Optical studies on thin copper films on Si(111)

Thin copper films of about 15 nm thickness were deposited on Si(1 1 1) subs trates at room temperature and subsequently annealed at higher temperatures . The ellipsometric analysis was performed in situ under UHV conditions in the wavelength range 400-800 nm. The as-deposited films can be described by a two-layer model taking into account the excitation of surface plasmon po laritons (SPP) at the rough copper-silicon interface. During annealing, two steep rises in the ellipsometrical angles Delta and psi are observed at 12 5 and 300 degreesC which are attributed to the coagulation of copper and th e silicide formation, respectively. (C) 2001 Elsevier Science B.V. All righ ts reserved.