Laser photodissociation of chlorine and methyl chloride on low-temperature silicon substrates

Abstract

Laser irradiation at 193 or 351 nm of a multilayer of Cl2 or CH3Cl on an Si wafer at 100 K leads to both photodissociation of these molecules and formation of photoetching products. The kinetic energy distributions of photofragments (Cl, CH3) and etching products (SiCl, SiCl2) were measured. The kinetic energy distribution of Cl or CH3 is bimodal for the case of thin deposition of parent molecules on substrates, in which the two‐component analysis of Maxwell–Boltzmann represents experimental results, assuming average kinetic energies of ∼1 and 10 kcal/mol. The etching products have kinetic energies of 1 kcal/mol. For the thick‐deposition case, the kinetic energy distribution of Cl or CH3 fragments is composed of a single component with an average kinetic energy of 10 kcal/mol.