Tungsten-based pillar deposition by helium ion microscope and beam-induced substrate damage

Abstract

Articles you may be interested inStructural characterization of He ion microscope platinum deposition and sub-surface silicon damage Analysis of subsurface beam spread and its impact on the image resolution of the helium ion microscope J. Vac. Sci. Technol. B 28, C6F6 (2010); 10.1116/1.3497012Direct-write patterning of microstructured porous silicon arrays by focused-ion-beam Pt deposition and metalassisted electroless etching Thermal stability and hydrogen atom induced etching of nanometer-thick a-Si:H films grown by ion-beam deposition on Si(100) surfaces J.The authors use a helium ion microscope (HIM) equipped with a tungsten hexacarbonyl gas injection system (GIS) to form tungsten-based pillars on carbon and silicon substrates by helium ion beaminduced deposition. Tungsten-based pillars with a width of $40 nm and height of $2 lm (aspect ratio of $50) are successfully fabricated using the HIM-GIS method. The pillars consist of face-centered cubic WC 1Àx and/or W 2 (C, O) grains. Columnar voids with a width of 1-15 nm form in the center of the pillars, suggesting that the pillars are continuously sputter-etched by the incident helium ion beam during deposition. In addition, the authors observe beam irradiation damage in the form of blistering of the Si substrate at the interface between the pillar and Si substrate. The columnar void width and Si blister height decreases as the volumetric growth rate of the pillars increases regardless of the deposition parameters. The authors consider that at least three phenomena compete during pillar formation, namely pillar deposition, sputter-etching, and Si blistering. Although there are numerous parameters involved in HIM-GIS deposition, it appears that the volumetric growth rate determines both the microstructure of the tungsten-based pillars and the degree of substrate damage.

Helium ion microscopy

“…112,[115][116][117][118] Recently, also a tungsten based metal precursor has successfully been used. 119 With this extremely flexible method, a wide range of features can be directly sculpted including 3D structures. Figure 11 shows examples of structures created using ion beam induced deposition in the group of Alkemade.…”

3D superconducting hollow nanowires with tailored diameters grown by focused He+ beam direct writing

“…Nevertheless, it is worth mentioning that its resolution, volume per dose and throughput are very sensitive to the selected growth conditions such as ion beam energy, ion beam current, precursor flux, surface interactions with the beam, and precursor molecules [ 29 – 30 ]. Hence, the He + FIBID technique is highly recommended for direct writing of 3D nano-objects with high resolution and aspect ratio [ 17 , 19 , 31 – 35 ]. A successful example of tailored 3D nano-objects grown by He + FIBID has been reported by Kohama and co-workers [ 35 ].…”

“…Hence, the He + FIBID technique is highly recommended for direct writing of 3D nano-objects with high resolution and aspect ratio [ 17 , 19 , 31 – 35 ]. A successful example of tailored 3D nano-objects grown by He + FIBID has been reported by Kohama and co-workers [ 35 ]. The authors deposited W-based pillars with diameters down to approx.…”

Comparison between Focused Electron/Ion Beam-Induced Deposition at Room Temperature and under Cryogenic Conditions

“…As a consequence, in the first approximation, the growth rate is given by the subtraction of the milling rate from the precursor dissociation rate. FIB milling can be reduced by the use of low ion beam currents [19]. An advantage of FIBID compared to FEBID is that each impacting ion triggers physical processes on the substrate that produce a large amount of secondary electrons on the substrate surface.…”