Electromagnetic radiation emitting semiconductor chip and procedure for its production

• US 7,129,528 B2
• Filed: 09/25/2003
• Issued: 10/31/2006
• Est. Priority Date: 09/30/2002
• Status: Active Grant

• Current Assignee: OSRAM GmbH (Ams-Osram AG)
• Original Assignee: OSRAM GmbH (Ams-Osram AG)
• Inventors: Hahn, Berthold, Kaiser, Stephan, Eisert, Dominik, Bader, Stefan
• Primary Examiner(s): TRAN, MINH LOAN
• Application Number:
  US10/671,854
• Publication Number:
  US 20040113167A1
• Time in Patent Office: 1,132 Days
• Field of Search: 257 94- 96, 257/98, 257/99, 257/103, 257/E33.072, 257/E33.068
• US Class Current: 257/98
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector

Abstract

Semiconductor chip which emits electromagnetic radiation, and method for fabricating it. To improve the light yield of semiconductor chips which emit electromagnetic radiation, a textured reflection surface (131) is integrated on the p-side of a semiconductor chip. The semiconductor chip has an epitaxially produced semiconductor layer stack (1) based on GaN, which comprises an n-conducting semiconductor layer (11), a p-conducting semiconductor layer (13) and an electromagnetic radiation generating region (12) which is arranged between these two semiconductor layers (11, 13). The surface of the p-conducting semiconductor layer (13) which faces away from the radiation-generating region (12) is provided with three-dimensional pyramid-like structures (15). A mirror layer (40) is arranged over the whole of this textured surface. A textured reflection surface (131) is formed between the mirror layer (40) and the p-conducting semiconductor layer (13). The textured reflection surface (131) can increase the amount of light which is decoupled at the radiation-outcoupling surface (111) by virtue of the fact that a beam (3), after double reflection on the reflection surface (131), is more likely not to be totally reflected.

Claims

1. A semiconductor chip which emits electromagnetic radiation, comprising:

an epitaxially produced semiconductor layer stack based on a nitride semiconductor material, which includes an n-conducting semiconductor layers, a p-conducting semiconductor layer and an electromagnetic radiation generating region which is arranged between said n-conducting and p-conducting semiconductor layers;

a base, on which the semiconductor layer stack is arranged; and

a mirror layer, which is arranged between the semiconductor layer stack and the base and reflects electromagnetic radiation emitted by the semiconductor layer stack in a direction of the base,

wherein the mirror layer has a plurality of planar reflection sub-surfaces, which are positioned obliquely with respect to a main plane of the electromagnetic radiation-generating region and each form an angle of between 10° and

50°

with respect to the main plane, and

wherein the p-conducting semiconductor layer faces the base, and the mirror layer is comprised of a reflection surface of the p-conducting semiconductor layer, which includes the plurality of planar sub-surfaces which are positioned obliquely with respect to the main plane of the electromagnetic radiation-generating region and each form the angle of between 10° and

50°

with respect to the main plane.

2. The semiconductor chip which emits electromagnetic radiation according to claim 1, wherein the reflection sub-surfaces form pyramid-like structures.

3. The semiconductor chip which emits electromagnetic radiation according to claim 1, wherein the mirror layer includes a plurality of different layers.

4. The semiconductor chip which emits electromagnetic radiation according to claim 1, wherein the mirror layer comprises a highly reflective layer, and at least one of a protective layer, and a joining layer.

5. The semiconductor chip which emits electromagnetic radiation according to claim 4, wherein the highly reflective layer contains silver or aluminum.

6. The semiconductor chip which emits electromagnetic radiation according to claim 4, wherein the protective layer contains titanium nitride.

7. The semiconductor chip which emits electromagnetic radiation according to claim 4, wherein the joining layer contains at least one of gold, tin and an alloy of these metals.

8. The semiconductor chip which emits electromagnetic radiation according to claim 1, wherein the semiconductor layer stack includes at least one trench which defines a plurality of individual semiconductor layer elements.

9. The semiconductor chip which emits electromagnetic radiation according to claim 8, comprising a plurality of trenches extending such that the semiconductor layer elements, in plan view, are in the shape of one of a circle, a hexagon, a quadrilateral, a triangle or a combination of these shapes.

10. The semiconductor chip which emits electromagnetic radiation according to claim 8, wherein the semiconductor layer elements each have a diameter or a width which includes at most ten pyramid-like structures.

11. The semiconductor chip which emits electromagnetic radiation according to claim 8, wherein the at least one trench is at least sufficiently deep so as to at least isolate the radiation-generating region.

12. The semiconductor chip which emits electromagnetic radiation according to claim 8, wherein a width of the at least one trench is at least double a depth of the at least one trench.

13. The semiconductor chip which emits electromagnetic radiation according to claim 8, wherein the at least one trench is filled with an electrically insulating material which transmits radiation generated by the radiation-generating region.

14. The semiconductor chip which emits electromagnetic radiation according to claim 1, comprising a radiation-transmitting electrically conductive contact layer arranged on the n-conducting semiconductor layer.

15. The semiconductor chip which emits electromagnetic radiation according to claim 14, wherein the contact layer contains at least one of indium tin oxide and ZnO.

16. The semiconductor chip which emits electromagnetic radiation according to claim 1, wherein the semiconductor chip does not contain a growth substrate.

17. The semiconductor chip which emits electromagnetic radiation according to claim 1, wherein the p-conducting semiconductor layer is doped with magnesium.

18. The semiconductor chip which emits electromagnetic radiation according to claim 1, wherein the base contains gallium arsenide or copper.