Patent ID: 6811933
Filing Date: 2004-11-02
Classification: G03F

Abstract:
An apparatus, comprising:a phase shift mask (PSM) substrate having a surface and a surface pattern, the surface for interacting with light of wavelength &lgr; and intensity I0 to change the phase of the light in a pattern determined by the surface pattern, wherein the intensity of the light after interacting with the surface is determined at least in part by the phase changes induced by the surface pattern, and wherein when the light passes through a lens of a lithographic system having a numerical aperture (N.A.) so that the surface is imaged on an image plane, the intensity of the light imaged on the image plane has a plurality of point images, each point image having an intensity minimum of intensity Imin surrounded by an annular area having intensity much greater than Imin throughout the entire annular area surrounding the intensity minimum, and wherein the full width of the intensity minimum is less than &lgr;/2 N.A.