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29 June 1998 Improved simulation of photoresists using new development models
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A new development rate model is proposed which is based on an equation derived by Huang, Reiser and Kwei for the concentration dependence of the dissolution rate of acidic resins in aqueous alkaline developers. This equation predicts cessation of development at a critical concentration c*. Experiments in which the developer strength was varied shows that the critical concentration c* is a linear function of the normalized sensitizer concentration m of positive-tone resists. The model is shown to reproduce the R(m) curves of conventional photoresists well, but it does not fully the unusual drop in the development rate curves at comparatively low relative sensitizer concentrations of m equals 0.4 to 0.7 shown by high- performance resist systems. This physical phenomenon can be related to a selective dissolution effect in which the lower molecular weight component of the two-component resins typically used in these resists is leached out of the surface areas. The onset of this phenomenon leads to a sudden lowering of the resist dissolution rate which is described by the introduction of a `notch function.'
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ralph R. Dammel, John P. Sagan, Elaine Kokinda, Neville Eilbeck, Chris A. Mack, Graham G. Arthur, Clifford L. Henderson, Steven A. Scheer, Benjamen M. Rathsack, and C. Grant Willson "Improved simulation of photoresists using new development models", Proc. SPIE 3333, Advances in Resist Technology and Processing XV, (29 June 1998);

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