Optimization of Wafer Thinning Process by Reducing Thickness Variation of Temporary Adhesive Layer for Medical Device

Abstract

This study focuses on optimization of wafer thinning process by reducing the thickness variation of the temporary adhesive layer. To optimize edge trimming parameters, we evaluated the edge bead height and the width of the adhesive layer coated on the device wafer. After optimizing edge trimming parameters, the thickness distribution of the device wafer and the adhesive layer after thinning was evaluated. There was no difference in the thickness distribution of the device wafer and the adhesive layer after thinning regardless of whatever the edge trimming was applied or not. In contrast, peeling occurred at the edge of the bonded wafer only in the wafer without edge trimming. By measuring the surface shape of the glass wafer at the edge part, it was found that the wafer without edge trimming had a larger deflection than the wafer with edge trimming. Edge trimming is conventionally performed to prevent an edge chipping. Moreover, it has been confirmed that it is also effective to prevent a peeling of a wafer from a supporting substrate.