Electron beam lens and deflection system for plural-level telecentric

Abstract

A charged particle beam deflection system provides a three or more level charged particle beam deflection arrangement and is therefore capable of extremely high speed and positional accuracy. The system preferably employs a major/minor magnetic deflection arrangement as well as orthogonal electrostatic deflectors at a level of speed and positional accuracy and which minimizes the need for dynamic correction to achieve high linearity and positioning accuracy at extremely low aberration levels. The system can also be made relatively noise insensitive by providing one or more split deflectors which are also useful in providing increased speed and adjustment of radial and azimuthal telecentricity. The use of a transfer lens allows the cluster and subfield deflectors to be optimally placed to exploit different forms of LAD to obtain telecentricity at all levels of the deflection hierarchy. The use of such lens assisted deflection allows the electron optical system and drivers therefor to be minimized in number or enabled noise to be reduced and adjustments of telecentricity to be made without increase of complexity over the prior art. By employing the deflection arrangement of the present invention in electron beam lithography apparatus, the throughput of such apparatus can be greatly improved.