Apparatus and method for thermal processing of semiconductor substrates

Abstract

A semiconductor substrate processing system and method of using a stable heating source with a large thermal mass relative to conventional lamp heating systems. The system dimensions and processing parameters are selected to provide a substantial heat flux to the substrate while reducing the potential of heat loss to the surrounding environment, particularly from the edges of the heat source and substrate. Aspects of the present invention include a dual resistive heater system comprising a base or primary heater, surrounded by a peripheral or edge heater. The impedance of the edge heater may be substantially matched to that of the primary heater such that a single power supply may be used to supply power to both heaters. Both resistive heaters deliver heat to a heated block, and the heaters and heated block are substantially enclosed within an insulated cavity. The walls of the insulated cavity may include multiple layers of insulation, and these layers may be substantially concentrically arranged. The innermost layers may comprise silicon carbide coated graphite; the outer layers may comprise opaque quartz. An embodiment of the invention includes a vacuum spool having a large conduction pathway for exhausting gases from the region of the chamber containing the resistive heaters, and a small conduction pathway for removing gases from other regions of the chamber. Temperature measurement sensors include thermocouples and optical pyrometers, with the advantage that a thermocouple may be used to calibrate an optical pyrometer in situ. An insulating shutter may be used to insulate the port through which substrates are inserted into the insulated and heated cavity. Support posts and gas injectors may include ports for optical pyrometers.