Silicide induced ion beam patterning of Si(001)

Abstract

Low energy ion beam pattern formation on Si with simultaneous co-deposition of Ag, Pd, Pb, Ir, Fe or C impurities was investigated by in situ scanning tunneling microscopy as well as ex situ atomic force microscopy, scanning electron microscopy, transmission electron microscopy and Rutherford backscattering spectrometry. The impurities were supplied by sputter deposition. Additional insight into the mechanism of pattern formation was obtained by more controlled supply through e-beam evaporation. For the situations investigated, the ability of the impurity to react with Si, i.e. to form a silicide, appears to be a necessary, but not a sufficient condition for pattern formation. Comparing the effects of impurities with similar mass and nuclear charge, the collision kinetics is shown to be not of primary importance for pattern formation. To understand the observed phenomena, it is necessary to assume a bi-directional coupling of composition and height fluctuations. This coupling gives rise to a sensitive dependence of the final morphology on the conditions of impurity supply. Because of this history dependence, the final morphology cannot be uniquely characterized by a steady state impurity concentration.

Nanostructures on fused silica surfaces produced by ion beam sputtering with Al co-deposition

“…Therefore, the main patterning mechanism in this region is controlled by the deposition. Such a smoothing effect due to increasing impurity content has also been reported in the IBS of Si with concurrent Au [32] and Fe [25,29] depositions.…”

“…Ion beam parameters (species, incidence angle, energy, flux, etc) and substrate parameters (material, temperature, initial surface topography, etc) interact to generate the features of such nanopatterns. Recently, numerous experiments on sputtering with simultaneous co-deposition [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] and theoretical studies [40][41][42][43][44][45][46][47] on simultaneous metal co-deposition during IBS or surfactant sputtering [32-38, 46, 47] have been performed to elucidate the formation mechanism of self-organized nanostructures and to generate various nanopatterns. In principle, the simultaneous use of metal atoms modulates the sputtering yield of the substrate during IBS, which results in diverse physical and chemical phenomena (e.g., island formation or phase separation).…”

Self-organized nanopatterning of silicon surfaces by ion beam sputtering

“…Silicide-induced patterning has been also addressed very recently by Engler and co-workers [123]. In this work, 2 keV Kr þ irradiation simultaneous with metal co-deposition has been performed using a similar experimental set-up for Pd, Ir, Ag, and Pb.…”

“…In agreement with [122], only the co-deposition of metals prone to silicide formation did lead to surface nanopatterning. However, the authors of [123] argue that the ability of the co-deposited metal to form silicide appears to be a necessary, but not a sufficient condition for nanopatterning. Such a conclusion is derived both, from the experiments in [123], and from comparison with previous experiments in which the co-deposited metal was supplied by evaporation, and, therefore, was uncoupled with the irradiation process [33].…”

“…However, the authors of [123] argue that the ability of the co-deposited metal to form silicide appears to be a necessary, but not a sufficient condition for nanopatterning. Such a conclusion is derived both, from the experiments in [123], and from comparison with previous experiments in which the co-deposited metal was supplied by evaporation, and, therefore, was uncoupled with the irradiation process [33]. In this sense, a bi-directional coupling between surface composition (phase separation) and height fluctuation is proposed to lead to the surface destabilization which finally leads to pattern formation.…”