DEFORMATION OF SI(100) WAFERS DURING RAPID THERMAL ANNEALING

In this paper in situ wafer curvature measurements are presented that were performed during rapid thermal annealing of silicon wafers. The w afer curvature due to thermal stress originating from a nonuniform tem perature distribution was measured as a function of time for a fixed s etting of the illumination source power. The presence of thermal stres s was clearly demonstrated. It was found that wafers deform during the complete annealing cycle and moreover that, the deformation is larges t during the heating and cooling transients. The influence of various wafer supports on the deformation was investigated. The use of a susce ptor and a guard ring reduce the wafer deformation compared to a free- standing wafer by a factor of 6 and 10, respectively.