Structure and manufacturing method for GaN light emitting diodes

• US 20040079948A1
• Filed: 10/29/2002
• Published: 04/29/2004
• Est. Priority Date: 09/20/2002
• Status: Active Grant

• Current Assignee: Formosa Epitaxy Incorporated (Epistar Corporation), Lumens Co., Ltd.
• Original Assignee: Formosa Epitaxy Incorporated (Epistar Corporation)
• Inventors: Chien, Fen-Ren, Chen, Lung-Chien, Lan, Wen-How
• Granted Patent: US 6,914,264 B2
• Time in Patent Office: Days
• US Class Current: 257/79
• 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

The present invention provides a structure and a manufacturing method of GaN light emitting diodes. First, a substrate is provided. Then, a GaN semiconductor stack layer is formed on top of the substrate. The said 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 said 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 II 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 structure of the GaN light emitting diode, comprising:

a substrate;

a GaN semiconductor stack layer, formed on said substrate;

said GaN semiconductor layer having a first upper surface and a second upper surface, wherein the distance between said non-conductive substrate and said first upper surface being greater than that of said substrate and said second upper surface;

a digital transparent layer, whose photo-penetrability being higher than 80% for wavelength rangeing between 380 nm and 560 nm, and carrier penetration being able to taking place within said digital transparent layer;

a first ohmic contact electrode, formed on said first upper surface 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 claimed as in claim 1, wherein said GaN semiconductor layer consisting of 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 claimed as in claim 1, whereinsaid digital transparent layer being made of two types of material;

one being Al(x)In(y)Ga(1-x-y)N(z)P(1-z), whose thickness increasing from 10 Å

to 90 Å

, and the other being Al(p)In(q)Ga(1-p-q)N(r)P(1-r), whose thickness decreasing from 90 Å

to 10 Å

, wherein the values of x, y, z, p, q, r, are all between 0 and 1, and whose conductivity is either P-type, N-type or I-type.

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

5. The first ohmic contact electrode claimed as in claim 4, wherein the thickness of said first ohmic contact ranging from 100 Å

to 20000 Å

, and preferred thickness ranging from 1000 Å

to 4000 Å

.

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

7. A structure of the GaN light emitting diode, 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 layer;

a digital transparent layer, whose photo-penetrability being higher than 80% for wavelength rangeing between 380 nm and 560 nm, and carrier penetration being able to taking place within said digital transparent layer;

a first ohmic contact electrode, formed on said first upper surface for P-type ohmic contact; and

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

8. The GaN light emitting diode structure claimed as in claim 7, whereinsaid digital transparent layer being made of two types of material;

one being Al(x)In(y)Ga(1-x-y)N(z)P(1-z), whose thickness increasing from 10 Å

to 90 Å

, and the other being Al(p)In(q)Ga(1-p-q)N(r)P(1-r), whose thickness decreasing from 90 Å

to 10 Å

, wherein the values of x, y, z, p, q, r, are all between 0 and 1, and whose conductivity is either P-type, N-type or I-type.

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

10. The first ohmic contact electrode claimed as in claim 9, wherein the thickness of said first ohmic contact ranging from 100 Å

to 20000 Å

, and preferred thickness ranging from 1000 Å

to 4000 Å

.

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

12. A method for manufacturing the GaN light emitting diodes, comprising:

providing a substrate;

forming a GaN semiconductor stack layer on said substrate, wherein said GaN semiconductor stack layer including, from the bottom up, an N-type GaN contact layer, a light emitting stack layer and a P-type contact layer;

forming a digital transparent layer on said p-type GaN contact layer;

using dry etching technique to etch downward through said digital transparent layer, said P-type GaN contact layer, said light emitting layer, said N-type GaN contact layer, and forming an N-metal forming area within said N-type GaN contact layer;

forming a first ohmic contact electrode on said P-type contact layer to serve as P-type ohmic contact;

forming a second ohmic contact electrode on said N-metal forming area to serve as N-type ohmic contact; and

forming bump pads on said first ohmic contact electrode and said second ohmic contact electrode, respectively.

13. The method for manufacturing the GaN light emitting diodes claimed as in claim 12, wherein said digital transparent layer being formed by using one of the following methods:

metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy, vapor phase epitaxy (VPE), or liquid phase epitaxy (LPE).

14. The method for manufacturing the GaN light emitting diodes claimed as in claim 13, wherein said digital transparent layer being made of a material photo-penetrability being higher than 80% for wavelength rangeing between 380 nm and 560 nm, and carrier penetration being able to taking place within said material.

15. The method for manufacturing the GaN light emitting diodes claimed as in claim 14, wherein said digital transparent layer being made of types of material;

one being Al(x)In(y)Ga(1-x-y)N(z)P(1-z), whose thickness increasing from 10 Å

to 90 Å

, and the other being Al(p)In(q)Ga(1-p-q)N(r)P(1-r), whose thickness decreasing from 90 Å

to 10 Å

, wherein the values of x, y, z, p, q, r, are all between 0 and 1, and whose conductivity is either P-type, N-type or I-type.

16. The method for manufacturing the GaN light emitting diodes claimed as in claim 12, wherein said dry etching technique being inductively coupled plasma-reactive ion etching (ICP-RIE).

17. The method for manufacturing the GaN light emitting diodes claimed as in claim 16, wherein said inductively coupled plasma-reactive ion etching technique forming an N-metal forming area of about 10000 Å

.

18. The method for manufacturing the GaN light emitting diodes claimed as in claim 12, wherein said first ohmic contact electrode is made of indium tin oxide.

19. The method for manufacturing the GaN light emitting diodes claimed as in claim 12, wherein said first ohmic contact layer is formed by using splash vapor-phase steam electroplate technique.

20. The method for manufacturing the GaN light emitting diodes claimed as in claim 12, wherein the thickness of said first ohmic contact ranging from 100 Å

to 20000 Å

, and preferred thickness ranging from 1000 Å

to 4000 Å

.

21. The method for manufacturing the GaN light emitting diodes claimed as in claim 12, wherein said second ohmic contact electrode is made of Ti/Al, Ti/Al/Ti/Au, or Ti/Al/Ni/Au.

22. The method for manufacturing the GaN light emitting diodes claimed as in claim 21, wherein preferred thickness of said material is 150 Å

/1500 Å

for Ti/Al, 150 Å

/1500 Å

/2000 Å

/1000 Å

for Ti/Al/Ti/Au, and 150 Å

/1500 Å

/2000 Å

/1000 Å

for Ti/Al/Ni/Au.

23. The method for manufacturing the GaN light emitting diodes claimed as in claim 12, wherein said GaN stack layer comprising a buffer layer;

said buffer layer being placed between said substrate and said N-type contact layer.

24. The method for manufacturing the GaN light emitting diodes claimed as in claim 12, wherein said bump pad is made of Ti/Au, Ti/Al/Ti/Au, or Ti/Al/Pt/Au.

25. The method for manufacturing the GaN light emitting diodes claimed as in claim 24, wherein the preferred thickness of said material is Ti/Au (150 Å

/20000 Å

), Ti/Al/Ti/Au (150 Å

/1500 Å

/2000 Å

/1000 Å

), and Ti/Al/Pt/Au (150 Å

/1500 Å

/2000 Å

/1000 Å

).