Heated lid for a process chamber

A heated lid for a process chamber, comprising:

• a body having a central region and a peripheral region, wherein the peripheral region is thicker than the central region, wherein the body includes a central opening in the central region, wherein the peripheral region includes a plurality of vertical slots that extend into an upper surface of the body and arranged along a circle to provide a thermal break, and wherein the upper surface of the body includes an annular recess in the central region, an annular plenum that is continuous and that extends into the body from a bottom surface the annular recess, and a plurality of holes extending through a bottom surface of the annular plenum to a lower surface of the body, wherein the bottom surface of the annular recess includes a second annular recess to receive an annular seal;
• a cap disposed in the annular recess to define an upper boundary of the annular plenum, wherein the cap includes one or more gas inlet holes;
• a first heater ring having one or more heating elements disposed therein, wherein the first heater ring is coupled to the central region of the body;
• and
• a second heater ring having one or more heating elements disposed therein, wherein the second heater ring is coupled to the central region of the body and disposed radially outward of the first heater ring and radially inward of the annular recess.