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

摘要

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 MnO_x and MnSi_yO_z 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 L_3/L_2 intensity ratio from EELS data enabled us to identify the possible compounds of the SFB layers including MnSiO_3 near the dielectric surface, Mn_2O_3 near the Cu layer, and Mn_3O_4 at the intermediate region.