Method for manufacturing nitride semiconductor device

• US 20090068779A1
• Filed: 05/08/2006
• Published: 03/12/2009
• Est. Priority Date: 05/09/2005
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Nakahara, Ken
• Granted Patent: US 7,718,450 B2
• Time in Patent Office: Days
• US Class Current: 438/47
• 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 in which a p-type nitride semiconductor layer is formed at a surface side of nitride semiconductor layers grown on a substrate by MOCVD method, comprising the steps of:

irradiating a laser beam having energy larger than binding energy of Mg which is an acceptor of the nitride semiconductor, and H, on a nitride semiconductor layer doped with the acceptor to make the p-type layer activate, thereby separating off a bonding between the Mg and the H; and

dispersing the H separated off out of the nitride semiconductor layer by carrying out a heat treatment at a temperature of 300 to 400°

C., thereby activating 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 2, wherein the laser beam has energy of 0.067 eV or more and 3.39 eV or less.

4. The method for manufacturing a nitride semiconductor device according to claim 2, wherein the laser beam has a wavelength of 18 μ

m or less and 365 nm or more.

5. The method for manufacturing a nitride semiconductor device according to claim 2, wherein the laser beam is obtained by any one of a YAG laser added with Nd, a CO₂ laser and a semiconductor laser having a wavelength of 0.8 μ

m.

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

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

8. 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.

9. The method for manufacturing a nitride semiconductor device according to claim 1, wherein a light emitting device is formed by forming a semiconductor lamination portion so as to form a light emitting layer by growing epitaxially an n-type layer, an active layer and a p-type layer in this order, made of nitride semiconductor, on the substrate by MOCVD method.

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

11. The method for manufacturing a nitride semiconductor device according to claim 1, wherein a buffer layer of single crystal made of Al_xGa_yIn_1-x-yN (0≦

x=≦

1, 0≦

y≦

1 and 0≦

x+y≦

1), in which a-axis and c-axis of the Al_xGa_yIn_1-x-yN are aligned, is grown on a surface of a substrate which is not lattice-matched with nitride semiconductor, by PLD method, and a nitride semiconductor crystal layer is grown on the buffer layer of single crystal by MOCVD method.