Method for forming thermal oxide film of silicon carbide semiconductor device

• US 6,265,326 B1
• Filed: 07/02/1998
• Issued: 07/24/2001
• Est. Priority Date: 07/04/1997
• Status: Expired due to Term

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: Ueno, Katsunori
• Primary Examiner(s): Lee, Eddie C.
• Assistant Examiner(s): Diaz, José R.
• Application Number:
  US09/109,761
• Time in Patent Office: 1,118 Days
• Field of Search: 438/305, 438/770, 438/585, 438/763, 438/706, 438/773, 438/787, 438/765, 438/931, 432/205, 257/77
• US Class Current: 438/767
• CPC Class Codes: C23C 8/10 Oxidising
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/02236 group IV semiconductor
• CPC Class Codes: H01L 21/02255 formation by thermal treatment H01L21/02252 takes precedence; after treatment of an insulating film H01L21/3105 and subgroups
• CPC Class Codes: H01L 21/049 Conductor-insulator-semiconductor electrodes, e.g. MIS contacts
• CPC Class Codes: H01L 21/31658 by thermal oxidation, e.g. of SiGe
• CPC Class Codes: Y10S 438/931 Silicon carbide semiconductor

Abstract

To increase the rate or speed of formation of a thermal oxide film of a silicon carbide semiconductor device, the partial pressure of water vapor is controlled to within the range of 0.1 to 0.95 when a surface of silicon carbide is oxidized under a mixed atmosphere of water vapor and oxygen. In a pyrogenic oxidation method in which hydrogen and oxygen are introduced to perform thermal oxidation, the ratio of the flow rate of hydrogen to that of oxygen is controlled to within the range of 1:0.55 to 1:9.5. In another pyrogenic oxidation method in which hydrogen and oxygen are introduced to perform thermal oxidation, a large portion of an oxide film is formed while the ratio of the flow rate of hydrogen to that of oxygen is controlled to about 1:4.5, and a remaining portion of the oxide film is then formed while the ratio of the flow rate of hydrogen to that of oxygen is controlled to about 1:0.55.

Claims

1. A method for forming a thermal oxide film of a silicon carbide semiconductor device, in which hydrogen and oxygen are introduced to thermally oxidize the surface of the silicon carbide by pyrogenic oxidation, wherein the flow rate of hydrogen to that of oxygen is controlled to within a range of 1:

2 to 1;

9.5 and a partial pressure of the water vapor is controlled to within a range of 0.1 to 0.4.

2. A method for forming a thermal oxide film of a silicon carbide semiconductor device according to claim 1, comprising the steps of:

forming a first portion of the silicon dioxide film at a first partial pressure of water vapor; and

forming a second portion of the silicon dioxide film on said first portion of the silicon dioxide at a partial pressure of water vapor that is higher than said first partial pressure.

3. A method for forming a thermal oxide film of a silicon carbide semiconductor device by pyrogenic oxidation according to claim 1, comprising the steps of:

forming a first portion of the silicon dioxide film having a first thickness, while controlling a ratio of a flow rate of hydrogen to that of oxygen to about 1;

4.5;

forming a second portion of the silicon dioxide film having a second thickness smaller than said first thickness, on said first portion of the silicon dioxide film, while controlling the ratio of the flow rate of hydrogen to that of oxygen to about 1;

0.55.