The Formation and Structure of Electroless Ni-Mo-B Alloy Films

Abstract

Electroless Ni-Mo-B alloy films plated from developed simple baths were investigated. The use of dimethylamine-borane as a reducing agent resulted in a higher Mo content (17.3 at %) than with the hypophosphite reducing agent bath. The initial addition of Na₂MoO₄ to the bath resulted in an abrupt decrease in B content and increase in Mo content in the plated film. The codeposited Mo atoms made the film amorphous even at low B contents. Crystallized Ni-Mo-B alloy films showed different structures despite the fact that they had almost the same film compositions. They were confirmed to be composed of two regions of high and low crystallization. This peculiar condition was found to be due to Mo atom segregation, which resulted in higher resistivity. The grain size of the crystallized Ni-Mo-B alloy films did not change even after heat treatment at 500°C for 1h.