Koichi Shiotani

Batch Fabrication of Sharpened Silicon Nitride Tips

A novel sharpening technique for silicon nitride protrusions is reported. A silicon-rich nitride film, which contains more silicon than a stoichiometric silicon nitride film, shows low film stress and has been applied to micro mechanical devices. We found that the edge of the silicon nitride pattern on the silicon wafer became thinner and tapered by thermal oxidation, followed by the removal of the oxidized layer. By applying this technique for sharpening the apex of a beak-like cantilever of silicon nitride, the tip of the acute-angle triangular plate portion of the cantilever terminated into one and was sharpened with a radius of curvature of 17 nm. The small cantilevers integrated with the sharp protrusions for high speed atomic force microscopy in water were batch fabricated. The technique is useful for the fabrication of small cantilevers when low cost is required.

Development of metal-bonded Langevin transducer using LiNbO3

We newly developed a metal-bonded Langevin transducer using LiNbO3 in order to realize a practical high-power LiNbO3 Langevin transducer. It utilizes metal bonding with a lead-free solder as an assembly method for a Langevin transducer, instead of a bolt as used in a conventional bolt-clamped Langevin transducer. The newly developed metal-bonded LiNbO3 Langevin transducer achieved a high vibration velocity of over 1.5 m/s and stable operation. Because of rigid metal bonding, it does not show nonlinear phenomena such as a jump phenomenon and/or a resonant frequency shift.