Abstract: Embodiments of the invention provide a system for heat treating a substrate which includes a first processing chamber having a first processing region coupled with a precursor source assembly configured to deliver a silicon containing gas to an upper surface of a substrate disposed within the first processing region in order to form an amorphous silicon film on the upper surface. The system further includes a substrate support having a heating element configured to heat the substrate to a temperature sufficient to crystallize the amorphous silicon film by solid phase crystallization and to create a temperature gradient in which a temperature at the lower surface of the substrate is greater than a temperature at the upper surface of the amorphous silicon film and the temperature gradient is within a range from about 2° C. to about 10° C.