Electroless nickel deposition over the surface of bismuth telluride wafer as a barrier layer

ABSTRACT

Technology of electroless-deposition nickel on the surface of thermoelectric cooling wafer (Bi₂Te₃) was investigated in the paper. It consists of coarsening, removing coarsened films, reduction, sensitization, activation, pre-reduction, electroless-deposition nickel, heat treating. Bi₂Te₃ is attributed to catalyze poison material to the electroless-deposition nickel bath. We adopted sensitization, activation and reduction to treat wafer, then catalytic activity crystal nucleus which adsorbed the surface of Bi₂Te₃ may rapidly induce nickel-deposited to the whole wafer, so as to keep Bi₂Te₃ form poisoning bath and retarding nickel-deposited. For controlling the thickness of film, the relation between the thickness of film and how long to dispose in the plating bath was observed by tests. At the same time, the process parameters of electroless-deposition nickel bath were discussed. For the complicated working processes are simplified to make it easier to operate and maintain, simplified test processes has been investigated in the paper. Short-cut test processes: before electroless-deposited nickel on the surface of wafer, thin bismuth coating was plating, Nickel coating was obtained by the way.

KEYWORDS:

• Bismuth telluride
• electroless nickel deposition
• coarsening
• activation

Funding

This work was financially supported by China Postdoctoral Science Foundation funded project (2012M511950).