Patent ID: 7521678
Filing Date: 2009-04-21
Classification: H01J

Abstract:
1. A charged particle beam apparatus comprising: a charged particle source which generates a charged particle beam and which applies the charged particle beam to a specimen having a microstructure formed on a surface thereof; an objective lens which excites at least one of an electric field and a magnetic field to converge the charged particle beam onto the specimen; a deflector which scans the specimen with the charged particle beam; a detector which detects at least one of a secondary charged particle, a reflection charged particle and a back scattering charged particle generated from the specimen by the application of the charged particle beam and which outputs a detection signal; a focusing area arranging unit which arranges a plurality of focusing areas including edge points of the microstructure therein in a surface area of the specimen; deflection controller which controls the deflector so that the focusing areas are sequentially scanned to correspond to excitation conditions while changing stepwise the excitation conditions, the excitation conditions being conditions for the objective lens to excite at least one of the electric field and the magnetic field; focus calculator which calculates an index indicating a convergence state in each excitation condition on the basis of the detection signal outputted by the detector for the excitation conditions and the focusing areas and which calculates an optimum excitation condition providing an optimum focal position from the obtained index; and an objective lens controller which drives the objective lens under the optimum excitation condition.