Etching-enhanced ablation and the formation of a microstructure in silicon by laser irradiation in an SF6 atmosphere

Sequential pulsed-laser irradiation of silicon in SF6 atmospheres induced the formation of an ensemble of microholes and rnicrocones. Profilometry measurements and direct imaging with an intensifying charge-coupled device camera were used to study the evolution of this microstructure and the laser-generated plume. Both the partial pressure of SF6 and the total pressure of an SF6-inert gas mixture strongly influenced the maximum height that the microcones attained over the initial surface. The cones first grew continuously with the number of pulses, reached a maximum, and then began to recede as the number of laser pulses increased further. The growth of the cones was closely connected with the evolution of the laser-generated plume.