Tuning the Mechanical Properties of SiO2 Thin Film for MEMS Application

2003 ◽  
Vol 795 ◽  
Author(s):  
Wang-Shen Su ◽  
Weileun Fang ◽  
Ming-Shih Tsai

ABSTRACTThis study reported a novel method for tuning thin film mechanical properties by means of plasma surface modification. In order to demonstrate the feasibility of this approach, various plasma treatments, including O2, H2, NH3 atmospheres, were implemented to tune the Young's modulus and residual stress of SiO2 film. Without plasma treatment, the static tip deflection of 200μm long SiO2 cantilever was 9.01μm. After treatment with H2, O2, and NH3 plasma, the tip deformation of the treated cantilevers became 10.22μm, 8.28μm, and -6.84μm respectively. The Young's modulus of the SiO2 cantilever without plasma treatment was 76.3GPa. After treated with H2, O2, NH3 plasma, the Young's modului of those treated cantilevers became 70.8 GPa, 74.7 GPa, and 71.4 GPa, respectively. Hence, after H2 and NH3 plasma treatment, the equivalent elastic modulus of SiO2 cantilever could be reduced about 7%.

2008 ◽  
Vol 33-37 ◽  
pp. 969-974 ◽  
Author(s):  
Bong Bu Jung ◽  
Seong Hyun Ko ◽  
Hun Kee Lee ◽  
Hyun Chul Park

This paper will discuss two different techniques to measure mechanical properties of thin film, bulge test and nano-indentation test. In the bulge test, uniform pressure applies to one side of thin film. Measurement of the membrane deflection as a function of the applied pressure allows one to determine the mechanical properties such as the elastic modulus and the residual stress. Nano-indentation measurements are accomplished by pushing the indenter tip into a sample and then withdrawing it, recording the force required as a function of position. . In this study, modified King’s model can be used to estimate the mechanical properties of the thin film in order to avoid the effect of substrates. Both techniques can be used to determine Young’s modulus or Poisson’s ratio, but in both cases knowledge of the other variables is needed. However, the mathematical relationship between the modulus and Poisson's ratio is different for the two experimental techniques. Hence, achieving agreement between the techniques means that the modulus and Poisson’s ratio and Young’s modulus of thin films can be determined with no a priori knowledge of either.


Author(s):  
Enboa Wu ◽  
Albert J. D. Yang ◽  
Ching-An Shao ◽  
C. S. Yen

Nondestructive determination of Young’s modulus, coefficient of thermal expansion, Poisson ratio, and thickness of a thin film has long been a difficult but important issue as the film of micrometer order thick might behave differently from that in the bulk state. In this paper, we have successfully demonstrated the capability of determining all these four parameters at one time. This novel method includes use of the digital phase-shifting reflection moire´ (DPRM) technique to record the slope of wafer warpage under temperature drop condition. In the experiment, 1-um thick aluminum was sputtered on a 6-in silicon wafer. The convolution relationship between the measured data and the mechanical properties was constructed numerically using the conventional 3D finite element code. The genetic algorithm (GA) was adopted as the searching tool for search of the optimal mechanical properties of the film. It was found that the determined data for Young’s modulus (E), Coefficient of Thermal Expansion (CTE), Poisson ratio (ν), and thickness (h) of the 1.00 um thick aluminum film were 104.2Gpa, 38.0 ppm/°C, 0.38, and 0.98 um, respectively, whereas that in the bulk state were measured to be E=71.4 Gpa, CTE=23.0 ppm/°C, and ν=0.34. The significantly larger values on the Young’s modulus and the coefficient of thermal expansion determined by this method might be attributed to the smaller dislocation density due to the thin dimension and formation of the 5-nm layer of Al2O3 formed on top of the 1-um thick sputtered film. The Young’s Modulus and the Poisson ratio of this nano-scale Al2O3 film were then determined. Their values are consistent with the physical intuition of the microstructure.


e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Sayant Saengsuwan

AbstractThe influence of annealing on the microstructure and molecular orientation, thermal behaviour and mechanical properties of uniaxially drawn iPP thin film was studied by wide-angle X-ray diffraction, differential scanning calorimetry and tensile testing, respectively. The correlations of mechanical and microstructural properties of annealed films were also examined. The transformation of smectic phase of iPP to the α-form was more pronounced with increasing annealing time and temperature. The true and apparent crystallinities and crystal thickness were strongly enhanced with annealing time and temperature. The relative molecular orientation tended to increase with annealing time. These results caused the significant improvement of modulus and tensile strength of the annealed films in both machine (MD) and transverse (TD) directions. The increases in MD-Young’s modulus and MD-tensile strength were well correlated with the increase in true crystallinity obtained in equatorial scans. Some relationship between the increase in crystal thickness and the increase in Young’s modulus in both MD and TD directions was also found.


2007 ◽  
Vol 1052 ◽  
Author(s):  
Yung-Dong Lau ◽  
Tso-Chi Chang ◽  
Hong Hocheng ◽  
Rongshun Chen ◽  
Weileun Fang

AbstractThis study has successfully demonstrated a novel tensile testing approach to mount the thin film test specimen onto the MEMS instrument using microfabrication process. The MEMS instrument consists of thermal actuator, differential capacitance sensor, supporting spring. The thermal actuator applies tensile load on the test specimen to characterize the Young's modulus and the residual stress of thin films. As compare with the existing approaches, the problems and difficulties resulting from the alignment and assembly of thin film test specimens with the testing instrument can be prevented. Furthermore, the parylene passivation technique of MEMS fabrication process allows the changing of testing film materials easily. In application, the present approach has been employed to determine the Young's modulus and the residual stress of Al films.


Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1072
Author(s):  
Sergio Sapienza ◽  
Matteo Ferri ◽  
Luca Belsito ◽  
Diego Marini ◽  
Marcin Zielinski ◽  
...  

3C-SiC is an emerging material for MEMS systems thanks to its outstanding mechanical properties (high Young’s modulus and low density) that allow the device to be operated for a given geometry at higher frequency. The mechanical properties of this material depend strongly on the material quality, the defect density, and the stress. For this reason, the use of SiC in Si-based microelectromechanical system (MEMS) fabrication techniques has been very limited. In this work, the complete characterization of Young’s modulus and residual stress of monocrystalline 3C-SiC layers with different doping types grown on <100> and <111> oriented silicon substrates is reported, using a combination of resonance frequency of double clamped beams and strain gauge. In this way, both the residual stress and the residual strain can be measured independently, and Young’s modulus can be obtained by Hooke’s law. From these measurements, it has been observed that Young’s modulus depends on the thickness of the layer, the orientation, the doping, and the stress. Very good values of Young’s modulus were obtained in this work, even for very thin layers (thinner than 1 mm), and this can give the opportunity to realize very sensitive strain sensors.


Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3709
Author(s):  
M. M. Harussani ◽  
S. M. Sapuan ◽  
A. H. M. Firdaus ◽  
Yaser A. El-Badry ◽  
Enas E. Hussein ◽  
...  

In this study, the effects of various quantities of sorbitol and glycerol plasticizers (0%, 30%, 45%, and 60%) on cornstarch-based film were examined to develop a novel polymer for usage with biodegradable materials. The film was prepared using the casting process. According to the test findings, the application of the plasticizer concentrations affected the thickness, moisture content, and water absorption of the film. When plasticizer concentrations were increased to 60%, the tensile stress and Young’s modulus of plasticized films dropped regardless of plasticizer type. However, the thin film with addition of 30% sorbitol plasticizer demonstrated a steady value of Young’s modulus (60.17 MPa) with an increase in tensile strength (13.61 MPa) of 46%, while the lowest combination of tensile strength and Young’s modulus is the film that was plasticized with 60% glycerol, with 2.33 MPa and 16.23 MPa, respectively. In summary, the properties and performance of cornstarch-based film were greatly influenced by plasticizer types and concentrations. The finest set of features in this research appeared in the film plasticized with 30% sorbitol, which achieved the best mechanical properties for food packaging applications.


Author(s):  
Yung-Dong Lau ◽  
Hong Hocheng ◽  
Rongshun Chen ◽  
Weileun Fang

This study has successfully demonstrated a novel tensile testing approach to mount a thin film test specimen onto a MEMS instrument using microfabrication processes. The MEMS instrument consists of a thermal actuator, differential capacitance sensor, and supporting spring. The thermal actuator applies a tensile load on the test specimen to characterize the Young’s modulus and the residual stress of the thin film. As compare with the existing approaches, the problems and difficulties resulting from the alignment and assembly of a thin film test specimen with the testing instrument can be prevented. Furthermore, the parylene passivation technique with the MEMS fabrication process allows the user to change the test materials easily. In application, the present approach has been employed to determine the Young’s modulus and the residual stress of Au and Al films.


2014 ◽  
Vol 875-877 ◽  
pp. 1642-1646
Author(s):  
Jing Zhang

Alumina and zirconia are important materials for energy and optical applications. In this study, the effect of thermal cycling on grain size and residual stress was reported. Residual stress was measured using X-ray diffraction (XRD) sin2ψ method for the as-received and the samples after thermal cycling up to 900 cycles. For alumina, the measured residual stress is approximately 96 MPa in tensile for the as-received material, and increases to its highest value of 480 MPa after 650 thermal cycles. The residual stress decreases from 480 MPa to 96 MPa in tensile with increased thermal cycling from 650 to 900 cycles. The crystallized grain size calculated from the diffraction pattern shows that the mean crystallized grain size is about 93 nm for the as-received and increases to 232 nm after 650 thermal cycles. This result is consistent with the enlarged grain size observed by scanning electron microscopy for the alumina after 650 thermal cycles reported earlier. With continued thermal cycling up to 900 cycles, the crystallized grain size is greatly reduced to 104 nm. It suggests that evolution of the crystallized grain size is correlated with the residual stress. For yttria-stabilized tetragonal zirconia (Y-TZP), the mechanical properties at room temperature, are consistent with the property values provided by the manufacturer. The Young’s modulus of shows a non-linear inverse relationship with increasing temperature. The degradation of the Young’s modulus mostly occurs prior to 400 °C and to a less extent in the temperature range of 400 °C up to 850 °C. The Vickers hardness number for the as-received Y-TZP material decreases to a very small extent after 560 thermal cycles and increases approximately 2%, after 1200 thermal cycles. This is consistent with the trend of the Young’s modulus for thermal-cycled specimens.


Micromachines ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 801 ◽  
Author(s):  
Jaweb Ben Messaoud ◽  
Jean-François Michaud ◽  
Dominique Certon ◽  
Massimo Camarda ◽  
Nicolò Piluso ◽  
...  

The stress state is a crucial parameter for the design of innovative microelectromechanical systems based on silicon carbide (SiC) material. Hence, mechanical properties of such structures highly depend on the fabrication process. Despite significant progresses in thin-film growth and fabrication process, monitoring the strain of the suspended SiC thin-films is still challenging. However, 3C-SiC membranes on silicon (Si) substrates have been demonstrated, but due to the low quality of the SiC/Si heteroepitaxy, high levels of residual strains were always observed. In order to achieve promising self-standing films with low residual stress, an alternative micromachining technique based on electrochemical etching of high quality homoepitaxy 4H-SiC layers was evaluated. This work is dedicated to the determination of their mechanical properties and more specifically, to the characterization of a 4H-SiC freestanding film with a circular shape. An inverse problem method was implemented, where experimental results obtained from bulge test are fitted with theoretical static load-deflection curves of the stressed membrane. To assess data validity, the dynamic behavior of the membrane was also investigated: Experimentally, by means of laser Doppler vibrometry (LDV) and theoretically, by means of finite element computations. The two methods provided very similar results since one obtained a Young’s modulus of 410 GPa and a residual stress value of 41 MPa from bulge test against 400 GPa and 30 MPa for the LDV analysis. The determined Young’s modulus is in good agreement with literature values. Moreover, residual stress values demonstrate that the fabrication of low-stressed SiC films is achievable thanks to the micromachining process developed.


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