LED stack manufacturing method and its structure thereof

• US 6,786,390 B2
• Filed: 02/04/2003
• Issued: 09/07/2004
• Est. Priority Date: 02/04/2003
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: United Epitaxy Company (Epistar Corporation)
• Inventors: Yang, Kuang-Neng, Wang, Pai-Hsiang, Chang, Chih-Sung, Chen, Tzer-Perng
• Primary Examiner(s): Stoner, Kiley
• Application Number:
  US10/357,445
• Publication Number:
  US 20040149810A1
• Time in Patent Office: 581 Days
• Field of Search: 228/179.1, 228/254, 228/225, 228/226, 228/227, 228/191, 228/264
• US Class Current: 228/179.1
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/641 characterized by the materials

Abstract

A LED stacking manufacturing method and its structure thereof, mainly uses a stacking method to integrate the epitaxial layer and the high-thermal-conductive substrate by twice bonding process, and the converted epitaxial layer of the temporary bonded substrate replaces the epitaxial wafer growth substrate, and the second bonded layer of the etch stop layer of the epitaxial layer is bonded with the second bonded layer of the high-thermal-conductive substrate to form an alloy layer with permanent connection, and then the temporary bonded substrate is removed, such that the process completes the integration of the epitaxial layer and the high-thermal-conductive substrate and makes the ohmic contact layer to face upward to provide a better reliability and efficiency of optical output of the LED.

Claims

1. A LED stack manufacturing method, producing LED by a twice bonding process for an epitaxial wafer layer grown on substrate bonded on a high-thermal-conductive substrate, comprising the steps of:

(a) providing an epitaxial wafer growth substrate with an epitaxial wafer layer on top of the epitaxial wafer growth substrate, and defining an upper layer and a lower surface layer of the epitaxial wafer layer as an ohmic contact layer and an etch stop layer;

(b) bonding the a first bonded layer on the ohmic contact layer of the epitaxial wafer layer with a temporary bonded substrate, and removing the epitaxial growth substrate after the bonding of the temporary bonded substrate is completed;

(c) forming a second bonded layer on the etch stop layer after the epitaxial wafer growth substrate is removed;

(d) providing a high thermal conductive substrate with a third bonded layer formed on top of the high-thermal-conductive substrate;

(e) bonding the second bonded layer and the third bonded layer as described in steps (c) and (d) to form an alloy layer, and removing the temporary bonded substrate;

such arrangement couples the epitaxial wafer layer and the high-thermal-conductive substrate and makes the ohmic contact layer facing upward to improve the stability and optical output efficiency of the LED.

2. The LED stack manufacturing method as claimed in claim 1, wherein said epitaxial wafer growth substrate being a III-V compound semiconductor substrate.

3. The LED stack manufacturing method as claimed in claim 2, wherein said compound semiconductor substrate being one selected from the group consisting of gallium arsenide (GaAs), indium phosphate (InP), gallium phosphate (GaP) and sapphire.

4. The LED stack manufacturing method as claimed in claim 1, wherein said epitaxial wafer layer being produced by a method selected from the group consisting of metal organic chemical vapor deposition (MOVCD), liquid phase epitaxial growth (LPE), and molecular beam epitaxial growth.

5. The LED stack manufacturing method as claimed in claim 1, wherein said first bonded layer being a metal layer with a melting point between 150°

C. and 350°

C.

6. The LED stack manufacturing method as claimed in claim 5, wherein said first bonded layer being one selected from the group consisting of indium, gold-tin (AuSn) alloy, and alloy with a melting point between 150°

C. and 400°

C.

7. The LED stack manufacturing method as claimed in claim 1, wherein said first bonded layer being an adhesive agent with a melting point between 150°

C. and 350°

C.

8. The LED stack manufacturing method as claimed in claim 1, wherein said second bonded layer being a metal layer with a melting point between 150°

C. and 400°

C.

9. The LED stack manufacturing method as claimed in claim 8, wherein said second bonded layer being one selected from the group consisting of indium and gold.

10. The LED stack manufacturing method as claimed in claim 1, wherein said third bonded layer being a metal layer with a melting point between 150°

C. and 400°

C.

11. The LED stack manufacturing method as claimed in claim 10, wherein said third bonded layer being one selected from the group consisting of gold and indium.

12. The LED stack manufacturing method as claimed in claim 1, wherein said first bonded layer being formed by adding pressure at the temperature from 150°

C. and 350°

C.

13. The LED stack manufacturing method as claimed in claim 1, wherein said second bonded layer and third bonded layer forming an alloy layer by adding pressure at the temperature from 150°

C. and 350°

C.

14. The LED stack manufacturing method as claimed in claim 1, wherein said third bonded layer and said high-thermal-conductive substrate having a barrier layer in between to prevent the third bonded layer from generating an internal diffusion.

15. The LED stack manufacturing method as claimed in claim 14, wherein said barrier layer and high-thermal-conductive substrate having a wetting layer in between to improve the activated coupling.

16. The LED stack manufacturing method as claimed in claim 14, wherein said barrier layer being made of a material selected from the group consisting of molybdenum, platinum, tungsten, indium oxide, tin oxide, indium tin oxide, zinc oxide, and magnesium oxide.

17. The LED stack manufacturing method as claimed in claim 15, wherein said wetting layer being made of a material selected from the group consisting of chromium, titanium, and nickel.

18. The LED stack manufacturing method as claimed in claim 1, wherein said high-thermal-conductive substrate having a thermal conductivity larger than 120 W/m-K.

19. The LED stack manufacturing method as claimed in claim 1, wherein said high-thermal-conductive substrate being made of a material selected from a group consisting of silicon (Si), aluminum (Al), copper (Cu), silver (Ag), silicon carbide (SiC), diamond, graphite, molybdenum, and aluminum nitride.