Intriguing kinetics for chlorine etching of the Si(100)-(2x1) surface

The desorption kinetics of SiCl2(g) species from the Cl covered nondefective Si(100)-(2 X 1) surface is investigated. During temperature programmed desorption, an extremely fast SiCl2(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 SiCl2(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 X 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 SiCl2(g) desorption since there are not any bare Si sites. As soon as this process turns on, the desorption of SiCl2(g) occurs catastrophically via the low energy desorption process. (C) 1999 American Institute of Physics. [S0021-9606(99)00708-4].