30 January 1989 Improved Thermal Stability Of High Resolution Positive Photoresists Via Elevated Softbake Temperatures
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This paper describes the effect of elevated softbake temperatures, up to 150°C, on the behavior of diazoquinone/novolac high resolution positive photoresists. The advantages of higher softbakes include improved thermal stablity, contrast and process latitude. For a standard g-line photoresist using a 2,1,5-diazo/THBP PAC (EPA-914-27, MacDermid Inc.), it was found that by increasing the softbake from 110° to 130°C, gamma increased from 2.4 to 3.8 and the thermal stability (the start of image rounding) increased from 120° to 130°C; while the required exposure energy increased by only about 30%. UV absorption revealed that about 90% (compared to 110°C softbake) of the diazo is retained at 130°C, and about 55% at 150°C. GPC analysis showed that resin/PAC reactions occurred to some extent at a softbake of 130°C, and extensively at 150°C. These resin/PAC interactions appear to be the source of the improved properties observed with higher softbake temperatures. Similar results were not found with 2,1,4-type resin. Several other systems were also investigated to further understand the photoresist chemistry.
© (1989) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Marc T. Aronhime, Marc T. Aronhime, Chava Gal, Chava Gal, Shoshana Silady, Shoshana Silady, John J. Grunwald, John J. Grunwald, Donald W. Johnson, Donald W. Johnson, Theodore A. Martin, Theodore A. Martin, Allen C. Spencer, Allen C. Spencer, David A. Sawoska, David A. Sawoska, } "Improved Thermal Stability Of High Resolution Positive Photoresists Via Elevated Softbake Temperatures", Proc. SPIE 1086, Advances in Resist Technology and Processing VI, (30 January 1989); doi: 10.1117/12.953022; https://doi.org/10.1117/12.953022

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