Multiple surfaces pretreatments of nanoporous SiO2-based dielectric layers for electroless plating of copper

G.S. Chen
Feng Chia University, TW

Keywords: nanoporous dielectric, vacuum plasma, self assembled monolayer, electroless palting, copper metallization

Summary:

In this work, Black Diamond II (DB II with a chemical formula of SiOC:H), a leading nanoporous chemically vapor deposited dielectric layer, is examined as a test case for the SiO2-derived nanoporous IMDs, demonstrating the feasibility of using multiple pretreatments to modify the DB II surface, which ends up with a resolution of the above-mentioned issues. Fourier transform infrared and synchrotron x-ray absorption spectroscopies indicate that pretreatments of DB II by N2/H2 vacuum plasma could induce a nitrogen-contained surface layer while its dielectric and insulation characteristics still remain normal. The plasma pretreatments also convert the originally hydrophobic DB II surface to hydrophilic surface, the contact angle of water droplet being reduced substantially from 90o to 5o. In contrast to the pristine hydrophobic counterpart, the plasma-pretreated hydrophilic BD II allows the SAMs to be evenly anchored onto the water-wetted surface. The roles of SAMs, in terms of acting as a passivated layer, facilitating the electroless plating of Cu films, improving the process/material integration of nanoporous DB II and Cu, will be presented.