Masahiko Okunuki

Optical properties of a multibeam column with a single-electron source

A novel single-column multi-electron-beam system, called a beam-split array, has been developed for a high-resolution, high-throughput lithography tool. In this system, a single electron beam is divided into 1024 beams by a multisource module (MSM) composed of an aperture array (a beam-dividing aperture), a static lens array (Einzel lenses for each divided beam), and a blanker array (BLA, blanking electrode pairs for each focused beam). The MSM is used to form multiple intermediate images of the electron source at the BLA. These images are demagnified to form final images through a projection optics consisting of a double lens doublet with a blanking aperture and deflector. To align the multiple beam paths in the MSM, aligners between these arrays are used, and the aligner conditions are determined by monitoring the blanking-aperture image. Moreover, because each beam current is about 0.1% of the total beam current on the specimen, a high-contrast transmission detection method is used to detect the electr...

Al/GaAs Schottky Diode Implanted by Focused Ion Beam

We investigated electrical characteristics of Al/p-type GaAs Schottky diodes with carrier concentrations of 1×1017 to 3×1018 cm-3, which were produced by focused-ion-beam (FIB) implantation and by defocused-ion-beam implantation. It was confirmed experimentally that the ideality factors and the Schottky barrier heights depended on the effects of thermionic field emission. Furthermore, the possibility of the FIB implantation process for fabrication of the Schottky diode with the high carrier concentration region was recognized.