Structure and manufacturing method for GaN light emitting diodes

• US 6,914,264 B2
• Filed: 10/29/2002
• Issued: 07/05/2005
• Est. Priority Date: 09/20/2002
• Status: Expired due to Fees

• Current Assignee: Formosa Epitaxy Incorporated (Ennostar, Inc.), Lumens Co., Ltd.
• Original Assignee: Formosa Epitaxy Incorporated (Ennostar, Inc.)
• Inventors: Chien, Fen-Ren, Chen, Lung-Chien, Lan, Wen-How
• Primary Examiner(s): Thompson, Craig A.
• Assistant Examiner(s): Dolan, Jennifer M
• Application Number:
  US10/283,886
• Publication Number:
  US 20040079948A1
• Time in Patent Office: 980 Days
• Field of Search: 257/9, 257/12, 257/13, 257/1, 257/22, 257/79, 257/94, 257/96, 257/99, 257/101, 257/103, 257/615, 257/14, 438/22, 438/46, 438/47
• US Class Current: 257/96
• CPC Class Codes: H01L 33/04 with a quantum effect structure or superlattice, e.g. tunnel junction
• CPC Class Codes: H01L 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/42 Transparent materials

Abstract

A GaN semiconductor stack layer is formed on top of a substrate for manufacturing a light emitting diode. The GaN semiconductor stack layer includes, from the bottom up, an N-type GaN contact layer, a light emitting stack layer and a P-type contact layer. The next step is to form a digital transparent layer on the P-type GaN contact layer, then use dry etching technique to etch downward through the digital transparent layer, the P-type GaN contact layer, the light emitting layer, the N-type GaN contact layer, and form an N-metal forming area within the N-type GaN contact layer. The next step is to form a first ohmic contact electrode on the P-type contact layer to serve as P-type ohmic contact, and a second ohmic contact electrode on the N-metal forming area to serve as N-type ohmic contact. Finally, a bump pad is formed on the first ohmic contact electrode and the second ohmic contact electrode, respectively.

Claims

1. A GaN light emitting diode structure, comprising:

a substrate;

a GaN semiconductor stack layer formed on said substrate;

said GaN semiconductor stack layer having a first upper surface and a second upper surface;

a digital transparent layer formed on said first upper surface, said digital transparent layer having a stack of alternating Al(x)In(y)Ga(1-x-y)N(z)P(1-z) and Al(p)In(q)Ga(1-p-q)N(r)P(1-r) layers, wherein the values of x, y, z, p, q, r, are between 0 and 1;

a first ohmic contact electrode formed on said digital transparent layer for P-type ohmic contact; and

a second ohmic contact electrode formed on said second upper surface for N-type ohmic contact.

2. The GaN light emitting diode structure as claimed in claim 1, wherein said GaN semiconductor stack layer comprises an N-type GaN contact layer, a light emitting stack layer and a P-type GaN contact layer.

3. The GaN light emitting diode structure as claimed in claim 1, wherein the layers of Al(x)In(y)Ga(1-x-y)N(1-z) in said digital transparent layer have thickness increasing from 10 Å

to 90 Å

, and the layers of Al(p)In(q)Ga(1-p-q)N(r)P(1-r) have thickness decreasing from 90 Å

to 10 Å

.

4. The GaN light emitting diode structure as claimed in claim 1, wherein said first ohmic contact electrode is made of indium tin oxide.

5. The GaN light emitting diode structure as claimed in claim 4, wherein the thickness of said first ohmic contact ranges from 100 Å

to 20000 Å

.

6. The GaN light emitting diode structure as claimed in claim 1, wherein the distance between said substrate and said first ohmic contact electrode is greater than the distance between said substrate and said second ohmic contact electrode.

7. A GaN light emitting diode structure, comprising:

a substrate;

a buffer layer formed on top of said substrate;

an N-type GaN contact layer formed on top of said buffer layer;

a light-emitting stack layer formed on top of said N-type contact layer;

a P-type GaN contact layer formed on top of said light emitting stack layer;

a digital transparent layer formed on said P-type GaN contact layer, said digital transparent layer having a stack of alternating Al(x)In(y)Ga(1-x-y)N(z)P(1-z) and Al(p)In(q)Ga(1-p-q)N(r)P(1-r) layers, wherein the values of x, y, z, p, q, r, are between 0 and 1;

a first ohmic contact electrode formed on said digital transparent layer for P-type ohmic contact; and

a second ohmic contact electrode formed on said N-type GaN contact layer for N-type ohmic contact.

8. The GaN light emitting diode structure as claimed in claim 7, wherein the layers of Al(x)In(y)Ga(1-x-y)N(z)P(1-z) in said digital transparent layer have thickness increasing from 10 Å

to 90 Å

, and the layers of Al(p)In(q)Ga(1-p-q)N(r)P(1-r) have thickness decreasing from 90 Å

to 10 Å

.

9. The GaN light emitting diode structure as claimed in claim 7, wherein said first ohmic contact electrode is made of indium tin oxide.

10. The GaN light emitting diode structure as claimed in claim 9, wherein the thickness of said first ohmic contact ranges from 100 Å

to 20000 Å

.

11. The GaN light emitting diode structure as claimed in claim 7, wherein the distance between said substrate and said first ohmic contact electrode is greater than the distance between said substrate and said second ohmic contact electrode.