LITHOGRAPHIC APPARATUS WITH IMPROVED PATTERNING PERFORMANCE

Disclosed herein is a lithographic apparatus comprising: a movable stage comprising a support structure configured to support a patterning device; a projection system configured to project a patterned radiation beam onto a target portion of a substrate; and a plate positioned between the movable stage and the projection system; wherein the plate comprises: a first surface that faces the movable stage; a second surface that faces the projection system; an opening through the plate such that the patterned radiation beam passes through the opening, wherein the opening has at least a first side and a second side that extend from the first surface to the second surface; one or more gas outlets in the first side of the opening and one or more gas outlets in the first surface of the plate, wherein the gas outlets are configured such that gas is supplied, via the gas outlets, to a region between the movable stage and the projection system; one or more gas inlets in the second side of the opening, wherein the gas inlets are configured such that gas is extracted from the region between the movable stage and the projection system via the gas inlets; and all of the one or more gas outlets in the first surface of the plate are positioned and configured such that, for each of the one or more gas outlets, a line that is both orthogonal to the first surface and intersects the gas outlet does not intersect the patterning device at any point during the entire range of movement of the patterning device. Advantageously, the overlay errors are lower than that achieved with known techniques. L'invention concerne un appareil lithographique comprenant : une platine mobile comprenant une structure de support configurée pour supporter un dispositif de formation de motifs ; un système de projection configuré pour projeter un faisceau de rayonnement à motifs sur une partie cible d'un substrat ; et une plaque positionnée entre la platine mobile et le système de projection. La plaque comprend : une première surface qui fait face à la platine mobile ; une seconde surface qui fait face au système de projection ; une ouverture dans la plaque qui permet de faire passer le faisceau de rayonnement à motifs à travers l'ouverture. L'ouverture possède : au moins un premier côté et un second côté qui s'étendent de la première surface à la seconde surface ; une ou plusieurs sorties de gaz situées sur le premier côté de l'ouverture et une ou plusieurs sorties de gaz situées sur la première surface