Electroless nickel plating of silicon semiconductor substrate - in nickel bath contg. boron cpd. as reducing agent

摘要

The substrate wafer (a) has p-type doping, and is immersed in a Ni bath contg. a boron cpd. (b) as redn. agent. In the pref. process, wafer (a) has a surface with regions of different dopant types (n,p) and different dopant concns. and is immersed alternately in a Ni bath contg. hypophosphite as redn. agent, and a Ni bath, contg. cpd. (b). Alternatively, wafer (a) may be immersed in a Ni bath contg. both hypophosphite and cpd. (b). Wafer (a) is esp. a Si substrate, and cpd. (b) is a borohydride, esp. a borane. The Ni coating obtd. using the bath is preferentially deposited on the type 'p' zones and provides good ohmic contact, whereas, conventional baths contg. hypophosphite result in the Ni being deposited preferentially on n-type zones. When both p-and n-type zones are not present, bath still has the advantage that the amt. of B in the Ni is much less than the amt. of P obtd. in the Ni from bath.