MSM 2000
MSM 2000
Technical Proceedings of the 2000 International Conference on Modeling and Simulation of Microsystems

Process Modeling Chapter 2

Simulation of Orientation-Dependent Etching of Silicon Using a New Step Flow Model of 3D Structuring

Authors: A. Horn, H. Schröder, E. Obermeier and G. Wachutka

Affilation: Munich University of Technology, Germany

Pages: 63 - 66

Keywords: orientation-dependent wet chemical etching, silicon, 3D-simulation

We present a new model of three-dimensional orientation-dependent etching of Si{100}. Recent experimental results suggest to conceive etching as a “peeling” process of terraced planes, leading to the concept of a “step flow model of 3D structuring”. In particular, a first implementation in a numerical simulation tool allowed us to correctly reproduce the observed details of convex corner (CC) undercutting in pure aqueous KOH solutions (Fig. 2). The new aspect incorporated in this model is the experimental finding that the so-called “fast etching planes”, which commonly are referred to as cause of the characteristic shape of underetched convex corners of the etchmask, are not really crystallographic planes. Instead these areas, denoted as “B” in Fig. 2, are the envelope surfaces of a bunched sequence of <110> oriented steplines with kink sites on the intersecting {111} planes. The typical morphology occurring at underetched convex corners is correctly retrieved by our simulation approach, as it can be verified by comparison with SEM micrographs (Fig. 1, Fig. 2).

ISBN: 0-9666135-7-0
Pages: 741

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