Extreme uniformity heated substrate support assembly

Implementations described herein provide a substrate support assembly which enables temperature uniformity across a workpiece surface. In one embodiment, a substrate support assembly is provided that includes a body. The body made from ceramic. The body having a workpiece support surface and a mounting surface. The workpiece support surface and the bonding chuck body surface having a flatness of less than 10 microns. A first heater is disposed on the bottom surface outside the body. A bonding layer is disposed over the first heater, wherein the bonding layer is electrically insulating and a cooling base having a body made from a metal. The cooling body having an upper cooling body surface and a lower cooling body surface wherein the upper cooling body surface is less than about 10 microns flat.