Localization and detailed investigation of gate oxide integrity defects in silicon MOS structures

Abstract

Grown-in crystal defects like crystal originated particles (COPs) in Czochralski grown silicon wafers deteriorate the yield of metal oxide semiconductor devices by causing dielectric breakdown of the insulating oxide layer. The technique of lock-in IR-thermography is presented, which allows the localization of active gate oxide integrity (GOI) defects with a lateral resolution of about 10 μm as well as to make a full wafer image of electrically broken down GOI defects. Using this technique, the density and the distribution of GOI defects was determined across whole wafers. MOS structures with Si substrate materials with different COP densities and with various oxide thickness were analyzed. Single GOI defects were activated by a current limited breakdown and localized with lock-in IR-thermography. Planar TEM specimens were prepared and the defect origin was examined.