New Metrology Technique for Measuring Wafer Geometry on a Full 300mm Silicon Wafer

Wave Front Phase Imaging (WFPI), a new wafer geometry technique, is presented, that acquires 7.65 million data points in 5 seconds on a full 300mm wafer providing lateral resolution of 96µm. The system has high repeatability with root-mean-square (RMS) standard deviation (σRMS) in the single digit nm for the global wafer geometry and in the sub ångström range for the full-wafer nanotopography for both 200mm and 300mm blank silicon wafer. WFPI can collect data on the entire wafer to within a single pixel, in our case 96µm, away from the wafer edge roll off. The flatness of the silicon wafers used to manufacture integrated circuits (IC) is controlled to tight tolerances to help ensure that the full wafer is sufficiently flat for lithographic processing. Advanced lithographic patterning processes require a detailed map of the wafer shape to avoid overlay errors caused by depth-of-focus issues. We present WFPI as a new technique with high resolution and high data count acquired at very high speed.