Patent ID: 6376137
Filing Date: 2002-04-23
Classification: B82Y,H01J,Y10S

Abstract:
In a charged-particle-beam (CPB) microlithography method in which an illumination beam is directed by an illumination-optical system to irradiate a region on a reticle mounted to a reticle stage and defining a pattern to be transferred to a sensitive substrate; and a corresponding patterned beam propagating downstream of the reticle from the irradiated region of the reticle is directed by a projection-optical system, comprising projection lenses, to projection-image the irradiated region of the reticle on an exposure surface of the sensitive substrate mounted to a wafer stage, a method for correcting at least one of a positional error (&Dgr;Pw) of the wafer stage and a positional error (&Dgr;Pm) of the reticle stage, the method comprising:(a) providing an electrostatic deflector situated within the projection-optical system; (b) providing respective electromagnetic deflectors situated within the illumination-optical system and the projection-optical system; (c) measuring the respective positional errors (&Dgr;PM, &Dgr;PW) of the reticle stage and wafer stage, respectively from respective predetermined ideal positions; (d) during exposure of the irradiated region of the reticle onto the substrate, energizing the electromagnetic deflector to reduce an aberration of the projection lenses, the energization of the electrostatic deflector being appropriate to impart a correction of âˆ’(&Dgr;PM/M+&Dgr;PW), wherein 1/M is a demagnification ratio of the projection-optical system; &Dgr;PM=PM-actualâˆ’PM-ideal, wherein PM-actual is an actual reticle-stage position during an exposure of a given subfield, and PM-ideal is a corresponding ideal reticle-stage position for PM-actual; and &Dgr;PW=PW-actualâˆ’PW-ideal, wherein PW-actual is an actual wafer-stage position during an exposure of the given subfield, and PW-ideal is a corresponding ideal wafer-stage position for PW-actual.