COPPER HYDRIDE FORMATION IN THE ELECTROLESS COPPER PLATING PROCESS - IN-SITU X-RAY-DIFFRACTION EVIDENCE AND ELECTROCHEMICAL STUDY

Copper hydride, CuH, has been shown by in situ X-ray diffraction metho d to form in the process of electroless copper deposition in alkaline solutions containing Cu-II complexes with tartrate and ammonia and bor ohydride, BH4-, as a reducing agent. The rate of possible chemical and electrochemical steps was measured and compared with the rate of auto catalytic Cu-II reduction process. Results indicate the existence of t wo process routes: (1) coupling of simultaneous electrochemical reacti ons of BH4- oxidation and Cu-II reduction with the enhancement of cath odic reaction due to H-2 evolution in anodic reaction, (2) electrochem ical steps of Cu-II reduction to Cu-I and consecutive chemical steps o f CuH formation and decomposition. The route including CuH intermediat e gives a lower Cu deposition rate. (C) 1998 Elsevier Science Ltd. All rights reserved.