Etching of latent tracks in amorphous SiO2 and Si3N4: Simulation and experiment

Abstract

The latent track formation in silicon dioxide (SiO2) and silicon nitride (Si3N4) irradiated with swift heavy ions (SHI) has been studied using computer simulation in the frame of the thermal spike model. We have calculated radii and lifetime of the molten regions, or the regions heated to the melting point, formed in SiO2 and Si3N4 along the ion trajectories for F, S, Cl, Ar, Kr and Xe ions in an energy range of (28–200) MeV. The radius of the molten region was chosen as a criterion for track “etchability” in the case of SiO2. The results of computer simulation have been compared with the experimental results of track etching in 4% aqueous solution of hydrofluoric acid (HF). The validity of the criterion taken for the creation of homogeneous “etchable” ion tracks in SiO2, namely, the formation of a molten region with radius larger than 3.0 nm [1] in the matrix along the ion trajectory, has been confirmed. It has been found that both the etched track depth and diameter increase with the fluence for the same type of ion species. Under our experimental conditions, for the case of Si3N4 we failed to etch regular conical channels with uniform size distribution.