Light generating semiconductor device and method of making the same

• US 20050040425A1
• Filed: 08/05/2004
• Published: 02/24/2005
• Est. Priority Date: 08/08/2003
• Status: Active Grant

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Akita, Katsushi
• Granted Patent: US 7,368,310 B2
• Time in Patent Office: Days
• US Class Current: 257/103
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: Y10S 438/977 Thinning or removal of substrate

Abstract

In a method of making a semiconductor light generating device, a GaN-based semiconductor portion is formed on a GaN or AlGaN substrate. The GaN-based semiconductor portion includes a light generating film. An electrode film is formed on the GaN-based semiconductor film. A conductive substrate is bonded to a surface of the electrode film using a conductive adhesive. After bonding the conductive substrate, the GaN or AlGaN substrate is separated from the GaN-based semiconductor portion to form the semiconductor light generating device.

Claims

1. A method of making a semiconductor light generating devices the method comprising the steps of:

forming a GaN-based semiconductor portion on a Al_XGa_1-XN (0≦

x≦

1) substrate, the GaN-based semiconductor portion including a light generating film;

forming an electrode film on the GaN-based semiconductor portion;

bonding a conductive substrate to a surface of the electrode film using a conductive adhesive; and

after bonding the conductive substrate, separating one of the Al_XGa_1-XN substrate and the GaN-based semiconductor portion from the other.

2. The method according to claim 1, wherein the conductive substrate is made of metal.

3. The method according to claim 1, wherein the Al_XGa_1-XN substrate is a GaN substrate.

4. The method according to claim 3, the method further comprising the step of:

prior to forming the GaN-based semiconductor portion, forming a sacrificial film on the GaN substrate, the sacrificial film being made of a first material, the first material having a band gap smaller than the material of the substrate,

wherein separating one of the GaN substrate and the GaN-based semiconductor film from the other includes a step of irradiating the sacrificial film with light to perform lift-off of one of the GaN substrate and the GaN-based semiconductor portion from the other, the light including a wavelength component corresponding to a energy smaller than a bandgap energy of GaN semiconductor.

5. The method according to claim 4, wherein the sacrificial film is made of nitride compound semiconductor containing indium.

6. The method according to claim 3, the method further comprising the steps of:

reconditioning the separated GaN substrate for reuse; and

performing the following steps using the reconditioned GaN substrate;

forming a GaN-based semiconductor portion on the reconditioned GaN substrate, the GaN-based semiconductor portion including a light generating film;

forming an electrode film on the GaN-based semiconductor portion;

bonding a conductive substrate to a surface of the electrode film; and

after bonding the conductive substrate, separating one of the reconditioned GaN substrate and the GaN-based semiconductor portion from the other.

7. The method according to claim 1, wherein the Al_XGa_1-XN substrate (0≦

x≦

1) is an Al_XGa_1-XN substrate (0<

x≦

1).

8. The method according to claim 7, the method further comprising the step of:

prior to forming the GaN-based semiconductor portion, forming a sacrificial film on the Al_XGa_1-XN substrate, the sacrificial layer being made of a first material, the first material having a bandgap smaller than material of the Al_XGa_1-XN substrate,

wherein separating one of the Al_XGa_1-XN substrate and the GaN-based semiconductor portion from the other includes a step of irradiating the sacrificial film with light to perform lift-off of one of the Al_XGa_1-XN substrate and the GaN-based semiconductor portion from the other, the light including a wavelength component corresponding to a energy smaller than a bandgap energy of material of the substrate.

9. The method according to claim 8, wherein the sacrificial layer is made of nitride compound semiconductor containing indium.

10. The method according to claim 7, the method further comprising the steps of:

reconditioning the separated Al_XGa_1-XN substrate for reuse; and

performing the following steps using the reconditioned Al_XGa_XN substrate;

forming a GaN-based semiconductor portion on the reconditioned Al_XGa_1-XN substrate, the GaN-based semiconductor portion including a light generating film;

forming an electrode film on the GaN-based semiconductor portion;

bonding a conductive substrate to a surface of the electrode film; and

after bonding the conductive substrate, separating one of the reconditioned Al_XGa_1-XN substrate and the GaN-based semiconductor portion from the other.

11. The method according to claim 1, wherein the light generating layer is made of material having a bandgap energy greater than material of the substrate.

12. The method according to claim 1, wherein the light generating film is made of nitride compound semiconductor containing aluminum.

13. The method according to claim 1, wherein the conductive substrate is made of one of Cu—

W alloy and Fe—

Ni alloy.

14. The method according to claim 1, wherein the conductive adhesive contains one of Au—

Sn solder and Pb—

Ni solder.

15. The method according to claim 1, wherein the electrode film is made of material having a reflectivity greater than the conductive substrate at a peak wavelength of light from the light generating layer.

16. A semiconductor light generating device comprising:

a GaN-based semiconductor portion including a light generating layer, the light generating layer having a density of threading dislocations smaller than 1×

10⁷ cm<sup>−

2;</sup>

an electrode provided on the GaN-based semiconductor portion;

a conductive substrate bonded to a surface of the electrode by a conductive adhesive.

17. The semiconductor light generating device according to claim 16, wherein the light generating layer is made of a GaN-based semiconductor having a bandgap energy greater than GaN semiconductor.

18. The semiconductor light generating device according to claim 16, wherein the light generating layer is made of a semiconductor material of a bandgap energy greater than Al_XGa_1-XN (0<

x≦

1).

19. The semiconductor light generating device according to claim 16, wherein the electrode is made of material having a reflectivity greater than the conductive substrate at a peak wavelength of light from the light generating layer.

20. The semiconductor light generating device according to claim 16, wherein the light generating layer is made of a nitride-based compound semiconductor containing aluminum.