Nondestructive SEM Studies of Localized Defects in Gate Dielectric Films of MIS Devices

A nondestructive technique to identify localized defects in the gate dielectric of MOS devices has been developed. The technique is based upon electron beam induced conductivity modulation which gives rise to a relatively large increase in gate current under an applied bias when the beam scans a localized defect area. Measurements on devices with low gate breakdown voltage have been made and correlated with regions where subsequent catastrophic gate breakdown occurred. A circuit description and physical model of the technique is presented.