Semiconductor device on a sapphire substrate

• US 6,232,623 B1
• Filed: 06/17/1999
• Issued: 05/15/2001
• Est. Priority Date: 06/26/1998
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Morita, Etsuo
• Primary Examiner(s): Tran, Minh Loan
• Application Number:
  US09/334,666
• Time in Patent Office: 698 Days
• Field of Search: 372/45, 372/46, 372/44, 257/103, 257/622, 257/627, 257/628, 257/631
• US Class Current: 257/103
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/0243 Surface structure
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 29/66462 with a heterojunction interface channel or gate, e.g. HFET, HIGFET, SISFET, HJFET, HEMT
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01S 5/0207 Substrates having a special shape
• CPC Class Codes: H01S 5/0213 Sapphire, quartz or diamond based substrates
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP

Abstract

To improve crystallographic property of a nitride III-V compound semiconductor layer grown on a sapphire substrate, a plurality of recesses are made on a major surface of the sapphire substrate, and the nitride III-V compound semiconductor layer is grown thereon. At least a part of the inner surface of each recess makes an angle not less than 10 degrees with respect to the major surface of the sapphire substrate. The recesses are buried with nitride III-V compound semiconductor crystal having a higher Al composition ratio than the nitride III-V compound semiconductor layer, such as Al_xGa_1−xN crystal whose Al composition ratio x is 0.2 or more, for example. Each recess has a depth not less than 25 nm and a width not less than 30 nm. The recesses may be made either upon thermal cleaning of the sapphire substrate or by using lithography and etching, thermal etching, or the like.

Claims

1. A semiconductor device using a nitride III-V compound semiconductor layer grown on a sapphire substrate, comprising:

recesses made on said sapphire substrate along an interface thereof with said nitride III-V compound semiconductor layer, wherein said nitride III-V compound semiconductor crystal having a larger Al composition ratio than said nitride III-V compound semiconductor layer is buried inside said recesses.

2. The semiconductor device according to claim 1 wherein each said recess has a depth not less than 10 nm and a width not less than 30 nm.

3. The semiconductor device according to claim 1 wherein said nitride III-V compound semiconductor layer is made of Al_x1Ga₁₋

x1−

y1In_y1N (0≦

x1≦

1, 0≦

y1≦

1, 0≦

x1+y1≦

1), said nitride III-V compound semiconductor crystal is made of Al_x2Ga<sub>1−

x2−

y2</sub>In_y2N (0≦

x2≦

1, 0≦

y2≦

1, 0≦

x2+y2≦

1), and x2−

x1≧

0.1.

4. The semiconductor device according to claim 1 wherein said nitride III-V compound semiconductor layer is a GaN layer, and said nitride III-V compound semiconductor crystal is made of Al_xGa₁₋

xN where 0.2≦

x≦

1.

5. The semiconductor device according to claim 4 wherein moire fringes with a distance from 1.37 to 1.67 nm are observed in portions of said recesses in a transmission electron microscopic image taken by exciting at least (0002) reflection of said nitride III-V compound semiconductor crystal and (0006) reflection of sapphire crystal.

6. A semiconductor device using a nitride III-V compound semiconductor layer grown on a sapphire substrate, comprising:

recesses made on said sapphire substrate along an interface thereof with said nitride III-V compound semiconductor layer, wherein said nitride III-V compound semiconductor crystal having a larger Al composition ratio than said nitride III-V compound semiconductor layer is provided along the interface between said sapphire substrate and said nitride III-V compound semiconductor layer to plug said recesses.

7. The semiconductor device according to claim 6 wherein said nitride III-V compound semiconductor layer is made of Al_x1Ga₁₋

x1−

y1In_y1N (0≦

x1≦

1, 0≦

y1≦

1, 0≦

x1+y1≦

1), said nitride III-V compound semiconductor crystal is made of Al_x2Ga<sub>1−

x2−

y2</sub>In_y2N (0≦

x2≦

1, 0≦

y2≦

1, 0≦

x2+y2≦

1), and x2−

x1≧

0.1.

8. The semiconductor device according to claim 6, wherein said nitride III-V compound semiconductor crystal is made of Al_xGa₁₋

xN where 0.2≦

x≦

1.

9. The semiconductor device according to claim 8 wherein moire fringes with a distance from 1.37 to 1.67 are observed in portions of said recesses in a transmission electron microscopic image taken by exciting at least (0002) reflection of said nitride III-V compound semiconductor crystal and (0006) reflection of sapphire crystal.

10. A semiconductor device using a nitride III-V compound semiconductor layer grown on a sapphire substrate, comprising:

recesses made on said sapphire substrate along an interface thereof with said nitride III-V compound semiconductor layer, wherein said nitride III-V compound semiconductor crystal is plugged inside said recesses, and moire fringes are observed in a transmission electron microscopic image of the portion of said nitride III-V compound semiconductor crystal.

11. A semiconductor device using a nitride III-V compound semiconductor layer grown on a sapphire substrate, comprising:

recesses made on said sapphire substrate along an interface thereof with said nitride III-V compound semiconductor layer, wherein said nitride III-V compound semiconductor crystal is plugged inside said recesses, and moire fringes with a distance from 1.37 to 1.67 nm are observed in portions of said recesses in a transmission electron microscopic image taken by exciting at least (0002) reflection of said nitride III-V compound semiconductor crystal and (0006) reflection of said sapphire crystal.