Modeling of rarefied gas heat conduction between wafer and susceptor

Gas-assisted wafer cooling/heating system is one of the key technologies for manufacturing microelectronic devices. The heat conduction in the gap between wafer and susceptor is modeled here as a one- or two dimensional (1-D or 2-D) rarefied gas problem. The simulation is performed for monatomic and diatomic gases by means of the Direct Simulation Monte Carlo (DSMC) method. In the 1-D case the gas heat conductivity is obtained for various factors (gas species, surface temperature, energy accommodation coefficient) as a function of the Knudsen number. All numerical data obtained can be summarized by a simple equation: Smoluchowski´s equation extended to the free molecular regime. In the 2-D case, the DSMC method is applied to the heat transfer between rough and smooth surfaces. The effect of surface roughness on heat conduction is clarified