Thermal analysis of a silicon wafer processing combination bake-chill station used in microlithography

Microlithography, the fabrication process for microchips and Micro-Electro-Mechanical Systems (MEMS) devices, involves a series of manufacturing processes performed on a silicon wafer, each in separate stations of a microlithography cluster. Bake (heating) and chill (cooling) of silicon wafers comprise an important manufacturing step in microlithography. Thermal analysis of an actual combination bake-chill station design using two-and three-dimensional numerical simulations are presented. In this bake-chill station, the wafer is heated to the desired bake temperature and chilled back to room temperature before being moved by the robot, resulting in tight temperature control of the wafer throughout the process. Two models, axi-symmetric and three-dimensional (geometrically similar to the new station), are generated for analyzing the thermal performance of the above station. The numerical simulations solving the transport equations in the computational domain are performed using the commercial CFD software Fluent®. Methods to improve wafer surface temperature uniformity, in light of bake-chill-station mechanical and thermal design losses, are discussed. Copyright © Taylor & Francis, Inc.