Apparatus to improve substrate temperature uniformity

A substrate processing chamber, comprising:

• a chamber body having a bottom portion and a sidewall having a slit valve opening to load and unload substrates;
• a lift pin hoop, disposed in a lift pin hoop opening formed in the bottom portion of the chamber body, having a plurality of substrate support pins coupled to the lift pin hoop;
• a movable substrate support heater having substrate support portion and a shaft;
• a cover plate supported by and covering the bottom portion of the chamber body, and disposed about the shaft of the movable substrate support, wherein the cover plate is stationary and includes an annular groove formed in a lower surface of the cover plate, wherein the annular groove aligns with and covers the lift pin hoop and lift pin hoop opening;
• an annular skirt coupled to and disposed about the substrate support portion of the movable substrate support heater;
• and
• a plurality of brackets attached along an outer edge of the substrate support portion of the movable substrate support, wherein the plurality of brackets support the annular skirt when the movable substrate support heater is in a raised processing position, and wherein the annular skirt covers the slit valve opening when the movable substrate support heater is in a raised processing position.