Patent Number: 
Section: claims

1. In a microlithography method utilizing a charged-particle illumination beam to irradiate a portion of a pattern defined by a reticle situated on a reticle plane and a projection-optical system to direct a corresponding charged-particle imaging beam from the irradiated portion to a sensitized substrate situated on a substrate plane, an improved beam-alignment or calibration method comprising the steps: (a) defining at least one upstream mark on the reticle plane and at least one downstream mark on the substrate plane, each upstream mark being selectively registrable with a downstream mark;  (b) providing a shield upstream of an upstream mark, the shield (i) serving to block downstream propagation of the illumination beam, and (ii) defining an aperture having a size and profile sufficient to pass therethrough only a portion of the illumination beam sufficient to irradiate the upstream mark; and  (c) when irradiating an upstream mark with the illumination beam, passing the illumination beam through the aperture of the shield before the illumination beam reaches the upstream mark. 2. The method of  claim 1 , wherein: claim 1 step (a) comprises defining at least one upstream mark on the reticle; and  step (b) comprises extending the shield over the reticle. 3. The method of  claim 2 , wherein: claim 2 step (a) comprises defining at least one upstream mark on a mark member; and  step (b) comprises extending the shield over the mark member.