J. Phys. IV France 09 (1999) Pr8-245-Pr8-250
Chemical mechanisms of tungsten CVDYu.V. Lakhotkin
Institute of Physical Chemistry, Russian Academy of Sciences, Leninsky Pr. 31, 117915 Moscow, Russia
A composition of adsorbed layers formed from a gaseous mixture of hydrogen with tungsten hexafluoride on single-crystal tungsten planes has been investigated. The heats and constants of adsorption, taking into account the strong lateral interaction of adsorbed W-F-H components, have been calculated by a simple procedure. The equilibrium composition of adsorbed layers at temperature range 400-1000 K, pressure range 1-100 kPa and for hydrogen to fluoride ratio from 4 to 10 has been presented. It has ben shown that adsorbed fluorine and lower-valent tungsten fluorides cover the tungsten surface. The film adsorbed on (100) W has a higher density than one on (110) W and the fluorine and fluoride concentrations are considerably higher on (100) W plane.
© EDP Sciences 1999