Focused electron beam-induced deposition of iron- and carbon-containing nanostructures from triiron dodecacarbonyl vapor

Abstract

93-96. Original Russian Text Copyright © 2005 by Bruk, Zhikharev, Grigor'ev, Spirin, Kal'nov, Kardash. 1 During the last fifteen years, a new area of microelectronics and nanotechnology, the image formation of solid substrates by sharply focused electron beam deposition from a vapor of organometallic (or other metal-containing) precursors have been intensively developed [1][2][3][4]. This technique makes it possible to apply with nanometer-scale accuracy 2D and 3D images with quite various (conducting, dielectric, emission, optical, sensor, etc.) properties of their elements. The deposition of iron-based materials by means of this technique is of considerable interest (in particular, from the viewpoint of magnetic properties). One of the most appropriate iron precursors is triiron dodecacarbonyl Fe 3 ( CO ) 12 (IDC), which is an intermediate of the thermal degradation of iron pentacarbonyl. However, no works on imaging with the use of this precursor have been performed.In this paper, we present preliminary results on image formation by deposition from IDC.EXPERIMENTAL Deposition was carried out in a Camscan scanning electron microscope at an electron energy E of 15 or 20 keV, a beam current I of 5-200 nA, and an IDC pressure ( p ) of 1-10 -5 Pa. The diameter of a focused electron beam was 0.2-0.5 µ m, the width of deposited lines (at half maximum) was 1 to 2 µ m, and the line height was 50-80 nm. The lines were deposited on singlecrystal silicon wafers coated with an Si 3 N 4 surface layer 1 E-mail: bruk@cc.nifhi.ac.ru of 0.2 µ m in thickness, on which gold electrodes were evaporated. The distance between the electrodes was 9 µ m, the length of a deposited line was about 13 µ m, and the pixel time was 20 ms. The values of current density in an incident electron beam were ~0.1-10 A/cm 2 . The electric resistance of deposited lines was measured with an integrated digital device Shch-300. RESULTS AND DISCUSSIONWe studied the dependence of the electric resistance R of deposited lines on the beam current during deposition, IDC vapor pressure, deposition time, and other parameters. It was found that depending on deposition conditions, R varied from 4 k Ω to 100 M Ω . As the beam current increases, R rapidly decreases. When I varies by a factor of 20-30, R changes approximately by four orders of magnitude (Fig. 1). The dependence of R on the deposition time τ is illustrated in Fig. 2. Additional irradiation of high-resistance lines (preliminarily deposited at low I values) at high I values leads to a considerable increase in the conductivity of lines.The short-term (for 10 min) heating at 170°ë of the lines deposited at room temperature practically does not alter their conductivity after cooling to room temperature. This refers to both low-and high-resistance lines. Note that according to published data [5], IDC effectively decomposes at temperatures about 150°ë yielding reduced iron. Hence, it follows that the deposited material does not contain intact IDC.Using scanning-force microscopy, the cross section of depo...

A critical literature review of focused electron beam induced deposition

“…For deposits from Fe 3 ͑CO͒ 12 , it was reported that "additional irradiation of high-resistance lines ͑preliminarily deposited at low beam current values͒ at high I values leads to a considerable increase in the conductivity of lines." 91 Similar results were found for deposits from W͑CO͒ 6 , where the resistivity decreased with a factor of 20. 73 Finally, postdeposition irradiation can be used to sculpt a deposit.…”

“…When the conductivity of deposits is measured as a function of accumulated charge, the general trend is that the resistance decreases with increasing accumulated charge. This is, for instance, the case in measurements by Bruk et al 91 They found that the resistance of wires deposited from Fe 3 ͑CO͒ 12 decreases with increasing accumulated charge. However, since the dimensions of the deposits were not reported, it is not possible to elucidate the mechanism by which the resistance decreased.…”

“…For instance, annealing at 170°C for 10 min had no effect on wires deposited from Fe 3 ͑CO͒ 12 . 91 The temperature may not have been high enough since annealing at 600°C did give an effect for similar Fe-containing deposits. [151][152][153] However, even at high temperatures, annealing does not necessarily lead to improved conductivity.…”

Gas-assisted focused electron beam and ion beam processing and fabrication

“…315 Other higher nuclei number iron carbonyls ͓Fe 3 ͑CO͒ 12 ͔ as precursor resulted in nanocomposite deposits, comparable to the simpler carbonyls. 316 The approach of increasing the metal content by increasing the number of metal to metal bonds and decreasing the number of ligands were already developed in focused laser beam 317 or focused ion beam 318,319 induced decomposition of metal organic compounds for multichip interconnects. It did improve the purity of the lines obtained in pyrolytic laser direct writing, but in FIB writing, reasonable electrical properties could only be obtained after reactive thermal annealing.…”

Beam‐Induced Fe Nanopillars as Tunable Domain‐Wall Pinning Sites

“…[1][2][3] In an envisioned 3-dimensional memory device, DWs are propagated between discrete sites along a nanostrip, forming a bit shift register with a very high data density. An interesting new route to 3-dimensional nanostructures is provided by focused-electron-beam-induced deposition (FEBID), [5][6][7][8][9][10][11][12][13][14][15][16] a tool that can be used to create nanoobjects of any desired shape. An interesting new route to 3-dimensional nanostructures is provided by focused-electron-beam-induced deposition (FEBID), [5][6][7][8][9][10][11][12][13][14][15][16] a tool that can be used to create nanoobjects of any desired shape.…”