Formation of PdS compounds in direct metallization via Pd/Sn catalyst activation

The reaction mechanism between a Pd/Sn catalyst and sulfide ions which were used to promote direct copper plating was studied. The identity of reactio n products after activation, acceleration, sulfide promotion, and plating b ath dipping were analyzed by infrared absorption spectroscopy and X-ray dif fraction. It wa found that the chemically adsorbed sulfides ions do not rea dily form PdS. The stable PdS appears only after it is dipped in the platin g bath. The major agent responsible for this transformation was found to be the sulfate ions. (C) 1999 The Electrochemical Society. S0013-4651(98)09-0 73-X. All rights reserved.