Method for manufacturing nitride semiconductor device

• US 7,718,450 B2
• Filed: 05/08/2006
• Issued: 05/18/2010
• Est. Priority Date: 05/09/2005
• Status: Expired due to Fees

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Nakahara, Ken
• Primary Examiner(s): LEE, HSIEN MING
• Application Number:
  US11/920,043
• Publication Number:
  US 20090068779A1
• Time in Patent Office: 1,471 Days
• Field of Search: 438/22, 438/46, 438/77, 438/93, 438/795, 257/E33.025, 257/E33.028, 257/E33.033, 257/102
• US Class Current: 438/22
• CPC Class Codes: H01L 21/0237 Materials
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02507 Alternating layers, e.g. superlattice
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02576 N-type
• CPC Class Codes: H01L 21/02579 P-type
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/268 using electromagnetic radiation, e.g. laser radiation
• CPC Class Codes: H01L 29/66462 with a heterojunction interface channel or gate, e.g. HFET, HIGFET, SISFET, HJFET, HEMT
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01L 33/305 characterised by the doping materials

Abstract

There is provided a method for manufacturing a nitride semiconductor device which has a p-type nitride semiconductor layer having a high carrier concentration (low resistance) by activating an acceptor without raising a problem of forming nitrogen vacancies which are generated when a high temperature annealing is carried out over an extended time. A semiconductor lamination portion (6) made of nitride semiconductor is formed on a substrate (1) so as to form a light emitting layer, and irradiated by a laser beam having a wavelength λ of λ=h·c/E or less (E is energy capable of separating off the bonding between Mg and H) from the front surface side of the semiconductor lamination portion. Then, a heat treatment is carried out at a temperature of 300 to 400° C. And, similarly to a process for normal nitride semiconductor LED, a light transmitting conductive layer (7) is provided, an n-side electrode (9) is formed on an n-type layer (3) exposed by removing a part of the semiconductor lamination portion by etching, and a p-side electrode (8) is formed on a surface of the light transmitting conductive layer, thereby a LED is obtained.

Claims

1. A method for manufacturing a nitride semiconductor device, wherein the nitride semiconductor device comprises a plurality of nitride semiconductor layers having an uppermost p-type nitride semiconductor layer in the plurality of nitride semiconductor layers, the method comprises the steps of:

utilizing an MOCVD method to grow the plurality of nitride semiconductor layers including the uppermost p-type nitride semiconductor layer;

irradiating a laser beam having a wavelength of 0.8 μ

m to 18 μ

m, which has an energy larger than a binding energy of Mg and H, on a surface of the p-type nitride semiconductor layer to activate the uppermost p-type nitride semiconductor layer, thereby separating off a bonding between the Mg and the H, wherein Mg is doped in the uppermost p-type nitride semiconductor layer and is an acceptor of the uppermost p-type nitride semiconductor layer and wherein H is absorbed by the uppermost p-type nitride semiconductor layer during growing the plurality of nitride semiconductor layer in MOCVD method; and

dispersing the H that is separated from the p-type nitride semiconductor layer by carrying out a heat treatment at a temperature of between about 300 and about 400°

C., to activate the acceptor.

2. The method for manufacturing a nitride semiconductor device according to claim 1, wherein the laser beam has energy corresponding to λ

or less in an equation λ

=h ·

c/E, λ

representing an oscillation wavelength of the laser, h a Planck'"'"'s constant, c a light velocity and E energy capable of separating off a bonding between the Mg and the H.

3. The method for manufacturing a nitride semiconductor device according to claim 1, wherein the laser beam is obtained by any one of a YAG laser with added Nd, a CO₂ laser, and a semiconductor laser having a wavelength of 0.8 μ

m.

4. The method for manufacturing a nitride semiconductor device according to claim 1, wherein the laser beam is directly irradiated on the p-type nitride semiconductor layer without being condensed.

5. The method for manufacturing a nitride semiconductor device according to claim 1, wherein the heat treatment is carried out for 1 to 10 min.

6. The method for manufacturing a nitride semiconductor device according to claim 1, wherein the laser beam irradiation and the heat treatment are carried out concurrently.

7. The method for manufacturing a nitride semiconductor device according to claim 1, wherein the method further comprises epitaxially growing an n-type nitride semiconductor layer, an active semiconductor layer and the p-type nitride semiconductor layer on the substrate by MOCVD method in a sequential order, to form a semiconductor lamination portion for a light emitting device.

8. The method for manufacturing a nitride semiconductor device according to claim 1, wherein the p-type nitride semiconductor layer is grown for a p-type operating layer of a transistor.

9. The method for manufacturing a nitride semiconductor device according to claim 1, wherein the method further comprises, prior to growing the plurality of nitride semiconductor layers by MOCVD method, growing a single crystal buffer layer on the substrate by plasma laser deposition method, wherein the single crystal buffer layer is made of Al_xGa_yIn_1-x-yN (0≦

x≦

1, 0≦

y≦

1 and 0≦

x+y≦

1), wherein both a-axis and c-axis of the Al_xGa_yIn_1-x-y N are aligned respectively, and wherein the single crystal buffer layer is not lattice-matched with the plurality of nitride semiconductor layers.