Fabrication of micromechanical structures in silicon using SF6/O2 gas mixtures

Ashok K. Paul; Askok K. Dimri; S. Mohan

doi:10.1117/12.369446

9 November 1999 Fabrication of micromechanical structures in silicon using SF₆/O₂ gas mixtures

Ashok K. Paul, Askok K. Dimri, S. Mohan

Proceedings Volume 3903, Indo-Russian Workshop on Micromechanical Systems; (1999) https://doi.org/10.1117/12.369446
Event: Indo-Russian Workshop on Micromechanical Systems, 1999, New Delhi, India

Abstract

Plasma etching has been used for the fabrication of micromechanical structures in silicon with fine feature size. In this paper, reactive ion etching (RIE) is used for micromachining applications in two steps, first for etching of SiO₂ layer and then machining of silicon. The first RIE step is for the patterning of the SiO₂ layer using photo-resist as mask. This process involves the use of gas mixture of CHF₃ and Ar. The photo-resist is then removed in the oxygen plasma. The second step is to delineate the patterned SiO₂ layer onto the silicon wafer using SF₆/O₂ plasma. The oxygen flow is varied from 2-10 sccm in SF₆. Silicon etch rates of 195 nm/min and Si/SiO₂ selectivity of 10:1 has been obtained. The process parameters such as gas flow, rf-power and etch pressure are optimized as per our reactor's configuration to have compromise for best selectivity, anisotropy, and high etch rates. A pattern transfer with nearly vertical walls is obtained for RIE based on SF₆/O₂/CHF₃ while maintaining the substrate at low temperature.

Citation Download Citation

Ashok K. Paul, Askok K. Dimri, and S. Mohan "Fabrication of micromechanical structures in silicon using SF₆/O₂ gas mixtures", Proc. SPIE 3903, Indo-Russian Workshop on Micromechanical Systems, (9 November 1999); https://doi.org/10.1117/12.369446

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