Optical beam enhanced defect detection with electron beam inspection tools

This paper presents an approach to enhance the defect detection sensitivity with the use of electron beam inspection tool in presence of optical light illumination. Optical light is believed to interact with reversed biased NMOS devices and gate oxide under inspection which either induces photocurrent across junction on NMOS, or stimulates leakage current across thin gate oxide. This enhances the voltage contrast between defective open contacts and normal contacts, and makes the detection of corresponding voltage contrast defects more sensitive and reliable.