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EP-3936646-B1 - SIC SUBSTRATE MANUFACTURING METHOD AND MANUFACTURING DEVICE, AND METHOD FOR REDUCING WORK-AFFECTED LAYER IN SIC SUBSTRATE

EP3936646B1EP 3936646 B1EP3936646 B1EP 3936646B1EP-3936646-B1

Inventors

  • KANEKO, TADAAKI
  • YOSHIDA, NATSUKI
  • AOKI, Kazufumi

Dates

Publication Date
20260506
Application Date
20200303

Claims (5)

  1. A method for manufacturing a SiC substrate comprising an etching process of etching a SiC substrate (10) under a vapor pressure environment of a gaseous species containing Si element and a gaseous species containing C element, wherein the etching process is a process of heating an etching space (S1) in which the SiC substrate (10) is arranged on a high temperature side of a temperature gradient, wherein the SiC substrate (10) is accommodated in a main container (20), which is made of material containing polycrystalline SiC.
  2. The method for manufacturing a SiC substrate according to claim 1, wherein the etching process is a process of performing etching by arranging the SiC substrate (10) in an etching space (S1) in which air is exhausted through an environment of vapor pressure of a gaseous species containing Si element.
  3. The method for manufacturing a SiC substrate according to claim 1 or 2, wherein the etching process is a process of performing etching by making the SiC substrate (10) arranged on the high temperature side of the temperature gradient face a portion of the main container (20) arranged on a low temperature side of the temperature gradient.
  4. The method for manufacturing a SiC substrate according to any one of claims 1 to 3, wherein the etching process comprises heating the main container (20) under an environment of vapor pressure of the gaseous species containing Si element in a manner to form a temperature gradient.
  5. The method for manufacturing a SiC substrate according to any one of claims 1 to 4, the etching process including a Si atom sublimation process of thermally sublimating Si atoms from a surface of the SiC substrate (10), and a C atom sublimation process of sublimating C atoms from the surface of the SiC substrate (10) by reacting C atoms remaining on the surface of the SiC substrate (10) with Si vapor in the main container (20).

Description

Technical Field The present invention relates to a method for manufacturing a SiC substrate from which a work-affected layer has been removed, a device for manufacturing the SiC substrate, and a method for reducing a work-affected layer of a SiC substrate. Background Art A silicon carbide (SiC) substrate is formed by mechanically processing (slicing, grinding, and polishing) an ingot of single crystal SiC prepared by a sublimation method or the like. On the surface of the SiC substrate subjected to mechanical processing, there is a surface layer (hereinafter, referred to as a work-affected layer) having scratches, crystal distortion, and the like introduced during processing. In order not to lower the yield in the device manufacturing process, it is necessary to remove the work-affected layer. Conventional removal of a work-affected layer has been mainly performed by surface processing using abrasive grains such as diamond. In recent years, various proposals have been made for a technique that does not use abrasive grains. For example, Patent Literature 1 discloses an etching technique (hereinafter, also referred to as Si vapor pressure etching) in which etching is performed by heating a SiC wafer under Si vapor pressure. WO 2017/188381 A1 discloses a SiC container formed from a material including polycrystalline SiC accommodated in a TaC container formed from a material including TaC. The TaC container is heated in an environment in which a temperature gradient is generated, while a base substrate is accommodated inside the SiC container, such that the inside of the TaC container reaches Si vapour pressure. As a result, C atoms sublimated as a result of etching the inner surface of the SiC container, and Si atoms in the atmosphere bond with each other, and a monocrystalline 3C-SiC epitaxial layer is grown on the base substrate. WO 2016079983 A1 discloses a method for controlling the etching rate of a SiC substrate based on the composition of a container. The etching method of this invention etches a SiC substrate by heating under the vapor pressure of Si in the state which accommodated the SiC substrate in the crucible. The crucible is configured to contain tantalum metal, a tantalum carbide layer is provided on the inner space side of the tantalum metal, and a tantalum silicide layer is further provided on the inner space side of the tantalum carbide layer. Then, the etching rate of the SiC substrate is controlled based on the difference in the composition of the tantalum silicide layer. Citation List Patent Literature Patent Literature 1: JP 2008-16691 A Summary of Invention Technical Problem An object of the present invention is to provide a method for manufacturing a SiC substrate in which a work-affected layer is reduced, and a device for manufacturing the SiC substrate. An object of the present invention is also to provide a method for manufacturing a SiC substrate in which a work-affected layer is removed, and a device for manufacturing the SiC substrate. Solution to Problem The technical problem is solved by the present invention by the provision of a method for manufacturing a SiC substrate comprising an etching process of etching a SiC substrate (10) under a vapor pressure environment of a gaseous species containing Si element and a gaseous species containing C element, wherein the etching process is a process of heating an etching space (S1) in which the SiC substrate (10) is arranged on a high temperature side of a temperature gradient,wherein the SiC substrate (10) is accommodated in a main container (20), which is made of material containing polycrystalline SiC. Disclosed herein, but not part of the invention is a device for manufacturing a SiC substrate, which includes: a main container capable of accommodating a SiC substrate and configured to generate vapor pressure of a gaseous species containing Si element and a gaseous species containing C element in an internal space by heating; and a heating furnace that accommodates the main container, generates vapor pressure of a gaseous species containing Si element in an internal space, and performs heating in a manner to form a temperature gradient, andthe main container including an etching space formed by making a portion of the main container arranged on a low temperature side of the temperature gradient face the SiC substrate in a state where the SiC substrate is arranged on a high temperature side of the temperature gradient. As described above, the SiC substrate can be etched without using machining by arranging the SiC substrate in the main container that generates vapor pressure of a gaseous species containing Si element and a gaseous species containing C element in an internal space and making the SiC substrate face a portion of the main container having a temperature lower than that of the SiC substrate. As a result, the SiC substrate from which the work-affected layer is reduced or removed can be manufactured. In this aspect, the main