Plasma treatment apparatus

Abstract

In order to prevent any possible electrical discharge between a lower electrode and a grounded member through a backside gas supply conduit when performing a plasma treatment with a supply of a backside gas such as He gas to the backside of a semiconductor wafer being held by an electromagnetic chuck on the lower electrode for the generation of a plasma within a plasma treatment chamber, the gas supply conduit is fitted therein with cylindrical flowpath members made of two types of electrically insulating materials each having a multiplicity of axially extending small-diameter conduction holes, at a position within an electrically insulating body disposed between the lower electrode and a grounded member. The small diameter conduction holes in the backside gas flowpath serve to increase an electrical discharge start voltage for the prevention of electrical discharge. The formation of the multiplicity of conduction holes provides a large conductance. The backside gas is exhausted by way of the gas supply conduit after the completion of the plasma treatment. Consequently, water is prevented from remaining between the wafer and the electromagnetic chuck or within the treatment chamber, whereby it is possible to remove the electric charge the wafer and to shorten the time required for the exhausting of the treatment chamber.