EP-4737890-A1 - CRYSTAL EALUATION METHOD, CRYSTAL EVALUATION DEVICE, SIC SUBSTRATE, SIC DEVICE, AND SIC EPITAXIAL WAFER

Abstract

Provided is a crystal evaluation method and a crystal evaluation device that can detect and evaluate efficiently in a short time multiple types of defects that may exist in SiC crystal, as well as a SiC substrate, a SiC device, and a SiC epitaxial wafer, each containing only a certain level or less of defects evaluated by the crystal evaluation method. A crystal evaluation method of evaluating a crystal state of a SiC crystal has at least a detection process of acquiring Kikuchi patterns at a plurality of measurement points of the SiC crystal using an electron backscatter diffraction method, and an evaluation process of evaluating the crystal state of the SiC crystal through image analysis of the Kikuchi pattern of each measurement point obtained in the detection process.

Inventors

• FUJIKAWA, YOHEI
• KUMAGAI, RYOTA

Assignees

• Resonac Corporation

Dates

Publication Date

20260506

Application Date

20251027

Claims (7)

1. A crystal evaluation method of evaluating a crystal state of a SiC crystal, the method comprising: a detection process of acquiring Kikuchi patterns at a plurality of measurement points of the SiC crystal using an electron backscatter diffraction method; and an evaluation process of evaluating the crystal state of the SiC crystal through image analysis of the Kikuchi pattern of each measurement point obtained in the detection process.
2. The crystal evaluation method according to claim 1 or 2, wherein the evaluation process includes a process of comparing a prepared Kikuchi pattern for reference with a Kikuchi pattern at each measurement point, and calculating an area ratio of measurement points determined to be identical.
3. The crystal evaluation method according to any one of claims 1 to 3, wherein the evaluation process includes a process of classifying a Kikuchi pattern for at least one crystal state in fine heterogeneous polytype, in-plane crystal orientation deviation, surface oxidation, processing damage, crystal disturbance, and micro epitaxial defects through machine learning, and displaying a distribution of the crystal state of the SiC crystal as an image mapping.
4. A crystal evaluation device configured to evaluate a crystal state of a SiC crystal, the device comprising: a scanning electron microscope including an electron backscatter diffraction device, and an analysis device configured to perform image analysis of a Kikuchi pattern output from the electron backscatter diffraction device, wherein the analysis device performs image analysis of a Kikuchi pattern at a measurement point of the SiC crystal, compares the Kikuchi pattern with a pre-stored Kikuchi pattern for reference, and evaluates a crystal state of the SiC crystal.
5. A SiC substrate comprising a crystal structure, wherein the crystal structure in which 90% of Kikuchi patterns at a plurality of measurement points in one main surface of the SiC substrate obtained by an electron backscatter diffraction method are identical to each other.
6. A SiC device comprising a crystal structure comprising, wherein the crystal structure including a SiC substrate and in which 90% or more of Kikuchi patterns at a plurality of measurement points in one main surface of the SiC substrate obtained by an electron backscatter diffraction method are identical to each other.
7. A SiC epitaxial wafer comprising a SiC epitaxial layer, wherein the SiC epitaxial layer including a crystal structure located on one main surface side of a substrate and in which 90% or more of Kikuchi patterns at a plurality of measurement points obtained by an electron backscatter diffraction method are identical to each other.

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a crystal evaluation method, a crystal evaluation device, a SiC substrate, a SiC device, and a SiC epitaxial wafer. Description of Related Art Silicon carbide (SiC) has a dielectric breakdown field slightly larger and a band gap three times larger than those of silicon (Si). In addition, silicon carbide (SiC) has a thermal conductivity about three times larger than that of silicon (Si). For this reason, silicon carbide (SiC) is expected to be used in power devices, high frequency devices, high temperature operation devices, etc. The SiC substrates used in such devices are required to be of high quality, free from cracks and other damage, and contain minimal amounts of unintended crystalline state material. Unintended crystal states that may exist in SiC crystals include, for example, fine heterogeneous polytypes, crystal orientation deviations, surface oxidation, processing damage, crystal disturbances, micro epitaxial defects, and the like. In the related art, as a method for detecting the crystal state of such SiC crystals, for example, Patent Document 1 discloses a wafer evaluation method in which a gas is supplied to one side of a SiC wafer and penetration defects are detected based on the presence or absence of changes in internal pressure. [Patent Document] [Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2024-085544 SUMMARY OF THE INVENTION However, in Patent Document 1, only one type of crystal state present in the SiC substrate could be detected, and it was not possible to detect multiple types of crystal states that may exist in the SiC substrate as described above. In order to detect and evaluate such multiple types of crystal states, the only option is to combine evaluation methods specialized for detection of each crystal state, but, when a plurality of evaluation methods are performed sequentially, accuracy of existence location information of the identified crystal states decreases, making it difficult to evaluate the crystal states. For this reason, there has been a demand for an evaluation method for SiC substrates that can efficiently detect multiple types of crystal states. In consideration of the above-mentioned technical background, the present invention is directed to providing a crystal evaluation method and a crystal evaluation device that can detect and evaluate multiple types of crystal states that may exist in SiC crystal efficiently in a short time, and to providing a SiC substrate, a SiC device, and a SiC epitaxial wafer in which the crystal states evaluated by such a crystal evaluation method are present at a certain level or less. In order to solve the above-mentioned problems, a crystal evaluation method, a crystal evaluation device, a SiC substrate, a SiC device, and a SiC epitaxial wafer according to an embodiment of the present invention provide the following means. (1) A crystal evaluation method of Aspect 1 of the present invention is a crystal evaluation method of evaluating a crystal state of a SiC crystal, the method having at least: a detection process of acquiring Kikuchi patterns at a plurality of measurement points of the SiC crystal using an electron backscatter diffraction method; and an evaluation process of evaluating the crystal state of the SiC crystal through image analysis of the Kikuchi pattern of each measurement point obtained in the detection process.(2) According to Aspect 2 of the present invention, in the crystal evaluation method of Aspect 1, the evaluation process includes a process of comparing a prepared Kikuchi pattern for reference with a Kikuchi pattern at each measurement point, and calculating an area ratio of measurement points determined to be identical.(3) According to Aspect 3 of the present invention, in the crystal evaluation method of Aspect 1, the evaluation process includes a process of classifying a Kikuchi pattern for at least one crystal state in fine heterogeneous polytype, in-plane crystal orientation deviation, surface oxidation, processing damage, crystal disturbance, and micro epitaxial defects through machine learning, and displaying a distribution of the crystal state of the SiC crystal as an image mapping.(4) A crystal evaluation device of Aspect 4 of the present invention is a crystal evaluation device configured to evaluate a crystal state of a SiC crystal, the device having: a scanning electron microscope including an electron backscatter diffraction device and an analysis device configured to perform image analysis of a Kikuchi pattern output from the electron backscatter diffraction device, wherein the analysis device performs image analysis of image data of a Kikuchi pattern at a measurement point of the SiC crystal, compares the Kikuchi pattern with a pre-stored Kikuchi pattern for reference, and evaluates a crystal state of the SiC crystal.(5) A SiC substrate of Aspect 5 of the present invention in