Step coverage comparison of Ti/TiN deposited by collimated and uncollimated physical vapor deposition techniques

Abstract

The step coverage and grain structure of Ti/TiN films sputtered with and without a collimator in a contact/via hole structure were compared using transmission electron microscopy, microelectron diffraction, and Auger electron spectroscopy with field emission microanalysis capability on cross-section samples. The holes have widths ranging from 0.40 to 0.75 μm and aspect ratios from 2.3 to 1.4, respectively. It was found that collimated Ti/TiN films demonstrate reasonably uniform coverage along the sidewall and at the bottom of holes. Collimated Ti bottom coverage is sufficient to assure good contact resistance. In contrast, uncollimated Ti/TiN films demonstrate an overhang on the top sidewall of holes and show decreased coverage when approaching the bottom corner along the sidewall or along the bottom of holes. Film property differences at different regions of a hole using either collimated or uncollimated deposition techniques will also be discussed.