A thermal processing system and method for processing a semiconductor substrate. A lamp system radiates through a window to heat the substrate. A dual gas manifold provides purge gas through a top showerhead to prevent deposits on the window and provides gas through a lower showerhead to deposit a material on the substrate. A thin support and a radiative cavity with thin radiation shields is used to support and insulate the substrate. A peripheral heater also heats the edges to enhance uniformity. An opaque quartz liner is used to reduce contaminants and undesired deposits and simplify cleaning.