Patent ID: 6563566
Filing Date: 2003-05-13
Classification: G03F

Abstract:
A method for printing a desired pattern on a semiconductor wafer having a photoactive material thereon, the method comprising the steps of:providing a diffraction relationship for determining at least one diffracted amplitude diffracted by a reticle having at least one diffraction parameter when said reticle is exposed to illumination energy from an illumination source having at least one source parameter; providing a merit function for computing a merit value of an image pattern on a wafer plane as a function of variables including said at least one diffracted amplitude; selecting at least one constraint on at least one of said variables; determining an optimal value of said at least one diffracted amplitude so that said merit function attains a merit value that is optimized in accordance with said at least one constraint; selecting a combination of at least one selected source parameter and at least one selected diffraction parameter to produce said optimal value of said at least one diffracted amplitude in accordance with said diffraction relationship; forming an optimal reticle having a diffractive feature with said at least one selected diffraction parameter; illuminating said optimal reticle with illumination energy from an illumination source having said at least one selected source parameter, so that said illumination energy is diffracted by said diffractive feature and projected through a lens aperture to form an optimal image pattern on the wafer plane in accordance with said at least one constraint; exposing the photoactive material to said optimal image pattern; and developing said exposed photoactive material to form the desired pattern.