Reticle design for alternating phase shift mask

摘要

The present invention provides a method and apparatus for producing 0 degree light and 180 degree phase shifted light having substantially equal intensities as both lights exit an alternating phase shift reticle. A material is inserted within the etched portion of the 180 degree phase shift channel of a reticle, wherein the material contains an index of refraction such that the first order light (+1, -1) is propagated through the 180 degree channel. The end result is a 180 degree phase shifted light having an intensity substantially equal to that of the 0 degree light.