Chemical Physics of Uniform Cyclic Etching.

Abstract : The chemisorption mechanisms of Cl2, Br2, and I2 on Si(100) 2x1 are very similar while those of F2 and 02 are very distinct. For the heavy diatomic halogens (Cl2, Br2, and I2), the sticking probability increases with incident translation energies above 0.1 eV, and the largest initial sticking probabilities are obtained at the highest incident energies, with So equal to 95-100% for I2 and Br2, and 80-85% for Cl2. At low incident energies the initial sticking probability, So decreases with increasing surface temperature while at high incident energies the sticking probability is independent of surface temperature. In addition, for Cl2 very low energy molecular beams can be prepared, and the sticking probability is observed to decrease with increasing incident energies between 0.02 eV and 0.06 eV. Therefore, all three heavy diatomic halogens can adsorb via precursor - mediated chemisorption at low incident translational energy and via direct - activated chemisorption activated chemisorption at high incident translational energy 1,2.