Electroless NiMoP Thin Film Deposition on Si/SiO2

NiMoP is one of the most important barrier layers for Cu interconnection. A pretreatment for initiating electroless plating on Si/SiO₂ based on palladium ion grains chemisorption on self-assembled monolayers (SAMs) of amidogen of silane coupling agent has been developed. The process and properties of electroless plating NiP/NiMoP compound thin films on Si/SiO₂ substrate have been investigated. When concentration ratios of [MoO₄ ^2-]/[Ni²⁺] is at 0.02-0.1, atom percent of phosphoric in NiMoP layer is about 4%, and the NiMoP film has typical mixed-crystal structure consist of the crystal Ni phase and the non-crystal Mo phase. The grain size is about 50nm. The NiMoP film has diffusion barrier effect at high temperatures up to 400degC. The adhesion with the surface of SiO₂/Si can be improved obviously by adding NiP transition layer and 200degC annealing treatment in nitrogen atmosphere. The NiP/NiMoP compound thin films exhibit high integrality and uniformity, good neatness degree, low surface roughness, strong adhesion and low resistivity. In all, NiMoP barrier layer has a potential use for preventing copper-to- silicon diffusion for the application of 3D packaging with TSVs.