The mechanism of electron-beam-induced immobilization of nanoparticles on a substrate has been studied both experimentally and theoretically. Experiments have been performed for the case of 200-350 nm Co-Ni nanoparticles secured to a substrate using a 30 keV electron beam. Atomic force microscopy studies reveal that the fixing occurs due to the formation of a deposit beneath the nanoparticles, causing strong bonding to the substrate, even for a thin layer. Measurements of the lateral forces required to displace the immobilized nanoparticles have shown that a deposit layer of 0.5 nm results in a tenfold increase in the bonding strength. A comparison of measured profiles with the results of computer simulations clearly reveals that the major role in the formation of the deposit is played by low-energy electrons generated by energetic primary electrons in both the nanoparticles and substrate. It is also shown that the efficiency of bonding decreases with decreasing energy of primary electrons. Different strategies for electron-beam-induced immobilization of nanoparticles and optimization of the processes are discussed.

Proximity effects causing thickening and bending of closely spaced, free-standing pillars grown by electron-beam-induced deposition are investigated. It is shown that growth of a new pillar induces deposition of a layer of additional material on the side of already grown pillars facing the new pillar. We present experimental results which suggest that the bending of pillars is caused by shrinkage of the newly formed layer on exposure to the primary electron beam.

Exposure of a sample to the electron beam in a scanning electron microscope (SEM) results in the growth of a film of amorphous carbon due to decomposition of hydrocarbon molecules, which are always present in small quantities in the SEM chamber. This growth is induced mainly by secondary electrons backscattered by atoms of both the sample and substrate. We show that, because the secondary electrons are spread beyond the exposed area, this deposit can be grown in areas of geometric shadow and therefore can be used for bonding of different complex 3D nano-objects to a substrate. This is demonstrated by welding 100 nm Fe-Co-Ni nanoparticles to the surface of 2D graphite. The tip of an atomic force microscope was used to probe the mechanical properties of the formed nanostructures. We observed that, for layers thicker than 25 nm, the nanoparticle is bonded so strongly that it is easier to break the particle than to separate it from the substrate.

We present the fabrication of specialized nanotools, termed nanoscalpels, and their application for nanolithography and nanomechanical manipulation of biological objects. Fabricated nanoscalpels have the shape of a thin blade with the controlled thickness of 20-30 nm and width of 100-200 nm. They were fabricated using electron beam induced deposition at the apex of atomic force microscope probes and are hard enough for a single cut to penetrate a approximately 45 nm thick gold layer; and thus can be used for making narrow electrode gaps required for fabrication of nanoelectronic devices. As an atomic force microscope-based technique the nanoscalpel provides simultaneous control of the applied cutting force and the depth of the cut. Using mammalian cells as an example, we demonstrated their ability to make narrow incisions and measurements of local elastic and inelastic characteristics of a cell, making nanoscalpels also useful as a nanosurgical tool in cell biology. Therefore, we believe that the nanoscalpel could serve as an important tool for nanofabrication and nanosurgery on biological objects.

The use of spot-exposure electron-beam-induced deposition (EBID) to immobilize targeted nanoparticles on a substrate is demonstrated, and investigated using experiment and simulation. Nanoparticles are secured in place through the build-up of carbonaceous material that forms in the region between a particle and substrate when an energetic electron beam is focused onto the particle and projected through to the substrate. Material build-up directly affects the strength of adhesion to the surface, and can be controlled through electron dosage and beam energy. By selectively immobilizing specific particles within surface agglomerations and removing the excess, we illustrate the potential for spot-exposure EBID as a new technique for nanofabrication.