Controller design for low voltage micro-columns

It is impossible to inspect contact/via hole on wafer through optic inspection system because of resolution. Now, Single-electron beam inspection system is used for it. But sample test below 10% is done because this method is quite slow on inspection. Micro-column is available in multi column array, high speed inspection, expansibility and productivity improvement. This paper presents the controller design for multi column array using micro column. Its lenses are electrostatic type and made of silicon with circular-shaped aperture. Its thickness is from a few μm to a couple hundred μm.