Interaction of SF6 Multiple PhotonDissociation Products With Siliconand SiO2 Surfaces

Experiments on etching Si and SiO 2 by the multiple photon dissociation products ofSF 6 molecule in IR laser field have been carried out. These experiments showed thatthe etching of Si and SiO 2 is the result of two qualitatively different processes and highselectivity (>10 3 ) can be achieved. The dependences of the etching process of the initialgas mixture pressure and composition, on the laser intensity and the number of laserpulses and on the direction of laser radiation have been studied. It has been found outthat the etching rates of “a monolayer per pulse” for Si and ~100 Å/min for SiO 2 arecomparable to the rates achieved in low-temperature plasma technique. Possiblemechanisms and chemical reactions which can cause Si and SiO 2 etching are discussed.It has been concluded that under the experimental conditions multiple photon dissociationforms the basis for the etching process.