Patent ID: 6362489
Filing Date: 2002-03-26
Classification: B82Y,H01J

Abstract:
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.