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Method for treating surface of silicon-carbide substrate

外国特許コード F160008779
整理番号 KG0120-US01
掲載日 2016年8月3日
出願国 アメリカ合衆国
出願番号 201414897342
公報番号 20160118257
出願日 平成26年6月6日(2014.6.6)
公報発行日 平成28年4月28日(2016.4.28)
国際出願番号 JP2014003049
国際公開番号 WO2014199615
国際出願日 平成26年6月6日(2014.6.6)
国際公開日 平成26年12月18日(2014.12.18)
優先権データ
  • 特願2013-125020 (2013.6.13) JP
  • 2014JP003049 (2014.6.6) WO
発明の名称 (英語) Method for treating surface of silicon-carbide substrate
発明の概要(英語) This method for treating a surface of a SiC substrate includes a first removal step in which a modified layer produced by subjecting the substrate (70) to mechanical polishing or chemical-mechanical polishing is removed by heating the substrate (70) under Si vapor pressure.
A second removal step in which macro-step bunching occurred in an epitaxial layer (71) is removed by heating the substrate (70) under Si vapor pressure may also be performed.
Since the etching rate can be varied, etching rate in the first removal step is high, so that the modified layer can be removed in a short time.
Meanwhile, etching rate in the second removal step is comparatively low, so that excessive removal of the epitaxial layer (71) can be prevented.
従来技術、競合技術の概要(英語) BACKGROUND ART
[0002] Silicon (Si), gallium arsenide (GaAs), and the like, are conventionally known as a semiconductor material.
Recently, the field of use of a semiconductor element is rapidly expanding.
The semiconductor element is accordingly more often used under severe environments such as a high temperature environment.
Therefore, achievement of a semiconductor element that is able to withstand a high temperature environment is one of important problems from the viewpoint of a reliable operation, processing of a large amount of information, and improvement in the controllability in wide ranges of applications and environments.
[0003] Silicon carbide (SiC) is of interest as one of materials that can be used for manufacturing a semiconductor element having an excellent heat resistance.
SiC has an excellent mechanical strength and a radiation hardness.
Moreover, adding impurities to SiC enables a valence electron such as an electron or a hole to be easily controlled, and SiC is characterized in a wide band gap (about 2.93 eV in 6H single crystal SiC; 3.26 eV in 4H single crystal SiC).
This is why SiC is expected as a material for a next-generation power device that achieves a high-temperature resistance, high frequency resistance, high voltage resistance, and high environment resistance, which cannot be achieved by the existing semiconductor material described above.
Methods for manufacturing a semiconductor material using SiC are disclosed in Patent Documents 1 to 3.
[0004] Patent Document 1 discloses a method for manufacturing a SiC semiconductor having high quality, when generation of SiC polycrystalline is suppressed by uniformizing the temperature in a growth furnace causing a growth of a seed crystal.
Patent Document 2 discloses a method for manufacturing a SiC semiconductor having little defect and high quality by forming a plurality of recesses in a seed crystal.

PRIOR-ART DOCUMENTS

Patent Documents
[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-193055
[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2012-176867

特許請求の範囲(英語) [claim1]
1. A method for treating a surface of a SiC substrate having an off angle, the substrate having at least its surface made of a SiC (0001)-face, the method comprising: performing a first removal step of removing a modified layer produced by subjecting the substrate to mechanical polishing or chemical-mechanical polishing by heating the substrate under Si vapor pressure.
[claim2]
2. The method for treating the surface of the SiC substrate according to claim 1, wherein in the first removal step, heating is performed in a temperature range of 1800 deg. C. or more and 2300 deg. C. or less and under Si pressure of 10-2 Pa or more.
[claim3]
3. The method for treating the surface of the SiC substrate according to claim 1, the method comprising: performing a second removal step of removing macro-step bunching produced on an epitaxial layer formed on the surface of the substrate using a chemical vapor deposition process by heating the substrate under Si pressure.
[claim4]
4. The method for treating the surface of the SiC substrate according to claim 3, wherein in the second removal step, etching rate is lower than that of the first removal step.
[claim5]
5. The method for treating the surface of the SiC substrate according to claim 3, wherein in the second removal step, heating is performed in a temperature range of 1600 deg. C. or more and 2000 deg. C. or less, and under Si pressure of 10-3 Pa or less.
[claim6]
6. The method for treating the surface of the SiC substrate according to claim 3, wherein in consideration of the relationship between heating condition including Si pressure, heating temperature and etching rate and the presence or absence of occurrence of macro-step bunching, the heating condition is determined in at least either one of the first removal step or the second removal step.
[claim7]
7. The method for treating the surface of the SiC substrate according to claim 6, wherein in further consideration of an off angle of the substrate, the heating condition is determined.
[claim8]
8. The method for treating the surface of the SiC substrate according to claim 1, wherein the surface of the substrate has an off angle of 4 degrees or less in the direction of <11-20>.
[claim9]
9. The method for treating the surface of the SiC substrate according to claim 1, wherein the surface of the substrate has an off angle of 4 degrees or less in the direction of <1-100>.
[claim10]
10. The method for treating the surface of the SiC substrate according to claim 1, wherein the surface of the substrate is terminated at a step having a full-unit height that corresponds to one periodic of SiC molecules in a stack direction or a half-unit height that corresponds to one-half periodic.
  • 発明者/出願人(英語)
  • KANEKO TADAAKI
  • OHTANI NOBORU
  • HAGIWARA KENTA
  • KWANSEI GAKUIN
国際特許分類(IPC)
米国特許分類/主・副
  • 438/492
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