Effects of copper line-edge roughness on TDDB at advanced technology nodes of 28NM and beyond

Abstract

Ultra low-k films are used in advanced technologies as dielectric interlayers in Cu interconnects. Due to its high porosity, manufacturing reliable low-k films faces many challenges. This paper discusses the reliability of time dependent dielectric breakdown (TDDB). Degradation of the TDDB lifetime can be observed when there is an abnormal I–V breakdown. Our study characterized the interaction of the breakdown leakage to the etch profile. It has shown that the etch profile weak points have impacts on the TDDB lifetime. By characterizing the Cu etching profile and establishing inline correlations to its TDDB lifetime, a new evaluation method was identified to quickly and precisely reflect the TDDB lifetime performance.