In a system for thermal processing of a semiconductor substrate, a reflector plate has a stepped surface facing the substrate during heating and cooling of the substrate. The raised surface of the reflector plate has reduced reflectivity, providing advantages during, among other things, cooling of the substrate. The reflector plate also includes a number of recesses to which one or more pyrometers are coupled. These recesses have a highly reflective surface, providing advantages in the performance of the pyrometers.