Method for detecting dislocation slip lines in silicon single crystals

Abstract

The application discloses a kind of detection methods of silicon single crystal dislocation slip line, especially suitable for the detection of <100> crystal direction silicon single crystal dislocation slip line with diameter greater than 300mm, dopant is B element.The method comprises: after the native <100> crystal direction silicon single crystal is drawn, the sample with the thickness of 2-10mm is intercepted, and the sample is cleaned with deionized water;Using mixed solution to etch the sample, immerse the sample in the mixed solution of 65-68% concentration nitric acid and 45-49% concentration hydrofluoric acid, the volume ratio of hydrofluoric acid and nitric acid in the mixed solution is HF:HNO3=10:1, and the soaking time is 30-40min;Using visual inspection lamp to determine the result after etching, determine the position and length of dislocation slip line;Using X-ray diffraction topography to assist in determining the sample.The detection method is simple and easy to realize, uses chromium-free liquid etching, and determines the position and length of dislocation slip line under strong light, which can eliminate interference factors and accurately identify dislocation slip line.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of detection of silicon single crystal, and relates to a detection method of dislocation slip lines of silicon single crystal. BACKGROUND

[0002] Dislocation is an internal micro defect of crystal material, that is, local irregular arrangement of atoms (crystallographic defect). Dislocation belongs to a kind of linear defect, and can be regarded as a boundary line between the slipped part and the unslipped part in the crystal. The existence of dislocation has a significant influence on the performance of silicon crystal material, especially the mechanical performance.

[0003] The chemical etching method is one of the most effective means for studying the crystal defects of a silicon wafer. The surface state of a single crystal is different, and the etching rate is different, so that the dislocation slip lines of the crystal are shown. However, the chemical etching method used at present mainly contains chromium, and it is difficult to handle and pollutes the environment. Therefore, it is urgent to develop a new type of single crystal dislocation slip detection method. A chromium-free etching solution emerges as the times require, and the etching rate of the single crystal surface is controlled by adjusting parameters, so that different states are shown on the single crystal surface. This etching method is expected to become an environmentally friendly production technology. SUMMARY

[0004] The purpose of the present application is to provide a detection method of dislocation slip lines of silicon single crystal, which is suitable for the detection of dislocation slip lines of large-diameter B-doped <100> crystal direction silicon single crystal. The detection method can accurately identify the dislocation slip lines, and has the characteristics of environmental protection and friendliness.

[0005] To achieve the above purpose, the following technical solutions are adopted in the present application:

[0006] A detection method of dislocation slip lines of silicon single crystal comprises the following steps:

[0007] (1) After the native <100> crystal direction silicon single crystal is drawn, a sample with a thickness of 2-10 mm is cut, and the sample is cleaned with deionized water;

[0008] (2) The sample is etched using a mixed solution, and the sample is immersed in a mixed solution of nitric acid with a concentration of 65-68% and hydrofluoric acid with a concentration of 45-49%, the volume ratio of hydrofluoric acid to nitric acid in the mixed solution is HF:HNO3=10:1, and the immersion time is 30-40 min;

[0009] (3) The result after etching is determined using a visual inspection lamp, and the position and length of the dislocation slip line are determined;

[0010] (4) The sample is determined by X-ray diffraction topography (XRT).

[0011] The detection method of the present application is particularly suitable for detecting dislocation slip lines of a <100> crystal direction silicon single crystal with a diameter greater than 300 mm and a dopant of B element.

[0012] As an embodiment of the present application, in step (1), the thickness of the intercepted sample is 4-10 mm.

[0013] As an embodiment of the present application, in step (3), visual inspection is performed using a visual inspection lamp with a light intensity of ≥7 klux.

[0014] As an embodiment of the present application, in step (4), due to the limitation of the fixture of the XRT, the detection sample has a sample thickness detection limit, i.e., the upper limit of the thickness is 3 mm, so when the sample thickness is less than 3 mm, the position and length of the dislocation slip line are determined using the XRT, and the result is compared with the visual inspection result of the physical sample.

[0015] The present application has the following advantages:

[0016] The detection method of the present application is simple and easy to implement, and uses chromium-free liquid corrosion for a <100> crystal direction silicon single crystal with a diameter greater than 300 mm and a dopant of B element. During the corrosion process, appropriate corrosion liquid and corrosion time are selected, and the position and length of the dislocation slip line are determined under a strong light lamp, which can eliminate interference factors and accurately identify the dislocation slip line. At the same time, the result is compared with the XRT topographic map, which can achieve the goal of environmental protection, cost reduction and efficiency improvement. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 (a) Figure 1 (e) are the appearance results of the dislocation slip lines under the visual inspection lamp after corrosion in Comparative Examples 1-3, Example 1, and Comparative Example 4, respectively.

[0018] Figure 2 (a) Figure 2 (e) are the appearance results of the dislocation slip lines under the visual inspection lamp after corrosion in Comparative Examples 5-7, Examples 2-3, respectively.

[0019] Figure 3 (a) Figure 3 (e) are the appearance results of the dislocation slip lines under the visual inspection lamp after corrosion in Comparative Examples 8-11, Example 4, respectively.

[0020] Figure 4 (a), Figure 4 (b) are microscope images of the silicon single crystal samples after corrosion in Comparative Example 8 and Example 4, respectively.

[0021] Figure 5 (a), Figure 5(b) are the results of the visual inspection of the dislocation slip lines after etching and the results of the XRT topography scan, respectively, for the silicon single crystal samples of Example 5.

[0022] Figure 6 (a) Figure 6 (d) are the results of the visual inspection of the silicon single crystal samples after etching for Comparative Example 12, Example 6, Example 7, and Comparative Example 13, respectively. DETAILED DESCRIPTION

[0023] In order to more clearly describe the technical solutions of the present application, the present application will be described in detail below in conjunction with the drawings and examples, which are all related to the present application, and the examples described are part of the embodiments of the present application, but do not mean to limit the scope of protection of the present application.

[0024] 1. Select a 8-inch B-doped <100> silicon single crystal rod, continuously cut into silicon single crystal samples with a thickness of 2.5±0.2 mm, and the sample numbers of the single crystal rod from the tail to the head are 1-5. Wash the samples with deionized water. Samples 1-5 are etched according to the following Comparative Examples 1-4 and Example 1 etching process.

[0025] Comparative Example 1

[0026] The sample is immersed in a mixed solution of hydrofluoric acid with a concentration of 45-49% and chromium trioxide in water, and the specific ratio and immersion time are according to the Schimmel etching solution in GB / T 1554-2009 (current) standard.

[0027] Comparative Example 2

[0028] The sample is immersed in a mixed solution of nitric acid with a concentration of 65-68% and hydrofluoric acid with a concentration of 45-49%, HF:HNO3 (volume ratio) = 5:1 solution, and the immersion time is 30 min. A visual inspection lamp with a light intensity of ≥7 klux is used to determine the position and length of the dislocation slip lines after etching.

[0029] Comparative Example 3

[0030] The sample is immersed in a mixed solution of nitric acid with a concentration of 65-68% and hydrofluoric acid with a concentration of 45-49%, HF:HNO3 (volume ratio) = 8:1 solution, and the immersion time is 30 min. A visual inspection lamp with a light intensity of ≥7 klux is used to determine the position and length of the dislocation slip lines after etching.

[0031] Example 1

[0032] The sample is immersed in a mixed solution of nitric acid with a concentration of 65-68% and hydrofluoric acid with a concentration of 45-49%, HF:HNO3 (volume ratio) = 10:1 solution, and the immersion time is 30 min; the results after corrosion are determined using a visual inspection lamp with a light intensity ≥ 7 klux, and the position and length of the dislocation slip line are determined.

[0033] Comparative Example 4

[0034] The sample is immersed in a mixed solution of nitric acid with a concentration of 65-68% and hydrofluoric acid with a concentration of 45-49%, HF:HNO3 (volume ratio) = 15:1 solution, and the immersion time is 30 min; the results after corrosion are determined using a visual inspection lamp with a light intensity ≥ 7 klux, and the position and length of the dislocation slip line are determined.

[0035] As shown in Figure 1 , Figure 1 (a) shows the appearance results of the dislocation slip line under the visual inspection lamp after corrosion in Comparative Example 1; Figure 1 (b) shows the appearance results of the dislocation slip line under the visual inspection lamp after corrosion in Comparative Example 2. Figure 1 (c) shows the appearance results of the dislocation slip line under the visual inspection lamp after corrosion in Comparative Example 3; Figure 1 (d) shows the appearance results of the dislocation slip line under the visual inspection lamp after corrosion in Example 1. Figure 1 (e) shows the appearance results of the dislocation slip line under the visual inspection lamp after corrosion in Comparative Example 4.

[0036] As can be seen from the figure, the appearance degree of the dislocation slip line in Example 1 is comparable to the appearance degree of the dislocation slip line in the chromium liquid corrosion required by the national standard. As the HF:HNO3 (volume ratio) decreases, the clarity of the dislocation slip line in Comparative Example 2 and Comparative Example 3 is poor, and the appearance is not obvious. As the HF:HNO3 (volume ratio) increases, the clarity of the dislocation slip line in Comparative Example 4 is poor, and the appearance is not obvious. Therefore, when the ratio in Example 1 is HF:HNO3 (volume ratio) = 10:1, the appearance degree of the dislocation slip line is better.

[0037] 2. Select a 8-inch silicon single crystal rod doped with B<100> crystal direction, continuously cut into silicon single crystal samples with a thickness of 2.5±0.2 mm, and the sample numbers of the single crystal rod from the tail to the head are 1~5, and the samples are cleaned with deionized water. Samples 1~5 are sequentially subjected to the corrosion processes of Comparative Examples 5~7 and Examples 2~3.

[0038] Comparative Example 5

[0039] The sample is immersed in a mixed solution of hydrofluoric acid with a concentration of 45-49% and chromium trioxide, the specific ratio and immersion time are according to the Schimmel etching solution in GB / T 1554-2009 (current) standard.

[0040] Comparative Example 6

[0041] The sample is immersed in a mixed solution of nitric acid with a concentration of 65-68% and hydrofluoric acid with a concentration of 45-49%, HF:HNO3 (volume ratio) = 10:1 solution, the immersion time is 10 min; the result after etching is determined using an inspection lamp with a light intensity of ≥7 klux, and the position and length of the dislocation slip line are determined.

[0042] Comparative Example 7

[0043] The sample is immersed in a mixed solution of nitric acid with a concentration of 65-68% and hydrofluoric acid with a concentration of 45-49%, HF:HNO3 (volume ratio) = 10:1 solution, the immersion time is 20 min; the result after etching is determined using an inspection lamp with a light intensity of ≥7 klux, and the position and length of the dislocation slip line are determined.

[0044] Example 2

[0045] The sample is immersed in a mixed solution of nitric acid with a concentration of 65-68% and hydrofluoric acid with a concentration of 45-49%, HF:HNO3 (volume ratio) = 10:1 solution, the immersion time is 30 min; the result after etching is determined using an inspection lamp with a light intensity of ≥7 klux, and the position and length of the dislocation slip line are determined.

[0046] Example 3

[0047] The sample is immersed in a mixed solution of nitric acid with a concentration of 65-68% and hydrofluoric acid with a concentration of 45-49%, HF:HNO3 (volume ratio) = 10:1 solution, the immersion time is 40 min; the result after etching is determined using an inspection lamp with a light intensity of ≥7 klux, and the position and length of the dislocation slip line are determined.

[0048] As shown in Figure 2 , wherein Figure 2 (a) shows the appearance of the dislocation slip line under the inspection lamp after etching in Comparative Example 5; Figure 2 (b) shows the appearance of the dislocation slip line under the inspection lamp after etching in Comparative Example 6. Figure 2 (c) shows the appearance of the dislocation slip line under the inspection lamp after etching in Comparative Example 7; Figure 2 (d) shows the appearance of the dislocation slip line under the inspection lamp after etching in Example 2. Figure 2 (e) shows the appearance of the dislocation slip line under the inspection lamp after etching in Example 3.

[0049] As can be seen from the figures, the degree of appearance of the dislocation slip lines in Examples 2 and 3 is comparable to the degree of appearance of the dislocation slip lines required by the national standard for the chromium liquid corrosion of Comparative Example 1. As the corrosion time decreases, the clarity of the dislocation slip lines in Comparative Examples 6 and 7 is poor and the appearance is not obvious.

[0050] 3. Select a 8-inch B<100> direction doped silicon single crystal rod, continuously cut into silicon single crystal samples with a thickness of 2±0.2 mm, and the sample numbers of the single crystal rod from the tail to the head are 1~5, and clean with deionized water. Samples 1~5 are sequentially corroded according to the following Comparative Examples 8~11 and the corrosion process of Example 4.

[0051] Comparative Example 8

[0052] Immerse the sample in a mixed solution of nitric acid with a concentration of 65-68%, hydrofluoric acid with a concentration of 45-49%, and glacial acetic acid, HF:HNO3:HAc (volume ratio) = 10:1:0.2, for 30 min; use a visual inspection lamp with a light intensity ≥7 klux to determine the position and length of the dislocation slip lines.

[0053] Comparative Example 9

[0054] Immerse the sample in a mixed solution of nitric acid with a concentration of 65-68%, hydrofluoric acid with a concentration of 45-49%, and glacial acetic acid, HF:HNO3:HAc (volume ratio) = 10:1:0.5, for 30 min; use a visual inspection lamp with a light intensity ≥7 klux to determine the position and length of the dislocation slip lines.

[0055] Comparative Example 10

[0056] Immerse the sample in a mixed solution of nitric acid with a concentration of 65-68%, hydrofluoric acid with a concentration of 45-49%, and glacial acetic acid, HF:HNO3:HAc (volume ratio) = 10:1:1, for 30 min; use a visual inspection lamp with a light intensity ≥7 klux to determine the position and length of the dislocation slip lines.

[0057] Comparative Example 11

[0058] Immerse the sample in a mixed solution of nitric acid with a concentration of 65-68%, hydrofluoric acid with a concentration of 45-49%, and glacial acetic acid, HF:HNO3:HAc (volume ratio) = 10:1:2, for 30 min; use a visual inspection lamp with a light intensity ≥7 klux to determine the position and length of the dislocation slip lines.

[0059] Example 4

[0060] The sample was immersed in a mixed solution of nitric acid with a concentration of 65-68% and hydrofluoric acid with a concentration of 45-49%, HF:HNO3 (volume ratio) = 10:1 solution, and the immersion time was 30 min; the results after corrosion were determined using an inspection lamp with a light intensity of ≥7 klux, and the position and length of the dislocation slip line were determined.

[0061] Figure 3 (a) is the appearance result of the dislocation slip line under the inspection lamp of Comparative Examples 8-11. Figure 3 (d) is the appearance result of the dislocation slip line under the inspection lamp of Comparative Example 8-11. Figure 3 (e) is the appearance result of the dislocation slip line under the inspection lamp of Example 4.

[0062] Figure 4 (a) is the microscope image of the sample after corrosion of Comparative Example 8. Figure 4 (b) is the microscope image of the sample after corrosion of Example 4, and the magnification is 100X. Among them, the dislocation slip line in Comparative Example 8 and Example 4 can be shown, but the surface state of the dislocation slip line in Comparative Example 8 is poor, which is all etch pits, and compared with Example 4, it is more difficult to distinguish the dislocation slip line.

[0063] Example 5

[0064] An 8-inch B<100> direction doped silicon single crystal sample with less known dislocation slip line was selected, with a thickness of 2±0.2 mm, and the sample was immersed in a mixed solution of nitric acid with a concentration of 65-68% and hydrofluoric acid with a concentration of 45-49%, HF:HNO3 (volume ratio) = 10:1 solution, and the immersion time was 30 min; the results after corrosion were determined using an inspection lamp with a light intensity of ≥7 klux, and the position and length of the dislocation slip line were determined; and XRT testing technology was used for scanning, and the difference between the inspection lamp and the XRT test results was compared.

[0065] Figure 5 (a) shows the appearance result of the dislocation slip line under the inspection lamp; Figure 5 (b) shows the XRT scanning result. The same sample was detected by two methods, and the length and position of the dislocation slip line under the inspection lamp were all matched with the XRT image.

[0066] Examples 6, 7

[0067] A large-diameter silicon single crystal sample with a known dislocation slip line was selected and continuously cut into silicon single crystal samples with a thickness of 4-10 mm. In Example 6, the sample thickness was 4 mm, and in Example 7, it was 5 mm. The samples were immersed in a mixed solution of 65-68% nitric acid and 45-49% hydrofluoric acid (HF:HNO3, volume ratio = 10:1) for 30 minutes. The etching results were then assessed using a visual inspection lamp with an intensity ≥7 klux to determine the position and length of the dislocation slip line.

[0068] Comparative Example 12

[0069] In Comparative Example 12, the sample thickness was the same as in Example 6, with a sheet thickness of 4 mm. The sample was immersed in a mixed solution of hydrofluoric acid and chromium trioxide with a concentration of 45-49%, and the specific ratio and immersion time were carried out according to the Schimmel etching solution in GB / T 1554-2009 (current) standard.

[0070] Comparative Example 13

[0071] In Comparative Example 13, the sample thickness was the same as in Example 7, with a sheet thickness of 5 mm. The sample was immersed in a mixed solution of hydrofluoric acid and chromium trioxide with a concentration of 45-49%, and the specific ratio and immersion time were carried out according to the Schimmel etching solution in GB / T 1554-2009 (current) standard.

[0072] like Figure 6 As shown, where Figure 6 (a) shows the results of visual inspection under a lamp after corrosion in Comparative Example 12; Figure 6 (b) shows the results of visual inspection under a lamp after corrosion in Example 6; Figure 6 (c) shows the results of visual inspection under a lamp after corrosion in Example 7; Figure 6 (d) shows the results of visual inspection under a lamp after corrosion in Comparative Example 13, revealing the dislocation slip lines.

[0073] As can be seen from the figures, the dislocation slip line length in Comparative Example 12 is 28 mm; the dislocation slip line length in Example 6 is 25 mm; the dislocation slip line in Example 7 is only on the side; and the dislocation slip line in Comparative Example 13 is only on the side. Compared to Comparative Example 12, the slip line length in Example 6 is reduced by 3 mm; compared to Comparative Example 13, the dislocation slip line in Example 7 is only on the side. This conforms to the rule that the dislocation slip line gradually shortens as the sample approaches the head of the silicon single crystal.

[0074] In summary, the detection method of the dislocation slip line of the silicon single crystal provided by the application is mainly for the <100> crystal direction silicon single crystal with a diameter greater than 300 mm and a dopant of B element, and mainly detects the dislocation slip line. The detection method is simple and easy to implement, adopts the method of abandoning the traditional chromium liquid for detection, can eliminate interference factors under a strong light lamp, accurately identifies the dislocation slip line, and is an environment-friendly method.

Claims

1. A method for detecting a dislocation slip line of a silicon single crystal, characterized by, The silicon single crystal is a <100> crystal direction silicon single crystal with a dopant of B element, and the detection method comprises the following steps: (1) after the native <100> crystal direction silicon single crystal is drawn, a sample with a thickness of 2-10 mm is cut, and the sample is cleaned with deionized water; (2) the sample is etched using a mixed solution, and the sample is immersed in a mixed solution of nitric acid with a concentration of 65-68% and hydrofluoric acid with a concentration of 45-49%, the volume ratio of hydrofluoric acid to nitric acid in the mixed solution is HF:HNO3=10:1, and the immersion time is 30-40 min; (3) the result after etching is determined using an inspection lamp with a light intensity of ≥7 klux, and the position and length of the dislocation slip line are determined; (4) the sample is determined using X-ray diffraction topography.

2. The method of detecting a dislocation slip line of a silicon single crystal according to Claim 1, wherein The diameter of the silicon single crystal is greater than 300 mm.

3. The method of detecting a dislocation slip line in a silicon single crystal according to Claim 1, wherein In the step (1), the thickness of the cut sample is 4-10 mm.

4. The method of detecting a dislocation slip line in a silicon single crystal according to Claim 1, wherein In the step (4), when the thickness of the sample is less than 3 mm, the position and length of the dislocation slip line are determined using XRT, and the result is compared with the visual inspection result of the physical sample.

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