Abstract
Decreasing process node size has increased the pressure on backside sample preparation techniques for flip chip backside sample preparation. Utilizing a 5 axis CNC mill, three sample groups of five samples each were processed down to a 15 micron thickness target. Each sample group was machined with a different maximum depth of cut. Group A was machined with a 200um, 35um and 10um process. Group B was machined with a 100um, 20um and 10um process. Group C was machined with a 50um and 10um process. The results were reviewed to determine the optimal depth of cut based on the accuracy and precision of the process. Group B had the highest precision and smallest total deviation across each step. Group B was also more accurate to the final target of 15um remaining silicon thickness than the other two processes with an average of 16um thickness and a standard deviation of 0.62um.