Plasma etchimg method and plasma etching apparatus

1. A plasma etching method comprising:

a cleaning step (a) in which a cleaning gas is supplied into a processing vessel and the cleaning gas is made plasma, so that a deposit adhering to an inside of the processing vessel is removed by means of the plasma;

a film depositing step (b), succeeding the cleaning step (a), in which a film depositing gas containing carbon and fluorine is supplied into the processing vessel and the film depositing gas is made plasma, so that a film containing carbon and fluorine is deposited on the inside of the processing vessel by means of the plasma;

an etching step (c), succeeding the film depositing step (b), in which a substrate is placed on a stage inside the processing vessel, and an etching gas is supplied into the processing vessel and the etching gas is made plasma, so that the substrate is etched by means of the plasma; and

an unloading step (d), succeeding the etching step (c), in which the substrate is unloaded from the processing vessel, wherein

after the unloading step (d) has been finished, the cleaning step (a) to the unloading step (d) are repeated again, and

the film depositing step (b) is performed with a dummy substrate being placed on the stage.

2. The plasma etching method according to claim 1 , wherein

the cleaning step (a) to the unloading step (d) are performed for every substrate.

3. The plasma etching method according to claim 1 , wherein

the cleaning gas is one of an oxygen gas, a mixture gas of an oxygen gas and an SF 6 gas, and a mixture gas of an oxygen gas and an NF 3 gas.

4. The plasma etching method according to claim 1 , wherein

the film depositing gas is a CxFyHz gas (in which x and y are integers not less than 1, and z is 0 or an integer not less than 1).

5. The plasma etching method according to claim 1 , wherein

the deposit includes a film containing carbon and fluorine deposited on the inside of the processing vessel.