Nikon Corporation

Chris Robinson

Michael S Gordon

James D Rockrohr

Steven D Golladay

Scott Messick

A small pinhole aperture and a scintillator are used to observe resolution in a charged particle beam system which is particularly applicable to electron beam projection devices in which the beam is several orders of magnitude larger than the desired resolution and minimum feature size to be produced. A pattern having a feature which is of comparable size to the desired resolution to be observed is scanned across the aperture in two dimensions and a synchronized display of measured light output from the scintillator allows real-time observation of the effects of correction adjustments on the resolution of the system. In this manner, a rough adjustment to near optimum corrections can be obtained over the deflection field in a much reduced number of iterations.

On-line dynamic corrections adjustment method

Temperature dependency on magnetic field strength of an electron optical element in an electron beam system due to variation of permeability with temperature of a ferromagnetic pole piece subject to radiant heating from another electron optical element is corrected by measurement of pole piece temperature and closed loop control of excitation current of a correction element which may be provided as a portion of a lens, stigmator, deflector or the like. A correction function may be computed to extrapolate correction values from empirically determined correction values or correction values may be retrieved from a memory such as a look-up table. Performance of the electron beam system is improved and constraints on choice of pole piece materials, mounting geometry, relative positioning of electron optical column elements and electron optical column length are relaxed since temperature dependencies of many electron optical elements can be corrected.

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Hyde Park, NY, United States of America

Chris Robinson