Apparatus and methods for monitoring self-aligned contact arrays using voltage contrast inspection

Abstract

Disclosed are methods and apparatus for detecting defects in a partially fabricated semiconductor device with self-aligned contacts. The self-aligned contacts are formed from a first layer with a plurality of contact portions, a second layer with a plurality of conductive lines that are each aligned proximate to an associated underlying contact portion, and a third insulating layer formed over the conductive lines and their proximate underlying contact portions. The third insulating layer has a plurality of vias formed therein that are each formed alongside a one of the conductive lines and over its proximate underlying contact portion. A charged particle beam is scanned over a portion of the vias to form a voltage contrast image of each via. When a minority of the vias in the image have a significantly different brightness level than a majority of the vias, it is then determined that the minority of vias have defects.