Highly reliable enhanced nitride interface process of barrier low-k using ultra-thin SiN with moisture blocking capability

Abstract

We developed a highly reliable enhanced nitride Interface (ENI) process of barrier low-k using an ultra-thin SiN (UT-SiN) for 40-nm node devices and beyond. The UT-SiN (3nm) exhibits stable thickness uniformity and an excellent moisture blocking capability. By using this process, a lower effective k and high via yields were obtained.Compared to the conventional SiCN bi-layer process, 5× via electro-migration improvement, 50× time dependent dielectric breakdown improvement and no stress induced voiding failure within 1000h were observed. The ENI process was analyzed using X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. From these analyses, we propose the mechanism for these reliability performance improvements.