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J. Bobinac, T. Reiter, J. Piso, X. Klemenschits, O. Baumgartner, Z. Stanojevic, G. Strof, M. Karner, L. Filipovic:
"Impact of Mask Tapering on SF6/O2 Plasma Etching";
Vortrag: Fourth International Conference on Microelectronic Devices and Technologies (MicDAT '2022), Corfu, Greece; 21.09.2022 - 23.09.2022; in: "Microelectronic Devices and Technologies: Proceedings of the 4rd International Conference on Microelectronic Devices and Technologies (MicDAT '2022)", (2022), ISBN: 978-84-09-43856-3; S. 90 - 94.

We implement a physical SF6/O2 plasma etching model which is based on Langmuir equations. The simulation is performed using Monte Carlo ray tracing to calculate the surface rates and coverages in order to ultimately obtain the final surface velocities. The model was implemented using the in-house Level Set-based process simulator ViennaPS and it was validated by matching the simulated profiles to published experimental studies. The variables which were used for the best fits matched well with those published in the literature. The model is then used to study the impact of mask tapering on the feature profile in a cylindrical trench. We found that increasing the positive tapering results in a higher etch rate at the bottom of the trench, ultimately resulting in a deeper vertical trench for tapered masks. Increasing the mask tapering also results in more bowing along the cylindrical walls. This is a consequence of particles reflecting off of the mask layer and striking the sidewalls at high angles.

Plasma Etching, high aspect ratio, 3D integration, SF6/O2, mask tapering