Variations of the field of view depending on the Si deflector shape in a microcolumn

A microcolumn is widely investigated as one of the strong candidates for multiple electron beam systems. In the microcolumn, one or two octupole deflectors are usually adopted to scan the electron beam, and the octupole deflector is assembled by placing eight deflector electrodes symmetrically around the electron beam path. The deflector electrodes are composed either of Mo rods or of Si electrodes fabricated through appropriate micro electro mechanical systems processes. Usually, to expand the field of view and reduce the electron beam distortion, the double-deflector method is used. However, the wiring for electrical connection to each electrode and the operation of the octupole deflector are rather complicated. In order to improve the assembly and performance of the octupole deflector, the authors devised a modified Si deflector and tested its performance.