Digital Repository, ICF12, Ottawa 2009

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Effect of Sidewall Morphology on the Fracture and Fatigue Properties of Polysilicon Structural Films
D. H. Alsem, B. L. Boyce, E. A. Stach, R. O. Ritchie

Last modified: 2013-05-07


This study highlights the difference in the sidewall morphology of n+-typepolysilicon films from two popular microelectromechanical systems (MEMS)processes and its effect on fracture and fatigue properties. Atomic force andtransmission electron microscopy show that thick silicon oxides (20 ± 5 nm) arefound in PolyMUMPs films, caused by galvanic corrosion from the presence ofgold on the chip, whereas in SUMMiT films a much thinner (3.5 ± 1.0 nm) nativeoxide was observed. These thicker oxide layers, in combination with differencesin sidewall roughness (14 ± 5 nm for PolyMUMPs and 10 ± 2 nm for SUMMiT),have a significant effect on the fracture and fatigue properties of polysiliconstructures; this is shown by measuring fracture strength (3.8 ± 0.3 GPa forPolyMUMPs and 4.8 ± 0.2 GPa for SUMMiT) and stress-lifetime high-cyclicfatigue curves

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