Experimental verification of the diffusion theory for wet isotropic etching of si via circular mask openings

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Svetovoy, V. and Berenschot, J.W. and Elwenspoek, M.C. (2006) Experimental verification of the diffusion theory for wet isotropic etching of si via circular mask openings. In: Fifth International Workshop on Physical Chemistry of Wet Etching of Semiconductors, 19-21 June 2006, Saarbrücken, Germany.

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Abstract:Isotropic etching of silicon in HF based solutions is expected to be controlled by the diffusion of
fluorine to the silicon surface. In order to gain quantitative understanding of the process we studied
etching of Si in HF/HNO3/H2O via circular mask openings and compared the results with the theoretical
expectations. The cavity edges due to etching under the mask were analyzed with a high precision by
processing the optical microscope images. Dependence on the etching time and opening size was
investigated. The time dependence was verified with 1% precision. Dependence on the opening size
predicted theoretically is not fully supported by the experiment. There is a small (4%) but clearly
observable deviation from the theory. A small anisotropy was observed in perfect agreement with the
crystal orientation symmetry. The anisotropy becomes larger with the decrease of the opening size for
(100) and (110) wafers.
Item Type:Conference or Workshop Item
Faculty:
Electrical Engineering, Mathematics and Computer Science (EEMCS)
Research Group:
Link to this item:http://purl.utwente.nl/publications/66834
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