Patent ID: 7030394

Claim:
A charged particle beam apparatus comprising: a stage on which a sample is mounted and movable at least in one direction; a charged particle optical unit for converging a charged particle beam emitted by a charged particle source; a scanning unit for irradiating and scanning said charged particle beam converged by said charged particle optical unit onto said sample; a focal point control unit for controlling a focal point of said charged particle beam converged by said charged particle optical system; an astigmatism adjustment unit for adjusting astigmatism of said charged particle beam converged by said charged particle optical system; a height detection unit for optically detecting a height of a surface of said sample mounted on said stage; an image detection unit for obtaining an image of said sample by detecting particles generated from said sample by the radiation of said charged particle beam converged by said charged particle optical unit; an image processing unit for computing a focal offset and said astigmatism of said converged charged particle beam on the basis of said detected image obtained by said image detection unit; and a control system for adjusting and controlling said astigmatism of said converged charged particle beam by feeding back an astigmatism correction quantity to said astigmatism adjustment unit based on said astigmatism computed by said image processing unit.