Anodic-oxidation equipment, anodic-oxidation method, and method for producing cathode of anodic-oxidation equipment

Patent metadata

Field	Value
Publication number	US-11248306-B2
Application number	US-201917052562-A
Country	US
Kind code	B2
Filing date	Apr 2, 2019
Priority date	Jun 6, 2018
Publication date	Feb 15, 2022
Grant date	Feb 15, 2022

Abstract

An anodic-oxidation equipment for forming a porous layer on a substrate to be treated, including: an electrolytic bath filled with an electrolytic solution; an anode and a cathode disposed in the electrolytic solution; and a power supply for applying current between the anode and the cathode in the electrolytic solution, wherein the anode is the substrate to be treated, and the cathode is a silicon substrate having a surface on which a nitride film is formed. This provides a cathode material in anodic-oxidation for forming porous silicon by an electrochemical reaction in an HF solution, the cathode material having a resistance to electrochemical reaction in an HF solution and no metallic contamination, etc., and furthermore, being less expensive than a conventional cathode material. Furthermore, high-quality porous silicon is provided at a lower cost than has been conventional.

First claim

The invention claimed is:

1. An anodic-oxidation equipment for forming a porous layer on a substrate to be treated, comprising:
an electrolytic bath filled with an electrolytic solution;
an anode and a cathode disposed in the electrolytic solution; and
a power supply for applying current between the anode and the cathode in the electrolytic solution,
wherein
the anode is the substrate to be treated, and
the cathode is a silicon substrate having a surface on which a nitride film is formed.

2. The anodic-oxidation equipment according to claim 1 , wherein the cathode is a silicon substrate having a surface from which a natural oxide film is removed and on which a nitride film is formed.

3. An anodic-oxidation method for applying current between an anode and a cathode in an electrolytic solution to form a porous layer on a substrate to be treated disposed in the electrolytic solution, wherein
the substrate to be treated is used as the anode and a silicon substrate having a surface on which a nitride film is formed is used as the cathode.

4. The anodic-oxidation method according to claim 3 , wherein a silicon substrate, which is obtained by removing a natural oxide film from a surface of a silicon substrate by a heat treatment in a non-oxidizing gas atmosphere other than a nitrogen gas atmosphere, and then forming a nitride film on the surface by a heat treatment in a nitriding gas atmosphere, is used as the silicon substrate having the surface on which the nitride film is formed.

5. A method for producing a cathode of an anodic-oxidation equipment, wherein
a silicon substrate is introduced into a heat treatment furnace, a temperature is raised to 1000° C. or more and 1350° C. or less, a first heat treatment is performed for less than 30 minutes in an atmosphere of a non-oxidizing gas other than a nitrogen gas at the raised temperature to remove a natural oxide film on a surface of the silicon substrate, a second heat treatment is performed with a nitriding gas atmosphere inside the heat treatment furnace to form a nitride film on the surface of the silicon substrate, and
the silicon substrate with the nitride film is used as the cathode of the anodic-oxidation equipment.

6. The method for producing a cathode of an anodic-oxidation equipment according to claim 5 , wherein an H 2 gas, an Ar gas, or a mixed gas thereof is used as the non-oxidizing gas in the first heat treatment.

Assignees

• Shinetsu Handotai Kk

Inventors

• Ohtsuki Tsuyoshi
• Tamatsuka Masaro

Classifications

• C25D11/005 Primary

  Apparatus specially adapted for electrolytic conversion coating (apparatus in general for electrolytic coating C25D17/00) · CPC title

• C25D17/10

  Electrodes {, e.g. composition, counter electrode} · CPC title

• C04B35/591

  obtained by reaction sintering · CPC title

• C25D11/32

  of semiconducting materials · CPC title

• C01B21/0682

  Preparation by direct nitridation of silicon · CPC title