Patent ID: 6221782
Filing Date: 2001-04-24
Classification: H01J

Abstract:
A method of adjusting the DC bias voltage at a first electrode in a semiconductor processing plasma chamber, comprising the steps of:(a) providing a vacuum chamber having an electrically conductive wall;(b) mounting a first electrode inside the vacuum chamber so as to be electrically insulated from the wall;(c) maintaining inside the chamber a gas pressure low enough to permit formation of a plasma;(d) applying RF electrical power between the first electrode and the chamber wall, the power being sufficient to form a plasma inside the chamber;(e) positioning a dielectric shield between the plasma and a portion of said wall so as to block direct contact between the plasma and said portion of the wall; and(f) adjusting the DC bias at the first electrode by adjusting at least one of the parameters within the group consisting of(i) the area of said portion of the wall blocked by the shield,(ii) the thickness of the shield,(iii) the spacing between the shield and the wall, and(iv) the dielectric constant of the shield.