Alkoxysilane layers compatible with Cu deposition: Towards new diffusion barriers?

Self-assembled monolayers (SAMs) deposited on SiO2 and on a porous dielectric material using a supercritical CO2 (SCCO2) process are investigated by X-ray reflectivity (XRR) and neutron reflectivity (NR). Monolayers of MPTMS and AEAPTMS were successfully grown on SiO2, whereas APTMS leads to thicker polycondensed films. The ability of these layers to receive Cu deposits is also examined. Most of these layers cannot endure PVD Cu deposition, leading to copper diffusion penetration into the porous dielectric material. Interestingly enough, AEAPTMS seems to successfully withstand PVD deposition, and could be compatible with this process. An important result of this study is that all silane layers remain intact after MOCVD Cu deposition, and prevent copper diffusion penetration into the dielectric material during metallization. Therefore, MPTMS and AEAPTMS monolayers can be considered as promising candidates as new barriers against copper diffusion.

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