A Novel Method to Measure Poisson's Ratio of Thin Films

Ziebart, V.; Oliver, Paul; Munch, U.; Baltes, H.

doi:10.1557/proc-505-27

Cited by 15 publications

(7 citation statements)

References 2 publications

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“…The indicated errors represent the standard deviation in the experimental results. These ν values are lower than the measurement of 0.28 for LPCVD silicon nitride films that is reported by Vlassak and Nix [10] and similar to the value of 0.253 that is reported by Ziebart et al using buckled PECVD membranes [17]. Table IV summarizes the calculated ν values for the two SiN x H y films using the different f (ν) expressions that are listed in Table I.…”

Section: Resultssupporting

confidence: 77%

Poisson's Ratio of Low-Temperature PECVD Silicon Nitride Thin Films

Walmsley

Liu

et al. 2007

J. Microelectromech. Syst.

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In this paper, the Poisson's ratio ν of lowtemperature plasma-enhanced chemical vapor deposited silicon nitride (SiN x H y ) thin films has been determined by a modified double-membrane bulge test. This test method utilizes a square membrane and a large-aspect-ratio rectangular membrane that is fabricated alongside from the same thin film. The Poisson's ratio is determined from the ratio of the bulge deflections of the two membranes under an applied pressure. The method is suitable for determining ν of either stress-free thin films or those containing low tensile residual stresses. Poisson's ratio values of 0.23 ± 0.02 and 0.25 ± 0.01 were measured for SiN x H y films that were deposited at 125 • C and 205 • C, respectively.[ 2006-0065]Index Terms-Amorphous materials, dielectric films, plasma chemical vapor deposition (CVD), thin films.

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Section: Resultssupporting

confidence: 77%

Poisson's Ratio of Low-Temperature PECVD Silicon Nitride Thin Films

Walmsley

Liu

et al. 2007

J. Microelectromech. Syst.

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“…The average film strain was calculated to be Using this value and a Young's modulus of GPa was obtained. A slightly higher value GPa was determined previously for the same silicon nitride by bulge testing [13].…”

Section: Comparison With Experimentsmentioning

confidence: 43%

“…Equations (4) and (5) are conveniently cast into dimensionless notation, using the dimensionless quantities defined earlier in this section and dimensionless energies of the form Integration by parts, use of the -symmetry, and insertion of the boundary conditions provide the dimensionless bending energy (8) and in-plane deformation energy (9) with Similarly (11) with constituting a base for the deflections with symmetry and skew reflection symmetries. The out-of-plane displacement is written as a truncated sum of these trial functions (12) Truncated at , consists of a total of terms, with the same number of variational parameters and Analogously, the in-plane displacements and are expanded as (13) in terms of the trial functions (14) with variational parameters and In view of their constitutive functions, and all satisfy the required boundary conditions. The sets of coefficients and are variational parameters available for the minimization of the energy and thus for the approximation of the buckling deformation.…”

Section: A Energy Minimization Methodsmentioning

confidence: 99%

“…10 shows profiles of four membranes with side lengths of 601, 841, 1014, and 1301 m. For comparison, profiles simulated using finite elements are also shown. For these simulations, was set to the value 0.25 consistent with the value determined previously for an identically processed PECVD silicon nitride [13]. The residual strain was adjusted to let the center deflection of simulated and measured profiles coincide.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

“…Ziebart The dependence of structural buckling on material parameters such as prestrain, elastic coefficients, and on external forces has been used for the extraction of material properties [5]- [13]. In MEMS, micromachined beams undergoing Euler buckling have been successfully used for this purpose.…”

Section: Introductionmentioning

confidence: 99%

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Strongly buckled square micromachined membranes

Ziebart

Oliver

Baltes

1999

J. Microelectromech. Syst.

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The buckling of compressively prestressed square membranes with built-in edges is investigated experimentally and analyzed theoretically. The buckling depends weakly on Poisson's ratio and essentially is a function of the reduced prestrain, " 0 = " 0 a 2 =h 2 , where " 0 is the physical prestrain, a is the width, and h is the thickness of the membrane. As " 0 becomes increasingly negative, the membrane undergoes two symmetry breaking buckling transitions. Beyond the first transition occurring at " cr1 , the buckling profile has all the reflection and rotation symmetries of a square. The reflection symmetries are lost through a second instability transition at "cr2: The bifurcation points, "cr1 and "cr2; and buckling profiles were calculated using analytical energy minimization and nonlinear finite-element simulation. Both methods agree. The buckling of micromachined plasma-enhanced chemical vapor deposition silicon nitride membranes on a silicon wafer is interpreted in terms of the theoretical results. Good matching between measured and calculated buckling profiles is found. The extracted strain values are consistent irrespective of the size and buckling mode of the membranes. From the average strain across the wafer " 0 = 03:50 2 10 04 and complementary wafer curvature measurements, a Young's modulus of 130 GPa is deduced. Methods for the straightforward extraction of " 0 from experimental center deflections of buckled square membranes are described. [443]

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Characterizing Micro and Nanomaterials UsingMEMSTechnology

Isono¹

2012

Characterization of Materials

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Micro‐ and nanoelectromechanical system (MEMS and NEMS) technology enables the development of smart products. MEMS and NEMS are not electronic devices such as LSI circuits, but they have distinctive features as mechanical systems consisting of actuators, accelerometers, pressure sensors, optical mirrors, power generators, and micromechanical switches with structures of micro/nanometer scale. For example, the accelerometers and pressure sensors detect the elastic deformation of the microscopic structures induced by the external mechanical force acting on the devices as the change of electric resistance or capacitance. Therefore, the development of MEMS and NEMS products requires the structural design of device that ensures the reliable deformation and movement statically and dynamically. In particular, the size effect of device components on their mechanical properties has to be considered in the structural design of MEMS. As a device size is reduced, the surface effect may begin to dominate the material response. In such a case, bulk properties measured on larger specimens are no longer valid. Knowledge of mechanical properties of MEMS and NEMS materials at the scale of the practical use is essential to the design and optimization of devices. In this chapter, technical issues of typical testing methods are introduced for the mechanical characterization of micro/nanometer scale materials including thin films used in MEMS and NEMS. The mechanical characterization technique using MEMS devices as a testing tool for one‐dimensional nanowire materials is also described.

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A Novel Method to Measure Poisson's Ratio of Thin Films

Cited by 15 publications

References 2 publications

Poisson's Ratio of Low-Temperature PECVD Silicon Nitride Thin Films

Poisson's Ratio of Low-Temperature PECVD Silicon Nitride Thin Films

Strongly buckled square micromachined membranes

Characterizing Micro and Nanomaterials UsingMEMSTechnology

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