US Patent 10246777 Heater block having continuous concavity

A heater block adapted to be installed in a plasma deposition or plasma etching apparatus that includes a showerhead and a reaction chamber, the heater block being adapted to be arranged in the reaction chamber to support a substrate and includes: at least one through-hole passing through the heater block, and on its upper face a plurality of surfaces separated from each other and defined by a continuous concavity; and the continuous concavity including: a plurality of main concaves or depressions, a plurality of concave channels connecting substantially every two adjacent main concaves or depressions, and a concave or depression, at the center of the heater block, of a different shape or size from the plurality of main concaves or depressions.