Semiconductor device, method for manufacturing the same, power supply apparatus and high-frequency amplification unit

1. A semiconductor device comprising:

a compound semiconductor multilayer structure;

a fluorine-containing barrier film that covers a surface of the compound semiconductor multilayer structure;

an insulating film placed on the fluorine-containing barrier film; and

a gate electrode that is arranged over the compound semiconductor multilayer structure and placed on the insulating film with the fluorine-containing barrier film placed between the gate and the compound semiconductor multilayer structure,

wherein the fluorine-containing barrier film is any one selected from the group consisting of fluorocarbon films, boron fluoride films, films having a side-chain containing fluorocarbon, films having a side-chain containing boron fluoride, films having a side-chain containing oxygen fluoride, and films having a side-chain containing nitrogen fluoride.

2. The semiconductor device according to claim 1 ,

wherein a nitride semiconductor multilayer structure includes a gate recess and the fluorine-containing barrier film covers at least a surface of the nitride semiconductor multilayer structure that is exposed at the bottom of the gate recess.

3. The semiconductor device according to claim 1 ,

wherein the fluorine-containing barrier film covers a whole surface of the nitride semiconductor multilayer structure that is located on the gate electrode side.

4. The semiconductor of claim 1 ,

wherein the insulating film contains an oxide, nitride, or oxy-nitride of at least one selected from the group consisting of aluminum, hafnium, tantalum, zirconium, and silicon.

5. A method for manufacturing a semiconductor device, comprising:

forming a nitride semiconductor multilayer structure;

forming a fluorine-containing barrier film over a surface of the nitride semiconductor multilayer structure;

forming an insulating film placed on the fluorine-containing barrier film; and

forming a gate electrode above the nitride semiconductor multilayer structure and placing it on the insulating film such that the fluorine-containing barrier film is located between the gate and the compound semiconductor multilayer structure,

wherein in the forming of the fluorine-containing barrier film, any one selected from the group consisting of fluorocarbon films, boron fluoride films, films having a side-chain containing fluorocarbon, films having a side-chain containing boron fluoride, films having a side-chain containing oxygen fluoride, and films having a side-chain containing nitrogen fluoride is formed.

6. The method according to claim 5 , further comprising:

forming a gate recess in the nitride semiconductor multilayer structure prior to the forming of the fluorine-containing barrier film,

wherein in the forming of the fluorine-containing barrier film, the fluorine-containing barrier film is formed over at least a surface of the nitride semiconductor multilayer structure that is exposed at the bottom of the gate recess.

7. The method according to claim 6 , further comprising:

subjecting at least the bottom of the gate recess to chemical solution treatment subsequently to the forming of the gate recess and prior to the forming of the fluorine-containing barrier film.

8. The method according to claim 5 ,

wherein in the forming of the fluorine-containing barrier film, the fluorine-containing barrier film is formed over a whole surface of the nitride semiconductor multilayer structure located on the side where the gate electrode is arranged.

9. The method according to claim 5 , further comprising:

forming an insulating film on the fluorine-containing barrier film subsequently to the forming of the fluorine-containing barrier film,

wherein in the forming of the gate electrode, the gate electrode is formed on the insulating film.

10. The method according to claim 9 ,

wherein in the forming of the insulating film, the insulating film is formed so as to contain an oxide, nitride, or oxy-nitride of at least one selected from the group consisting of aluminum, hafnium, tantalum, zirconium, and silicon.

11. A power supply system comprising:

a transformer;

a high-voltage circuit; and

a low-voltage circuit,

wherein the transformer is placed between the high-voltage circuit and the low-voltage circuit, the high-voltage circuit includes a transistor, the transistor including a compound semiconductor multilayer structure, a fluorine-containing barrier film that covers a surface of the compound semiconductor multilayer structure, an insulating film placed on the fluorine-containing barrier film, and a gate electrode placed over the compound semiconductor multilayer structure and placed on the insulating film with the fluorine-containing barrier film placed between the gate and the compound semiconductor multilayer structure, and

wherein the fluorine-containing barrier film is any one selected from the group consisting of fluorocarbon films, boron fluoride films, films having a side-chain containing fluorocarbon, films having a side-chain containing boron fluoride, films having a side-chain containing oxygen fluoride, and films having a side-chain containing nitrogen fluoride.