Patent ID: 6906781

Claim:
A photolithography system for projecting a mask image onto a wafer that comprises: a ringfield camera; a source of radiation; a condenser for processing radiation from said source of radiation to produce a ringfield illumination field for illuminating a mask; a reticle that is positioned at the ringfield camera's object plane and from which a reticle image in the form of an intensity profile is reflected into the entrance pupil of the ringfield camera, wherein the reticle is secured to a stage that moves in a direction that is transverse to the length of the ringfield illumination field that illuminates the reticle; a linear array of discrete photodiodes for measuring the entire intensity along the length of the ringfield illumination field that is projected onto the reticle wherein each photodiode generates an electrical signal that is indicative of intensity; a multiplexer that is connect to the discrete photodiode for selectively acquiring one of the electrical signals; and a wafer onto which the reticle imaged is projected from the ringfield camera.