T. Laurila, K. Zeng, J.M.T. Molarius*, I. Suni*, and J.K.Kivilahti. Helsinki University of Technology, Electronics Production Technology, P.O. Box 3000, FIN- 02015 HUT, Finland, E-mail: Tomi.Laurila@hut.fi, *VTT Microelectronics, P.O.Box 1101, FIN-02044 VTT. Finland.

The reactions in the Si/Ta/Cu metallisation system produced by the sputtering process were investigated by means of sheet resistance measurements, XRD, RBS, SEM anbd the optical microscopy. In particular, the reaction sequence was emphasised. The reaction mechanisms and their relation to the microstructure and defect density of the thin films are discussed on the basis of the experimental results and the calculated temary Si-Cu-Ta phase diagram at 973 K.