Contamination monitoring of Si wafers using photocarrier radiometry

Abstract
The ability of photocarrier radiometry to perform lifetime imaging of Si wafers is reported. The methodology involves PCR imaging of the sample at one or several frequencies with frequency scans performed at positions of interest. The frequency scans are fit to theory to obtain carrier lifetimes that are used in conjunction with the PCR amplitude and phase images to produce lifetime images. The direct correlation between contamination and carrier lifetime in Si allows for generation of contamination/defect concentration images in a completely non-contact, preparation free process suitable for in line monitoring of contamination.