Mjm. Vugts et al., SI XEF2 ETCHING - TEMPERATURE-DEPENDENCE, Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 14(5), 1996, pp. 2766-2774
Citations number
31
Categorie Soggetti
Physics, Applied","Materials Science, Coatings & Films
The temperature dependence of the Si(100)/XeF2 etch reaction is studie
d quantitatively in a molecular beam setup. At a sample temperature of
150 K the reaction probability reaches unity initially, after which t
he XeF2 condenses on the surface and blocks the etching process. For i
ncreasing temperatures the XeF2 reaction probability initially decreas
es from 100% at 150 K down to 20% around 400 K, but for temperatures a
bove 600 K it increases again up to 45% at 900 K. In a simple reaction
scheme the high etch rate at low temperatures is explained by a XeF2-
precursor, with an activation energy for desorption of 32+/-4 meV. Fur
thermore the increased etch rate at high temperatures is explained by
the desorption of SiF2 with an activation energy of 260+/-30 meV. The
steady-state fluorine content of the SiFx reaction layer, measured usi
ng thermal desorption spectroscopy, reaches a maximum of 5.5 monolayer
s at 300 K. For increasing temperatures it decreases to a submonolayer
coverage above 700 K. The temperature dependence of the formation of
the reaction layer is described well by including the XeF2-precursor i
n a previously developed adsorption model. (C) 1996 American Vacuum So
ciety.