Film forming method and method of manufacturing thin film transistor
Provided is a film forming method to minimize decreases in the electrical resistance of an oxide semiconductor film even when a fluorinated silicon nitride film is formed directly on the oxide semiconductor film. The film forming method includes: a surface treatment process in which a substance including an oxide semiconductor film on a substrate is prepared, plasma is generated using a mixed gas of oxygen and hydrogen which contains hydrogen at a rate of 8% or less (not including 0), and plasma is used to treat surface of oxide semiconductor film; a film formation process in which a fluorinated silicon nitride film (a SiN:F film) is subsequently forming on oxide semiconductor film by a plasma CVD method in which plasma is generated using a raw material gas containing silicon tetrafluoride gas and nitrogen gas; and an annealing process in which substrate and film thereon are subsequently heated.
1. A film forming method comprising:
performing a surface treatment process of preparing a substance in which an oxide semiconductor film is formed on a substrate, generating a plasma using a mixed gas of oxygen and hydrogen in which a proportion of hydrogen is 8% or less (not including 0), and treating a surface of the oxide semiconductor film with the plasma;
then performing a film forming process of forming a fluorinated silicon nitride film containing fluorine in a silicon nitride film on the oxide semiconductor film by a plasma CVD method in which a plasma is generated using a raw material gas containing silicon tetrafluoride gas and nitrogen gas; and
then performing an annealing process of heating the substrate and the film thereon.
2. The film forming method according to claim 1 , wherein in the surface treatment process and the film forming process, the plasma is generated using an inductive coupling type plasma generation method in which a plasma is generated by inductive coupling.
3. A method of manufacturing a thin film transistor, comprising:
forming an oxide semiconductor film on a substrate, forming a gate insulating film on the oxide semiconductor film, and forming a gate electrode on gate insulating film to form a structure of a top gate type thin film transistor,
wherein a fluorinated silicon nitride film as the gate insulating film is formed using the film forming method according to claim 1 .
4. A method of manufacturing a thin film transistor, comprising:
forming a gate electrode on a substrate, forming a gate insulating film on the gate electrode, and forming an oxide semiconductor film on gate insulating film, and forming a protective film on the oxide semiconductor film to form a structure of a bottom gate type thin film transistor,
wherein a fluorinated silicon nitride film as the protective film is formed using the film forming method according to claim 1 .
5. A method of manufacturing a thin film transistor, comprising:
forming an oxide semiconductor film on a substrate, forming a gate insulating film on the oxide semiconductor film, and forming a gate electrode on gate insulating film to form a structure of a top gate type thin film transistor,
wherein a fluorinated silicon nitride film as the gate insulating film is formed using the film forming method according to claim 2 .
6. A method of manufacturing a thin film transistor, comprising:
forming a gate electrode on a substrate, forming a gate insulating film on the gate electrode, and forming an oxide semiconductor film on gate insulating film, and forming a protective film on the oxide semiconductor film to form a structure of a bottom gate type thin film transistor,
wherein a fluorinated silicon nitride film as the protective film is formed using the film forming method according to claim 2 .