A Vapor Phase Self-Assembly of Porphyrin Monolayer as a Copper Diffusion Barrier for Back-End-of-Line CMOS Technologies

We integrate the first vapor phase self-assembled monolayer (VPSAM) of hydroxy-phenyl zinc porphyrin (ZnTPPOH) on the interlayer dielectric materials and investigate its properties as a copper diffusion barrier. The ZnTPPOH VPSAMs show a 1.5× improvement over the earlier investigated 3-aminopropyltrimethoxysilane self-assembled monolayers (SAMs) in bias temperature stress (BTS) studies. We show that with the porphyrin SAMs, one can achieve an improvement in breakdown field of a low-K dielectric by two times and a drop in copper diffusion by six times as measured by secondary ion mass spectroscopy.