Electromagnetic radiation generating semiconductor chip and method for making same

• US 8,330,175 B2
• Filed: 06/16/2005
• Issued: 12/11/2012
• Est. Priority Date: 06/30/2004
• Status: Expired due to Fees

• Current Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Original Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Inventors: Eisert, Dominik, Strauss, Uwe
• Primary Examiner(s): Warren, Matthew E
• Assistant Examiner(s): Lin, John
• Application Number:
  US11/154,292
• Publication Number:
  US 20060011923A1
• Time in Patent Office: 2,735 Days
• Field of Search: 257/98, 257/E33.068, 257/79, 257/E33.001, 257/E33.055, 257/E33.067, 257/E33.074, 438/29, 438/22
• US Class Current: 257/98
• CPC Class Codes: H01L 2933/0016 relating to electrodes
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/382 the electrode extending partially in or entirely through the semiconductor body
• CPC Class Codes: H01L 33/387 with a plurality of electrode regions in direct contact with the semiconductor body and being electrically interconnected by another electrode layer
• CPC Class Codes: H01L 33/405 Reflective materials

Abstract

An electromagnetic radiation generating semiconductor chip is disclosed. A semiconductor layer sequence suitable for generating electromagnetic radiation is grown on a first main face of a radioparent, electrically conductive growth substrate, for example, a SiC growth substrate. Provided on a second main face of said growth substrate that faces away from said semiconductor layer sequence is a roughening that acts as a diffuser for an electromagnetic radiation emitted into said growth substrate by said semiconductor layer sequence and that in particular has a scattering factor higher than 0.25. A layer or layer sequence reflective of the electromagnetic radiation is applied to said roughening. A method for making the semiconductor chip is also disclosed.

Claims

1. An electromagnetic radiation generating semiconductor chip comprising:

a first set of layers including a radioparent, electrically conductive growth substrate and a semiconductor layer sequence for generating electromagnetic radiation grown on a first main face of the growth substrate;

a radiation-diffusing structure provided on a main face of the first set of layers, wherein the electromagnetic radiation emitted to the radiation-diffusing structure from said semiconductor layer sequence is scattered by said radiation-diffusing structure; and

a layer or layer sequence reflective to the electromagnetic radiation applied to said radiation-diffusing structure.

2. The electromagnetic radiation generating semiconductor chip as specified in claim 1 wherein the main face of the first set of layers is a second main face of said growth substrate remote from said semiconductor layer sequence.

3. The semiconductor chip as specified in claim 2, wherein said growth substrate has a thickness that is between 50 μ

m inclusive and 150 μ

m inclusive.

4. The semiconductor chip as specified in claim 3, wherein said growth substrate has a thickness of about 100 μ

m.

5. The semiconductor chip as specified in claim 2, wherein said electromagnetic radiation generating semiconductor layer sequence is based on nitride III/V compound semiconductor material.

6. The semiconductor chip as specified in claim 5, wherein said electromagnetic radiation generating semiconductor layer sequence contains at least one semiconductor layer based on In_xAl_yGa_1-x-yN, where 0≦

x≦

1, 0≦

y≦

1 and x+y≦

1.

7. The semiconductor chip as specified in claim 2, wherein said growth substrate is a SiC growth substrate implanted with a nitrogen dopant adjacent said layer or layer sequence reflective to the electromagnetic radiation to increase the majority charge carrier density and provide increased electrical conductivity.

8. The semiconductor chip as specified in claim 2, wherein said layer or layer sequence reflective to the electromagnetic radiation contains a metal that is reflective to the electromagnetic radiation emitted by said semiconductor layer sequence.

9. The semiconductor chip as specified in claim 8, wherein said metal contains one or more of Al, Ag, Ru, and Ir.

10. The semiconductor chip as specified in claim 2, wherein the radiation-diffusing structure has a pyramid structure.

11. The semiconductor chip as specified in claim 2, wherein a radiation-diffusing structure is also provided on a side opposite to the side on which said reflective layer or layer sequence is disposed.

12. The semiconductor chip as specified in claim 2,

wherein a second radiation-diffusing structure is provided on a front side of the first set of layers, the front side facing away from said reflective layer or layer sequence and configured for coupling out electromagnetic radiation during operation.

13. The semiconductor chip as specified in claim 2, further comprising a transparent or semitransparent, electrically conductive front-side contact layer disposed on a front side of the first set of layers, said front side being opposite to said reflective layer or layer sequence and configured for coupling out electromagnetic radiation operation.

14. The semiconductor chip as specified in claim 2, wherein the growth substrate comprises SiC.

15. The semiconductor chip as specified in claim 2, wherein the semiconductor chip comprises an electrical contact layer, wherein the electrical contact layer is arranged between the radiation-diffusing structure and the layer or layer sequence reflective to the electromagnetic radiation and is covered by the reflective layer or layer sequence.

16. The semiconductor chip as specified in claim 15, wherein the electrical contact layer comprises at least one element of the group consisting of spaced-apart lands, individual dots, and a lattice-like structure, or the electrical contact layer is a thin, semitransparent contact layer.

17. The semiconductor chip as specified in claim 15, wherein the electrical contact layer is configured to provide an electrical contact to the semiconductor layer sequence through the electrically conductive growth substrate.

18. The semiconductor chip as specified in claim 2, wherein the radiation-diffusing structure produces a scattering factor higher than 0.25.

19. The electromagnetic radiation generating semiconductor chip as specified in claim 1 wherein the main face of the first set of layers is a main face of said semiconductor layer sequence remote from said growth substrate.

20. The semiconductor chip as specified in claim 19, wherein the growth substrate comprises SiC.

21. The semiconductor chip as specified in claim 19, wherein the semiconductor chip comprises an electrical contact layer, wherein the electrical contact layer is arranged between the radiation-diffusing structure and the layer or layer sequence reflective to the electromagnetic radiation and is covered by the reflective layer or layer sequence.

22. The semiconductor chip as specified in claim 21, wherein the electrical contact layer comprises at least one element of the group consisting of spaced-apart lands, individual dots, and a lattice-like structure, or the electrical contact layer is a thin, semitransparent contact layer.

23. The semiconductor chip as specified in claim 21, wherein the electrical contact layer is configured to provide an electrical contact to the semiconductor layer sequence through the electrically conductive growth substrate.

24. The semiconductor chip as specified in claim 19, wherein the radiation-diffusing structure produces a scattering factor higher than 0.25.

25. The semiconductor chip as specified in claim 19, wherein said growth substrate has a thickness that is between 50 μ

m inclusive and 150 μ

m inclusive.

26. The semiconductor chip as specified in claim 19, wherein said electromagnetic radiation generating semiconductor layer sequence is based on nitride III/V compound semiconductor material.

27. The semiconductor chip as specified in claim 26, wherein said electromagnetic radiation generating semiconductor layer sequence contains at least one semiconductor layer based on In_xAl_yGa_1-x-yN, where 0≦

x≦

1, 0≦

y≦

1 and x+y≦

1.

28. The semiconductor chip as specified in claim 19, wherein said growth substrate is a SiC growth substrate implanted with a nitrogen dopant adjacent said reflective layer to increase the majority charge carrier density and provide increased electrical conductivity.

29. The semiconductor chip as specified in claim 19, wherein said reflective layer contains a metal that is reflective to the electromagnetic radiation emitted by said semiconductor layer sequence.

30. The semiconductor chip as specified in claim 29, wherein said metal contains one or more of Al, Ag, Ru, and Ir.

31. The semiconductor chip of claim 1, wherein the radiation-diffusing structure has a diffuse roughening.

32. A light-emitting assembly comprising:

a housing; and

the semiconductor chip of claim 1 mounted to a chip mounting surface of the housing.

33. The semiconductor chip as specified in claim 1, wherein a semitransparent conductive layer is placed between the first set of layers and the reflective layer.

34. The semiconductor chip as specified in claim 32, wherein the thickness of the semitransparent conductive layer is less than 10 nm.