Shinji Sakaguchi

Selectively DNQ-esterified PAC for high-performance positive photoresists

DNQ-PACs with varying number of OH groups unesterified were examined for their imaging performance in novolac-based positive resists by means of a dissolution rate study. PACs generally lost dissolution inhibition with increasing numbers of the unesterified OH groups when compared to fully esterified PACs, whereas certain particular PACs still retained strong inhibition even when an OH was left unesterified. Such PACs lost inhibition quickly when one or more OH was left unesterified and gave a large dissolution discrimination upon exposure that resulted in high resolution of the resist. High hydrophobicity and remote DNQ configuration of the PAC molecule, and probably the steric crowding around the OH group appear to be structural requirements for obtaining such a high performance PAC. The PACs also provided an advantage in good solubility to resist solvent, and can be practically made by a proposed selective DNQ esterification.

Studies of dissolution inhibition mechanism of DNQ-novolak resist (II): effect of extended ortho-ortho bond in novolak

A p-cresol trimer sequence was incorporated into a polymeric chain of novolak by copolymerization with m-cresol of a reactive precursor which was prepared by attaching two units of m-cresol to the terminal ortho positions of p-cresol trimer. The resulting novolak was characterized by 13C NMR and FTIR in an attempt to correlate novolak structure with dissolution inhibition function based on physicochemical analysis of molecular interactions between novolak and DNQ-PAC in solid films.