PULSED PLASMA SYSTEM WITH PULSED SAMPLE BIAS FOR ETCHING SEMICONDUCTOR STRUCTURE

PROBLEM TO BE SOLVED: To provide a pulsed plasma system for etching a semiconductor structure with a constant etching rate without depending on structure density.SOLUTION: A pulsed plasma etching process comprises a plurality of duty cycles, and each duty cycle represents the combination of an ON state and an OFF state of plasma. Plasma is generated from reactive gas, and the reactive gas is replenished not during the ON state of plasma, but during the OFF state. In another embodiment, a first portion of a sample is removed by applying a continuous plasma etching process. Then, the continuous etching process is terminated, and a second portion of the sample is removed by applying a pulsed plasma etching process with a pulsed sample bias.