Nitride semiconductor device comprising bonded substrate and fabrication method of the same

• US 7,105,857 B2
• Filed: 07/08/2003
• Issued: 09/12/2006
• Est. Priority Date: 07/08/2002
• Status: Expired due to Term

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Yamamoto, Masashi, Sakamoto, Keiji, Sano, Masahiko, Nagahama, Shinichi, Morita, Daisuke, Yanamoto, Tomoya
• Primary Examiner(s): Wilson, Allan R.
• Application Number:
  US10/614,342
• Publication Number:
  US 20040072383A1
• Time in Patent Office: 1,162 Days
• Field of Search: 257/31, 257/86, 257/103, 257/E33.026, 257/E33.041
• US Class Current: 257/86
• CPC Class Codes: H01L 21/76251 using bonding techniques
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/49171 Fan-out arrangements
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01013 Aluminum [Al]
• CPC Class Codes: H01L 2924/01037 Rubidium [Rb]
• CPC Class Codes: H01L 2924/12032 Schottky diode
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/483 Containers
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

A substrate 1 for growing nitride semiconductor has a first and second face and has a thermal expansion coefficient that is larger than that of the nitride semiconductor. At least n-type nitride semiconductor layers 3 to 5, an active layer 6 and p-type nitride semiconductor layers 7 to 8 are laminated to form a stack of nitride semiconductor on the first face of the substrate 1. A first bonding layer including more than one metal layer is formed on the p-type nitride semiconductor layer 8. A supporting substrate having a first and second face has a thermal expansion coefficient that is larger than that of the nitride semiconductor and is equal or smaller than that of the substrate 1 for growing nitride semiconductor. A second bonding layer including more than one metal layer is formed on the first face of the supporting substrate. The first bonding layer 9 and the second bonding layer 11 are faced with each other and, then, pressed with heat to bond together. After that, the substrate 1 for growing nitride semiconductor is removed from the stack of nitride semiconductor so that a nitride semiconductor device is provided.

Claims

1. A nitride semiconductor device comprising:

a substrate having two opposed main faces and having a thermal expansion coefficient higher than that of a nitride semiconductor;

a bonding layer placed on one main face of said substrate and comprising an eutectic layer;

a p-electrode on said bonding layer;

one or more p-type nitride semiconductor layers electrically connected to the p-electrode;

an active layer comprising at least a well layer of Al_aIn_bGa_1-a-bN, (0≦

a≦

1, 0≦

b≦

1, a+b≦

1) and a barrier layer of Al_cIn_dGa_1-c-dN, (0≦

c≦

1, 0≦

d≦

1, c+d≦

1), the active layer being on said p-type nitride semiconductor layers; and

one or more n-type nitride semiconductor layers on said active layer;

a n-electrode electrically connected to one or more of said n-type nitride semiconductor layers;

wherein said p-type nitride semiconductor layers, said active layer and said n-type nitride semiconductor layers are sandwiched between said p-electrode and said n-electrode, and

wherein said n-type nitride semiconductor layers contain Al at least in a part of said n-type nitride semiconductor layers that is in contact with said n-electrode.

2. The nitride semiconductor device according to claim 1, wherein said substrate is conductive.

3. The nitride semiconductor device according to claim 1, wherein said substrate includes one or more metals selected from Ag, Cu, Au and Pt and one or more metals selected from W, Mo, Cr and Ni.

4. The nitride semiconductor device according to claim 1, wherein said substrate is made of a metal composite comprising two or more metals, wherein the two or more metals have substantially no solid solubility in each other.

5. The nitride semiconductor device according to claim 1, wherein said substrate is a composite of a metal and a ceramic.

6. The nitride semiconductor device according to claim 1, wherein said nitride semiconductor device comprises an n-electrode contacting with the surface of said n-type nitride semiconductor layers,

and wherein said n-type nitride semiconductor layers comprising at least two layers;

a first n-type nitride semiconductor layer doped with an n-type impurity as a layer contacting with said n-electrode and a second n-type nitride semiconductor layer un-doped or doped with an n-type impurity in a less amount than that of said first n-type nitride semiconductor layer near to said active layer side than said first n-type nitride semiconductor layer.

7. The nitride semiconductor device according to claim 1, wherein said p-type nitride semiconductor layers include a p-type contact layer of Al_fGa_1-fN, (0<

f<

1).

8. The nitride semiconductor device according to claim 7, wherein said p-type contact layer has a graded composition with a high p-type impurity concentration and a small mixed crystal ratio of Al in the substrate side.

9. The nitride semiconductor device according to claim 8, wherein said p-type contact layer is composed of two layers and said two layers are an Al_gGa_1-gN, (0<

g<

0.05) layer formed adjacent to said p-electrode and an Al_hGa_1-hN, (0<

h<

0.1) layer formed adjacent to the active layer side and said Al_gGa_1-gN, (0<

g<

0.05) layer has a higher p-type impurity concentration than that of said Al_hGa_1-hN, (0<

h<

0.1) layer.

10. The nitride semiconductor device according to claim 1, wherein said nitride semiconductor device is a light emitting device and comprises a coating layer containing a phosphor substance capable of absorbing light from said light emitting device and emitting luminescence with wavelength difference from that of the light emitting device and said coating layer is formed in at least a portion of the surface of said light emitting device.

11. A nitride semiconductor device comprising:

a substrate having two opposed main faces;

a bonding layer placed on one main face of said substrate and comprising an eutectic layer;

a p-electrode on said bonding layer;

one or more p-type nitride semiconductor layers electrically connected to the p-electrode;

an active layer comprising at least a well layer of Al_aIn_bGa_1-a-bN, (0≦

a≦

1, 0≦

b≦

1, a+b≦

1) and a barrier layer of Al_cIn_dGa_1-c-dN, (0≦

c≦

1, 0≦

d≦

1, c+d≦

1), the active being on said p-type nitride semiconductor layers; and

n-type nitride semiconductor layers on said active layer

an n-electrode electrically connected to one or more of said n-type nitride semiconductor layers;

wherein said p-type nitride semiconductor layers, said active layer and said n-type nitride semiconductor layers are sandwiched between said p-electrode and said n-electrode, and

wherein at least a part of said n-type nitride semiconductor layers, the part that is in contact with said n-electrode, is made of a nitride semiconductor which does not substantially absorb the light emitted from said active layer.

12. The nitride semiconductor device according to claim 11, wherein said nitride semiconductor device comprises an n-electrode contacting with the surface of said n-type nitride semiconductor layers

and wherein said n-type nitride semiconductor layers comprising at least two layers;

a first n-type nitride semiconductor layer doped with an n-type impurity as a layer contacting with said n-electrode and a second n-type nitride semiconductor layer un-doped or doped with an n-type impurity in a less amount than that of said first n-type nitride semiconductor layer near to said active layer side than said first n-type nitride semiconductor layer.

13. The nitride semiconductor device according to claim 11, wherein said p-type nitride semiconductor layers include a p-type contact layer of Al_fGa_1-fN, (0<

f<

1).

14. The nitride semiconductor device according to claim 13, wherein said p-type contact layer has a graded composition with a high p-type impurity concentration and a small mixed crystal ratio of Al in the substrate side.

15. The nitride semiconductor device according to claim 14, wherein said p-type contact layer is composed of two layers and said two layers are an Al_gGa_1-gN, (0<

g<

0.05) layer formed adjacent to said p-electrode and an Al_hGa_1-hN, (0<

h<

0.1) layer formed adjacent to the active layer side and said Al_gGa_1-gN, (0<

g<

0.05) layer has a higher p-type impurity concentration than that of said Al_hGa_1-hN, (0<

h<

0.1) layer.

16. The nitride semiconductor device according to claim 11, wherein said nitride semiconductor device is a light emitting device and comprises a coating layer containing a phosphor substance capable of absorbing light from said light emitting device and emitting luminescence with wavelength difference from that of the light emitting device and said coating layer is formed in at least a portion of the surface of said light emitting device.