This paper studies the chemistry of image reversal resists composed of diazonaphthoquinone/novolac resins and varying amounts of aliphatic and aromatic amines. Special emphasis is placed on understanding the mechanism of decarboxylation as impacted by 2,1,4- vs. 2,1,5-diazonaphthoquinone esters. It is shown that the electron-withdrawing effect of the sulfonyl group in the 4- position of the diazo is much stronger compared to the same effect of the same group in the 5- position. The 2,1,4-type resists are therefore more effective in image reversal, requiring lower amine concentrations to be operative. The impact of the weaker electron-withdrawing effect in the 2,1,5-type sensitizer can be compensated for by increasing the concentration of the amine. Higher basicity of the amine allows lower concentrations for satisfactory image reversal performance. Unlike image reversal systems based on acid-catalyzed, heat-induced crosslinking, which tend to favor negative slopes, sidewall profiles of the systems studied here can be controlled from negative, to vertical, to positive, by changing the diazo content of the resist and the PEB temperature. It has also been found that some of the decarboxylation type, image reversal formulations display shelf-life stabilities greater than six months, making them viable production products.

Date Published: 30 January 1989
PDF: 11 pages
Proc. SPIE 1086, Advances in Resist Technology and Processing VI, (30 January 1989); doi: 10.1117/12.953025

Published in SPIE Proceedings Vol. 1086:
Advances in Resist Technology and Processing VI
Elsa Reichmanis, Editor(s)