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Proceedings Paper

Dissolution/swelling behavior of cycloolefin polymers in aqueous base
Author(s): Hiroshi Ito; Robert D. Allen; Juliann Opitz; Thomas I. Wallow; Hoa D. Truong; Donald C. Hofer; Pushkara Rao Varanasi; George M. Jordhamo; Saikumar Jayaraman; Richard Vicari
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Paper Abstract

Polycycloolefins prepared by addition polymerization of norbornene derivatives are quite different from hydroxystyrene-based polymers in terms of their interaction with aqueous base. Their dissolution kinetics monitored on a quartz crystal microbalance is not a smooth function of the ratio of the polar to nonpolar functionalities in polymer but abruptly changes from very fast dissolution to massive swelling within a narrow range of composition. The maximum swelling is a function of thickness and the entire film thickness can swell in a few seconds at > 3,000 angstroms/sec or at immeasurably fast rates. The initial concentration of a pendant carboxylic acid in polymer has to be selected to minimize swelling and the concentration of an acid-labile group to induce fast dissolution in the exposed area. Furthermore, swelling which occurs in the partially- exposed regions must be minimized by incorporating a third monomer unit or by adding a dissolution modifying agent (DMA) such as t-butyl cholate. However, the function of DMA which is also acid-labile is quite complex; depending on the matrix polymer composition and its dissolution/swelling behavior, DMA could function as a swelling suppressor or promoter and a carboxylic acid generated by acidolysis of DMA as a dissolution or swelling promoter. Photochemically generated sulfonic acid could also affect the dissolution/swelling behavior. Base hydrolysis of anhydride during development is controlled by the polarity (carboxylic acid concentration) in polymer film, which has been demonstrated in an unequivocal fashion by IR spectroscopy under the condition strongly mimicking the development process and thus could boost development contrast but could hurt performance as well. Thus, incorporation of carboxylic acid in the form of methacrylic acid, for example, in radical copolymerization of norbornene with maleic anhydride must be handled carefully as it would increase the susceptibility of the anhydride hydrolysis and could introduce heterogeneity in the polymer as methacrylic acid is rapidly consumed, producing a terpolymer containing a different molar concentration of norbornene and maleic anhydride (a proof against the commonly believed charge transfer polymerization mechanism).

Paper Details

Date Published: 23 June 2000
PDF: 11 pages
Proc. SPIE 3999, Advances in Resist Technology and Processing XVII, (23 June 2000); doi: 10.1117/12.388254
Show Author Affiliations
Hiroshi Ito, IBM Almaden Research Ctr. (United States)
Robert D. Allen, IBM Almaden Research Ctr. (United States)
Juliann Opitz, IBM Almaden Research Ctr. (United States)
Thomas I. Wallow, IBM Almaden Research Ctr. (United States)
Hoa D. Truong, IBM Almaden Research Ctr. (United States)
Donald C. Hofer, IBM Almaden Research Ctr. (United States)
Pushkara Rao Varanasi, IBM Microelectronics Div. (United States)
George M. Jordhamo, IBM Microelectronics Div. (United States)
Saikumar Jayaraman, BFGoodrich (United States)
Richard Vicari, BFGoodrich (United States)

Published in SPIE Proceedings Vol. 3999:
Advances in Resist Technology and Processing XVII
Francis M. Houlihan, Editor(s)

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