Radiant energy – With charged particle beam deflection or focussing – Magnetic lens
Patent
1985-01-04
1988-08-09
Eisenzopf, Reinhard J.
Radiant energy
With charged particle beam deflection or focussing
Magnetic lens
250396ML, 382 22, 324404, G01M 2300
Patent
active
047630043
ABSTRACT:
A method of correcting the aberration of an electron beam due to astigmatism and field curvature of focus by feeding a correction current through stigmator coils and a focus correction coil. The correction currents are determined by measuring a sharpness P of the electron beam. The sharpness P is defined as a product of p.sub.x, a sharpness measured when the electron beam is deflected in X direction, and p.sub.y, a sharpness measured when the electron beam is deflected in Y direction: P=p.sub.x .times.p.sub.y. The use of the sharpness P provides good convergence of the measurements and it becomes possible to calibrate the electron beam for many points in the scanning field. Thus, it is possible to attain maximum resolution over an entire scanning field. Optimum correction currents are determined from data obtained by varying each correction current while keeping the other correction currents constant to obtain several values of P and then using a least square approximation of the measured values of P with a quadrature curve.
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Miyazaki Takayuki
Yasuda Hiroshi
Eisenzopf Reinhard J.
Fujitsu Limited
Solis Jose M.
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