GROUP III NITRIDE SEMICONDUCTOR MULTILAYER STRUCTURE AND PRODUCTION METHOD THEREOF

• US 20090289270A1
• Filed: 05/19/2009
• Published: 11/26/2009
• Est. Priority Date: 05/23/2008
• Status: Abandoned Application

• Current Assignee: Showa Denko KK (Resonac Holdings Corp.)
• Original Assignee: Showa Denko KK (Resonac Holdings Corp.)
• Inventors: SASAKI, Yasumasa, HANAWA, Kenzo, YOKOYAMA, Yasunori
• Application Number:
  US12/468,644
• Publication Number:
  US 20090289270A1
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 25/183 being provided with a buffer layer, e.g. a lattice matching layer
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: C30B 29/68 Crystals with laminate structure, e.g. "superlattices"
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/02433 Crystal orientation
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02513 Microstructure
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02573 Conductivity type
• CPC Class Codes: H01L 21/02609 Crystal orientation
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer
• CPC Class Codes: H01L 33/16 with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous

Abstract

According to the invention it is possible to obtain a flat AlN crystal film seed layer with a high degree of crystallinity, and particularly, a flat AlN crystal film seed layer that is homogeneous throughout can be used even with large substrates having diameters of 100 mm and greater, in order to obtain highly crystalline GaN-based thin-films for highly reliable, high-luminance LED elements and the like. The invention relates to a Group III nitride semiconductor multilayer structure obtained by layering an n-type semiconductor layer, composed of a Group III nitride semiconductor, a luminescent layer and a p-type semiconductor layer, on a sapphire substrate, the Group III nitride semiconductor multilayer structure having an AlN crystal film that is accumulated as the seed layer by sputtering on the sapphire substrate surface, and the AlN crystal film having a grain boundary spacing of 200 nm or greater. The arithmetic mean surface roughness (Ra) of the AlN crystal film surface is preferably no greater than 2 angstrom. The oxygen content of the AlN crystal film is preferably no greater than 5 atomic percent.

Claims

1. A Group III nitride semiconductor multilayer structure obtained by layering an n-type semiconductor layer, composed of a Group III nitride semiconductor, a luminescent layer and a p-type semiconductor layer, on a sapphire substrate, the Group III nitride semiconductor multilayer structure being characterized by having an AlN crystal film that is accumulated as the seed layer by sputtering on the sapphire substrate surface, the AlN crystal film having a grain boundary spacing of 200 nm or greater.

2. The Group III nitride semiconductor multilayer structure according to claim 1, wherein the arithmetic mean surface roughness (Ra) of the AlN crystal film surface is no greater than 2 angstrom.

3. The Group III nitride semiconductor multilayer structure according to claim 1, wherein the rocking curve half-widths in X-ray diffraction for the (0002) plane and (10-10) plane of the AlN crystal film are no greater than 100 arcsec and no greater than 1.7 degrees, respectively.

4. The Group III nitride semiconductor multilayer structure according to claim 1, wherein the oxygen content of the AlN crystal film is no greater than 5 atomic percent.

5. The Group III nitride semiconductor multilayer structure according to claim 1, wherein the sapphire substrate is a C-plane sapphire substrate.

6. The Group III nitride semiconductor multilayer structure according to claim 1, wherein the sapphire substrate has an off-angle of 0.1-0.7 degrees.

7. The Group III nitride semiconductor multilayer structure according to claim 1, wherein the sputtering method is RF sputtering.

8. The Group III nitride semiconductor multilayer structure according to claim 1, wherein the AlN crystal film is accumulated by sputtering with the sapphire substrate situated in plasma.

9. The Group III nitride semiconductor multilayer structure according to claim 1, wherein the AlN crystal film is accumulated on the sapphire substrate surface after the sapphire substrate surface has been treated with N₂ plasma or O₂ plasma.

10. The Group III nitride semiconductor multilayer structure according to claim 1, wherein the substrate temperature during accumulation of the AlN crystal film on the sapphire substrate surface is 300-800°

C.

11. The Group III nitride semiconductor multilayer structure according to claim 1, wherein the film thickness of the AlN crystal film is 10-50 nm.

12. The Group III nitride semiconductor multilayer structure according to claim 11, wherein the film thickness of the AlN crystal film is 25-35 nm.

13. The Group III nitride semiconductor multilayer structure according to claim 1, wherein the diameter of the sapphire substrate is 100 mm or greater.

14. The Group III nitride semiconductor multilayer structure according to claim 1, wherein the rocking curve half-widths of the p-contact layer as the final p-type semiconductor layer are no greater than 60 arcsec and no greater than 250 arcsec for the (0002) plane and (10-10) plane, respectively.

15. A light emitting device comprising a Group III nitride semiconductor multilayer structure according to claim 1.

16. The light emitting device according to claim 15, wherein a cathode is provided on the n-type semiconductor layer and an anode is provided on the p-type semiconductor layer.

30. A lamp comprising a light emitting device according to claim 16.

31. An electronic device incorporating a lamp according to claim 30.

32. A machine incorporating an electronic device according to claim 31.

17. A production method for a Group III nitride semiconductor multilayer structure, characterized in that, for production of a Group III nitride semiconductor multilayer structure obtained by layering an n-type semiconductor layer, composed of a Group III nitride semiconductor, a luminescent layer and a p-type semiconductor layer, on a sapphire substrate, an AlN crystal film having a grain boundary spacing of 200 nm or greater is formed as the seed layer by sputtering on the sapphire substrate surface, while controlling the oxygen content to no greater than 5 atomic percent.

18. The production method for a Group III nitride semiconductor multilayer structure according to claim 17, wherein the center line surface roughness (Ra) of the AlN crystal film surface is no greater than 2 angstrom.

19. The production method for a Group III nitride semiconductor multilayer structure according to claim 17, wherein the rocking curve half-widths in X-ray diffraction for the (0002) plane and (10-10) plane of the AlN crystal film are no greater than 100 arcsec and no greater than 1.7 degrees, respectively.

20. The production method for a Group III nitride semiconductor multilayer structure according to claim 17, wherein the sapphire substrate is a C-plane sapphire substrate.

21. The production method for a Group III nitride semiconductor multilayer structure according to claim 17, wherein the sapphire substrate has an off-angle of 0.1-0.7 degrees.

22. The production method for a Group III nitride semiconductor multilayer structure according to claim 17, wherein the sputtering method is RF sputtering.

23. The production method for a Group III nitride semiconductor multilayer structure according to claim 17, wherein the AlN crystal film is accumulated by sputtering with the sapphire substrate situated in plasma.

24. The production method for a Group III nitride semiconductor multilayer structure according to claim 17, wherein the AlN crystal film is formed under conditions in which no oxygen-attributed peak is seen in gas analysis during plasma discharge, to obtain an AlN crystal film with an oxygen content of no greater than 5 atomic percent.

25. The production method for a Group III nitride semiconductor multilayer structure according to claim 17, wherein the AlN single-crystal film is accumulated on the sapphire substrate surface after the sapphire substrate surface has been treated with N₂ plasma or O₂ plasma.

26. The production method for a Group III nitride semiconductor multilayer structure according to claim 17, wherein the substrate temperature during accumulation of the AlN crystal film on the sapphire substrate surface is 300-800°

C.

27. The production method for a Group III nitride semiconductor multilayer structure according to claim 17, wherein the film thickness of the AlN crystal film is 10-50 nm.

28. The production method for a Group III nitride semiconductor multilayer structure according to claim 27, wherein the film thickness of the AlN crystal film is 25-35 nm.

29. The production method for a Group III nitride semiconductor multilayer structure according to claim 17, wherein the diameter of the sapphire substrate is 100 mm or greater.