Self-Formed Mn Oxide Barrier on SiOCH for Nanoscale Copper Interconnect by Metal Organic Chemical Vapor Deposition of Mn

Abstract

Both the formation of self-formed barrier (SFB) of Mn oxide on porous low dielectric constant (low-k) SiOCH trench and Cu filling (MOCVD) in order were carried out by in-situ metal organic chemical vapor deposition to make Cu interconnect. Oxygen-plasma pretreatment of the low-k dielectrics surface enhanced the uniformity of deposited Mn layers as well as the formation of SFB prior to Cu MOCVD. X-ray photoelectron spectroscopy confirmed the presence of amorphous MnOx and MnSi(y)Oz layers in SFB. Electron energy loss spectroscopy (EELS) measurements of cross-sectional samples of the deposited layers on porous low-k blanket and trench surfaces enabled in-depth analysis of the elemental composition of the Cu/SFB multilayers with high spatial resolution. The effectiveness of the SFB layer in protecting Cu diffusion into the low-k layer was proven by EELS and energy dispersive X-ray spectroscopy (EDX) analyses. The Mn L3/L2 intensity ratio from EELS data enabled us to identify the possible compounds of the SFB layers including MnSiO3 near the dielectric surface, Mn2O3 near the Cu layer, and Mn3O4 at the intermediate region.