The Effect of Substituents on the Photosensitivity of 2‐Nitrobenzyl Ester Deep U.V. Resists

2‐Nitrobenzyl cholate/poly(methyl methacrylate‐co‐methacrylic acid) is a high contrast , high resolution photoresist which has a sensitivity of 150–200 mJ/cm2 at . However, because of the low deep u.v. intensity of most conventional exposure "tools," it is desirable to improve this sensitivity. This may be accomplished by substitution on the o‐nitrobenzyl chromophore. Appropriate substitution can be used to enhance the absorption characteristics of the ester and, thereby, improve the photochemical response of the system. A variety of o‐nitrobenzyl esters have been prepared by standard synthetic techniques and examined for use in this two‐component resist system. Improvements in sensitivity by a factor of ~2 have been obtained with the 2,6‐dinitrobenzyl alcohol based inhibitor. Other resist characteristics remain unaffected by substitution. All materials examined exhibit contrast as high as the parent o‐nitrobenzyl cholate system, and they retain its high resolution characteristics.