Tuning the surface morphology in self-organized ion beam nanopatterning of Si(001) via metal incorporation: from holes to dots

Abstract

We report on the selective production of self-organized nanohole and nanodot patterns on Si(001) surfaces by ion beam sputtering (IBS) under normal-incidence of 1 keV Ar(+) ions extracted with a cold cathode ion source. For a fixed ion fluence, nanohole patterns are induced for relatively low ion current densities (50-110 µA cm(-2)), evolving towards nanodot patterns for current densities above 190 µA cm(-2). Both patterns display similar characteristics in terms of wavelength, short-range hexagonal order and roughness. Rutherford backscattering spectrometry measurements show that the surface morphology is tuned by the incorporation of metals coming from the ion source and sample surroundings during the IBS process. The metal content measured in nanohole patterns is almost twice that found in nanodot morphologies. Thus, the pattern morphology results from the balance between the dependences of the erosion rate on the ion flux, the local surface topography and composition. These nanostructures have promising applications as growth templates for preferential growth on either hillocks or cavities.

The role of phase separation for self-organized surface pattern formation by ion beam erosion and metal atom co-deposition

“…A similar TEM analysis made of a dot pattern (not shown) also reveals a higher Mo concentration in the dot regions. A lateral inhomogeneous Fe and Mo concentration in a surface layer with dot patterns on Si was also reported earlier [6]. Figure 4 shows a compilation of AFM images of surface patterns obtained for either Fe, Ni, Mo, W, or Pt codeposition and for an ion fluence of 5 × 10 17 /cm 2 .…”

“…The simultaneous co-deposition of small amounts of atoms during ion beam erosion of surfaces has a tremendous influence on the self-organized nano pattern formation [1][2][3][4][5][6].…”

“…Several groups have recently demonstrated that in particular co-deposition of Fe and Mo surfactant atoms at room temperature induce pronounced dot and ripple patterns on Si substrates, even during normal and near normal ion incidence sputter erosion [2][3][4][6][7][8]. Without co-deposition, the surface remains very uniform and flat [2,7,9].…”

Observation and Modeling of Interrupted Pattern Coarsening: Surface Nanostructuring by Ion Erosion

“…This masking procedure introduces metal (Fe) impurities during the IBS process, which could influence the pattern morphology. For example, nanohole morphologies are induced instead of nanodot pattern when the residual metal content on the target surface is high [18]. In our case, these Fe impurities are incorporated systematically in all samples and within the same range (1-2 Â 10 15 at=cm 2 ), as assessed by Rutherford backscattering spectrometry, and only dot patterns are induced.…”

Sharp transition from ripple patterns to a flat surface for ion beam erosion of Si with simultaneous co-deposition of iron

“…[5][6][7][8][9][10][11][12][13][14] In particular, metallic surfactants like Fe and Mo induce pronounced dot and ripple patterns on Si substrates even during normal and near normal ion incidence sputter erosion. 2,8,9,[11][12][13] In the absence of co-deposition of foreign atoms and for normal and near normal ion incidence, even for incidence angles up to 50…”