Application of a Plasma Arc Lamp for Thermal Processing of Semiconductor Wafers

This paper describes the application of a vortex water wall high-pressure argon lamp for a semiconductor annealing process. These lamps have been designed to operate up to a 500-kW power level, have a continuous spectrum, similar to daylight, and have been used to characterize solar cells. Precise control of the radiated power generated by the lamps is required, which, in turn, requires an accurate electrothermooptical dynamic model of the lamp and an optothermal model of the wafer. This paper discusses general aspects regarding the modeling of the system consisted of the lamp and the wafer. The main contributions of the paper are the following: (1) a simplified means of relating the radiation exiting the lamp to the electrical power injected into the lamp, taking into account radiation from an isothermal core and absorption in the cold swirling argon gas, the water wall, and the quartz envelope; and (2) a model to describe energy exchange between the lamp and the wafer and experimental results to indicate the good agreement between the model and the actual apparatus. Two companion papers discuss the details of the arc model and the discrete-time control algorithms developed to model the wafer subsystem and the arc subsystem.