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Proceedings Paper

Percolation view of novolak dissolution and dissolution inhibition
Author(s): Tung-Feng Yeh; Hsiao-Yi Shih; Arnost Reiser
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Paper Abstract

The dissolution of novolak and other phenolic resins in aqueous alkali is controlled by the diffusion of developer base in the solid matrix. The base penetrates the resin by a series of transfers or jumps from one hydrophilic (phenol/phenolate) site to the next and requires an unbroken sequence of sites in the diffusional pathway. This view brings novolak dissolution into the realm of percolation theory, which predicts for it a scaling law of the form: R equals constant (p - pc)n. R is the dissolution rate, the percolation parameter p measures the fraction of occupied percolation cells, and pc is a percolation threshold. The scaling law of percolative dissolution was tested and confirmed on a group of partially methylated poly(vinylphenol) resins. Inhibitors affect the percolation process by blocking some of the hydrophilic sites and effectively removing them from the percolation field. This is equivalent to lowering the value of p and leads to a decrease in the dissolution rate. Theory predicts a relation between the inhibition effect and the derivative dlogR/dp, and that too has been confirmed by experiment. The percolation model thus provides a consistent and unified interpretation of the functional mechanism of positive resists based on dissolution inhibition.

Paper Details

Date Published: 1 June 1992
PDF: 10 pages
Proc. SPIE 1672, Advances in Resist Technology and Processing IX, (1 June 1992); doi: 10.1117/12.59731
Show Author Affiliations
Tung-Feng Yeh, Polytechnic Univ. (United States)
Hsiao-Yi Shih, Polytechnic Univ. (United States)
Arnost Reiser, Polytechnic Univ. (United States)

Published in SPIE Proceedings Vol. 1672:
Advances in Resist Technology and Processing IX
Anthony E. Novembre, Editor(s)

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