characterized in that: In the step S1, the length of the first crystal ingot with the end face being the diameter is equal to the diameter of the crystal rod.

3. The method for preparing a sample for distinguishing native defect areas of a crystal rod according to claim 1, characterized in that: In step S2, the length and width of the rectangular block are equal.

4. The method for preparing a sample for distinguishing native defect areas of a crystal rod according to claim 3, characterized in that: In step S2, the length of the rectangular block is obtained by the following steps: S21: Obtaining the thickness of the rectangular block according to the predetermined number of slices; S22: Obtaining the length of the rectangular block according to the thickness of the rectangular block.

5. The method for preparing a sample for distinguishing native defect areas of a crystal rod according to claim 4, characterized in that: The length L of the rectangular block is: ； Where: L is the length of the rectangular block, in mm; r is the radius of the crystal rod, in mm; d is the thickness of the rectangular block, in mm.

6. The method for preparing a sample for distinguishing native defect areas of a crystal ingot according to claim 1, characterized in that: In the step S3, the difference between the diameter of the second crystal ingot whose end faces are different length segments of the crystal rod and the length of the rectangular block is 0-20 mm.

7. The method for preparing a sample for distinguishing native defect areas of a crystal rod according to claim 1, characterized in that: In the step S4, before slicing, it is necessary to first groove the second crystal ingot whose end faces are different length segments of the crystal rod to mark the head and the tail.

8. The method for preparing a sample for distinguishing native defect areas of a crystal ingot according to claim 7, characterized in that: In the step S5, the post-processing is to chamfer, grind and polish the circular sample.

Images