Characterization of residual stress in metallic films on silicon with micromechanical devices

Mathilde Boutry; Alain Bosseboeuf; Gerard Coffignal

doi:10.1117/12.251239

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23 September 1996 Characterization of residual stress in metallic films on silicon with micromechanical devices

Mathilde Boutry; Alain Bosseboeuf; Gerard Coffignal

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Proceedings Volume 2879, Micromachining and Microfabrication Process Technology II; (1996) https://doi.org/10.1117/12.251239
Event: Micromachining and Microfabrication '96, 1996, Austin, TX, United States

Abstract

Al and Cr cantilever microbeams, microbridges and suspended microrings were fabricated by isotropic etching of silicon with a SF₆/O₂ plasma after film patterning. They were used for the characterization of both compressive stress, extensive stress and stress gradients in the metallic films. It is shown that valid residual stress measurements with such micromechanical devices must take into account stress changes due to process fabrication, underetching at the clamped ends, edge effects and stress gradients. This is demonstrated by bucking threshold measurements of microbridges and microrings of various sizes and 3D finite element linear static and linear buckling analyses including underetching or stress gradients. Cantilever microbeam profile measurements shows that temperature rise during etching must be carefully minimizes to avoid thermally induced stress gradients. Stress gradients in the deposited films have no effect on microbridges critical buckling stress but lead to a distortion of the microrings before the occurrence of buckling.

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Mathilde Boutry, Alain Bosseboeuf, and Gerard Coffignal "Characterization of residual stress in metallic films on silicon with micromechanical devices", Proc. SPIE 2879, Micromachining and Microfabrication Process Technology II, (23 September 1996); https://doi.org/10.1117/12.251239

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