A support for a substrate processing chamber comprises a chuck having a substrate receiving surface, and a base comprising an upper wall comprising a recessed trench having (i) an attachment face at a first depth, and (ii) a fluid channel at a second depth. A lower wall is seated in the recessed trench and attached to the attachment face of the upper wall, to close the fluid channel. A fluid inlet is provided to supply a heat transfer fluid to the fluid channel and a fluid outlet provided to discharge the heat transfer fluid from the fluid channel.