PVD and ECD-competition, alternative or combination?

Physical vapour deposition (PVD) and electrochemical deposition (ECD) both lead to film formation by the deposition of the material in atomic scale. O n the base of advanced vacuum and plasma technologies, PVD processes have f ound their role in coating and thin film deposition, even if not comparable with "traditional" processes regarding the application volume. A lack of k nowledge, coupled with bias towards one or other technique often results in a false estimation of their relative benefits. Also judging the processes as inexorably competing is an inappropriate approach. On the basis of the fundamentals of both techniques the potentials and limi tations are outlined. The major advantages of ECD are, for example, the coa tability of almost all substrate shapes, specific surface structures, possi ble levelling of surface roughness or deposition of dispersion coatings. Di sadvantages might be the problems with hazardous substances and waste water . The major advantages of PVD are the almost unlimited variation in the che mical composition of the coating material, the principal tolerance of all s ubstrate materials and the deposition of compounds like nitrides, carbides etc, or materials like carbon or diamond. The advantages also are the easy realization of layered or graded film structures. The disadvantages are, fo r example, the need of vacuum and plasma equipment and the line-of-sight pr ocess, with the need for complex sample movement. As a practical application one or other of the techniques will be applied. In other cases the processes might be competing, and often process-combinat ion solve problems best. The final decision with respect to the process sel ection, however, is often governed by non-technical aspects like economic a nd ecological facts. (C) 1999 Elsevier Science S.A. All rights reserved.