Surface treatment method for gallium oxide-based semiconductor substrate and semiconductor device
In a surface treatment method for a gallium oxide-based semiconductor substrate, a surface of the gallium oxide-based semiconductor substrate is flattened by dry etching with a self-bias of 150 V or more. After the surface of the gallium oxide-based semiconductor substrate is flattened, the surface of the gallium oxide-based semiconductor substrate is washed with a chemical solution containing H 2 SO 4 to expose a step terrace structure on the surface of the gallium oxide-based semiconductor substrate.
1. A surface treatment method for a gallium oxide-based semiconductor substrate, comprising:
flattening a surface of the gallium oxide-based semiconductor substrate by a dry etching with a self-bias of 150 V or more; and
exposing a step terrace structure on the surface of the gallium oxide-based semiconductor substrate by washing the surface of the gallium oxide-based semiconductor substrate with a chemical solution containing H 2 SO 4 after the surface of the gallium oxide-based semiconductor substrate is flattened.
2. The surface treatment method according to claim 1 , wherein
the flattening includes performing the dry etching using a gas containing chlorine.
3. The surface treatment method according to claim 2 , wherein
the flattening includes:
a first process of performing the dry etching using a gas containing boron and chlorine;
a second process of performing the dry etching using a gas containing chlorine and not containing boron after the first process; and
a third process of performing the dry etching using a gas containing boron and chlorine after the second process.
4. The surface treatment method according to claim 3 , wherein
the first process uses the gas containing BCl 3 ,
the second process uses the gas containing Cl 2 , and
the third process uses the gas containing BCl 3 .
5. The surface treatment method according to claim 1 , wherein
the gallium oxide-based semiconductor substrate is a mixed-crystal gallium oxide substrate containing at least one of indium, aluminum, and zinc.