CALIBRATION METHODS AND DEVICES USEFUL IN SEMICONDUCTOR PHOTOLITHOGRAPHY

Several embodiments of photolithography devices and associated methods of focal calibration are disclosed herein. In one embodiment, a method for determining a focus shift in a photolithography system include placing a microelectronic substrate on a substrate support of the photolithography system and producing first and second refraction patterns on the photoresist layer corresponding to first and second grating patterns, respectively, of a single reticle by illuminating the first and second grating patterns with an asymmetric monopole source perpendicular to the first and second grating patterns. The method further includes measuring an image shift between the first and second refraction patterns on the photoresist layer and determining a defocus shift of the illumination source based on the image shift.