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Microstructural and Geometrical Factors Influencing the Mechanical Failure of Polysilicon for MEMS

Published online by Cambridge University Press:  01 February 2011

Krishna Jonnalagadda  and
Ioannis Chasiotis
Krishna Jonnalagadda
Affiliation:
kjonnal2@uiuc.edu, University of Illinois at Urbana-Champaign, Aerospace Engineering, 104 S. Wright Street, Urbana, IL, 61801, United States
Ioannis Chasiotis
Affiliation:
chasioti@uiuc.edu, University of Illinois at Urbana-Champaign, Aerospace Engineering, 104 S. Wright Street, Urbana, IL, 61801, United States
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Abstract

The failure strength of polycrystalline silicon is discussed in terms of activation of critical flaws, as well as the material microstructure and inhomogeneity. The Weibull probability density function parameters were obtained to deduce the scaling of material and component strength and to identify critical flaw populations, especially when two or more flaw sets are concurrently active. It was shown that scaling of strength changes for small feature sizes, which limits the applicability of strength data from large MEMS components to self-similar small MEMS components. On the other hand, the probability of failure of small components is described by a larger Weibull material stress parameter, which makes uniaxial strength data a conservative design approach. Furthermore, according to mode I and mixed mode I/II fracture studies for polysilicon, it is concluded that microstructural inhomogeneity alone accounts for 50% scatter in strength (with reference to the minimum recorded value). Thus, the conditions for applicability of the Weibull probability density function are rather weak in polycrystalline silicon, because flaws of the same length that are subjected to the same macroscopic stresses are not always critical.

Keywords

microelectro-mechanical (MEMS)fracturestrength
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1052: Symposium DD – Microelectromechanical Systems–Materials and Devices , 2007 , 1052-DD02-01
Copyright
Copyright © Materials Research Society 2008

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References

1 Chasiotis, I., Knauss, W.G, “The Mechanical Strength of Polysilicon Films: 2. Size Effects Associated with Elliptical and Circular Perforations”, J. of the Mechanics and Physics of Solids 51, pp. 1551–1572, (2003).Google Scholar
2 Boyce, B. L., Grazier, J.M, Buchheit, T.E, Shaw, M.J, “Strength Distributions in Polycrystalline Silicon MEMS,” Journal of Microelectromechanical Systems, 16 (2), pp. 179–190, (2007).Google Scholar
3 Isono, Y., Namazu, T., Tanaka, T., “AFM Bending Testing of Nanometric Single Crystal Wire at Intermediate Temperatures for MEMS,” 14th IEEE Intl. Conf. on Microelectromechanical Systems, pp. 135–138, (2001).Google Scholar
4 Chasiotis, I., Cho, S.W, Jonnalagadda, K., “Fracture Toughness and Subcritical Crack Growth in Polycrystalline Silicon”, Journal of Applied Mechanics 73 (5), pp. 714–722, (2006).Google Scholar
5 Ballarini, R., Mullen, R. L., Heuer, A.H, “The effects of heterogeneity and anisotropy on the size effect in cracked polycrystalline films,” International Journal of Fracture 95, pp. 19–39, (1999).Google Scholar
6 Ballarini, R., Mullen, R. L., Yin, Y., Kahn, H., Stemmer, S., Heuer, A.H, “The fracture toughness of polysilicon microdevices: A first report,” Journal of Materials Research 12(4), pp. 915–922. (1997).Google Scholar
7 Cho, S.W, Chasiotis, I., Friedman, T.A, Sullivan, J., “Young's modulus, Poisson's ratio and failure properties of tetrahedral amorphous diamond-like carbon for MEMS devices”, Journal of Micromechanics and Microengineering 15 (4), pp. 728–735, (2005).Google Scholar
8 Jonnalagadda, K., Cho, S., Chasiotis, I., Friedman, T.A, Sullivan, J., “Effect of Intrinsic Stress Gradient on the Effective Mode-I Fracture Toughness of Amorphous Diamond-like Carbon Films for MEMS,” (in press) Journal of the Mechanics and Physics of Solids, (2008).Google Scholar
9 Sharpe, W.N, Jadaan, O., Beheim, G.M, Quinn, G.D, Nemeth, N.N, “Fracture Strength of Silicon Carbide Microspecimens,” Journal of Microelectromechanical Systems, 14(5), pp. 903–913, (2005).Google Scholar
10 Roy, S., DeAnna, R.G, Zorman, C.A, Mehregany, M., “Fabrication and Characterization of Poycrystalline SiC Resonators,” IEEE Transactions on Electron Devices, 49(12), pp. 2323, (2002).Google Scholar
11 Chasiotis, I., Knauss, W.G, “The Mechanical Strength of Polysilicon Films: 1. The Influence of Fabrication Governed Surface Conditions”, J. of the Mechanics and Physics of Solids 51, pp. 1533–1550, (2003).Google Scholar
12 Kahn, H., Deeb, C., Chasiotis, I., Heuer, A.H, “Anodic oxidation during MEMS processing of silicon and polysilicon: native oxides can be thicker than you think”, Journal of Microelectromechanical Systems 14 (5), pp. 914–923, (2005).Google Scholar
13 Miller, D.C, Boyce, B.L, Gall, K., “Galvanic Corrosion Induced Degredation Of Tensile Properties In Micromachined Polycrystalline Silicon,” Applied Physics Letters, 90, 191902, pp. 1–3, (2007).Google Scholar
14 Alan, T., Hines, M., and Zehnder, A., “Effect of Surface Morphology on the Fracture Strength of Silicon Nanobeams,” Applied Physics Letters, 89, pp. 091901, (2006).Google Scholar
15 Bagdahn, J., Sharpe, W.N, Jadaan, O., “Fracture strength of polysilicon at stress concentrations”, Journal of Microelectromechanical Systems 12 (3) pp. 302–312, (2003).Google Scholar
16 McCarty, A., Chasiotis, I., “Description of Brittle Failure of Non-uniform MEMS Geometries”, Thin Solid Films 515, pp. 3267–3276, (2007).Google Scholar
17 LaVan, D.A, Tsuchiya, T., Coles, G., Knauss, W.G, Chasiotis, I., Read, D., “Cross Comparison of Direct Tensile Techniques on SUMMiT Polysilicon Films”, Mechanical Properties of Structural Films, ASTM STP 1413, pp. 1–12, ASTM, W. Conshohocken, PA (2001).Google Scholar
18 Mani, S.S, Fleming, J.G, Walraven, J.A., Sniegowski, J.J, Boer, M.P. de, Irwin, L.W, Tanner, D.M, LaVan, D.A, Dugger, M.T, Jakubczak, J., Miller, W.M, “Effect of W Coating on Microengine Performance”, 38th Annual International Reliability Physics Symposium, pp.146–151, (2000).Google Scholar
19 Cho, S.W Jonnalagadda, K., Chasiotis, I., “Mode I and Mixed Mode Fracture of Polysilicon for MEMS,” Fatigue and Fracture of Engineering Materials and Structures 30 (1), pp. 21–31, (2007).Google Scholar
20 Jonnalagadda, K., Chasiotis, I., “Mixed Mode Fracture in Brittle Materials for MEMS,” Proceedings of 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006 -Microelectromechanical Systems, (2006).Google Scholar
21 Anderson, T.L, Fracture Mechanics, 2nd Edition, CRC Press, (1995).Google Scholar
22 Cho, S.W, Chasiotis, I., “Elastic Properties and Representative Volume Element of Polycrystalline Silicon for MEMS,” Experimental Mechanics 47 (1), pp. 37–49, (2007).Google Scholar
23 Theocaris, P.S, Papadopoulos, G.A, “The influence of edge cracked plates on KI and KII components of the stress intensity factor studied by caustics”, Journal of Physics D: Applied Physics 17, 2339–2349, (1984).Google Scholar