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Proceedings Paper

Thermal stability of naphthodiazoquinone sensitizers
Author(s): Wayne M. Moreau
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Paper Abstract

1,2-Napthoquinone diazides function as both photoactive dissolution inhibitors (PAC) for i-line positive resists and as photoacid generators (PAG) for chemically amplified resists. Traditionally, the 5-sulfonyl esters of 1,2- napthodiazoquinones (DQ) are used as PACS and recently the 4- sulfonyl (DQ) esters function as both PACS or PAGS. Knowledge of the thermal stability of the DQ is important for defining process conditions that stabilize the films prior to exposure or in post-treatments involving specific thermally induced reactions of PAC and resin. The thermal decomposition and photochemical decomposition of 1,2-napthodiazoquinones (DQ) follows similar pathways with the expulsion of nitrogen followed by formation of a reactive ketene. In absence of water (to form the indene carboxylic acid) many participatory bimolecular pathways involving reactant, products and resins are possible. Studies of the rate of decomposition of esters indicate that of 1-naptho-2-diazoquinone-4-sulfonyl derivatives are more thermally stable than the 5-sulfonyl counterparts and afford longer solution shelf life and higher thermal decomposition temperatures of 130 - 150 C. In addition, the 4-sulfonyl substituted DQ can form sulfonic acids upon thermolysis and hydrolysis. In solution, the napthodiazoquinones decompose at faster rates with lower activation energy (20 - 30 Kcal/mole) than in the solid state with higher activation energies of 40 - 50 Kcal/mole. When the DQ dissolution inhibitors are dispersed in resins, the interaction of the resin and DQ can influence the stability of the PAC. DQ mixed with novolak are more thermally stable than when blended with polyhydroxystyrene. The higher thermal stability of the 4-sulfonyl DQ esters is attributed to the electron resonance deactivation of diazo group by the sulfone subsituent.

Paper Details

Date Published: 7 July 1997
PDF: 10 pages
Proc. SPIE 3049, Advances in Resist Technology and Processing XIV, (7 July 1997); doi: 10.1117/12.275864
Show Author Affiliations
Wayne M. Moreau, IBM Microelectronics Div. (United States)

Published in SPIE Proceedings Vol. 3049:
Advances in Resist Technology and Processing XIV
Regine G. Tarascon-Auriol, Editor(s)

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