Nitride semiconductor device and method for manufacturing a nitride semiconductor substrate, and method for manufacturing a nitride semiconductor device

• US 20050184299A1
• Filed: 02/22/2005
• Published: 08/25/2005
• Est. Priority Date: 02/20/2004
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Hirao, Tsuyoshi, Matsumura, Hiroaki, Sakamoto, Keiji
• Granted Patent: US 8,089,093 B2
• Time in Patent Office: Days
• US Class Current: 257/79
• CPC Class Codes: H01L 21/28575 on semiconductor bodies comprising AIIIBV compounds
• CPC Class Codes: H01L 29/2003 Nitride compounds
• CPC Class Codes: H01L 29/452 on AIII-BV compounds
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

A nitride semiconductor device having a substrate electrode establishing an excellent ohmic contact with a nitride semiconductor substrate is provided. The nitride semiconductor device includes a substrate having an electrode formed on at least one main surface. The substrate is a nitride semiconductor substrate whose surface includes two regions. The first region has an electrode formed thereon and a second region does not have any electrodes formed thereon. A first n-type impurity is included in a higher concentration in the first region than that in the second region in the vicinity of the surface of the substrate.

Claims

1. A nitride semiconductor device comprising:

a substrate having an electrode formed on at least one main surface, wherein said substrate is a nitride semiconductor substrate and a surface of said substrate has a first region and a second region, said first region having an electrode formed thereon, and said first region includes a first n-type impurity with a higher concentration than in said second region.

2. A nitride semiconductor device according to claim 1, wherein said first n-type impurity has a higher concentration adjacent said at least one main surface than in another region further from said at least one main surface.

3. The nitride semiconductor device according to claim 1, wherein said nitride semiconductor substrate has n-type conductivity.

4. The nitride semiconductor device according to claim 1, wherein said nitride semiconductor substrate includes a second n-type impurity that is chemically different than said first n-type impurity.

5. The nitride semiconductor device according to claim 4, wherein said second n-type impurity is oxygen.

6. The nitride semiconductor device according to claim 4, wherein said second n-type impurity is distributed unevenly in a surface parallel with said one main surface.

7. The nitride semiconductor device according to claim 1, wherein said first n-type impurity is silicon.

8. The nitride semiconductor device according to claim 1, wherein said electrode has a first layer in contact with said substrate, said first layer including at least one elemental metal selected from the group consisting of vanadium (V), tungsten (W), molybdenum (Mo), chromium (Cr), zirconium (Zr), niobium (Nb), hafnium (Hf), tantalum (Ta), and titanium (Ti).

9. The nitride semiconductor device according to claim 8, wherein said electrode further includes a second layer on said first layer, wherein said second layer is thicker than said first layer, and includes at least one elemental metal which is different than the elemental metal in said first layer and is selected from the group consisting of aluminum (Al), tungsten (W), molybdenum (Mo), platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), osmium (Os), and Iridium (Ir).

10. The nitride semiconductor device according to claim 1, wherein another surface which is an opposite surface from said at least one main surface includes a plurality of stacked nitride semiconductor layers.

11. A nitride semiconductor device comprising:

a substrate having an electrode disposed on at least one main surface, wherein said substrate is a nitride semiconductor substrate and includes a first n-type impurity having a higher concentration adjacent said at least one main surface than in another region further from said at least one main surface.

12. The nitride semiconductor device according to claim 11, wherein said nitride semiconductor substrate has n-type conductivity.

13. The nitride semiconductor device according to claim 11, wherein said nitride semiconductor substrate includes a second n-type impurity that is chemically different than said first n-type impurity.

14. The nitride semiconductor device according to claim 13, wherein said second n-type impurity is oxygen.

15. The nitride semiconductor device according to claim 13, wherein said second n-type impurity is distributed unevenly in a surface parallel with said one main surface.

16. The nitride semiconductor device according to claim 11, wherein said first n-type impurity is silicon.

17. The nitride semiconductor device according to claim 11, wherein said electrode has a first layer in contact with said substrate, said first layer including at least one elemental metal selected from the group consisting of vanadium (V), tungsten (W), molybdenum (Mo), chromium (Cr), zirconium (Zr), niobium (Nb), hafnium (Hf), tantalum (Ta), and titanium (Ti).

18. The nitride semiconductor device according to claim 17, wherein said electrode further includes a second layer on said first layer, wherein said second layer is thicker than said first layer, and includes at least one elemental metal which is different than the elemental metal in said first layer and is selected from the group consisting of aluminum (Al), tungsten (W), molybdenum (Mo), platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), osmium (Os), and Iridium (Ir).

19. The nitride semiconductor device according to claim 11, wherein another main surface which is an opposite surface from said one main surface includes a device structure comprising a plurality of stacked nitride semiconductor layers.

20. A method for manufacturing a nitride semiconductor substrate comprising the steps of:

polishing one main surface of the substrate which has two main surfaces;

etching the one main surface which is polished by way of dry-etching;

wherein at least one element selected from the group consisting of Group IV elements and Group IV elements is included as at least an active species or an ambient gas during said step of etching.

21. The method for manufacturing the nitride semiconductor substrate according to claim 20, wherein said step of polishing further includes chemical mechanical polishing after mechanical polishing.

22. The method for manufacturing the nitride semiconductor device according to claim 20, further comprising the steps of:

forming a device structure by stacking nitride semiconductor layers on another main surface which is opposite surface from the one main surface of the substrate prior to said step of etching, and

disposing at least an electrode on the device structure.

23. The method for manufacturing the nitride semiconductor device according to claim 22, further comprising the step of:

conducting a heat treatment so as to establish ohmic contact in said step of disposing at least an electrode on the device structure.

24. The method for manufacturing the nitride semiconductor device according to claim 22, further comprising the step of:

immersing the one main surface in an acidic or alkaline aqueous solution following said step of etching and prior to said step of disposing an electrode on the device structure.

25. The method for manufacturing the nitride semiconductor device according to claim 20, said method further comprising the steps of:

forming a device structure by stacking nitride semiconductor layers on another main surface which is an opposite surface from the one main surface of the substrate; and

disposing at least an electrode on the device structure.

26. A method for manufacturing the nitride semiconductor device including a nitride semiconductor substrate having a first main surface and a second main surface, the method comprising the steps of:

etching the second main surface by dry-etching, and

disposing an electrode which establishes ohmic contact with the second main surface on the second main surface following said step of etching;

wherein at least one element selected from the group consisting of Group IV elements and Group IV elements is included as at least an active species or an ambient gas during said step of etching.

27. The method for manufacturing the nitride semiconductor device according to claim 26, further comprising the step of:

polishing the second main surface prior to said step of etching;

wherein said step of polishing includes a chemical mechanical polishing after a mechanical polishing.

28. The method for manufacturing the nitride semiconductor device according to claim 27, further comprising the steps of:

forming a device structure by stacking nitride semiconductor layers on the first main surface of the substrate prior to said step of etching, and

disposing at least an electrode on the device structure.

29. The method for manufacturing the nitride semiconductor device according to claim 28, further comprising the step of:

conducting a heat treatment so as to establish ohmic contact in said step for disposing an electrode on the device structure.

30. The method for manufacturing the nitride semiconductor device according to claim 28, further comprising the step of:

immersing the second main surface in an acidic or alkaline aqueous solution following said step of etching and prior to said step of disposing an electrode on the device structure.

31. The method for manufacturing the nitride semiconductor device according to claim 26, further comprising the steps of:

forming a device structure by stacking nitride semiconductor layers on the first main surface prior to said step of etching; and

disposing at least an electrode on the device structure.