Gate Oxide Defects Connected to Submicron Isolation Regions Subjected to Selective Oxidation

Abstract

Defect detection of gate oxide films thermally grown on Si substrates subjected to selective oxidation for isolation oxides has shown that gate oxide defects are induced in the active device regions adjacent to small size isolation oxide regions. The size of the small regions proves to be less than 1 μm. The isolation oxide thickness and also the bird's beak length are suppressed to a great extent. A simple semiquantitative model, derived from the bird's beak configuration, is presented to account for the bird's beak length suppression and the gate oxide defects. The gate oxide defects are attributed to gate oxide thinning which results from some Si nitride formed on the Si substrate during selective oxidation.