Polymers from aryl cyclic sulfonium zwitterions—photosensitive materials cast from and developed in water

✍ Scribed by Ying-Hung So; Donald L. Schmidt; Matt T. Bishop; Daniel R. Miller; Patrick B. Smith; Michael J. Radler; Mindy Magyar; Britton L. Kaliszewski

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 150 KB
• Volume: 38
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(20000415)38:8<1283::aid-pola12>3.0.co;2-#

✦ Synopsis

Upon photolysis or heating, aryl cyclic sulfonium (ACS) zwitterions polymerize by ring-opening and loss of charge to yield nonionic polymers. These watersoluble monomers potentially are useful for photolithography because they can be cast from and developed in water. The ACS zwitterion from bisphenol A, 1,1Ј-[isopropylidenebis(6-hydroxy-3,1-phenylene)] bis (tetrahydrothiophenium hydroxide) bis(inner salt) (1) is a negative-tone, photosensitive material that after photolysis yields a crosslinked film. Unexposed regions are removed by water. The cured film has a low dielectric constant, high volume resistivity, a high degree of planarization, low residual stress, thermogravimetric stability, acceptable fracture toughness, and high hardness. These are desirable properties for a dielectric material used in microelectronic applications. However, a shortcoming of the material is its low T g , at about 140 °C. A second ACS zwitterion, 1,1Ј-[fluorenylidenebis(6-hydroxy-3,1-phenylene)] bis(tetrahydrothiophenium hydroxide) bis(inner salt) (2) was prepared that yields a crosslinked polymer with a higher T g of about 190 °C.