Nanopatterning of silicon surfaces by low-energy ion-beam sputtering: dependence on the angle of ion incidence

Abstract

We report on the production of nanoscale patterning on Si substrates by low-energy ion-beam sputtering. The surface morphology and structure of the irradiated surface were studied by atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HRTEM). Under ion irradiation at off-normal incidence angle (∼50• ), AFM images show the formation of both nanoripple and sawtooth-like structures for sputtering times longer than 20 min. The latter feature coarsens appreciably after 60 min of sputtering, inducing a large increase in the surface roughness. This behaviour is attributed to the preferential direction determined on the substrate by the ion beam for this incidence angle, leading to shadowing effects among surface features in the sputtering process. Under irradiation at normal incidence, the formation of an hexagonal array of nanodots is induced for irradiation times longer than 2 min. The shape and crystallinity of the nanodots were determined by HRTEM. At this incidence angle, the surface roughness is very low and remains largely unchanged even after 16 h of sputtering. For the two angle conditions studied, the formation of the corresponding surface structures can be understood as the interplay between an instability due to the sputtering yield dependence on the local surface curvature and surface smoothing processes such as surface diffusion.

Angular distribution of atoms sputtered from germanium by 1–20 keV Ar ions

“…This may be connected with a low conductivity of Si samples used in our experiments (specific resistance 5 k cm). However, a distinct nanorelief similar to that revealed in [14] was observed by using AFM for both Ge and Si samples. Figure 6 shows the AFM-image of Ge target after bombardment with 10 keV Ar + ions at fluence of about 10 18 ion/cm 2 .…”

Thin Film Synthesis of New Nanolaminated Ternary Carbides

“…Hence, depositions on complex-shaped substrates are usually challenging for PVD processes, which can be seen from the differences of microstructure, density and growth rate from on-axis and off-axis deposited thin films [75]. In the following subsections, brief introduction is presented for the PVD methods used in this work, namely the direct current magnetron sputtering and the pulsed cathodic arc deposition processes.…”

Linear dynamics of ion sputtered surfaces: instability, stability and bifurcations

“…As several articles in this volume describe, for a variety of surface types and system parameters (e.g. ion type and energy, beam angle and temperature, substrate type), the evolving surface patterns can take the form of ordered or disordered arrays of one-dimensional ripples or two-dimensional structure of dots, whose typical length scales are 10 2±1 nm [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The large separation of scales between the patterns and the characteristic penetration depth of ions into a solid surface (typically at least an order of magnitude) suggests that evolution of surface morphology can be described as a dynamics of continuous media.…”