Equipment design and control of advanced thermal processing system in lithography

A programmable multizone thermal processing module is developed to achieve temperature uniformity of a silicon wafer during the thermal cycling process in lithography. In the proposed unit, the bake and chill steps are conducted sequentially within the same module without any substrate movement. The unit includes two heating sources. The first is a mica heater which serves as the dominant means for heat transfer. The second is a set of thermoelectric devices (TEDs) which are used to provide a distributed amount of heat to the substrate for uniformity and transient temperature control. The TEDs also provide active cooling for chilling the substrate to a temperature suitable for subsequent processing steps. The system is designed via detailed modeling and simulations based on first principle heat transfer analysis. Experimental results on initial prototype demonstrates less than 0.1degC spatial uniformity during the entire thermal cycle.