Photolithography in Integrated Circuit Mask Metrology

Photoresist technology is shown to have important advantages over the use of high-resolution silver halide films in dimensional metrology for integrated circuit masks. Experimental techniques are shown for the use of photoresist and chrome images in the study of image quality and uniformity and in analysis of the causes of image degradation. This method is applied to in situ lens evaluation and to the measurement of the precision of photorepeater stepping tables used in mask fabrication. In addition, the value of 0.3 µm is established as the practical limit of dimensional tolerance in the present photolithographic technology, and its significance to the advancement of the state of the art in mask manufacture is discussed.