Patent ID: 7843552
Filing Date: 2010-11-30
Classification: G03F

Abstract:
1. A lithographic apparatus comprising: a support structure to support a mask, the mask serving to impart a beam of radiation with a pattern in its cross-section and having a pellicle attached thereto by a frame; a substrate table to hold a substrate; and a projection system to project the patterned beam onto a target portion of the substrate, wherein the frame varies in stiffness along a periphery thereof and the pellicle is arranged on the frame such that a sag of the mask is substantially one-dimensional when the mask is mounted to the support structure, and wherein the frame includes two substantially parallel elongated members defining part of the outer periphery of the frame, the elongated members being connected to a transverse member, and wherein the pellicle is rigidly attached to and in contact with the two elongated members without contacting the transverse member such that the transverse member is spaced apart from the pellicle.