In-line XPS to quantify the changes in interfacial layers of advanced node gate stacks

Abstract

In-line X-ray photoelectron spectroscopy (XPS) is a powerful tool for accurate thickness measurements on repeating ultrathin multilayer stacks using feed-forward methodology and provides composition analysis of individual elements. However, when material underneath is affected along with the surface, there is no direct method to determine loss. In this work, we present a method for quick assessment of oxidation of the various layers in a multi-layer metal gate stack as it undergoes fabrication processes post metal deposition using in-line XPS. This work also presents a study of the effect of removal processes on underlying layers of repeating multi-layer gate stacks using normalized elemental composition ratios.