A sort of <111> Methods for detecting facets in silicon single crystals with crystal orientation

Abstract

This invention discloses a <111> A method for detecting crystal-oriented silicon single-crystal facets. The method includes: (1) native <111> (1) After the silicon single crystal is pulled, a sample of a certain thickness is cut; (2) The sample is surface-ground to obtain a flat surface; (3) The ground sample is chemically etched to remove surface mechanical damage; (4) The sample is positioned according to its crystal orientation and edge position; (5) The X-ray diffraction position of the positioned sample is determined by using an X-ray diffractometer, and the X-ray source is rotated to scan in the ω direction. After determining the diffraction position, the test is performed; (6) The test results are judged to determine the position and size of the small plane. The detection method implemented in this invention can quickly realize the original <111> The detection method of this invention for the small facets of silicon single crystals with crystal orientation is simple to operate and easy to implement. <111> Visualizing the facets of silicon single crystals with crystal orientation is beneficial for improving... <111> The uniformity of radial resistivity of silicon single crystals is of great significance.

Description

Technical Field

[0001] This invention belongs to the field of Czochralski silicon single crystal detection technology, and relates to a method for detecting small facets of <111> oriented silicon single crystals. Background Technology

[0002] During the Czochralski (CZ) growth of silicon single crystals, the solid-liquid interface is typically curved due to the influence of the thermal field, melt in the crucible, and heat dissipation from the crystal. A small, flat plane often appears at the solid-liquid interface of <111> oriented silicon single crystals; this plane is the (111) atom close-packed plane, referred to as the planar facet. The impurity concentration in the planar facet region differs significantly from that in the non-planar facet region. This abnormal distribution of impurities in the planar facet region is called the planar facet effect, which is a major cause of the non-uniform radial resistivity of <111> oriented silicon single crystals. The resistivity uniformity of silicon single crystals affects the consistency of device quality; therefore, device manufacturers have high requirements for the radial resistivity uniformity of silicon single crystal wafers. To improve the radial resistivity uniformity of <111> oriented silicon single crystals, obtaining accurate planar facet information is crucial.

[0003] Existing technologies typically employ a four-probe resistivity meter to measure the center and edges of a silicon single crystal wafer and then calculate the radial resistivity uniformity for monitoring. The four-probe resistivity testing method can only indirectly reflect the facets within the <111> silicon single crystal through the calculated resistivity uniformity results; it cannot directly obtain the facet location information. To obtain complete facet information, it is necessary to select a large number of test points on the silicon single crystal wafer to measure the resistivity at each point, and then superimpose the large amount of data to indirectly obtain the distribution of facets within the silicon single crystal wafer. This measurement method requires a large amount of test data and is not intuitive.

[0004] X-ray diffraction can accurately determine various invisible defects in silicon crystals. The principle is that the crystal can be used as a spatial diffracting beam for X-rays. When a beam of X-rays passes through the crystal, diffraction will occur. The superposition of diffracted waves will strengthen the intensity of the rays in some directions and weaken them in other directions. By analyzing the diffraction pattern, the crystal structure can be determined.

[0005] The samples used for X-ray diffraction (XRD) to determine defects in silicon single crystals must possess geometric features that meet diffraction conditions. If the sample's geometry does not meet these conditions, a clear diffraction pattern cannot be obtained, or even XRD may not occur. The XRD testing process requires rotating the sample or X-ray beam in both the Φ and ω directions to find the required diffraction geometry. Native <111> oriented silicon single crystal samples are not regular discs; directly placing them on the test stage and rotating the silicon single crystal can easily cause slippage, resulting in the sample's crystal orientation and position not meeting the required diffraction geometry. Therefore, an improved detection method is needed to ensure that irregular <111> oriented silicon single crystal discs can be accurately positioned by XRD during measurement to meet the diffraction conditions. Summary of the Invention

[0006] The purpose of this invention is to provide a method for detecting facets in <111> oriented silicon single crystals. This method can directly test facets in irregular <111> oriented silicon single crystal wafers, and can quickly and stably test facets in <111> oriented silicon single crystals, with the feature of intuitive test results.

[0007] To achieve the above objectives, this invention proposes a technical solution for X-ray diffraction topography (XRT) testing of a <111> oriented silicon single crystal wafer after surface treatment, using a device to position the sample.

[0008] Specifically, the detection method for a <111> oriented silicon single crystal facet provided by the present invention includes the following steps:

[0009] (1) After the native <111> oriented silicon single crystal is pulled, a sample of a certain thickness is cut;

[0010] (2) The sample is subjected to surface grinding and cleaning to obtain a smooth and clean surface;

[0011] (3) The cleaned sample is chemically polished to remove surface mechanical damage;

[0012] (4) Use a positioning device to locate the crystal orientation and edge position of the sample;

[0013] (5) Use an X-ray diffractometer to determine the X-ray diffraction position of the positioned sample. Rotate the X-ray source to scan in the ω direction, and then perform the test after determining the diffraction position.

[0014] (6) Judge the test results and determine the position and size of the small plane.

[0015] The detection method of the present invention is particularly applicable to native <111> orientation silicon single crystal samples.

[0016] In one embodiment of the present invention, the thickness of the sample cut in step (1) is 1-2 mm. For example, the sample is a silicon single crystal wafer with a complete diameter portion of the original single crystal cut by a diamond wire saw or band saw.

[0017] In one embodiment of the present invention, in step (2), the surface grinding removal amount is 0.1 to 0.5 mm, the flatness of the silicon single wafer is preferably 10 to 100 μm, and then the sample is cleaned with deionized water to form a flat and clean surface.

[0018] In one embodiment of the present invention, the chemical polishing treatment in step (3) includes: immersing the sample in a mixed solution of nitric acid with a mass percentage concentration of 65-68% and hydrofluoric acid with a mass percentage concentration of 45-49%, wherein the volume ratio of nitric acid to hydrofluoric acid is HNO3:HF = 5:1, and the immersion time is 1-10 min, so as to remove mechanical damage to the surface of the sample.

[0019] In one embodiment of the present invention, in step (4), the positioning device includes a base, a baffle, a slot, a pin, and a locking screw. The baffle is adjacent to the slot, the wide facet of the silicon single crystal is accommodated in the slot and blocked by the baffle, the pin is positioned on the other side of the silicon single crystal relative to the slot, and the pin is connected to a locking handle via the locking screw. By rotating the locking handle, the locking screw is controlled to drive the pin to realize the mounting and positioning of the silicon single crystal, positioning the silicon single crystal between the slot and the pin.

[0020] The part of the ejector pin that contacts the silicon single crystal wafer matches the outer periphery shape of the silicon single crystal wafer.

[0021] The mounting and positioning method for silicon single crystal wafers is as follows: First, place the positioning device in a fixed position on the XRT test stage, so that the projection of the X-ray incident direction on the test stage is parallel to the axis of the base. Then, place the <111> crystal orientation silicon single crystal sample between the slot and the ejector pin, and press the wide facet of the silicon single crystal wafer against the baffle. Then, rotate the locking screw to push the ejector pin to lock the silicon single crystal wafer between the slot and the ejector pin.

[0022] In one embodiment of the present invention, in step (5), an X-ray diffractometer is used to determine the X-ray diffraction position of the positioned sample, the X-ray source is rotated to scan in the ω direction, the diffraction position is determined and then tested, the test results are judged, and the position and size of the small plane are determined; preferably, the point-by-point scanning speed is 50 to 300 mm / min.

[0023] The advantages of this invention are:

[0024] This invention provides a method for detecting <111> oriented single-crystal facets using XRT scanning. This method can rapidly detect native <111> oriented silicon single-crystal facets, solving the problem that four-probe resistivity meters cannot directly measure silicon single-crystal facets due to resistivity inhomogeneity. Furthermore, the tooling used in this invention improves the detection efficiency and ensures the accuracy of facet detection. The method is simple to operate, has a high facet detection rate, and offers intuitive and efficient facet detection. Attached Figure Description

[0025] Figure 1 A schematic diagram showing the facets and wide edges of a <111> oriented silicon single crystal.

[0026] Figure 2 This is a schematic flowchart of the detection method for the <111> oriented silicon single crystal facet of the present invention.

[0027] Figure 3 This is a schematic diagram of the positioning device used for positioning <111> crystal-oriented silicon single crystal wafers in this invention.

[0028] Figure 4 This is a comparison between the existing X-ray diffractometer testing procedure (a) and the X-ray diffractometer testing procedure (b) used in this invention.

[0029] Figure 5 This is a schematic diagram showing the rotation of the sample or X-ray along the Φ and ω directions during X-ray diffraction testing.

[0030] Figure 6 Comparison of XRT test image (a) and four-probe measurement image (b) of the <111> crystal orientation silicon single crystal facet in Example 1.

[0031] Figure 7 This is a comparison of test results using the positioning method and not using the positioning method in Example 2.

[0032] Figure 8 This is a comparison of XRT tests before and after using the surface treatment method of the present invention in Example 2. Detailed Implementation

[0033] To more clearly describe the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and embodiments. All of the above are related technologies to this case, and the embodiments described are some embodiments of the present invention, but do not mean that the scope of protection of the present invention is limited.

[0034] Figure 1 This is a schematic diagram showing the facets and ridges of a <111> oriented silicon single crystal. The diagram shows facets 12 formed on the surface of silicon single crystal wafer 11, and ridges 13 located on the outer surface of the silicon single crystal wafer.

[0035] When growing silicon single crystals with the <111> crystal orientation, a small flat plane often appears at the solid-liquid interface, which is called a small plane. It is the result of silicon atoms at the solid-liquid interface nucleating at the center of the small plane and then moving laterally in a single atomic layer along the crystal diameter direction. The small planes are all {111} crystal planes. Figure 1 The diagram shows a schematic of the central facet appearing radially on a silicon single-crystal wafer. The high lateral growth rate of the facet increases the effective segregation coefficient of doped impurities, causing impurities to accumulate in the facet region. The position of the facet on the silicon single-crystal wafer has different effects on radial resistivity uniformity; its appearance at the center has a greater impact than at the edges. The location of the facet is related to the crystal growth conditions. To improve the radial resistivity uniformity of <111> oriented silicon single crystals, the position and size of the facet should be changed by altering the crystal growth conditions. It should appear as close to the edges as possible and be as small as possible, even disappearing altogether. The outer surface of <111> oriented silicon single crystals typically has three symmetrical edges regularly distributed. These edges are the intersection lines formed at the boundaries of various {111} crystal planes during crystal growth. The appearance of the single-crystal edges is closely related to the formation of the edge facets. The appearance of the edge facets gives the crystal edges a wide edge characteristic. The presence of wide edges means that samples taken from the <111> oriented native silicon single crystal along the diameter direction are not regular circular slices.

[0036] Therefore, as Figure 2 The diagram shown is a flowchart illustrating a method for detecting a <111> oriented silicon single crystal facet provided by the present invention. The method includes the following steps:

[0037] Step 201: Take a sample of a certain thickness from the pulled <111> orientation native Czochralski silicon single crystal. In this step, a complete sample of the same diameter portion of the native single crystal can be cut from a designated position using a diamond wire saw or diamond band saw. The sample should have a certain thickness, preferably 1-2 mm. Too little thickness is not conducive to grinding and surface cleaning, while too much thickness will result in insufficient XRT transmittance, affecting the test results.

[0038] Step 202: The sample is subjected to surface grinding and cleaning to obtain a smooth and clean surface. In this step, the sample is ground to remove cutting marks and cleaned to remove contaminants introduced by the cutting, thereby making the sample flat and clean. The flatness of the sample is preferably 10-100 μm. The surface grinding removal amount (removal thickness) of the sample is 0.1-0.5 mm to ensure that the entire sample surface is treated; deionized water is used for cleaning to form a smooth and clean surface.

[0039] Step 203: Perform chemical polishing on the cleaned sample to remove surface damage. In this step, chemical polishing is used to remove surface damage from the sample. The purpose of chemical polishing is to completely remove surface damage and contamination introduced in the previous steps, eliminating interference in subsequent tests. The method used is to immerse the sample in a mixture of 65-68% nitric acid and 45-49% hydrofluoric acid (HNO3:HF = 5:1 by volume) for 1-10 minutes.

[0040] Step 204: The crystal orientation and edge positions of the sample are calibrated. In this step, a positioning device is used to fix the irregular sample in place, ensuring it meets the diffraction requirements, while also preventing displacement caused by sample slippage during the test.

[0041] Figure 3 This is a schematic diagram of the positioning device used for positioning <111> crystal-oriented silicon single crystal wafers in this invention. Figure 3 The components of the positioning device shown are labeled as follows: 1. Base; 2. Silicon wafer; 3. Locking screw; 4. Baffle; 5. Slot; 6. Ejector pin; 7. Screw support; 8. Locking handle. In the positioning device, the baffle 4 is adjacent to the slot 5. The wide facet of the silicon wafer 1 is accommodated in the slot 5 and contacts the baffle 4. The ejector pin 6 is positioned on the other side of the silicon wafer 2 relative to the slot 5. The ejector pin 6 is connected to the locking handle 8 via the locking screw 3, which is supported by the screw support 7. By rotating the locking handle 8, the locking screw 3 is controlled to drive the ejector pin 6, thus positioning the silicon wafer 2 between the slot 5 and the ejector pin 6. The portion of the ejector pin 6 that contacts the silicon wafer 2 matches the outer periphery of the silicon wafer 2.

[0042] The method for mounting and positioning a silicon single crystal wafer using a positioning device is as follows: First, fix the base 1 of the positioning device on the test stage of the X-ray diffractometer, so that the projection of the X-ray incident direction on the test stage is parallel to the axis of the base; Second, place the silicon single crystal wafer 2 between the slot 5 and the ejector pin 6 of the positioning device, with the wide facet of the silicon single crystal wafer placed in the slot and close to the baffle 4; Third, rotate the locking handle 8 to push the ejector pin 6 to press the silicon single crystal wafer 2 through the locking screw 3, thus locking the silicon single crystal wafer and completing the fixing of the silicon single crystal wafer.

[0043] Step 205: Sample inspection using X-ray diffraction morphology. In this step, the mechanochemically treated sample is fixed by a positioning device, and the X-ray diffraction position of the positioned sample is determined using an X-ray diffractometer. The X-ray source is rotated to scan in the ω direction to determine the diffraction position, and the morphology map of the <111> orientation silicon single crystal sample is obtained by scanning the sample using X-ray diffraction morphology. Figure 4The document shows a comparison between existing X-ray diffraction testing procedures and the X-ray diffraction testing procedures used in this invention. Figure 4 (a) is a test flowchart when the silicon single crystal is fixed without a positioning device. When testing the diffraction position, it is necessary to make continuous adjustments in both the ω and Φ directions to determine the diffraction position. Figure 4 (b) Flowchart of the test process after fixing the silicon single crystal wafer using a positioning device. After positioning the silicon single crystal wafer using the positioning device, only the ω direction needs adjustment, avoiding mutual interference caused by adjustments in two directions and significantly shortening the test time. The lattice distortion energy caused by the concentration gradient difference inside and outside the small plane is small, so it is necessary to use the smallest possible micro-focus X-ray and perform a comprehensive scan of the sample. The scanning speed for point-by-point scanning is 50–300 mm / min.

[0044] Step 206: Determine the location and size of the small plane by evaluating the results. In this step, the XRT test topography results are evaluated to exclude images that are unclear or have overlapping light and shadow, and to determine the small plane region by selecting topography images with clear boundaries.

[0045] In the following embodiments, the method of the present invention is used to test silicon single crystal samples from different native <111> crystal orientations.

[0046] Example

[0047] Example 1 is a whole circular wafer. The sample is a 6-inch diameter N-type <111> crystal orientation wafer. The sample position is a circular wafer radially cut from the equal diameter part of a single crystal. The sample is tested using the test method of this invention and the four-probe resistivity test method respectively, and the case of the small plane is compared.

[0048] Example 2 is a whole circular wafer. The sample is a 6-inch diameter N-type <111> crystal orientation wafer. The sample position is a circular wafer radially cut from the equal diameter part of a single crystal. XRT tests were performed on the sample using the positioning method of the present invention and without the positioning method of the present invention, and the differences in the test results were compared.

[0049] Example 3 is a whole circular wafer. The sample is a 6-inch diameter P-type <111> crystal orientation wafer. The sample position is a circular wafer radially cut from the equal diameter part of a single crystal. XRT tests were performed on this sample using the test method of the present invention and on an untreated sample, and the differences in test results were compared.

[0050] In the sample testing of the three embodiments, the XRT equipment used was the Rigaku XRTmicron detector, the transmission mode was employed, and the Mo target was used.

[0051] Example 1

[0052] In this embodiment, a native <111> oriented N-type heavily antimony-doped silicon single crystal wafer with a diameter of 6 inches was selected. The sample was located on the radial wafer of the single crystal with a diameter of 2.0 mm.

[0053] The sample underwent surface grinding and cleaning to obtain a smooth and clean surface. 0.2 mm of surface roughness was removed during grinding, resulting in a sample flatness of 50 μm. The sample was then thoroughly cleaned with deionized water. Next, the sample was immersed in a mixed solution of 68% HNO3 and 49% HF (volume ratio 3:1) for 5 minutes to remove surface damage.

[0054] Using the present invention Figure 3 The positioning device shown is used to fix the sample position on the XRT equipment test stage. The fixing method is as follows: First, fix the base 1 of the positioning device on the test stage of the X-ray diffractometer, so that the projection of the X-ray incident direction on the test stage is parallel to the axis of the base; Second, place the silicon single crystal 2 between the positioning device slot 5 and the ejector pin 6, with the wide facet of the silicon single crystal 2 placed in the slot and close to the baffle 4; Third, rotate the locking handle 8 to push the ejector pin 6 to press the silicon single crystal 2 through the locking screw 3, thus locking the silicon single crystal and completing the fixing of the silicon single crystal.

[0055] X-ray diffraction morphology (XRT) was used to morphologically analyze the localized samples according to... Figure 4 (b) shows the procedure for scanning in the ω direction to determine the diffraction position. After the diffraction position is determined, the sample is scanned and tested point by point. Figure 6 (a) is a test result image after sample scanning. There is an irregular circular pit pattern a near the center of the silicon single crystal wafer.

[0056] XRT test conditions are as follows: Diffraction vector: 220; 2θ B =21.28° / incident angle=11.3°; resolution: 4×4 (21.6μm×21.6μm); scanning speed: 50mm / min.

[0057] After XRT testing, the resistivity uniformity of the samples was measured using a four-probe resistivity meter at close-point depth. Figure 6 (b), Figure 6 (b) A region b with low resistivity in the central area, exhibiting a significant resistivity gradient difference with the surrounding area, is confirmed as a small planar region of a silicon single-wafer. (Comparison) Figure 6 (a) and Figure 6 (b) Display, Figure 6 (b) shows the low resistance region and Figure 6 (a) shows that the pits overlap, confirming that the area is a small plane distribution area, and the characteristics conform to the small plane distribution law of the <111> crystal orientation.

[0058] Example 2

[0059] In this embodiment, a native <111> oriented N-type heavily doped arsenic silicon single crystal wafer with a diameter of 6 inches was selected. The sample was located in the radial section of the single crystal with a thickness of 1.9 mm.

[0060] First test:

[0061] The sample underwent surface grinding and cleaning to obtain a smooth and clean surface. The surface grinding removed 0.15 mm of imperfection, achieving a flatness of 50 μm, and the sample was then thoroughly cleaned with deionized water. The sample was then immersed in a mixed solution of 68% HNO3 and 49% HF (volume ratio 3:1) for 5 minutes to remove surface damage.

[0062] Using the present invention Figure 3 The positioning device shown is used to fix the sample position on the XRT equipment test stage. The fixing method is as follows: First, fix the base 1 of the positioning device on the test stage of the X-ray diffractometer, so that the projection of the X-ray incident direction on the test stage is parallel to the axis of the base; Second, place the silicon single crystal 2 between the positioning device slot 5 and the ejector pin 6, with the wide facet of the silicon single crystal 2 placed in the slot and close to the baffle 4; Third, rotate the locking handle 8 to push the ejector pin 6 to press the silicon single crystal 2 through the locking screw 3, thus locking the silicon single crystal and completing the fixing of the silicon single crystal.

[0063] X-ray diffraction morphology (XRT) was used to morphologically analyze the localized samples according to... Figure 4 (b) shows the procedure for scanning in the ω direction to determine the diffraction position. After the diffraction position is determined, the sample is scanned and tested point by point. Figure 7 (a) shows the test results after the sample was scanned. The total test time was 32 minutes.

[0064] XRT test conditions are as follows: Diffraction vector: 220; 2θ B =21.28° / incident angle=11.3°; resolution: 4×4 (21.6μm×21.6μm); scanning speed: 50mm / min.

[0065] Second test:

[0066] After the XRT test is completed, remove the sample from the positioning device and move the positioning device out of the XRT testing platform. Place the sample back in the center of the testing area on the testing platform, according to... Figure 4 (b) shows the procedure for scanning in the ω direction to determine the diffraction position. After the diffraction position is determined, the sample is scanned point by point for testing. The XRT test conditions are exactly the same as the first test. After the test is completed, the XRT results are obtained. Figure 7 (b) Test results graph. Total test time: 32 minutes.

[0067] Third test:

[0068] After the XRT test is completed, the sample is placed back in the center of the test bench in the test area, according to... Figure 4 (a) shows the procedure for scanning in both the ω and Φ directions to determine the diffraction position. The XRT test conditions are exactly the same as the first test. After the test is completed, the results are obtained. Figure 7 (c) Test results graph. Total test time: 45 minutes.

[0069] By comparison Figure 7 (a) and Figure 7 (b) It can be seen that the test results after positioning Figure 7 (a) shows small plane a, but the test results are not localized. Figure 7 (b) The small plane at position b in the corresponding image is invisible; therefore, the test image after localization is clearer and has more obvious contrast. (Comparison) Figure 7 (a) and Figure 7 (c) It is evident that, Figure 7 (a) small plane a and Figure 7 The sharpness of the small plane c in (c) is not significantly different, but the detection time is reduced by 40.6% because the scanning for diffraction position in the Φ direction is reduced, thus improving the detection efficiency.

[0070] Example 3

[0071] In this embodiment, a lightly doped P-type boron-doped silicon single crystal wafer with a native <111> crystal orientation was selected. The sample diameter was 6 inches, the sample position was a radial wafer with equal diameter, and the target sample thickness was 2.2 mm.

[0072] First test:

[0073] Samples were taken from diamond wire, with a maximum thickness deviation of 0.2 mm. After cleaning with deionized water, XRT testing was performed. The results are as follows. Figure 8 (a) Test conditions: XRT test conditions are as follows: Diffraction vector: 220; 2θ B =21.28° / incident angle=11.3°; resolution: 4×4 (21.6μm×21.6μm); scanning speed: 50mm / min.

[0074] Second test:

[0075] For the samples completed in the first test, surface grinding and cleaning were performed to obtain a smooth and clean surface. The surface grinding removed 0.25 mm of material, achieving a flatness of 55 μm, and the samples were then cleaned with deionized water. The samples were then immersed in a mixed solution of 68% HNO3 and 49% HF (volume ratio 3:1) for 5 minutes to remove surface damage.

[0076] Using the present invention Figure 3The positioning device shown is used to fix the sample position on the XRT equipment test stage. The fixing method is as follows: First, fix the base 1 of the positioning device on the test stage of the X-ray diffractometer, so that the projection of the X-ray incident direction on the test stage is parallel to the axis of the base; Second, place the silicon single crystal 2 between the positioning device slot 5 and the ejector pin 6, with the wide facet of the silicon single crystal 2 placed in the slot and close to the baffle 4; Third, rotate the locking handle 8 to push the ejector pin 6 to press the silicon single crystal 2 through the locking screw 3, thus locking the silicon single crystal and completing the fixing of the silicon single crystal.

[0077] X-ray diffraction morphology (XRT) was used to morphologically analyze the localized samples according to... Figure 4 (b) shows the procedure for scanning in the ω direction to determine the diffraction position. After the diffraction position is determined, the sample is scanned and tested point by point. Figure 8 (b) is a graph of the test results after the sample was scanned.

[0078] XRT test conditions are as follows: Diffraction vector: 220; 2θ B =21.28° / incident angle=11.3°; resolution: 4×4 (21.6μm×21.6μm); scanning speed: 50mm / min.

[0079] contrast Figure 8 (a) and Figure 8 (b) It is evident that, Figure 8 The small plane at position a in (a) is not visible. Figure 8 The small plane b can be seen at the corresponding position in (b). Therefore, the test image of the small plane after surface treatment is clearer and the contrast is more obvious.

[0080] in conclusion:

[0081] This invention utilizes surface treatment on native <111> oriented silicon single crystal samples, followed by rapid positioning using a positioning device and XRT scanning to test single crystal facets. This method enables rapid detection of native <111> oriented silicon single crystal facets, overcoming the limitation of four-probe resistivity meters which cannot directly measure resistivity inhomogeneities in silicon single crystal facets. The detection method is simple to operate, has a high facet detection rate, and offers intuitive and efficient facet detection.

Claims

1. A kind <111> A method for detecting small facets of silicon single crystals with specific crystal orientation, characterized in that, The detection method includes the following steps: (1) Original <111> After the crystal-oriented silicon single crystal is pulled, a sample with a thickness of 1~2mm is cut off; (2) The sample is subjected to surface grinding treatment to obtain a smooth surface; (3) The ground sample is chemically polished to remove surface mechanical damage; (4) Locate the crystal orientation and edge positions of the sample using... <111> The silicon single-crystal positioning device positions the sample on the test stage according to its crystal orientation and edge lines. (5) Use an X-ray diffractometer to determine the X-ray diffraction position of the positioned sample, rotate the X-ray source to scan in the ω direction, and test after determining the diffraction position; the positioning device includes a baffle, a slot, a pin and a locking screw set on the base, wherein the baffle is adjacent to the slot, the wide facet of the silicon single crystal is accommodated in the slot and blocked by the baffle, the pin is set on the other side of the silicon single crystal relative to the slot, the pin is connected to the locking handle via the locking screw, and by rotating the locking handle, the locking screw is controlled to drive the pin to realize the mounting and positioning of the silicon single crystal, and the silicon single crystal is positioned between the slot and the pin; (6) Judge the test results and determine the position and size of the small plane.

2. The detection method according to claim 1, characterized in that, In step (2), the surface grinding removal amount is 0.1~0.5mm, the flatness of the silicon single crystal wafer is 10~100µm, and then the sample is cleaned with deionized water.

3. The detection method according to claim 1, characterized in that, In step (3), the chemical polishing treatment includes immersing the sample in a mixed solution of nitric acid with a mass percentage concentration of 65-68% and hydrofluoric acid with a mass percentage concentration of 45-49%, wherein the volume ratio of nitric acid to hydrofluoric acid is HNO3:HF=3:1, and the immersion time is 1-10 min.

4. The detection method according to claim 1, characterized in that, The part of the ejector pin that contacts the silicon single crystal wafer matches the outer periphery shape of the silicon single crystal wafer.

5. The detection method according to claim 1, characterized in that, The mounting and positioning method for silicon single crystal wafers is as follows: First, place the positioning device in a fixed position on the X-ray diffraction test stage, ensuring that the projection of the X-ray incident direction onto the test stage is parallel to the axis of the base. Then... <111> The crystal-oriented silicon single crystal sample is placed between the slot and the ejector pin, and the wide facet of the silicon single crystal is pressed against the baffle. Then, the locking screw is rotated to push the ejector pin to lock the silicon single crystal between the slot and the ejector pin.

6. The detection method according to claim 1, characterized in that, In step (5), point-by-point scanning is performed at a speed of 50~300mm / min.

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