Takeshi Shiomi

Electron Spin Resonance and Photoluminescence Study of Charge Trap Centers in Silicon Nitride Films and Fabrication of Proposed Oxide?Nitride?Oxide Sidewall 2-bit/Cell Nonvolatile Memories

We have proposed a novel oxide–nitride–oxide (ONO)-sidewall 2-bit/cell nonvolatile memory and fabricated 70-nm-node nonvolatile memory devices. For low-pressure chemical-vapor-deposition (LPCVD)-SiN films, with increasing SiH4/NH3 mixture gas ratio, we have found from ESR and PL evaluation that the paramagnetic defect density increases and some PL emission energy levels become deeper. We consider that the energy-level shift is due to the effects of trap potential overlapping, where the trap centers are generated at the excess silicon atoms in the SiN films. In this study, a SiH4/NH3 mixture gas ratio of less than 1:100 was used to suppress the potential overlapping. As a result, we have also shown that the proposed memory device has high performance and excellent scalability.

Asymmetric AC electrophoresis with insulated electrodes: Toward positional control of microand nanoscale devices

This paper demonstrates electrophoresis of silicon micro-rods by applying asymmetric AC bias to two electrodes capped with a thin dielectric film. The silicon micro-rods migrate bi-directionally when asymmetric AC bias is applied to the electrodes. The insulated electrodes significantly contribute to elimination of bubbling and contamination originating from electrochemical reactions, which makes adoption of the technique to mass production processes realistic. This technique is widely applicable to positional control of small objects including micro- and nanoscale devices.

Bidirectional migration of Au colloids and silicon microrods in liquid using asymmetrical alternating current electric field with insulated electrodes

In this study, we demonstrate the migration of Au colloids and silicon microrods in deionized (DI) water and isopropyl alcohol (IPA) by applying asymmetrical AC bias to two electrodes capped with a thin dielectric film. Both Au colloids and silicon microrods successfully migrate from one electrode to the other when asymmetrical AC bias is applied to the electrodes. Furthermore, the direction of the migration can be easily reversed by inverting the wave form. The insulated electrodes have the potential to prevent contamination and bubbling originating from electrochemical reactions, which makes the adoption of the technique for mass production processes easy and realistic. The bidirectional migration acts similarly to electrophoresis and is effective even in DI water and IPA in which conventional DC electrophoresis with insulated electrodes is ineffective. This technique is widely applicable to the positional control of small objects including nano- and micro-sized devices.