Electron beam induced deposition from W(CO)6 at 2 to 20 keV and its applications

Abstract

Formation of submicron oxide widths on aluminum in the presence of keV electron beams and CO2 or N2O J. Vac. Sci. Technol. A 4, 241 (1986); 10.1116/1.573435Electron beam lithography from 20 to 120 keV with a high quality beam Electron beam induced deposition from W͑CO͒ 6 was studied for beam energies between 2 and 20 keV and a range of exposure doses, to investigate the dependence of deposit thickness and electrical conductivity on energy and the dependence of deposit conductance on cumulative exposure dose. Larger deposited thicknesses and higher conductivities were produced at the lower beam energies and were attributed to the higher secondary electron yield at lower energies. The deposit thickness was found to scale linearly with exposure dose. The initial dependence of conductance on exposure dose ͑and deposit thickness͒ was nonlinear and was attributed to the change from a discontinuous to a continuous film, and to increased backscattering. The subsequent dependence of conductance on exposure dose was linear for deposit thicknesses which were small compared with the electron range, implying that burial precludes the further decomposition of partially decomposed W͑CO͒ 6 molecules incorporated in the deposit. Transmission electron microscope examination showed that the structure of the deposits depended on the beam scanning conditions. Deposits were used to form a mask for CF 4 plasma etching of Si, while deposits on a doped GaAs substrate were found to form a Schottky contact with an ideality factor of 1.40, enabling the repair of a metal-semiconductor field-effect transistor gate to be demonstrated.

Fabrication of Free-Standing Tungsten-Nanowhiskers on SiO<SUB>2</SUB> Substrates with Electron-Beam Induced Deposition

“…Tungsten hexacarbonyl (W(CO) 6 ) powder was used as a precursor, of which the vapor pressure is approximately 2 Pa at room temperature. The precursor has been proved to be suitable for fabricating nano-sized structures on conductive substrates 1,3,5,7) as well as on insulator substrates 9,10) with EBID. Crystalline SiO 2 thinfilm specimens suitable for TEM observation were used as substrates.…”

“…Due to the controllability of the beam, zero, one, two, or three dimensional small-sized objects have been fabricated. [1][2][3][4][5][6][7][8] Conductive substrates are generally used in these fabrications, because they provide stable fabrication conditions. Recently, by using insulator substrates, Al 2 O 3 , nanometer-sized (nano-sized) tungstenstructures (W-structures), namely, wire-like, dendrite-like and tree-like W-structures, have been fabricated with EBID using a precursor W(CO) 6 in a 200 kV transmission electron microscope.…”

Electron induced dissociation of trimethyl (methylcyclopentadienyl) platinum (IV): Total cross section as a function of incident electron energy

“…It is possible to measure deposition yields ͑the amount of material deposited per electron͒, but a measurement of tot requires an estimate of the steady state coverage of precursor molecules on the surface. Total reaction cross sections have been estimated in this way; for example by Scheuer and Koops 8 ͑who found a value of 2 ϫ 10 −17 cm 2 at an energy of 40 keV for Ru 3 ͑CO͒ 12 ͒ and Hoyle et al 9 ͓who observed values in the order of 0.5-1.5 ϫ 10 −18 cm 2 for W͑CO͒ 6 at incident electron energies between 2 and 20 keV͔.…”

Substrate temperature and electron fluence effects on metallic films created by electron beam induced deposition

“…6,7 In situ techniques focus mainly on changing the electron beam parameters, namely, the spot size, dwell time, or current density. [8][9][10][11][12] Another in situ approach to improve purity has involved performing EBID on a heated substrate. 8 For example, using the Me 2 Au(tfac) precursor Koops et al showed that depositions carried out at a substrate temperature of 80 C resulted in EBID materials with lower resistivity compared to deposits created on substrates maintained at room temperature.…”