Study of methods for measuring mechanical properties of thin films in microelectromechanical systems (MEMS)

Author(s):  
Quanbo Zou ◽  
Zhijian Li ◽  
Litian Liu
2001 ◽  
Vol 16 (8) ◽  
pp. 2223-2228 ◽  
Author(s):  
J. N. Ding ◽  
Y. G. Meng ◽  
S. Z. Wen

A new microtensile test device using a magnetic-solenoid force actuator was developed to evaluate the mechanical properties of microfabricated polysilicon thin films that were 100–660 mm long, 20–200 μm wide, and 2.4-μm thick. It was found that the measured average value of Young's modulus, 164 GPa ± 1.2 GPa, falls within the theoretical bounds. The average fracture strength is 1.36 GPa with a standard deviation of 0.14 GPa, and the Weibull modulus is 10.4–11.7. Statistical analysis of the specimen size effects on the tensile strength predicated the size effects on the length, the surface area, and the volume of the specimens. The fracture strength increases with an increase of the ratio of surface area to volume. In such cases, the size effect can be corrected to the ratio of the surface area to volume as the governing parameter. The test data accounts for the uncertainties in mechanical properties and may be used to enhance the reliability and design of polysilicon microelectromechanical systems devices.


2002 ◽  
Vol 741 ◽  
Author(s):  
H.D. Espinosa ◽  
B. Peng ◽  
K.-H. Kim ◽  
B.C. Prorok ◽  
N. Moldovan ◽  
...  

ABSTRACTMicrocantilever deflection and the membrane deflection experiment (MDE) were used to examine the elastic and fracture properties of ultrananocrystalline diamond (UNCD) thin films in relation to their application to microelectromechanical systems (MEMS). Freestanding microcantilevers and membranes were fabricated using standard MEMS fabrication techniques adapted to our UNCD film technology. Elastic moduli measured by both methods described above are in agreement, with the values being in the range 930 and 970 GPa with both techniques showing good reproducibility. The MDE test showed fracture strength to vary from 3.95 to 5.03 GPa when seeding was performed with ultrasonic agitation of nanosized particles.


2003 ◽  
Vol 125 (4) ◽  
pp. 361-367 ◽  
Author(s):  
Xiaoqin Huang ◽  
Assimina A. Pelegri

MEMS (MicroElectroMechanical Systems) are composed of thin films and composite nanomaterials. Although the mechanical properties of their constituent materials play an important role in controlling their quality, reliability, and lifetime, they are often found to be different from their bulk counterparts. In this paper, low-k porous silica thin films spin coated on silicon substrates are studied. The roughness of spin-on coated porous silica films is analyzed with in-situ imaging and their mechanical properties are determined using nanoindentation. A Berkovich type nanoindenter, of a 142.3 deg total included angle, is used and continuous measurements of force and displacements are acquired. It is shown, that the measured results of hardness and Young’s modulus of these films depend on penetration depth. Furthermore, the film’s mechanical properties are influenced by the properties of the substrate, and the reproduction of the force versus displacement curves depends on the quality of the thin film. The hardness of the studied low-k spin coated silica thin film is measured as 0.35∼0.41 GPa and the Young’s modulus is determined as 2.74∼2.94 GPa.


2000 ◽  
Vol 657 ◽  
Author(s):  
G. F. Dirras ◽  
G. Coles ◽  
A. J. Wagner ◽  
S. Carlo ◽  
C. Newman ◽  
...  

ABSTRACTThe microstructure of Low Pressure Chemical Vapor Deposition (LPCVD) Polycrystalline silicon (Polysilicon) thin films was investigated by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and Auger electron spectroscopy (AES). SEM characterization of tensile tested samples showed a brittle like-rupture, along with grooves located at the surface sides of the sample. TEM investigations of as-deposited samples showed equiaxed or fully columnar grains bridging from the bottom to the top of the films. A microstructural coarsening was observed with annealing. In the as-deposited state, the films exhibited a {110} texture as showed by the XRD analysis. The films' top and bottom surfaces were observed to be smooth with a roughness (standard deviation) of about 11nm and 20 nm respectively. A chemical analysis of the thin films showed the presence of carbon and oxygen impurities on the surface and oxygen through the sample as observed in the depth profile. The hypothetical influence of these findings is subsequently discussed in relation to the measured mechanical properties.


1999 ◽  
Vol 594 ◽  
Author(s):  
J. M. Jungk ◽  
B. T. Crozier ◽  
A. Bandyopadhyay ◽  
N. R. Moody ◽  
D. F. Bahr

AbstractPiezoelectric films are attractive materials for use in microelectromechanical systems (MEMS) due to their ability to act as both sensors and actuators. One of the primary modes of deformation is the deflection of lead zirconate titantate (PZT) beams and membranes, where the adhesion of the film is critical for the reliability of the device. Thin films of PZT between 250 and 750 nm have been grown via solution deposition routes onto platinized silicon substrates. The films have been tested using nanoindentation techniques. Two failure mechanism in these films have been observed Indentation induced delamination at the PZT-Pt interface occurs after the indenter tip is removed from the film when loads between 1 and 10 mN are applied to the sample, and at large loads (>75 mN) failure can be generated between the underlying oxide film and the silicon substrate while the tip is still engaged with the sample. Since each of these failure modes has a different mechanics solution, the results are compared to determine adhesion energy of the films. Fracture around the delaminated regions has been examined using scanning probe and electron microscopy. Freestanding PZT membranes above micromachined cavities have been mechanically deformed to examine the mechanical response and failure modes in these structures. The adhesion of the PZT improves with increased percent crystallization due to the introduction of residual tensile stresses. Processing, mechanical properties, and failure modes in these devices will be discussed.


2011 ◽  
Vol 99 (2) ◽  
pp. 239-244 ◽  
Author(s):  
T.T.H. Pham ◽  
E. Le Bourhis ◽  
P. Goudeau ◽  
P. Guérin

1996 ◽  
Vol 444 ◽  
Author(s):  
Hyeon-Seag Kim ◽  
D. L. Polla ◽  
S. A. Campbell

AbstractThe electrical reliability properties of PZT (54/46) thin films have been measured for the purpose of integrating this material with silicon-based microelectromechanical systems. Ferroelectric thin films of PZT were prepared by metal organic decomposition. The charge trapping and degradation properties of these thin films were studied through device characteristics such as hysteresis loop, leakage current, fatigue, dielectric constant, capacitancevoltage, and loss factor measurements. Several unique experimental results have been found. Different degradation processes were verified through fatigue (bipolar stress), low and high charge injection (unipolar stress), and high field stressing (unipolar stress).


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