Interface broadening due to ion mixing during thin film growth at the radio-frequency-biased electrode in a plasma-enhanced chemical vapor deposition environment
- Regroupement quebecois sur les materiaux de pointe (RQMP) and Department of Engineering Physics, Ecole Polytechnique de Montreal, P.O. Box 6079, Station Centre-ville, Montreal, Quebec H3C 3A7 (Canada)
The authors show that ion bombardment in the range of tens to a few hundreds of eV, used in ion- and plasma-assisted deposition processes, can lead to thin film growth dominated by subsurface deposition due to subplantation (shallow implantation). This can cause significant interface broadening during the initial stages of film deposition as a result of ion mixing. First, by studying the modifications of a c-Si(100) target exposed to an O{sub 2} plasma at the radio-frequency (rf)-biased electrode using in situ real-time spectroscopic ellipsometry (RTSE), the authors detect implantation, damage, and oxidation to a depth of up to {approx}10 nm. They validate these results using high resolution transmission electron microscopy and simulate the effects of ion-surface interactions at the rf-biased electrode by using Monte Carlo TRIDYN simulations. The simulation code, which was modified specifically to consider a broadband ion energy source, enabled the authors to reproduce depth and time relevant experimental results with good agreement. In situ RTSE was then used to monitor TiO{sub 2} deposition on SiO{sub 2} under similar ion bombardment conditions. The authors observed the formation of a 2- to 4-nm-thick interfacial layer, depending on the ion-to-neutral flux ratio ({phi}{sub i}/{phi}{sub n}), which was controlled by varying the deposition rate. TRIDYN simulations revealed that oxygen subplantation causes interfacial broadening during the growth through ballistic mixing of Ti and Si atoms at the interface; the interface width scales as {approx}({phi}{sub i}/{phi}{sub n}){sup 12.} Intensive ion mixing at {phi}{sub i}/{phi}{sub n}>1 is also shown to be responsible for the ballistic displacement of the majority of surface-deposited Ti atoms into the bulk, so that the growth appears to be dominated by subsurface deposition under conditions of intense ion bombardment.
- OSTI ID:
- 20853793
- Journal Information:
- Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films, Vol. 24, Issue 6; Other Information: DOI: 10.1116/1.2348642; (c) 2006 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1553-1813
- Country of Publication:
- United States
- Language:
- English
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