Apparatus for enabling concentricity of plasma dark space

A substrate processing apparatus, comprising:

• a lid configured to be movable coupled to a substrate process chamber;
• a target assembly coupled to the lid, the target assembly including a target of material to be deposited on a substrate;
• an annular dark space shield having an inner wall disposed about an outer edge of the target;
• a support member coupled to the lid proximate an outer end of the support member and extending radially inward, the support member including a feature that, when the support member is coupled to the lid, biases the annular dark space shield against the target assembly;
• and
• a seal ring disposed adjacent to an outer edge of the dark space shield and between the support member and the target assembly, wherein the support member provides sufficient compression when coupled to the lid such that a seal is formed between the support member and the seal ring and the seal ring and the target assembly.