Study on the Thermo-Fluid Coupling Model of Hot Plates for Wafer Spin Coaters

Wafer spin coating for lithography is a critical process in semiconductor manufacturing. After coating, a thermal treatment is required to dry the photoresist before exposure. During drying, the temperature uniformity of the wafer surface directly affects photoresist quality and device yield. To analyze the wafer surface temperature distribution during drying, this study designs an 8-inch wafer hot-plate unit and heating chamber, establishes a thermo-fluid coupling model for the hot-plate heating chamber, and employs the finite element method (FEM) to investigate the effects of resistance-wire layout, wafer-to-hot-plate gap, and aluminum-plate thickness on the aluminum-plate surface temperature distribution. The flow characteristics inside the heating chamber and the corresponding wafer surface temperature distribution were obtained.To validate the proposed model, an 8-inch wafer hot-plate prototype was fabricated, and temperature uniformity tests were conducted at various setpoints. Experimental results show that, under an optimized resistance-wire layout, the hot plate achieves ±1 °C uniformity at 150 °C. The deviation between simulation and experimental results is within 2%, confirming the model’s accuracy and its feasibility for hot-plate design in spin coating and developing equipment.