| Autor: |
Francio Rodrigues, Luiz Felipe Aguinsky, Josef Weinbub, Georg Wachter, Michael Trupke, Andreas Hössinger, Alexander Scharinger, Ulrich Schmid, Alexander Toifl |
| Rok vydání: |
2021 |
| Předmět: |
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| Zdroj: |
2021 Joint International EUROSOI Workshop and International Conference on Ultimate Integration on Silicon (EuroSOI-ULIS). |
| DOI: |
10.1109/eurosoi-ulis53016.2021.9560685 |
| Popis: |
Low-bias etching of Si using SF 6 plasma is a valuable tool in the manufacturing of semiconductor and MEMS devices. This kind of etching has strong isotropic tendencies, since the low voltage bias does not provide enough vertical acceleration and kinetic energy to the ions. This near-isotropy can be difficult to precisely reproduce in a topography simulation, since experimentally realized surfaces cannot be reproduced by a strictly isotropic velocity model. We present a three-dimensional top-down Monte Carlo particle tracing model for calculating the velocity field in a level-set based simulation. We compare it to profilometer measurements of optical cavities, which are of interest to quantum science, fabricated using a two-step SF 6 plasma etching process. We contrast our approach to conventional models: a strictly isotropic model and a bottom-up direct flux calculation. We show that our top-down model leads to a more accurate description of the final surface by introducing a sticking probability at the surface and also multiple reflections. We are able to reproduce cavities fabricated from different initial photoresist configurations with a single silicon etch rate (V Si = 2.15µmmin−1), while the conventional models require a separate V Si for each photoresist geometry. The model successfully reproduces a Si/photoresist selectivity of 10, which, combined with the low calibrated sticking probability (β Si = 7.5%), corroborates with F radicals being the main drivers of etching. By exploring the state of the surface after the first etch step, which is not readily available experimentally, we anticipate the phenomena of underetching and photoresist tapering. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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