Charged particle beam exposure device exhibiting reduced image blur

Abstract

Charged-particle-beam microlithography apparatus and methods are disclosed that reduce spherical aberrations and other aberrations of the beam without increasing blurring from Coulomb effects or space-charge effects. The beam semi-angle of the beam as incident on the reticle and/or substrate is limited to a range greater than zero but less than an upper limit, so as to remove paraxial portions of the beam. Also, the substrate can be moved as required along the optical axis to place the substrate at the optimal image plane where beam spreading from spherical aberration is minimal. The beam semi-angle is preferably limited by passage of the beam through an annular aperture placed axially upstream of the substrate. A preferred range for beam semi-angle at the reticle is 1.5 to 3 mrad. Alternatively, at least six deflectors are disposed on the reticle side of a scattering aperture located in the projection-optical system, and at least three deflectors are disposed on the substrate side of the scattering aperture to simultaneously correct, respectively, deflection-induced image-plane inclination, deflection coma, deflection astigmatism, deflection chromatic aberration, deflection-induced secondary distortion (x and y directions), axial propagation of the beam through the scattering aperture, incidence of the beam at a target position on the substrate, and zero angle of incidence of the beam on the substrate.