Patent ID: 7335602

Claim:
A method for etching a material, comprising: forming a film on a material by impinging the material with a first neutral molecular species created through a charge exchange reaction between a third charged species and a fourth neutral species; and etching the material by impinging the film with a second species; wherein the method further comprises: providing a first chamber equipped with a first gas supply and a second chamber, equipped with a second gas supply, which is in communication with the first chamber by way of an acceleration grid; oscillating the gas flow into the first chamber between a first state in which the gas flow into the first chamber has the composition f 11 and the gas flow into the second chamber has the composition f 21 , and a second state in which the gas flow into the first chamber has the composition f 12 and the gas flow into the second chamber has the composition f 22 ; and oscillating the potential applied to the acceleration grid such that the voltage applied to the grid is V 1 when the gas flow into the first chamber is in the first state, and the voltage applied to the grid is V 2 when the gas flow into the first chamber is in the second state.