RBS characterization of the deposition of very thin SiGe/SiO2 multilayers by LPCVD

Multilayer structures consisting of several alternated layers of SiGe and SiO2 with thickness ranging from <5 to 25 nm were deposited by LPCVD. The samples were analyzed by RBS to determine the composition and thickness of each layer. The deposition of SiGe on SiO2 or Si as well as the deposition of SiO2 on Si show negligible incubation times. The deposition of SiO2 on SiGe, however, exhibits an incubation time of several minutes, which would be related to the oxidation of the surface necessary for the SiO2 deposition to start. In all cases the film thickness increases linearly with deposition time, thus allowing the growth rates to be determined. These data allow the deposition process of these very thin layers to be accurately controlled.