Characterization of Microscale Wear in a Polysilicon-Based MEMS Device Using AFM and PEEM-NEXAFS Spectromicroscopy

• Published in: Tribology letters Vol. 36; no. 3; pp. 233 - 238
• Main Authors: Grierson, D. S, Konicek, A. R, Wabiszewski, G. E, Sumant, A. V, de Boer, M. P, Corwin, A. D, Carpick, R. W
• Format: Journal Article
• Language: English
• Published: Boston Boston : Springer US 01.12.2009; Springer US; Springer Nature B.V
• Subjects: Atomic beam spectroscopy; Atomic force microscopy; Change detection; Chemistry and Materials Science; Corrosion and Coatings; Emission analysis; Emission microscopy; Emissions control; Fine structure; Materials Science; Microelectromechanical systems; Microscopes; Microscopy; Nanotechnology; Organic chemistry; Original Paper; Oxidation; Photoelectrons; Physical Chemistry; Silicon dioxide; Spatial resolution; Spectrum analysis; Surfaces and Interfaces; Theoretical and Applied Mechanics; Thin Films; Tribology; Wear mechanisms; X ray absorption; Atomic force microscopy (AFM); Microscale wear; Microelectromechanical systems (MEMS); Photoelectron emission microscopy (PEEM); Nanotractor
• ISSN: 1023-8883; 1573-2711
• DOI: 10.1007/s11249-009-9478-7

Mechanisms of microscale wear in silicon-based microelectromechanical systems (MEMS) are elucidated by studying a polysilicon nanotractor, a device specifically designed to conduct friction and wear tests under controlled conditions. Photoelectron emission microscopy (PEEM) was combined with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and atomic force microscopy (AFM) to quantitatively probe chemical changes and structural modification, respectively, in the wear track of the nanotractor. The ability of PEEM-NEXAFS to spatially map chemical variations in the near-surface region of samples at high lateral spatial resolution is unparalleled and therefore ideally suited for this study. The results show that it is possible to detect microscopic chemical changes using PEEM-NEXAFS, specifically, oxidation at the sliding interface of a MEMS device. We observe that wear induces oxidation of the polysilicon at the immediate contact interface, and the spectra are consistent with those from amorphous SiO₂. The oxidation is correlated with gouging and debris build-up in the wear track, as measured by AFM and scanning electron microscopy (SEM).