Etching method

1. An etching method of etching a silicon carbide substrate placed on a platen in a processing chamber, comprising:

alternately repeating a first step in which the silicon carbide substrate is heated to a temperature equal to or higher than 200° C., a processing gas including a fluorine-containing gas is supplied into the processing chamber and plasma is generated from the processing gas, and RF power is supplied to the platen to thereby apply a bias potential to the platen, thereby etching the silicon carbide substrate, and a second step in which the silicon carbide substrate is heated to a temperature equal to or higher than 200° C., supplying a processing gas including oxygen gas or nitrogen gas into the processing chamber and generating plasma from the processing gas, and supplying RF power to the platen thereby to apply a bias potential to the platen, thereby forming a silicon oxide film or a silicon nitride film as passivation film on the silicon carbide substrate.

2. An etching method according to claim 1 , in which:

in the first step, the silicon carbide substrate is isotropically etched, and

in the second step, a processing gas including a fluorine-containing gas in addition to the oxygen gas or nitride gas is supplied into the processing chamber.

3. An etching method according to claim 2 , in which:

in the first step, a processing gas including oxygen gas in addition to the fluorine-containing gas is supplied into the processing chamber and plasma is generated from the processing gas.

4. An etching method according to claim 2 , in which:

in the first step, a processing gas including oxygen gas in addition to the fluorine-containing gas is supplied into the processing chamber and plasma is generated from the processing gas, and a supply flow rate of the oxygen gas is equal to or less than 1.25 times a supply flow rate of the fluorine-containing gas, and

in the second step, a processing gas including a fluorine-containing gas in addition to the oxygen gas is supplied into the processing chamber and plasma is generated from the processing gas, and a supply flow rate of the oxygen gas is equal to or more than 0.75 times a supply flow rate of the fluorine-containing gas.

5. An etching method according to claim 2 , in which:

in the first step, a processing gas including oxygen gas in addition to the fluorine-containing gas is supplied into the processing chamber and plasma is generated from the processing gas, and a supply flow rate of the oxygen gas is equal to or less than 1 time a supply flow rate of the fluorine-containing gas; and

in the second step, a processing gas including a fluorine-containing gas in addition to the oxygen gas is supplied into the processing chamber and plasma is generated from the processing gas, and a supply flow rate of the oxygen gas is equal to or more than 1 time a supply flow rate of the fluorine-containing gas.

6. An etching method according to claim 2 , in which:

in the first step, a processing gas including oxygen gas in addition to the fluorine-containing gas is supplied into the processing chamber and plasma is generated from the processing gas, and a supply flow rate of the oxygen gas is equal to or less than 0.25 times a supply flow rate of the fluorine-containing gas; and

in the second step, a processing gas including a fluorine-containing gas in addition to the oxygen gas is supplied into the processing chamber and plasma is generated from the processing gas, and a supply flow rate of the oxygen gas is equal to or more than 1.5 times a supply flow rate of the fluorine-containing gas.

7. An etching method according to claim 1 , in which:

in the second step, RF power equal to or more than 300 W is supplied to the platen to thereby apply a bias potential to the platen.

8. An etching method according to claim 1 , in which:

in the second step, a processing gas including a silicon-containing gas in addition to the oxygen gas or nitrogen gas is supplied into the processing chamber and plasma is generated from the processing gas, and a silicon oxide film or a silicon nitride film is formed as passivation film on the silicon carbide substrate.

9. An etching method according to claim 8 , in which:

in the first step, a processing gas including oxygen gas in addition to the fluorine-containing gas is supplied into the processing chamber and plasma is generated from the processing gas.

10. An etching method according to claim 8 , in which the silicon-containing gas is SiCl 4 gas.

11. An etching method according to claim 1 , in which:

in the second step, a processing gas including a fluorine-containing gas and a silicon-containing gas in addition to the oxygen gas is supplied into the processing chamber and plasma is generated from the processing gas to form a silicon oxide film as passivation film on the silicon carbide substrate.

12. An etching method of etching a silicon carbide substrate placed on a platen in a processing chamber, comprising:

heating the silicon carbide substrate to a temperature equal to or higher than 200° C;

supplying a processing gas including a silicon-containing gas as well as oxygen gas or nitrogen gas into the processing chamber and generating plasma from the processing gas, the silicon-containing gas including at least SiF 4 gas or SiCl 4 gas; and

etching the silicon carbide substrate while forming a silicon oxide film or a nitrogen oxide film as passivation film on the silicon carbide substrate.

13. An etching method according to claim 12 , in which the processing gas further includes a fluorine-containing gas.

14. An etching method according to claim 13 , in which RF power is supplied to the platen to thereby apply a bias potential to the platen.

15. An etching method according to claim 14 , in which RF power equal to or more than 300 W is supplied to the platen.

16. An etching method according to claim 12 , in which RF power is supplied to the platen to thereby apply a bias potential to the platen.

17. An etching method according to claim 16 , in which RF power equal to or more than 300 W is supplied to the platen.