Backside thinning of GaAs wafer by lapping using DOE approach

In this paper, a procedure to achieve efficient and high quality backside thinning of GaAs wafer using the lapping machine is demonstrated and the precautions and set of rules to be followed to utilize it productively are given. We selected the 4 main parameters affecting the lapping process i.e. concentration of the slurry (5 μm Al₂O₃ used here), pressure on the lapping plate, drop rate from the cylinder, rotations per minute of the lapping plate as the major independent variables and statistically designed the experiment in order to get the best lapping rate. The lapping process was carried out using Logitech PM2A lapping and polishing machine. Best lapping rate of 2 μm/min was observed in the case when rpm was kept low and all other parameters high. Thus this work provides a set of key notes and observations necessary for the lapping of GaAs wafer using the Logitech PM2A machine with the help of the statistical data of the Design of Experiment (DOE) results to achieve the best lapping rate.