Wafer defect detection by polarization insensitive external differential interference contrast module

Received XX Month XXXX; revised XX Month, XXXX; accepted XX Month XXXX; posted XX Month XXXX (Doc. ID XXXXX); published XX Month XXXX Abstract: We present a system, which is based on a new external, polarization-insensitive differential interference contrast (DIC) module, specifically adapted for detecting defects in semiconductor wafers. We obtained defect signal enhancement relative to the surrounding wafer pattern when compared to bright-field imaging. The new DIC module proposed is based on a shearing interferometer, which connects externally at the output port of an optical microscope, and enables imaging thin samples, such as wafer defects. This module does not require polarization optics (such as Wollaston or Nomarski prisms), and is insensitive to polarization, unlike traditional DIC techniques. In addition, it provides full control of the DIC shear and orientation, which allows obtaining a differential phase image directly on the camera (with no further digital processing), while enhancing defect detection capabilities, even if the size of the defect is smaller than the resolution limit. Our technique has the potential of future integration into semiconductor production lines. © 2018 Optical Society of America