DEVELOPMENT OF SINGLE-ELECTRON-TRANSISTOR

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Single electron devices based on Coulomb blockade phenomena in ultrasmall tunnel junctions are promising candidates of elemental logic devices in nanometer/angstrom-era's ULSI.Coulomb blockade phenomena has been observed at very low temperatures of mK-30K range. If the very small tunnel junctions of about 10nm^2 are fabricated with sufficient reproducibility, there is great possibility of room-temperature single electron logic devices. The aim of this work is to develop fundamentals of room-temperature single electron devices : (1) a new logic circuit configuration with feed-back loop and (2) nano fabrication technology based on selective Al CVD.At first, we have developed Monte Carlo simulator which can analyze the SET circuit. We have proposed a new circuit configuration ; the inverter circuit with feed-back loop, With the feed back loop, the circuit instability due to the atochastic tunneling is found to be suppressed.As nanometer fabrication technology, we have investigated selective Al CVD technology. The selective Al-CDV technology is a key technology to fabricated metal/insulator/metal ultrasmall tunnel junctions with sufficient reproducibility. We have proposed a new atomic hydrogen resist process based on the selective Al CVD.In the atomic hydrogen resist process, monolayr thick terminated-H on Si surface is exposed by the electron beam. The terminated-H which is irradiated by the electron beam is removed and then the surface is oxidized. Aluminum is selectively deposited on the remaining terminated-H area. Using this atomic hydrogen resist process, we have successfully fabricated the Al pattern and Al wires on Si surface.