Method for fabricating semiconductor device and the semiconductor device
A method for fabricating a semiconductor device including GaN (gallium nitride) that composes a semiconductor layer and includes forming a gate insulating film, in which at least one film selected from the group of a SiO 2 film and an Al 2 O 3 film is formed on a nitride layer containing GaN by using microwave plasma and the formed film is used as at least a part of the gate insulating film.
1. A method for fabricating a semiconductor device including GaN (gallium nitride) that composes a semiconductor layer, the method comprising:
forming a first nitride layer on a substrate;
forming a second nitride layer on the first nitride layer;
forming a field oxide layer on the second nitride layer;
forming a gate insulating film in which an Al 2 O 3 film is formed to penetrate the field oxide layer, the first nitride layer, and the second nitride layer, the Al 2 O 3 film is subject to radical oxidation, and
then a SiO 2 film is formed by using microwave plasma, the SiO 2 film penetrating the field oxide layer and the second nitride layer only, and the SiO 2 film located between the Al 2 O 3 film and a gate electrode, wherein
the gate electrode is at least partially located in an opening of the SiO 2 film of the gate insulating film, and
in the forming the gate insulating film, the microwave plasma is generated by using microwaves at a frequency of 2.45 GHz by using a radial line slot antenna.
2. The method for fabricating the semiconductor device according to claim 1 , wherein the forming the gate insulating film includes a plasma-enhanced CVD process using microwave plasma.
3. The method for fabricating the semiconductor device according to claim 1 , wherein the forming the gate insulating film includes a plasma-enhanced ALD process using microwave plasma.
4. The method for fabricating the semiconductor device according to claim 1 , wherein the forming the gate insulating film includes forming a film in which the SiO 2 film and the Al 2 O 3 film are stacked.
5. The method for fabricating the semiconductor device according to claim 4 , wherein the forming the gate insulating film includes forming the Al 2 O 3 film by a thermal ALD process and forming the SiO 2 film by a plasma-enhanced CVD process.
6. The method for fabricating the semiconductor device according to claim 1 , wherein the forming the gate insulating film includes forming the SiO 2 film to form the gate insulating film and includes forming the SiO 2 film by both plasma-enhanced CVD and plasma-enhanced ALD processes.
7. The method for fabricating the semiconductor device according to claim 1 , wherein the forming the gate insulating film includes introducing gas containing nitrogen oxides (NOx) for processing.
8. The method for fabricating the semiconductor device according to claim 1 , wherein the plasma-enhanced ALD process includes introducing deposition gas containing BTBAS (bis-tertiaryl-buthyl-amino-silane) onto the nitride layer.
9. The method for fabricating the semiconductor device according to claim 1 , wherein the forming the gate insulating film includes successively performing the plasma-enhanced ALD and plasma-enhanced CVD processes.
10. The method for fabricating the semiconductor device according to claim 1 , wherein the first nitride layer and the second nitride layer have a heterojunction.
11. The method for fabricating the semiconductor device according to claim 10 , wherein the forming the first nitride layer and the second nitride layer includes forming a nitride layer composed of at least one of a GaN layer and an AlGaN (aluminum gallium nitride) layer.