Patent ID: 7806983

Claim:
A method for controlling the temperature of a substrate in an atomic layer deposition (ALD) process chamber comprising: retaining a substrate on an electrostatic chuck assembly by electrostatic attraction, said substrate, when retained by said chuck assembly, forming a backside gas volume bounded by a backside surface of said substrate, a surface of the chuck assembly, and an annular seal; providing a single backside gas inlet into the electrostatic chuck assembly connected to a backside gas source; providing a backside gas by a first gas outlet arrangement leading to the backside gas volume for supplying said backside gas under pressure to said backside gas volume, said backside gas providing a heat transfer medium between said chuck assembly and said backside surface of said substrate, the first gas outlet arrangement receiving gas from the single backside gas inlet; and creating a pressure gradient across an edge of said substrate by a second gas outlet arrangement, coupled to the backside gas source, to prevent reactive gases from causing deposition on a backside surface of said substrate or deposition on a surface of said chuck assembly, the second gas outlet arrangement comprising a first plurality of gas openings arranged in a ring surrounding the first gas outlet arrangement and surrounding the backside gas volume outside of the annular seal, the second gas outlet arrangement receiving gas from the single backside gas inlet, said step of creating a pressure gradient across an edge of said substrate comprising outputting a gas from said first plurality of gas openings to create a pressure gradient along an edge of said substrate to reduce the partial pressure of reactive gases along said edge.