Surface Structuring and Phase Formation in Thin Metallic Layers Deposited at Various Temperatures

Scanning electron microscopy, atomic force microscopy and x-ray diffraction analyses were performed for the study of the influence of substrate temperature during deposition on the surface structuring and phase formation on thin metallic double layers. Thin layers of Au, Al and Cr were deposited at 150 and 300degreesC on 30 nm thick Cu layers evaporated on Si (100) wafer substrates. Possible applications of such layers are Raman-active surfaces and model layers for diffusion experiments. The topographical investigation revealed an increase of surface structuring with temperature that is related to the formation of intermetallic and oxide phases. At 150degreesC deposition temperature the average roughness (R-a) of the films was determined to be 2-3 nm and the surfaces appeared smooth. In agreement with previous ion beam analysis measurements, a significant surface roughness occurred at 300degreesC, depending on the type of the metallic films. The lowest average surface roughness value was measured for the Al/Cu/Si system (R-a = 14.1 nm) and, about double the roughness was measured for the Au/Cu/Si and Cr/Cu/Si layer systems. In contrast, for single Cu layers a high value of R-a = 93.0 nm was determined. The combined analyses showed that the formation of intermetallic phases such as AlCu and CuAl2, reduces a surface roughening. However, the formation of oxide phases such as CuO2, increases, the average surface roughness. Copyright (C) 2002 John Wiley Sons, Ltd.