Electron-Beam-Induced Deposition For Nanodevice Formation

Abstract

Electron-beam(EB) induced deposition will be very attractive method for producing nanometer-scale dots array to investigate single electron transport devices because of its simplicity without any successive processes such as etching and metal lift-off. In addition, there is the advantage of independent controllability of junction characteristics such as tunnel resistance and capacitance. In this work, hndamental properties of deposition process and deposits using m 6 gas are described. The EB system used here has been already reported, which can be evacuated down to Torr with the beam diameter of about 3nm with minimum increment of 2.5nm in deflection. The gas of w F 6 was introduced from the nozzle equipped in this system up to 1-2x Au electrodes with 0.8pm gap on SiOJSi substrate were used to measure the current-voltage(1-V) characteristics of wire, single tunnel junction and transistor At first, thickness profiles of deposited film is investigated, which is strongly dependent upon beam scanning method. It is revealed that secondary electrons generated by primary beam make a major role for chemical reaction from experiments and simulation Therefore the width of wire is about 13 nm in spite of the 3-nm incident beam. The resistivity of wires in the dose region more than 15pUshot is estimated to be less than 0.6mS1 cm and independent of the temperature between 230 and 300K. However at lower doses the resistance rapidly increases by 5 orders of magnitudes. In order to evaluate controllability of junction properties, tunnel barrier are produced. Most of I-V curves for them are fitted to Fowler-Nordheim plot a gradient of which changes systematically with the increase in designed space. This result indicates clearly the junction properties can be controlled at least with the accuracy of minimum deflection increment. From these results, the barrier height is estimated to be more than 0.2 eV. The reason for the lower barrier height is described. By using this technique, single electron transistors with in-plane gate are produced and electrical property shows Coulomb oscillation (drain current oscillation by gate modulation) at 230 K Torr following the EB exposure, where