In-process measurement of the grinding force in silicon wafer self-rotating grinding process

Silicon wafer thinning is mostly performed by self-rotating grinding process. In grinding, the grinding force is a crucial factor of affecting the machining accuracy and surface/subsurface quality. In this paper, a novel apparatus and method are developed to measure the grinding force in silicon wafer self-rotating grinding process. Four thin film force sensors are equidistantly embedded beneath the silicon wafer along radial direction and the measured signal is transmitted wirelessly through WiFi protocol. Based on the proposed method, the normal grinding force and its distribution along wafer radial are obtained. The test data indicates that the proposed approach is effective to measure the grinding force with high reliability, high precision and low cost.