Radiant energy – With charged particle beam deflection or focussing – Magnetic lens
Patent
1998-05-29
2000-02-15
Nguyen, Kiet T.
Radiant energy
With charged particle beam deflection or focussing
Magnetic lens
250396ML, 250310, H01J 37252
Patent
active
060256001
ABSTRACT:
A method for calculating and correcting an astigmatism error in a charged particle beam system. Images are collected during a single focus sweep of the charged particle beam system. Different orientations of image features, such as lines on a stigmation target, are analyzed. Optimum sharpness or best focus values are obtained as a function of the objective lens settings. Appropriate changes to the settings of the astigmatism correctors are computed by taking a linear combination of optimum sharpness values associated with the different orientations of image features. Proper settings of the objective lens and the astigmatism correctors result in focusing of the beam into a "small" spot. In a scanning electron microscope, for example, two sets of quadrupole compensation coils are typically used as astigmatism correctors.
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Archie Charles N.
Rogers Steven R.
Solecky Eric P.
Applied Materials Inc.
International Business Machines - Corporation
Nguyen Kiet T.
Schnurmann H. Daniel
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