Intriguing kinetics for chlorine etching of the Si(100)-(2 * 1) surface

摘要

The desorption kinetics of SiCl_2(g) species from the Cl covered nondefective Si(100)-(2 * 1) surface is investigated. During temperature programmed desorption, an extremely fast SiCl_2(g) desorption with the full width at half maximum of 14 K at 953 K is observed from the superheated Cl saturated Si(100). The coverage-dependent desorption kinetics of SiCl_2(g) follows a second order dependence on the coverage of adsorbed Cl and on the coverage of bare Si sites. The activation barrier and preexponential factor of 197 +- 19 kJ/mole and 5 * 10~(10 +- 1) s~(-1), respectively, are obtained from the model. On the Cl-saturated Si(100) surface, an additional high energy kinetic step is necessary to initiate the SiCl_2(g) desorption since there are not any bare Si sites. As soon as this process turns on, the desorption of SiCl_2(g) occurs catastrophically via the low energy desorption process.