Integrated Platform for Testing MEMS Mechanical Properties at the Wafer Scale by the IMaP Methodology

Boer, Maarten P. de; Smith, Norman F.; Masters, N.; Sinclair, Michael B.; Pryputniewicz, Emily J.

doi:10.1520/stp10983s

Cited by 9 publications

(5 citation statements)

References 15 publications

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“…We have recently demonstrated an integrated platform to determine mechanical properties by this method at the wafer scale [29]. Along a wafer column, we found little variation in GPa , but significant changes in and residual stress.…”

Section: Discussionmentioning

confidence: 89%

Interferometry of actuated microcantilevers to determine material properties and test structure nonidealities in MEMS

Jensen

Boer

Masters

et al. 2001

J. Microelectromech. Syst.

125

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By integrating interferometric deflection data from electrostatically actuated microcantilevers with a numerical finite difference model, we have developed a step-by-step procedure to determine values of Young's modulus while simultaneously quantifying nonidealities. The central concept in the methodology is that nonidealities affect the long-range deflections of the beams, which can be determined to near nanometer accuracy. Beam takeoff angle, curvature and support post compliance are systematically determined. Young's modulus is then the only unknown parameter, and is directly found. We find an average value of Young's modulus for polycrystalline silicon of 164.3 GPa and a standard deviation of 3.2 GPa (2%), reflecting data from three different support post designs. Systematic errors were assessed and may alter the average value by 5%. An independent estimate from grain orientation measurements yielded 163.4-164.4 GPa (the Voigt and Reuss bounds), in agreement with the step-by-step procedure. Other features of the test procedure include that it is rapid, nondestructive, verifiable and requires only a small area on the test chip. [619] Index Terms-Free-standing thin films, characterization, mechanical properties, statistical accuracy assessments. I. INTRODUCTION K NOWLEDGE of mechanical properties is critical to the design of MEMS. Nanoindentation [1] is commonly used to determine properties of thin films attached to a substrate, but substrate compliance and tip shape effects introduce considerable complexity into analysis methods (see, for example, [2] and references, therein). Free standing thin-film structures are Manuscript

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Section: Discussionmentioning

confidence: 89%

Interferometry of actuated microcantilevers to determine material properties and test structure nonidealities in MEMS

Jensen

Boer

Masters

et al. 2001

J. Microelectromech. Syst.

125

View full text Add to dashboard Cite

show abstract

“…In that case, however, active techniques must be employed. Such techniques are under development [34]. Bent-beam structures are a reasonable alternative in the absence of active methods.…”

Section: Discussionmentioning

confidence: 99%

“…Once implemented, electrical actuation adds little in cost or time to the measurement process and can be used to obtain and average multiple data points from beams subject to either tensile or compressive residual strain. An integrated platform to accomplish interferometry of actuated devices at the wafer scale is under development [34].…”

Section: Case Of Tensile Residual Stressmentioning

confidence: 99%

Side-by-Side Comparison of Passive MEMS Strain Test Structures under Residual Compression

Masters

Boer

Jensen

et al. 2001

Mechanical Properties of Structural Films

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Knowledge and control of residual strain is critical for device design in MEMS, and therefore it is important to establish standards for residual strain measurement. In this study, pointer, microring, bent-beam, and fixed-fixed beam test structures are used to evaluate residual strain both theoretically and experimentally. An equation that enables easier evaluation of bentbeam structures is derived. Also, a finite difference model that incorporates the non-idealities of fixed-fixed beams and determines an optimum fit to the measured deflection curve is presented. The model allows accurate residual strain evaluation of each buckled fixed-fixed beam. Experimentally, pointer structures were found to be susceptible to adhesion. Microrings, intended for residual tension assessment, also could not be evaluated because the residual strain was compressive. Bent-beam and fixed-fixed beams could both be evaluated. The main criterion for test structure effectiveness was taken to be the repeatability of residual strain on structures in close proximity; each should exhibit the same value. Using optical microscopy, the residual strain of bent-beams was determined with ± 13 µε repeatability based on standard deviation of adjacent structures of similar design. Using optical interferometry, the residual strain of fixed-fixed beams was determined with ± 2 µε repeatability based on standard deviation for adjacent beams of different lengths. The strain values obtained from the two structures are in reasonably good agreement. Cantilevers were also evaluated to obtain film curvature values.

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“…Although, the MEMS beam is not completely rigid on both ends; there is still a dependence on the compliance of the anchor. This study does not fully consider the effects of the beam take-off angle [43][44][45][46][47][48][49]. The out-of-plane displacement (see Fig.…”

Section: Beam Theory: Fmed-fixed Beamsmentioning

confidence: 99%

Ultra-lightweight telescope with MEMS adaptive optic for distortion correction.

Spahn¹,

Cowan²,

Shaw³

et al. 2004

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DO NOT DESTROY RETURN TO LIBRARY VAULTABSTRACT Recent world events have underscored the need for a satellite based persistent global surveillance capability. To be useful, the satellite must be able to continuously monitor objects the size of a person anywhere on the globe and do so at a low cost.One way to satisfy these requirements involves a constellation of satellites in low earth orbit capable of resolving a spot on the order of 20 cm. To reduce cost of deployment, such a system must be dramatically lighter than a traditional satellite surveillance system with a high spatial resolution. The key to meeting this requirement is a lightweight optics system with a deformable primary and secondary mirrors and an adaptive optic subsystem correction of wavefront distortion. This proposal is concerned with development of MEMS micromirrors for correction of aberrations in the primary mirror and improvement of image quality, thus reducing the optical requirements on the deployable mirrors. To meet this challenge, MEMS micromirrors must meet stringent criteria on their performance in terms of flatness, roughness and resolution of position. Using Sandia's SUMMIT foundry which provides the world's most sophisticated surface MEMS technology as well as novel designs optimized by finite element analysis will meet severe requirements on mirror travel range and accuracy.

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Integrated Platform for Testing MEMS Mechanical Properties at the Wafer Scale by the IMaP Methodology

Cited by 9 publications

References 15 publications

Interferometry of actuated microcantilevers to determine material properties and test structure nonidealities in MEMS

Interferometry of actuated microcantilevers to determine material properties and test structure nonidealities in MEMS

Side-by-Side Comparison of Passive MEMS Strain Test Structures under Residual Compression

Ultra-lightweight telescope with MEMS adaptive optic for distortion correction.

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