Influence Of The Structure And Functionality Of Photoactive Compounds On The Performance Of Novolak Based E-Beam Resists

Photoactive compounds were prepared from 2,3,4-trihydroxy-, 2,3,4,4'-tetrahydroxy- and 2,3,4,3',4',5'-hexahydroxybenzophenone by esterification with diazonaphthoquinone-4 (or 5)-sulfonyl chlorides at several relative concentration ratios. These photoactive compounds were formulated into resists with a conventional cresol novolak resin. The percent diazonaphthoquinone moieties destroyed by exposure was determined by FTIR spectroscopy as a function of dose. The resist development rates were measured on a Development Rate Monitor (DRM) as a function of the electron beam or optical exposure dose. The relation between percent diazonaphthoquinone (DNQ) moieties remaining and the development rate is shown for two resists for both optical and electron beam exposures. The electron beam sensitivity for these resists were investigated to determine the effect of the number of hydroxyl groups in the backbone and the esterification level with diazonaphthoquinone-4-sulfonyl chloride. The lithographic performance of several similar 4- and 5-sulfonate diazonaphthoquinone esters were compared.