Electrode for light-emitting semiconductor devices and method of producing the electrode

• US 20040173809A1
• Filed: 03/16/2004
• Published: 09/09/2004
• Est. Priority Date: 05/08/1997
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Showa Denko KK (Resonac Holdings Corp.)
• Inventors: Miki, Hisayuki, Okuyama, Mineo, Muraki, Noritaka, Udagawa, Takashi
• Granted Patent: US 7,057,210 B2
• Time in Patent Office: Days
• US Class Current: 257/99
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/01005 Boron [B]
• CPC Class Codes: H01L 2924/01012 Magnesium [Mg]
• CPC Class Codes: H01L 2924/01015 Phosphorus [P]
• CPC Class Codes: H01L 2924/01022 Titanium [Ti]
• CPC Class Codes: H01L 2924/01024 Chromium [Cr]
• CPC Class Codes: H01L 2924/01027 Cobalt [Co]
• CPC Class Codes: H01L 2924/01028 Nickel [Ni]
• CPC Class Codes: H01L 2924/01029 Copper [Cu]
• CPC Class Codes: H01L 2924/0103 Zinc [Zn]
• CPC Class Codes: H01L 2924/01046 Palladium [Pd]
• CPC Class Codes: H01L 2924/0105 Tin [Sn]
• CPC Class Codes: H01L 2924/01078 Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2933/0016 relating to electrodes
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/40 Materials therefor
• CPC Class Codes: H01L 33/42 Transparent materials

Abstract

An electrode for a light-emitting semiconductor device includes a light-permeable electrode formed to come into contact with the surface of the semiconductor, and a wire-bonding electrode that is in electrical contact with the light-permeable electrode and is formed to come into partial contact with the surface of the semiconductor with at least a region in contact with the semiconductor having a higher contact resistance per unit area with respect to the semiconductor than a region of the light-permeable electrode in contact with the semiconductor. This device electrode is formed by forming a wire-bonding electrode on a portion of the surface of a p-type GaN-base compound semiconductor, forming on the surface of the semiconductor a first layer that is of at least one member selected from the group consisting of Au, Pt and Pd and is formed to overlay the upper surface of the wire-bonding electrode at a portion at which the wire-bonding electrode is located, forming on the first layer a second layer that is of at least one metal selected from the group consisting of Ni, Ti, Sn, Cr, Co, Zn, Cu, Mg and In, and forming a light-permeable electrode by heat-treating the first and second layers in an atmosphere that contains oxygen.

Claims

1. An electrode for a light-emitting semiconductor device, formed on a surface of a p-type GaN-base compound semiconductor, comprising a light-permeable electrode formed to come into contact with the surface of the semiconductor, and a wire-bonding electrode that is in electrical contact with the light-permeable electrode and is formed to come into partial contact with the surface of the semiconductor with at least a region in contact with the semiconductor having a higher contact resistance per unit area with respect to the semiconductor than a region of the light-permeable electrode in contact with the semiconductor.

2. The electrode according to claim 1, wherein the region of the wire-bonding electrode in contact with the semiconductor comprises at least one member selected from a group consisting of Tl, In, Mn, Ti, Al, Ag, Sn, AuBe, AuZn, AuMg, AlSi, TiSi and TiBe.

3. The electrode according to claim 1, wherein the region of the wire-bonding electrode in contact with the semiconductor comprises at least one member selected from a group consisting of Ti, Al and AuBe.

4. The electrode according to claim 1, wherein the region of the light-permeable electrode in contact with the semiconductor comprises one metal selected from a group consisting of Au, Pd, Pt, Ni and Cr.

5. The electrode according to claim 1, wherein the wire-bonding electrode has a multilayer structure in which a topmost layer is formed of Al or Au.

6. The electrode according to claim 1, wherein the light-permeable electrode comprises a first layer formed to come into contact with the surface of the semiconductor and comprising at least one member selected from a group consisting of Au, Pt and Pd, and a second layer formed on the first layer and comprising a light-permeable metal oxide containing an oxide of at least one metal selected from a group consisting of Ni, Ti, Sn, Cr, Co, Zn, Cu, Mg and In.

7. The electrode according to claim 6, wherein the first layer is comprised of Au and the second layer is comprised of an oxide of Ni.

8. The electrode according to claim 6, wherein the second layer has an oxygen composition that gradually decreases from the second layer toward the first layer in a region near an interface between the second layer and the first layer.

9. The electrode according to claim 6, wherein the first layer contains a metal element which is a main component of the metal oxide constituting the second layer.

10. The electrode according to claims 1 to 5, wherein the light-permeable electrode is formed to overlay an upper surface of the wire-bonding electrode at a portion at which the wire-bonding electrode is disposed.

11. The electrode according to claims 6 to 9, wherein the light-permeable electrode is formed to overlay an upper surface of the wire-bonding electrode at a portion at which the wire-bonding electrode is disposed.

12. The electrode according to claim 10, wherein the light-permeable electrode is formed to overlay a periphery of the upper surface of the wire-bonding electrode.

13. The electrode according to claim 11, wherein the light-permeable electrode is formed to overlay a periphery of the upper surface of the wire-bonding electrode.

14. The electrode according to claim 10, wherein the light-permeable electrode is formed to cover an entire upper surface of the wire-bonding electrode.

15. The electrode according to claim 11, wherein the light-permeable electrode is formed to cover an entire upper surface of the wire-bonding electrode.

16. The electrode according to claim 11, wherein the first layer of the light-permeable electrode is exposed at the portion of the second layer, that overlays the wire-bonding electrode.

17. The electrode according to claim 16, wherein at least a part of the exposed portion of the first layer is laminated with Al or Au.

18. An electrode for a light-emitting semiconductor device, formed on a surface of a p-type GaN-base compound semiconductor, comprising a light-permeable electrode comprised of a first layer of Au formed to come into contact with the surface of the semiconductor, and a second layer of NiO formed on the first layer, and a wire-bonding electrode that is formed to be in electrical contact with the light-permeable electrode and in partial contact with the surface of the semiconductor, said wire-bonding electrode comprising a lamination of, from the semiconductor side, AuBe and Au, with the light-permeable electrode being formed to overlay an upper surface of the wire-bonding electrode at a portion at which the wire-bonding electrode is disposed.

19. The electrode according to claim 18, wherein the first layer of the light-permeable electrode is exposed at the portin of the second layer that overlays the wire-bonding electrode.

20. The electrode according to claim 19, wherein the exposed portion of the first layer of the light-permeable electrode is laminated with Au.

21. An electrode for a light-emitting semiconductor device, formed on a surface of a p-type GaN-base compound semiconductor, comprising a light-permeable electrode comprised of a first layer constituted of at least one member selected from a group consisting of Au, Pt and Pd and formed to come into contact with the surface of the semiconductor, and a second layer formed on the first layer and comprising a light-permeable metal oxide containing an oxide of at least one metal selected from a group consisting of Ni, Ti, Sn, Cr, Co, Zn, Cu Mg and In, and a wire-bonding electrode that is formed to be in electrical contact with the light-permeable electrode and in partial contact with the surface of the semiconductor.

22. The electrode according to claim 21, wherein the first layer is comprised of Au and the second layer is comprised of an oxide of Ni.

23. The electrode according to claim 21, wherein the second layer has an oxygen composition that gradually decreases from the second layer toward the first layer in a region near an interface between the second layer and the first layer.

24. The electrode according to claim 21, wherein the first layer contains a metal element which is a main component of the metal oxide constituting the second layer.

25. The electrode according to claims 21 to 24, wherein the light-permeable electrode is formed to overlay an upper surface of the wire-bonding electrode at a portion at which the wire-bonding electrode is disposed.

26. The electrode according to claim 25, wherein the light-permeable electrode is formed to overlay a periphery of the upper surface of the wire-bonding electrode.

27. The electrode according to claim 25, wherein the light-permeable electrode is formed to cover the entire upper surface of the wire-bonding electrode.

28. The electrode according to claim 27, wherein the first layer of the light-permeable electrode is exposed at the portion of the second layer that overlays the wire-bonding electrode.

29. The electrode according to claim 28, wherein at least a part of the exposed portion of the first layer is laminated with Al or Au.

30. An electrode for a light-emitting semiconductor device, formed on a surface of a p-type GaN-base compound semiconductor, comprising a light-permeable electrode formed to come into contact with the surface of the semiconductor, and a wire-bonding electrode that is in electrical contact with the light-permeable electrode and is formed with a bottom surface in partial contact with the surface of the semiconductor and an upper surface overlaid by the light-permeable electrode.

31. The electrode according to claim 30, wherein the light-permeable electrode is formed to overlay a periphery of the upper surface of the wire-bonding electrode.

32. The electrode according to claim 30, wherein the light-permeable electrode is formed to cover an entire upper surface of the wire-bonding electrode.

33. A method of producing an electrode for a light-emitting semiconductor device, formed on a surface of a p-type GaN-base compound semiconductor, comprising a first step of forming a wire-bonding electrode on a portion of the surface of the semiconductor, a second step of forming a first layer on the surface of the semiconductor, the first layer comprising at least one member selected from a group consisting of Au, Pt and Pd and being formed to overlay an upper surface of the wire-bonding electrode at a portion at which the wire-bonding electrode is located, a third step of forming on the first layer a second layer that comprises at least one metal selected from a group consisting of Ni, Ti, Sn, Cr, Co, Zn, Cu, Mg and In, and a fourth step of forming a light-permeable electrode by heat-treating the first and second layers in an atmosphere that contains oxygen.

34. The method of producing an electrode according to claim 33, wherein the atmosphere containing oxygen has an oxygen concentration of not less than 1 ppm.

35. A method of producing an electrode for a light-emitting semiconductor device, formed on a surface of a p-type GaN-base compound semiconductor, comprising a first step of forming a wire-bonding electrode on a portion of the surface of the semiconductor, a second step of forming an alloy layer on the surface of the semiconductor, the alloy layer comprising an alloy that contains at least one metal selected from a group consisting of Au, Pt and Pd and at least one metal selected from a group consisting of Ni, Ti, Sn, Cr, Co, Zn, Cu, Mg and In and being formed to overlay an upper surface of the wire-bonding electrode at a portion at which the wire-bonding electrode is located, and a third step of forming a light-permeable electrode by heat-treating the alloy layer in an atmosphere containing oxygen to form on the semiconductor side a first layer comprised of metal or alloy, and a second layer comprised of a light-permeable metal oxide formed on the first layer.

36. The method of producing an electrode according to claim 35, wherein the atmosphere containing oxygen has an oxygen concentration of not less than 1 ppm.