A Study of Carbon Effects in Implantation Process for Non-Silicide Contact Formation

Abstract

With a continuous semiconductor devices shrinking approaching to a nanoscale area, the ion implantation processes used for formation of ultra shallow electrically active areas become more sensitive to the material properties at the surface and near surface region. Active control of surface condition and contamination, which can occur during the process of ion implantation, is very important and helps to improve implanted layer parameters and device characteristics. Surface properties modification and mitigation of contaminants by introducing a small amount of gases directed precisely near the target surface during ion implantation is investigated. It is shown that introducing of reactive gases containing oxygen and water vapor into a process chamber results to a significant reduction of surface carbon contamination. Typically, the carbon particles are generated by ion beam striking carbon‐based surfaces such as graphite, which is a commonly used material within ion implantation systems. Additionally, photoresist material, which is usually used as a mask for ion implantation, contains carbon, which can then be released as gaseous by‐product during ion implantation. Surface adsorption is considered as a potential mechanism of carbon contamination mitigation. It was demonstrated that a suggested method can be applied to control contact resistance of p‐MOS transistors and improves DRAM characteristics.