Nanopatterning of metal-coated silicon surfaces via ion beam irradiation: Real time x-ray studies reveal the effect of silicide bonding

Abstract

We investigated the effect of silicide formation on ion-induced nanopatterning of silicon with various ultrathin metal coatings. Silicon substrates coated with 10 nm Ni, Fe, and Cu were irradiated with 200 eV argon ions at normal incidence. Real time grazing incidence small angle x-ray scattering (GISAXS) and x-ray fluorescence (XRF) were performed during the irradiation process and real time measurements revealed threshold conditions for nanopatterning of silicon at normal incidence irradiation. Three main stages of the nanopatterning process were identified. The real time GISAXS intensity of the correlated peaks in conjunction with XRF revealed that the nanostructures remain for a time period after the removal of the all the metal atoms from the sample depending on the binding energy of the metal silicides formed. Ex-situ XPS confirmed the removal of all metal impurities. In-situ XPS during the irradiation of Ni, Fe, and Cu coated silicon substrates at normal incidence demonstrated phase separation and the formation of different silicide phases that occur upon metal-silicon mixing. Silicide formation leads to nanostructure formation due the preferential erosion of the non-silicide regions and the weakening of the ion induced mass redistribution. V

Nanostructures formed on carbon-based materials with different levels of crystallinity using oxygen plasma treatment

“…The pattern formation on Si was reported to have a critical value with re-deposited metal ion flux, over which the nanopattern formation may occur [18,23,24]. To examine the flux effect of the co-deposited metallic compounds for plasma treatment, a PET sample was placed next to the stainless steel, a source for metallic compounds, which is similar to the experiment in the previous report [17].…”

Self-organized nanopatterning of silicon surfaces by ion beam sputtering

“…Hence, all the patterns described in this section will be rippled structures. There are, however, some especial cases in which ordered Si nanodots can be obtained for very low levels of impurities [51][52][53] or on clean targets [54]. These examples are interesting for device applications in which nanostructured impurity-free silicon surfaces are required.…”

“…These examples are interesting for device applications in which nanostructured impurity-free silicon surfaces are required. In the works by ElAtwani et al [51][52][53], nanodots are obtained at normal incidence by employing several thin metal-coated Si substrates. Even after removing all the metallic impurities, the nanostructures persist for some time before the pattern begins to smooth out.…”

Investigation of the mechanism of impurity assisted nanoripple formation on Si induced by low energy ion beam erosion

“…Subsequently, a different sputtering rate of Fe rich and Fe depleted regions results in pattern formation at the surface. Zhou et al 36 also suggest that a phase separation occurs at the surface. On the other hand, Bradley et al have further extended his theory to explain the impurity assisted nanopattern formation.…”

“…35 Recently, the effect of bonding strength of metal silicide formation on the pattern formation has been studied in detail. 36 Zhou et al developed a continuum model to describe the pattern formation at normal incidence with the incorporation of Fe. 37 In which surface stress induced instability competes with the surface relaxation mechanism leading to the observed pattern formation.…”