Study on Solid Cooling by Low-pressure Gas of Normal Temperature (1^st report)

—Development of Evaluation Apparatus on Heat Transfer Characteristics and its Performance Estimation—

Abstract

The evaluation apparatus on heat transfer characteristic for low-pressure gas of normal temperature is developed with the object of improving in the numerical prediction accuracy for thermal deformation of the silicon wafer caused during exposure, and constructing of the novel wafer chuck systems with cooling effect by such gas condition in the Next-Generation Lithography exposure tools. As the first phase, the heat transfer characteristics between low-pressure helium gas and aluminum disc, which is well known as a vacuum equipment material, are evaluated using this apparatus. The heat transfer coefficients of low-pressure helium gas are obtained as by curve fitting for experimental data using finite element analysis. These obtained heat transfer coefficients show good agreement with theoretical data, except high-pressure condition corresponding to the bending of aluminum disc. The cooling effect of low-pressure helium gas on the silicon wafer is confirmed using developed apparatus.