Wafer [1-100] crystal orientation detection method and system

Abstract

The application belongs to the technical field of wafer positioning, and specifically provides a wafer [1-100] crystal direction detection method and system, which comprises the following steps: performing corner X-ray testing on a (1-106) crystal surface of a wafer to be detected according to preset test parameters to obtain a Phi angle corresponding to the wafer to be detected; and judging whether the [1-100] crystal direction is deflected or not according to the obtained Phi angle; the Phi angle of the (1-106) crystal surface is tested by an X-ray diffractometer and a positioning tool, and whether the position of the [1-100] crystal direction is accurate or not is judged by the positive and negative of the Phi angle, and the crystallization quality of the wafer can also be tested, the testing is fast and simple, and it is a nondestructive testing, thereby saving production cost.

Description

Technical Field

[0001] This invention belongs to the field of wafer positioning technology, specifically relating to a wafer [1-100] crystal orientation detection method and system. Background Technology

[0002] Silicon carbide wafers possess many excellent properties, making them important in numerous fields, including power electronic devices, microwave devices, and high-temperature sensors. Currently commercially available silicon carbide wafers, such as 4H-SiC, have a 0001 crystal plane. This 0001 plane has two characteristic directions: the [11-20] direction and the [1-100] direction. [11-20] is the step flow direction, and [1-100] is perpendicular to it. These two directions have different atomic arrangements and exhibit six-degree symmetry. Generally, linearly arranged base-plane dislocation defects correspond to stacking faults in the crystal, and this direction is parallel to the [1-100] direction. Therefore, the [1-100] direction has significant physical meaning in silicon carbide crystals. During crystal processing, this crystal orientation is typically marked with a flat edge or a notch to facilitate subsequent wafer processing and photolithography positioning. Before the ingot or ingot is cut into wafers, a positioning device is generally used to orient the characteristic crystal orientation. However, since the processing of ingots is mechanical, errors are unavoidable. Furthermore, during processes such as cutting and grinding, orthogonal orientation deviations may occur, causing slight shifts in the crystal orientation of the surface. These shifts will affect subsequent epitaxial processes. Therefore, it is crucial to find a simple and convenient method to detect whether the crystal orientation of silicon carbide wafers [1-100] is accurate.

[0003] Existing detection methods mostly detect whether the [1-100] crystal direction has shifted by detecting the normal perpendicular to the [1-100] crystal direction. They cannot directly detect the [1-100] crystal direction, and the detection process is relatively complicated. Summary of the Invention

[0004] To address the shortcomings of existing technologies that cannot directly detect the [1-100] crystal orientation and have a relatively complex detection process, this invention provides a wafer [1-100] crystal orientation detection method and system.

[0005] In a first aspect, the present invention provides a wafer [1-100] crystal orientation detection method, comprising:

[0006] Preprocessing of the wafer to be inspected;

[0007] The pre-processed wafer to be tested is placed on the sample stage of the X-ray diffractometer, and the [1-100] crystal orientation of the wafer to be tested is positioned on the positioning point of the sample stage using a positioning tool.

[0008] According to the preset test parameters, the (1-106) crystal plane of the wafer to be tested is subjected to corner X-ray test to obtain the Ph i angle corresponding to the wafer to be tested;

[0009] Determine whether the [1-100] crystal orientation has been deflected based on the obtained Ph i angle;

[0010] If the Ph i angle is positive, then the [1-100] crystal orientation is determined to be shifted to the right in the 1-100 direction;

[0011] If the Ph i angle is negative, then the [1-100] crystal orientation is determined to be shifted to the left in the 1-100 direction;

[0012] If the Ph i angle is zero, then the [1-100] crystal orientation is determined to have not shifted.

[0013] Further improvements to this technical solution include pretreatment of the wafer to be tested, specifically including cleaning the wafer to be tested with dilute hydrochloric acid.

[0014] A further improvement to this technical solution is that the concentration of dilute hydrochloric acid is 4 mol per liter.

[0015] Further improvements to this technical solution include test parameters such as the movement step size of the Ph i angle, the movement range of the Ph i angle, the scanning range of the Omega angle in Omega mode, the step size of the Omega angle, and the test duration.

[0016] Further improvements to this technical solution include: the movement step size of the Phi angle is 0.001 degrees, the movement range of the Phi angle is -4 degrees to +4 degrees, the scanning range of the Omega angle in Omega mode is 0.5 degrees to 1.5 degrees, the step size of the Omega angle is 0.001 degrees, and the test duration is 3 minutes.

[0017] Further improvements to this technical solution include performing corner X-ray testing on the (1-106) crystal planes of the wafer to be tested according to preset test parameters, specifically including:

[0018] The sample stage rotates the wafer to be tested according to the preset movement step size and movement range;

[0019] An X-ray source installed at a preset position emits X-rays onto the (1-106) crystal plane of the wafer to be inspected;

[0020] An X-ray detector installed at a preset position receives X-rays diffracted from the (1-106) crystal plane and sends them to a host computer that is connected to the X-ray detector for calculation and analysis.

[0021] Further improvements to this technical solution include the ability to perform corner X-ray testing on the (1-106) crystal plane of the wafer to be tested, thereby obtaining the full width at half maximum (FWHM) data corresponding to the (1-106) crystal plane.

[0022] Further improvements to this technical solution include that when the [1-100] crystal orientation of the wafer to be tested is detected, the triangular positioning end of the positioning tool is engaged with the Notch edge slot of the wafer to be tested, and the end of the positioning tool away from the triangular positioning end is connected to the positioning hole configured on the sample stage.

[0023] A further improvement to this technical solution is that the triangular positioning end of the positioning tool is made of polytetrafluoroethylene.

[0024] In a second aspect, the present invention provides a wafer [1-100] crystal orientation detection system, comprising:

[0025] X-ray diffractometer is used to perform corner X-ray testing on wafers to be inspected;

[0026] The positioning tool is used to position the [1-100] crystal orientation of the wafer to be tested on the positioning point of the sample stage.

[0027] The beneficial effects of this invention are that it uses an X-ray diffractometer and positioning tools to test the Phi angle of the (1-106) crystal plane, and determines the accuracy of the position of the [1-100] crystal orientation by the sign of the Phi angle. At the same time, it can also test the crystal quality of the wafer. The test is fast and simple, and it is a non-destructive test that saves production costs.

[0028] Furthermore, the design principle of this invention is reliable, the structure is simple, and it has a very wide range of application prospects. Attached Figure Description

[0029] 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, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic flowchart of a method according to an embodiment of the present invention.

[0031] Figure 2 This is a spatial structure diagram of the 0001 and (1-106) crystal planes of the wafer.

[0032] Figure 3 This is a schematic diagram of wafer placement and rotation.

[0033] Figure 4 This is a schematic diagram showing the installation positions of the auxiliary tools and the wafer to be tested.

[0034] Figure 5 This is a test result diagram output by one embodiment of the present invention.

[0035] 410 is the wafer to be tested, 420 is the sample stage, 430 is the flat edge auxiliary tool, 440 is the notch edge auxiliary tool, and 450 is the positioning hole. Detailed Implementation

[0036] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0038] Figure 1 This is a schematic flowchart of a wafer [1-100] crystal orientation detection method provided by the present invention. Figure 1 The executing entity can be a wafer [1-100] crystal orientation detection system. Depending on different requirements, the order of the steps in this flowchart can be changed, and some can be omitted.

[0039] like Figure 1 As shown, the method includes:

[0040] Step 110: Preprocess the wafer to be inspected;

[0041] Step 120: Place the pre-processed wafer to be tested on the sample stage of the X-ray diffractometer, and use a positioning tool to position the [1-100] crystal orientation of the wafer to be tested on the positioning point of the sample stage.

[0042] Step 130: Perform corner X-ray testing on the (1-106) crystal plane of the wafer to be tested according to the preset test parameters to obtain the Phi angle corresponding to the wafer to be tested;

[0043] Step 140: Determine whether the [1-100] crystal direction has been deflected based on the obtained Ph i angle; if the Ph i angle is positive, it is determined that the [1-100] crystal direction has shifted to the right in the 1-100 direction; if the Ph i angle is negative, it is determined that the [1-100] crystal direction has shifted to the left in the 1-100 direction; if the Ph i angle is zero, it is determined that the [1-100] crystal direction has not shifted.

[0044] To facilitate understanding of the present invention, the following description further illustrates the wafer [1-100] crystal orientation detection method provided by the present invention, based on the principle of the wafer [1-100] crystal orientation detection method and in conjunction with the process of detecting the wafer [1-100] crystal orientation in the embodiments.

[0045] Specifically, the wafer [1-100] crystal orientation detection method includes:

[0046] Wafers are cut from crystal rods using a wire cutter. The cut wafers may have a small amount of iron filings remaining on their surface. To improve the accuracy of the inspection, they need to be cleaned with a weak acid solution. The weak acid solution can also reduce the surface roughness of the wafer. Specifically, a dilute hydrochloric acid solution with a concentration of 4 mol / L can be used to clean the wafer to be inspected. In addition, the wafer can be ground and polished first, because the roughness of the ground and polished wafers will be even lower.

[0047] In the internal structure of the wafer under test, the spatial structure of the 0001 crystal plane and the (1-106) crystal plane is as follows: Figure 2 As shown, there is a certain angle between the two crystal planes.

[0048] like Figure 3 and Figure 4As shown, when inspecting a wafer, the sample stage needs to be rotated, generally counterclockwise. The sample stage drives the wafer to rotate, requiring a positioning tool to fix it on the stage. In the [1-100] direction, a positioning flat edge or notch edge is manually created. This positioning flat edge / notch edge is used to mark the characteristic crystal orientation of the wafer. Correspondingly, the positioning tools include flat edge auxiliary tools and notch edge auxiliary tools. Specifically, when inspecting the flat edge of the wafer, the planar positioning end of the flat edge auxiliary tool is bonded to the flat edge of the wafer, and the end of the flat edge auxiliary tool away from the planar positioning end is connected to the positioning hole on the sample stage. When inspecting the notch edge of the wafer, the triangular positioning end of the notch edge auxiliary tool is engaged with the notch edge slot of the wafer, and the end of the notch edge auxiliary tool away from the triangular positioning end is connected to the positioning hole on the sample stage. To prevent the flat-edge auxiliary tool and the notch-edge auxiliary tool from scratching the wafer under test, the material of the planar positioning end in the flat-edge auxiliary tool and the material of the triangular positioning end in the notch-edge auxiliary tool are both made of polytetrafluoroethylene (PTFE).

[0049] Before testing, test parameters need to be set to ensure that the test can be performed automatically. Specifically, the test parameters include the movement step size of the Phi angle, the movement range of the Phi angle, the scanning range of the Omega angle in Omega mode, the step size of the Omega angle, and the test duration.

[0050] When performing corner X-ray testing on the (1-106) crystal plane of the wafer to be tested, an X-ray source and an X-ray detector need to be installed at a suitable position on the sample stage. Specifically, the method for performing corner X-ray testing on the (1-106) crystal plane of the wafer to be tested according to preset test parameters includes:

[0051] S131. The sample stage rotates the wafer to be tested according to the preset moving step size and moving range.

[0052] S132. An X-ray source installed at a preset position emits X-rays onto the (1-106) crystal plane of the wafer to be inspected;

[0053] S133. An X-ray detector installed at a preset position receives X-rays diffracted from the (1-106) crystal plane and sends them to a host computer that is connected to the X-ray detector for calculation and analysis.

[0054] In addition, when performing corner X-ray testing on the (1-106) crystal plane of the wafer to be tested, this method can also obtain the full width at half maximum (FWHM) data corresponding to the (1-106) crystal plane. The crystal quality of the wafer can be judged based on the obtained FWHM data. Specifically, the smaller the FWHM value, the better the crystal quality.

[0055] Specifically, in Omega mode, the movement step of the Phi angle is set to 0.001 degrees, the movement range of the Phi angle is -4 degrees to +4 degrees, the scanning range of the Omega angle in Omega mode is 0.5 degrees to 1.5 degrees, the step size of the Omega angle is 0.001 degrees, the test duration is 3 minutes, and the output test results are as follows: Figure 5 As shown, the obtained Phi angle is 0.5° and the obtained half-width at half-maximum (WHM) is 0.07874°, indicating that the Notch edge / positioning flat edge is shifted to the right in the 1-100 direction, and the crystal quality of the WHM value is relatively good.

[0056] In addition, the present invention also provides a wafer [1-100] crystal orientation detection system, comprising:

[0057] X-ray diffractometer is used to perform corner X-ray testing on wafers to be inspected;

[0058] The positioning tool is used to position the [1-100] crystal orientation of the wafer to be tested on the positioning point of the sample stage.

[0059] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the invention should also be covered within the protection scope of the invention. Therefore, the protection scope of the invention should be determined by the scope of the claims.

Claims

1. A method for detecting the crystal orientation of a wafer [1-100], characterized in that, include: Preprocessing of the wafer to be inspected; The pre-processed wafer to be tested is placed on the sample stage of the X-ray diffractometer, and the [1-100] crystal orientation of the wafer to be tested is positioned on the positioning point of the sample stage using a positioning tool. According to the preset test parameters, the (1-106) crystal plane of the wafer to be tested is subjected to corner X-ray test to obtain the Phi angle corresponding to the wafer to be tested; Determine whether the [1-100] crystal orientation has been deflected based on the obtained Phi angle; If the Phi angle is positive, then the [1-100] crystal orientation is determined to be shifted to the right in the 1-100 direction; If the Phi angle is negative, then the [1-100] crystal orientation is determined to be shifted to the left in the 1-100 direction; If the Phi angle is zero, then the [1-100] crystal orientation is determined to have not shifted.

2. The wafer [1-100] crystal orientation detection method according to claim 1, characterized in that, Pre-treatment of the wafer to be tested includes cleaning it with dilute hydrochloric acid.

3. The wafer [1-100] crystal orientation detection method according to claim 2, characterized in that, The concentration of the dilute hydrochloric acid is 4 mol per liter.

4. The wafer [1-100] crystal orientation detection method according to claim 1, characterized in that, The test parameters include the movement step size of the Phi angle, the movement range of the Phi angle, the scanning range of the Omega angle in Omega mode, the step size of the Omega angle, and the test duration.

5. The wafer [1-100] crystal orientation detection method according to claim 4, characterized in that, The Phi angle has a movement step of 0.001 degrees and a movement range of -4 degrees to +4 degrees. In Omega mode, the Omega angle has a scanning range of 0.5 degrees to 1.5 degrees and a step size of 0.001 degrees. The test duration is 3 minutes.

6. The wafer [1-100] crystal orientation detection method according to claim 5, characterized in that, According to preset test parameters, corner X-ray testing is performed on the (1-106) crystal planes of the wafer to be tested, specifically including: The sample stage rotates the wafer to be tested according to the preset movement step size and movement range; An X-ray source installed at a preset position emits X-rays onto the (1-106) crystal plane of the wafer to be inspected; An X-ray detector installed at a preset position receives X-rays diffracted from the (1-106) crystal plane and sends them to a host computer that is connected to the X-ray detector for calculation and analysis.

7. The wafer [1-100] crystal orientation detection method according to claim 1, characterized in that, By performing corner X-ray testing on the (1-106) crystal plane of the wafer to be tested, the full width at half maximum (FWHM) data corresponding to the (1-106) crystal plane can also be obtained.

8. The wafer [1-100] crystal orientation detection method according to claim 1, characterized in that, When the [1-100] crystal orientation of the wafer to be tested is detected, the triangular positioning end of the positioning tool is engaged with the slot of the wafer to be tested, and the end of the positioning tool away from the triangular positioning end is connected to the positioning hole configured on the sample stage.

9. The wafer [1-100] crystal orientation detection method according to claim 8, characterized in that, The triangular positioning end of the positioning tool is made of polytetrafluoroethylene.

10. A wafer [1-100] crystal orientation detection system, characterized in that, The system for performing the wafer [1-100] crystal orientation detection method as described in any one of claims 1-9 includes: X-ray diffractometer is used to perform corner X-ray testing on wafers to be inspected; The positioning tool is used to position the [1-100] crystal orientation of the wafer to be tested on the positioning point of the sample stage.

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