Patent ID: 7223974
Filing Date: 2007-05-29
Classification: H01J

Abstract:
1. A method of directing a primary charged particle beam onto a sample, the method comprising: (i) directing the primary charged particle beam along an initial beam propagation axis towards a focusing assembly that comprises an objective lens arrangement defining an optical axis; (ii) passing the primary charged particle beam propagating along the initial axis through a beam shaper to compensate for aberrations of focusing produced by the objective lens arrangement; (iii) thereafter, passing the primary charged particle beam through an opening of a detector having detecting regions outside said opening, the detector accommodated such that said initial axis intersects with said opening and being capable of detecting a secondary charged particle beam resulting from an interaction of the primary charged particle beam with the sample; (iv) aligning the axis of the primary charged particle beam, with respect to the optical axis of the objective lens arrangement by applying at least two deflecting fields to the primary charged particle beam, said at least two deflecting fields being arranged along the optical axis of the objective lens arrangement and disposed between the detector and the objective lens arrangement.