Photoactive Compound Structure And Resist Function: The Influence Of Chromophore Proximity

In this study the influence of polyPAC structure was determined by examining the dissolution characteristics of various experimental photoresists. The PACs in these materials have structures in which the PAC chromophores are deployed at low and high density but otherwise have the same functionality, with three diazoquinone (DAQ) moieties per PAC molecule. Our studies indicate that the greatest degree of dissolution inhibition is obtained when the DAQ groups are spread broadly across the same molecule. Furthermore, those PACs which showed the strongest inhibition in unexposed and lightly exposed resists exhibited the least dissolution rate enhancement in exposed resists. Resists made with PACs whose DAQ moieties are widely separated exhibit an extraordinary supralinear relationship between the dissolution rate and the exposure energy. Energy reaction orders for these materials have values much greater than the expected value of three predicted by polyphotolysis theory. A possible mechanism for this phenomenon is proposed. In addition, the lithographic implications of the dissolution characteristics of these experimental resists are discussed as they relate to resist optimization.