Patent ID: 8193511

Claim:
A method of calibrating a beam position in a charged-particle beam system in which a focused charged-particle beam is made to hit a material at an arbitrary position by deflecting the beam, said method comprising the steps of: finding a focus deviation on a material surface accompanying beam deflection performed by application of a deflection voltage of V D to a deflector for each point within a deflection field and determining a focus correction voltage V F necessary to cancel out the focus deviation; determining focus correction voltages V F1 and V F2 about two arbitrary points given by u i1 =d i ·V D1 and u i2 =d i ·V D2 , respectively, based on the determined correction voltage, the two points providing point symmetry with respect to the center of a deflection field, and measuring beam position deviations dU i1 and dU i2 at the points u i1 and u i2 , respectively, under a focus-corrected condition; finding a beam position deviation f i per unit focus correction voltage from the beam position deviations dU i1 and dU i2 and from the focus correction voltages V F1 and V F2 ; measuring a deflection field distortion while correcting the deflection voltage so as to cancel out the product f i ·V F of the focus correction voltage V F and the beam position deviation f i while making a focus correction based on the obtained focus correction voltages V F at each point within the deflection field; correcting the deflection voltage so as to cancel out the sum of the product f i ·V F and the measured deflection field distortion while making a focus correction based on the obtained focus correction voltage V F ; and repeating the measurement of the deflection field distortion while correcting the deflection voltage so as to cancel out the sum to converge the deflection field distortion to less than a given value.