Patent ID: 8252193

Claim:
A method for plasma-processing a substrate, comprising: holding said substrate on a main surface of an RF electrode, said RF electrode being disposed opposite to an opposing electrode in a chamber, an interior of said chamber being evacuated under a predetermined vacuum condition; applying an RF voltage with a predetermined frequency only to said RF electrode such that said RF electrode is self-biased negatively; applying a pulsed voltage to said RF electrode such that said pulsed voltage is superimposed with said RF voltage; and controlling a timing of applying said pulsed voltage and defining a pause period of said pulsed voltage; and controlling a pulse width t 1 (s) so that the relation of t 1 <((∈ 0 ×∈ s )/(Z×e×Ni×vb))×(Vmax/d) is satisfied (herein, ∈ 0 : vacuum dielectric constant, ∈ s : relative dielectric constant of trench bottom under processing, Z: ionic valency number, Ni: ion density (/m 3 ), vb: Bohm velocity represented by the equation of (k×Te)/Mi, d: thickness of bottom dielectric material, Vmax/d: dielectric withstand electric field strength, Te: electron temperature (eV)).