Abstract
An electroless nickel plating bath was examined using hydrazine as a reducing agent to improve the bath stability. The plating films obtained from the basic bath are pure nickel, however, the plating films tend to show a dendrite structure of a black appearance. Therefore, the deposited films are not applicable to electronics fields. This report examines smoothing the plating films obtained from a basic bath using hydrazine as a reducing agent.
Smoothing the plating films was accomplished by lowering the reducing power of hydrazine whilst the basic bath is left at a high temperature for several days. Sulphur compounds as additives and gluconic acid as a complexing agent were also effective in achieving bath stability and smoothness of deposits.
Nickel can be directly deposited on copper substrate from a hydrazine reduced electroless nickel bath without a palladium activation step. Therefore, the applicability of the formation of capping metal on ULSI devices was also investigated. As a result, it was confirmed that selective capping metal deposition on the 250nm copper pads can be accomplished by this bath without palladium catalyst treatment.
