Patent ID: 6352799
Filing Date: 2002-03-05
Classification: B82Y,H01J,Y10S

Abstract:
In a charged-particle-beam (CPB) microlithography method in which a charged particle beam is used to transfer a pattern, defined in a pattern-transfer field on a reticle, onto a sensitive substrate by passing the beam through selected regions of the pattern and through a CPB optical system to the sensitive substrate so as to imprint the substrate with the pattern, a method for measuring beam drift, the method comprising the steps:(a) dividing the pattern-transfer field into multiple stripes and each stripe into multiple deflection fields, wherein each deflection field has a length corresponding to a width dimension of the respective stripe and to a beam-deflection range of the CPB optical system; (b) disposing multiple beam-drift test patterns in one or more deflection fields located at an end of a stripe, wherein any of the beam-drift test patterns forms the charged particle beam into a test-pattern-detection beam whenever the charged particle beam passes through the beam-drift test pattern; (c) disposing corresponding beam-test marks in regions on the substrate corresponding to the one or more deflection fields on the reticle containing the beam-drift test patterns, such that the pattern-detection beam passing through a beam-drift test pattern on the reticle can impinge on a corresponding beam-test mark on the substrate; (d) passing the charged particle beam through the beam-drift test patterns on the reticle to form the pattern-detection beam, and scanning the pattern-detection beam over the corresponding beam-test marks on the substrate; (e) detecting charged particles emitted from the beam-test marks on the substrate produced by impingement of the pattern-detection beam on the beam-test marks so as to obtain data corresponding to beam drift experienced during the scanning; and (f) from the data, obtaining a measurement of beam drift.