Self-standing GaN single crystal substrate, method of making same, and method of making a nitride semiconductor device

• US 20070131967A1
• Filed: 04/28/2006
• Published: 06/14/2007
• Est. Priority Date: 12/08/2005
• Status: Abandoned Application

• Current Assignee: Hitachi Cable Limited (Proterial Ltd.)
• Original Assignee: Hitachi Cable Limited (Proterial Ltd.)
• Inventors: Meguro, Takeshi, Kawaguchi, Yusuke
• Application Number:
  US11/413,115
• Publication Number:
  US 20070131967A1
• Time in Patent Office: Days
• US Class Current: 257/190
• CPC Class Codes: H01L 21/02008 Multistep processes

Abstract

A self-standing gallium nitride-based semiconductor single crystal substrate has a surface (Ga-face) mirror-polished, and a rear surface (N-face) having an arithmetic mean roughness Ra of 1 micrometer or more and 10 micrometers or less. A nitride semiconductor device is fabricated such that, before the gallium nitride-based semiconductor single crystal substrate is attached to a substrate holder of a vapor phase growth apparatus, the substrate is adjusted such that its rear surface (N-face) has a arithmetic mean roughness Ra to be in face-to-face contact with the substrate holder.

Claims

1. A self-standing gallium nitride-based semiconductor single crystal substrate, comprising:

a surface (Ga-face) mirror-polished; and

a rear surface (N-face) comprising an arithmetic mean roughness Ra of 1 micrometer or more and 10 micrometers or less.

2. A method of making a self-standing gallium nitride-based semiconductor single crystal substrate, comprising:

a surface treatment step that a surface (Ga-face) of the substrate is mirror-polished; and

a rear-surface treatment step that a rear surface (N-face) of the substrate is lapped and then etched.

3. The method according to claim 2, wherein:

the rear-surface treatment step is conducted such that the rear surface (N-face) comprising an arithmetic mean roughness Ra of 1 micrometer or more and 10 micrometers or less.

4. A method of making a nitride semiconductor device, comprising the step of:

growing the nitride semiconductor device on the gallium nitride-based semiconductor single crystal substrate made by the method according to claim 2 by a vapor phase growth method.

5. The method according to claim 4, wherein:

the rear-surface treatment step is conducted such that the rear surface (N-face) comprising an arithmetic mean roughness Ra of 1 micrometer or more and 10 micrometers or less.

6. A method of making a nitride semiconductor device, comprising:

providing a self-standing gallium nitride-based semiconductor single crystal substrate; and

an adjustment step that, before the gallium nitride-based semiconductor single crystal substrate is attached to a substrate holder of a vapor phase growth apparatus, the gallium nitride-based semiconductor single crystal substrate is adjusted such that its rear surface (N-face) comprises a arithmetic mean roughness Ra to be in face-to-face contact with the substrate holder.

7. The method according to claim 6, wherein:

the adjustment step comprises etching the rear surface of the substrate.

8. The method according to claim 6, wherein:

the adjustment step comprises adjusting the arithmetic mean roughness Ra to be 1 micrometer or more and 10 micrometers or less.