Integration of modified plasma-enhanced chemical vapor deposited tetraethoxysilane intermetal dielectric and chemical-mechanical polishing processes for 0.35 mu m IC device reliability improvement

Abstract

The process of interlevel dielectrics (ILD) between poly-Si and metal is critical to device characteristics and reliability. Also, the shrinking design rules demand greater hot carrier reliability, which is strongly influenced by the ILD process. In this paper we describe a process for improving the reliability of 0.35 mu m devices by using modified plasma-enhanced chemical vapor deposited tetraethoxysilane (PECVD-TEOS) N2O-rich or O-2-rich ILD films which contain less hydrogen concentration and excellent moisture resistance, and less mobile ion penetration after chemical-mechanical polishing (CMP), relative to standard PE-TEOS oxides. The hot carrier lifetime and the held isolation device threshold voltage are monitored and compared between devices with ILD layers based on different combinations of subatomespheric O-3-TEOS borophosphorus silicate glass (BPSG), standard PE-TEOS, O-2-rich and N2O-rich oxides. The material characteristics contributing to the reduction in post-CMP mobile ion levels and the improvement in device reliability will be discussed.