Abstract

Experiments on etching Si and SiO₂ by the multiple photon dissociation products of SF₆ molecule in IR laser field have been carried out. These experiments showed that the etching of Si and SiO₂ is the result of two qualitatively different processes and high selectivity (>10³) can be achieved. The dependences of the etching process of the initial gas mixture pressure and composition, on the laser intensity and the number of laser pulses and on the direction of laser radiation have been studied. It has been found out that the etching rates of “a monolayer per pulse” for Si and ~100 Å/min for SiO₂ are comparable to the rates achieved in low-temperature plasma technique. Possible mechanisms and chemical reactions which can cause Si and SiO₂ etching are discussed. It has been concluded that under the experimental conditions multiple photon dissociation forms the basis for the etching process.