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Proceedings Paper

Simulation of structure profiles in optical lithography of thick DNQ-novolak-based photoresists
Author(s): Song-Jo Chung; Joachim Schulz; Herbert Hein; Juergen Mohr
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Paper Abstract

DNQ-Novolak based photoresists are applied in many fields of microstructure technology. A common feature of such resist structures (>10 micrometer) described in the literature is a concave profile with the narrowest part at approximately 2/3 of the resist height. By newly including effects of residual solvent concentration, the simulation program accurately describes characteristic resist profiles for AZ4562 between 10 and 100 micrometer resist thickness. The program calculates the vertical distribution of the residual solvent concentration by modeling the evaporation during prebake as a three step process: diffusion of solvent within the resist film to the surface, a transfer to the ambient air described by a phase equilibrium and a transport away from the surface described by convection. Required parameters of the model have been obtained by fitting measured evaporation rates as function of time with the prebake temperature as a parameter to calculated ones. Resist exposure is simulated in vertical and one lateral dimension using the well known Dill's theory with ABC-parameters for DNQ resists. The development process is described by percolation theory where the residual solvent concentration increases the percolation parameter and therefore the local development rate. This paper describes details of the mathematical models used, demonstrates good agreement between experimentally observed profiles and simulated ones and shows that the influence of process parameters such as prebake temperature or time on resist profiles can be accurately simulated.

Paper Details

Date Published: 23 June 2000
PDF: 10 pages
Proc. SPIE 3999, Advances in Resist Technology and Processing XVII, (23 June 2000); doi: 10.1117/12.388290
Show Author Affiliations
Song-Jo Chung, Forschungszentrum Karlsruhe GmbH (Germany)
Joachim Schulz, Forschungszentrum Karlsruhe GmbH (Germany)
Herbert Hein, Forschungszentrum Karlsruhe GmbH (Germany)
Juergen Mohr, Forschungszentrum Karlsruhe GmbH (Germany)

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

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