Application of atomic force microscopy to detect edge of mask contaminations that may hinder titanium silicide formation

摘要

An atomic force microscope (AFM) was used to study anomalies in the titanium disilicide formation of narrow (0.26μm) poly lines at the edge of n+ and p+ implant masks; a special test structure was designed both for morphological and electrical evaluations. On poly lines along the borders of the n+ mask, before titanium deposition, the AFM was able to detect some material build-up exactly on the locations where the silicide is severely reduced in thickness or interrupted, as inferred by electrical data and SEM analysis on finished samples. A carbon (or nitrogen) atom knock-on during the arsenic implant was invoked to explain the observed local hindering of the silicide formation.