Apparatus and methods for charged-particle-beam microlithography exhibiting reduced four-fold aberrations

摘要

Charged-particle-beam microlithography apparatus are disclosed that exhibit minimal deflection aberrations while providing large-magnitude deflections of the charged particle beam using a relatively small excitation current. The apparatus comprises multiple deflectors. A representative deflector comprises a toroidal deflector coil having a semi-angle of 72° and a toroidal saddle deflector coil having a semi-angle of 36°. By adjusting the dimensions and number of windings of each coil, and the excitation current applied to each coil, magnetic-field components associated with cos[3&phgr;] and with cos[5&phgr;], which are higher-order components in the deflection field, are minimized. As a result, four-fold aberrations are minimized and deflection sensitivity is increased.