Investigation into the relationship between grinding force and total thickness variation using embedded force sensor

초록

The semiconductor industry is fundamental to modern technology, driving advancements in electronics, communications, and computing. In semiconductor manufacturing, precise wafer thickness, surface flatness, and microcrystalline structure are crucial. To make ultra-thin and uniform wafer, back-grinding process are required. Key parameters such as total thickness variation (TTV) and grinding force play critical roles in ensuring wafer quality and structural integrity. Back-grinding is used to thin silicon wafers to the desired thickness, and TTV measures the uniformity of the wafer's thickness. TTV control is influenced by grinding parameters like wheel speed, wafer speed, feed rate, and grinding angle, all of which affect grinding forces and wafer uniformity. This study develops a real-time grinding force measurement system using an in-house back-grinding setup. The system includes four sensors positioned beneath the wafer chuck for precise force measurement, with calibration to improve data accuracy. Real-time grinding force data was collected under variations in the alpha angle (between the wafer plane and the grinding wheel plane). As results, as the radial distance of the wafer increases, both the cutting depth and grinding force increase. With an increase in grinding force, the cutting depth also increases. Concerning the angle alpha, as it decreases, the TTV gradually increases. Through the analysis of cutting depth and TTV results, it was observed that as the radial distance of the wafer decreases, the cutting depth decreases and the TTV increases.

키워드