Patent ID: 7811941

Claim:
A method for etching a silicon body substrate using a device having an ICP source for generating a radio-frequency electromagnetic alternating field, a reactor for generating an inductively coupled plasma from reactive particles by the action of the radio-frequency electromagnetic alternating field on a reactive gas, and a first means for generating plasma power pulses to be injected into the inductively coupled plasma by the ICP source, comprising: matching an impedance of one of an inductive coupled plasma and the ICP source to an ICP coil generator; and injecting a pulsed radio-frequency power into the inductively coupled plasma as a pulsed plasma power; wherein the pulsing of the injected, pulsed radio-frequency power is accompanied by a change of a frequency of the injected, pulsed radio-frequency power, the change in the frequency being controlled so that the plasma power injected into the inductively coupled plasma during the pulsing is maximized; wherein the ICP coil generator causes a variation of the frequency of the radio-frequency electromagnetic alternating field so that the impedance is matched as a function of the pulsed plasma power to be injected, so as to provide rapid switching between the pulses of the pulsed plasma power and interpulse periods; wherein the variation of the frequency is automatically performed by a Meissner oscillator feedback loop between the ICP coil and the ICP coil generator input without measuring the ratio of magnitudes of applied and reflected power of the generator.