On-Chip Testing of Mechanical Properties of MEMS Devices

MRS Bulletin ◽  
2001 ◽  
Vol 26 (4) ◽  
pp. 300-301 ◽  
Author(s):  
H. Kahn ◽  
A.H. Heuer ◽  
R. Ballarini
Keyword(s):  
Mechanical Properties ◽  
Physical Environment ◽  
Microelectromechanical Systems ◽  
Mems Devices ◽  
Electrical Signals ◽  
Chip Testing ◽  
On Chip

The field of microelectromechanical systems (MEMS) involves the interaction of the physical environment with electrical signals through the use of microbatchfabricated devices. MEMS is a growing technology, and commercial MEMS products are becoming commonplace.

Utilizing On-Chip Testing and Electron Microscopy to Study Fatigue and Wear in Polysilicon Structural Films

2004 ◽  
Vol 821 ◽  
Author(s):  
D.H. Alsem ◽  
E.A. Stach ◽  
C.L. Muhlstein ◽  
M.T. Dugger ◽  
R.O. Ritchie
Keyword(s):  
Electron Microscopy ◽  
Failure Modes ◽  
Microelectromechanical Systems ◽  
Fatigue Behavior ◽  
Side Wall ◽  
Ambient Air ◽  
Wall Friction ◽  
Native Oxide ◽  
Chip Testing ◽  
On Chip

AbstractWear and fatigue are important factors in determining the reliability of microelectromechanical systems (MEMS). While the reliability of MEMS has received extensive attention, the physical mechanisms responsible for these failure modes have yet to be conclusively determined. In our work, we use a combination of on-chip testing methodologies and electron microscopy observations to investigate these mechanisms. Our previous studies have shown that fatigue in polysilicon structural thin films is a result of a ‘reaction-layer’ process, whereby high stresses induce a room-temperature mechanical thickening of the native oxide at the root of a notched cantilever beam, which subsequently undergoes moisture-assisted cracking. Devices from a more recent fabrication run are fatigued in ambient air to show that the post-release oxide layer thicknesses that were observed in our earlier experiments were not an artifact of that particular batch of polysilicon. New in vacuo data show that these silicon films do not display fatigue behavior when the post release oxide is prevented from growing, because of the absence of oxygen. Additionally, we are using polysilicon MEMS side-wall friction test specimens to study active mechanisms in sliding wear at the microscale. In particular, we have developed in vacuo and in situ experiments in the scanning electron microscope, with the objective of eventually determining the mechanisms causing both wear development and debris generation.

On the Micromechanical Characterization of Metallic MEMS by a Hybrid Microtester

2015 ◽  
Author(s):  
Jennifer Wardlow ◽  
Seyed Allameh
Keyword(s):  
Mechanical Properties ◽  
Microelectromechanical Systems ◽  
Local Deformation ◽  
Small Scale ◽  
Large Displacements ◽  
Mems Devices ◽  
Surface Flaws ◽  
Micromechanical Characterization ◽  
Position Monitoring

Mechanical testing of microelectromechanical systems (MEMS) components helps investigate the reliability of MEMS devices used especially in vital applications such as life-supporting, medical, aerospace or automotive technologies. This paper discusses the development and use of a hybrid micromechanical system that combines the advantages of a macroscale slow-action screw-driven stage producing large displacements with a small-scale fast-action piezo-driven actuator. The main advantage is to study mechanical properties of small structures such as thick and thin films developing cracks that travel on millimeter scale during fatigue. The combination of piezo position monitoring with image-recognition-based local deformation determination allows specification of the beginning of phenomena such as micro-void-induced softening with relative accuracy. Such studies are most useful for investigation of the onset of nucleation of microcracks from fatigue-induced surface flaws. The significance of finding the onset of crack propagation lies in the fact that crack initiation constitutes the major portion of fatigue life for small structures (occasionally up to 99.3%).

The Fracture Toughness of Polysilicon Microdevices

1998 ◽  
Vol 518 ◽  
Author(s):  
R. Ballarini ◽  
R.L. Mullen ◽  
H. Kahn ◽  
A.H. Heuer
Keyword(s):  
Fracture Toughness ◽  
Microelectromechanical Systems ◽  
Maximum Tensile Stress ◽  
Monotonic Loading ◽  
Modulus Of Rupture ◽  
External Loading ◽  
Mems Devices ◽  
Average Maximum ◽  
Average Modulus ◽  
On Chip

AbstractThe development of polysilicon fracture mechanics specimens with characteristic dimensions comparable to those of typical microelectromechanical systems (MEMS) devices is presented. The notched cantilever specimens are fully integrated with a simultaneously microfabricated electrostatic actuator, which allows on-chip testing of the specimens without the need of an external loading device, and without any possible influences from external sources. Under monotonic loading, the average maximum tensile stress (strength) and average nominal fracture toughness were measured as 4.2 GPa and 3.5 MPa-m½ for boron-doped specimens, and 5.0 GPa and 4.0 MPa-m½ for undoped specimens. An average modulus of rupture of 3.3 GPa and average nominal toughness of 2.7 MPa-m½ were measured for specimens cracked under cyclic resonance loading. The differences between the monotonic loading and cyclic loading data are attributed to fatigue initiation of a sharp crack from the 1 ýtm radius notch. The experimental data is consistent with a critical flaw size in the fabricated devices, a, that is related to the fracture toughness Klc by Klc/a1/2=4600 MPa.

Developing a New Material for MEMS: Amorphous Diamond

2000 ◽  
Vol 657 ◽  
Author(s):  
J. P. Sullivan ◽  
T. A. Friedmann ◽  
M. P. de Boer ◽  
D. A. LaVan ◽  
R. J. Hohlfelder ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Microelectromechanical Systems ◽  
Heat Treating ◽  
Cantilever Beams ◽  
Mems Devices ◽  
Unique Form ◽  
Electrostatically Actuated ◽  
Comb Drives ◽  
New Material ◽  
Diamond Mems

ABSTRACTAmorphous diamond is a new material for surface-micromachined microelectromechanical systems (MEMS) that offers promise for reducing wear and stiction of MEMS components. The material is an amorphous mixture of 4-fold and 3-fold coordinated carbon with mechanical properties close to that of crystalline diamond. A unique form of structural relaxation permits the residual stress in the material to be reduced from an as-deposited value of 8 GPa compressive down to zero stress or even to slightly tensile values. Irreversible plastic deformation, achieved by heat treating elastically strained structures, is also possible in this material. Several types of amorphous diamond MEMS devices have been fabricated, including electrostatically-actuated comb drives, micro-tensile test structures, and cantilever beams. Measurements using these structures indicate the material has an elastic modulus close to 800 GPa, fracture toughness of 8 MPa.m½, an advancing H2O contact angle of 84° to 94°, and a surface roughness of 0.1 to 0.9 nm R.M.S. on Si and SiO2, respectively.

On the Fracture Toughness of Polysilicon MEMS Structures

2000 ◽  
Vol 657 ◽  
Author(s):  
H. Kahn ◽  
R. Ballarini ◽  
A.H. Heuer
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Microelectromechanical Systems ◽  
Materials Science ◽  
Grain Structure ◽  
Processing Conditions ◽  
Mems Devices ◽  
Electrostatic Actuators ◽  
Wide Range ◽  
Sensitive Property

ABSTRACTThe mechanical properties of micromachined polysilicon are of great interest to designers of microelectromechanical systems (MEMS) devices. Numerous investigations have been carried out to determine the strength of MEMS-fabricated polysilicon structures, and the experimental results vary widely, depending on the experimental techniques, specimen geometries, and processing conditions. In order to determine whether these variations are inherent to all mechanical properties of MEMS materials, the fracture toughness, Kcrit, of micromachined polysilicon has been investigated, using a wide range of material microstructures (microstructure is used here in the Materials Science sense to mean the grain structure visible in a microscope, and not in the MEMS sense to mean small structures). Since fracture toughness is a fundamental materials property, whether or not it varies with microstructure and processing is an interesting question. We have confirmed that Kcrit is not a microstructure-sensitive property, using surface-micromachined specimens with sharp pre-cracks which are integrated with electrostatic actuators. The measured Kcrit is 1.0±0.1 MPa √m for a wide range of miscrostructures.

scholarly journals A Stochastic Model to Describe the Scattering in the Response of Polysilicon MEMS

2021 ◽  
Vol 2 (1) ◽  
pp. 95
Author(s):  
Luca Dassi ◽  
Marco Merola ◽  
Eleonora Riva ◽  
Angelo Santalucia ◽  
Andrea Venturelli ◽  
...  
Keyword(s):  
Silicon Film ◽  
Micro Fabrication ◽  
Micro Electro Mechanical Systems ◽  
Local Fluctuations ◽  
Stochastic Framework ◽  
On Line ◽  
Chip Testing ◽  
On Chip ◽  
Time Required ◽  
Polycrystalline Silicon Film

The current miniaturization trend in the market of inertial microsystems is leading to movable device parts with sizes comparable to the characteristic length-scale of the polycrystalline silicon film morphology. The relevant output of micro electro-mechanical systems (MEMS) is thus more and more affected by a scattering, induced by features resulting from the micro-fabrication process. We recently proposed an on-chip testing device, specifically designed to enhance the aforementioned scattering in compliance with fabrication constraints. We proved that the experimentally measured scattering cannot be described by allowing only for the morphology-affected mechanical properties of the silicon films, and etch defects must be properly accounted for too. In this work, we discuss a fully stochastic framework allowing for the local fluctuations of the stiffness and of the etch-affected geometry of the silicon film. The provided semi-analytical solution is shown to catch efficiently the measured scattering in the C-V plots collected through the test structure. This approach opens up the possibility to learn on-line specific features of the devices, and to reduce the time required for their calibration.

scholarly journals A Tunable-Gain Transimpedance Amplifier for CMOS-MEMS Resonators Characterization

Micromachines ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 82
Author(s):  
Rafel Perelló-Roig ◽  
Jaume Verd ◽  
Sebastià Bota ◽  
Jaume Segura
Keyword(s):  
Cmos Technology ◽  
Open Loop ◽  
Transimpedance Amplifier ◽  
Mems Devices ◽  
Monolithically Integrated ◽  
Mems Resonators ◽  
Electromechanical Performance ◽  
Cmos Mems ◽  
Promising Solution ◽  
On Chip

CMOS-MEMS resonators have become a promising solution thanks to their miniaturization and on-chip integration capabilities. However, using a CMOS technology to fabricate microelectromechanical system (MEMS) devices limits the electromechanical performance otherwise achieved by specific technologies, requiring a challenging readout circuitry. This paper presents a transimpedance amplifier (TIA) fabricated using a commercial 0.35-µm CMOS technology specifically oriented to drive and sense monolithically integrated CMOS-MEMS resonators up to 50 MHz with a tunable transimpedance gain ranging from 112 dB to 121 dB. The output voltage noise is as low as 225 nV/Hz1/2—input-referred current noise of 192 fA/Hz1/2—at 10 MHz, and the power consumption is kept below 1-mW. In addition, the TIA amplifier exhibits an open-loop gain independent of the parasitic input capacitance—mostly associated with the MEMS layout—representing an advantage in MEMS testing compared to other alternatives such as Pierce oscillator schemes. The work presented includes the characterization of three types of MEMS resonators that have been fabricated and experimentally characterized both in open-loop and self-sustained configurations using the integrated TIA amplifier. The experimental characterization includes an accurate extraction of the electromechanical parameters for the three fabricated structures that enables an accurate MEMS-CMOS circuitry co-design.

scholarly journals The description of friction of silicon MEMS with surface roughness: virtues and limitations of a stochastic Prandtl–Tomlinson model and the simulation of vibration-induced friction reduction

2010 ◽  
Vol 1 ◽  
pp. 163-171 ◽  
Author(s):  
W Merlijn van Spengen ◽  
Viviane Turq ◽  
Joost W M Frenken
Keyword(s):  
Surface Roughness ◽  
Critical Role ◽  
Measurement Data ◽  
Friction Model ◽  
Friction Reduction ◽  
Atomic Scale ◽  
Mems Devices ◽  
Tomlinson Model ◽  
Atomic Force ◽  
On Chip

We have replaced the periodic Prandtl–Tomlinson model with an atomic-scale friction model with a random roughness term describing the surface roughness of micro-electromechanical systems (MEMS) devices with sliding surfaces. This new model is shown to exhibit the same features as previously reported experimental MEMS friction loop data. The correlation function of the surface roughness is shown to play a critical role in the modelling. It is experimentally obtained by probing the sidewall surfaces of a MEMS device flipped upright in on-chip hinges with an AFM (atomic force microscope). The addition of a modulation term to the model allows us to also simulate the effect of vibration-induced friction reduction (normal-force modulation), as a function of both vibration amplitude and frequency. The results obtained agree very well with measurement data reported previously.

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