LITHOGRAPHIC APPARATUS AND METHOD FOR PREVENTING PERIPHERAL EXPOSURE OF A SUBSTRATE

A lithographic apparatus (10) and method for preventing exposure of a peripheral portion (P) of a substrate (S). An edge mask (M) has a radial concave edge (E) that extends over less than half a circle arch. The edge mask (M) is connected to a mask carrier (4) that circumnavigates the projection system (2) to adjust a tangential coordinate (Φ) and a radial coordinate (R) of the edge mask (M) with respect to the optical axis (A) of the projection system (2) for inserting the edge mask (M) at a variable distance into the beam of radiation (B). The tangential and radial positions (Φ,R) of the edge mask (M) are coordinated with a changing position (X,Y) of the substrate (S) to prevent exposure of the peripheral portion (P) of the substrate (S) during exposure of the target region (T).