Galvanic corrosion: a microsystems device integrity and reliability concern

David C. Miller; William L. Hughes; Zhong Lin Wang; Ken Gall; Conrad R. Stoldt

doi:10.1117/12.644932

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5 January 2006 Galvanic corrosion: a microsystems device integrity and reliability concern

David C. Miller, William L. Hughes, Zhong Lin Wang, Ken Gall, Conrad R. Stoldt

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Proceedings Volume 6111, Reliability, Packaging, Testing, and Characterization of MEMS/MOEMS V; 611105 (2006) https://doi.org/10.1117/12.644932
Event: MOEMS-MEMS 2006 Micro and Nanofabrication, 2006, San Jose, California, United States

Abstract

We have studied the corrosion of phosphorus-doped polySi when contacted to a gold metallization layer and exposed to various hydrofluoric acid (HF) based chemistries, including mixtures with HCl, C₂H₆O, H₂O, NH₄F, Triton-X-100, as well as vapor-based HF. Here, we utilize optical-, electron-, and atomic-force-microscopy, optical interferometry, as well as instrumented indentation ("nanoindentation") to characterize test and reference specimens exposed to the various HF solutions. These measurements provide information concerning the appearance, roughness, physical dimensions, hardness, elastic modulus, and reverse phase transformation activity of the various polysilicon specimens. In general, some of the chemistries produced time-dependent darkening or "staining" visibly seen on free surfaces, roughening and attack at grain boundaries, nano-scale pitting of the free surfaces, decrease in thickness, decrease in hardness and mechanical modulus, and diminished elbow and reverse excursion activity for those silicon specimens electrically connected to metal. Change in performance is attributed to the formation of a galvanic cell during the HF immersion, and the corresponding damage driven by an anodic current. The results here can be used to explain previous work, which focused on the change in performance of designated MEMS diagnostic structures.

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David C. Miller, William L. Hughes, Zhong Lin Wang, Ken Gall, and Conrad R. Stoldt "Galvanic corrosion: a microsystems device integrity and reliability concern", Proc. SPIE 6111, Reliability, Packaging, Testing, and Characterization of MEMS/MOEMS V, 611105 (5 January 2006); https://doi.org/10.1117/12.644932

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