Semiconductor device and method for manufacturing semiconductor device
A method for manufacturing a semiconductor device includes forming an electron transit layer on a semiconductor substrate, forming an electron supply layer on the electron transit layer, forming a cap layer on the electron supply layer, forming a protection layer on the cap layer, the protection layer having an opening part, through which a part of the cap layer is exposed, and forming an oxidation film on an exposed surface of the cap layer by a wet process.
1. A semiconductor device comprising:
a semiconductor substrate;
an electron transit layer formed on the semiconductor substrate;
an electron supply layer formed on the electron transit layer;
a cap layer formed on the electron supply layer; and
a groove penetrating through the cap layer to reach to the inside of the electron supply layer; and
a gate insulating film formed in the groove,
wherein the electron supply layer and the cap layer have an oxidation film at the interface between the electron supply layer and the gate insulating film and at the interface between the cap layer and the gate insulating film, respectively.
2. The semiconductor device according to claim 1 , wherein
the electron supply layer and the cap layer comprise gallium, and
the oxidation film is a gallium oxide film.
3. A method for manufacturing a semiconductor device comprising:
forming an electron transit layer on a semiconductor substrate;
forming an electron supply layer on the electron transit layer;
forming a cap layer on the electron supply layer;
forming a groove penetrating through the cap layer to reach to the inside of the electron supply layer;
forming a gate insulating film in the groove; and
forming an oxidation film on an exposed surface of the electron supply layer and an exposed surface of the cap layer in the groove by a wet process; wherein
the oxidation film is formed at an interface between the electron supply layer and the gate insulating film and at an interface between the cap layer and the gate insulating film, respectively.
4. The method for manufacturing the semiconductor device according to claim 3 , comprising cleaning the exposed surface of the electron supply layer and the exposed surface of the cap layer in the groove before forming the oxidation film.
5. The method for manufacturing the semiconductor device according to claim 3 , wherein the wet process is performed with any one of ammonia-hydrogen peroxide mixture, sulfuric acid-hydrogen peroxide mixture, hydrochloric acid-hydrogen peroxide mixture and phosphoric acid.
6. The method for manufacturing the semiconductor device according to claim 3 , wherein
the electron supply layer and the cap layer comprise gallium, and
the oxidation film is a gallium oxide film.