Comparison of Precursors for Self-Assembled Monolayers as Cu Barriers

摘要

Self-assembled monolayers (SAMs) are the emerging materials as the candidate of barriers for application in back-end-of-line interconnects in advanced integrated circuits. In this study, SAMs derived from organic molecules with different structures are compared in terms of electrical characteristics, Cu diffusion inhibition, and Cu-SiO2 adhesion promotion. Experimental results indicated that all SAMs formed in this study enhanced the breakdown filed of SiO2 film, promote Cu-SiO2 adhesion, and prevent Cu-silicate formation under thermal annealing. Among the studied SAMs, APTMS-SAM derived from 3-aminopropyltrimethoxysilane (APTMS) has the most pronounced enhancement. Moreover, APTMS-SAM blocks the drift of Cu under electrical stress. The terminal group -NH2 attached to Cu layer in the APTMS is the key for the improvement.