Patent ID: 7316764

Claim:
A system for performing sputter etching, comprising: (a) an ion source that generates an ion current directed at a substrate; (b) an electron source that generates an electron current directed at the substrate; (c) biasing circuitry that biases the substrate with an a-symmetric bi-polar DC voltage pulse signal, the circuitry being formed from a positive voltage source with respect to ground, a negative voltage source with respect to ground and a high frequency switch; (d) at least one current sensor, coupled to the biasing circuitry, that monitors a positive current and a negative current from the substrate during one or more cycles of the a-symmetric bi-polar DC voltage pulse signal; (e) a controller, coupled to the at least one current sensor, that varies the ion current independently from the electron current; (f) wherein the ion and electron sources create a continuous plasma proximate the substrate, and the biasing circuitry causes the substrate to alternatively attract ions and electrons from the plasma; (g) wherein the ions attracted from the plasma sputter etch the substrate; and (h) wherein the electrons attracted from the plasma neutralize accumulated charge on the substrate.