An example semiconductor processing system may include a chamber body having sidewalls and a base. The processing system may also include a substrate support extending through the base of the chamber body. The substrate support may include a support platen configured to support a semiconductor substrate, and a shaft coupled with the support platen. The processing system may further include a plate coupled with the shaft of the substrate support. The plate may have an emissivity greater than 0.5. In some embodiments, the plate may include a radiation shied disposed proximate the support platen. In some embodiments, the plate may include a pumping plate disposed proximate the base of the chamber body. In some embodiments, the emissivity of the plate may range between about 0.5 and about 0.95.