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ABSTRACT: We developed a quasi-static tensile test system that controls environmental conditions, such as pressure, temperature, and surrounding gasses. Using this system, we evaluated the fracture properties of micron- and submicron-thick single-crystal-silicon film under several conditions. The strength of silicon measured in vacuum or helium was slightly higher than that in laboratory air. We measured the fracture toughness at different temperatures ranging from room temperature (RT) to 500degC and found a brittle-to-ductile transition at 70degC for micron-sized silicon film. The fracture toughness drastically increased at the transition temperature and saturated at a level of 2.5 MParadicm, which is twice the value at RT. On the other hand, submicron-thick silicon was less brittle: its fracture toughness was already 2.7 MParadicm at RT.
Solid-State Sensors, Actuators and Microsystems Conference, 2007. TRANSDUCERS 2007. International; 07/2007
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ABSTRACT: In order to improve the reliability of Micro-electro-mechanical Systems (MEMS) designs, evaluations of the mechanical properties of soft magnetic materials are needed. In this paper, we present a tensile testing method to characterize the mechanical properties of microscale electroplated permalloy (80 wt% Ni, 20 wt% Fe) films. The gauge section of the specimen is 50 mum wide, 100 long and 5 mum thick. The measured Young's modulus of permalloy films is 113 GPa, and the tensile strength is 1.57 GPa. Both the properties are lower than those of thick permalloy films. The fracture strain measured by the images of specimens is about 2%.
Solid-State Sensors, Actuators and Microsystems Conference, 2007. TRANSDUCERS 2007. International; 07/2007
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ABSTRACT: We performed tensile tests on single-crystal-silicon film at temperatures ranging from RT (room temperature) to 600°C. We made notched specimens by using a focused ion beam (FIB) process. The fracture toughness did not change from room temperature to 60°C. However, between 60°C and 80°C, it rapidly increased to almost double that at room temperature, and it saturated at temperatures higher than 80°C. Some specimens tested at 150°C and 300°C showed the nonlinear relationships between stress and strain. Shapes of the fractures that occurred from 80°C to 600°C were clearly different from the fracture shape at 60°C. These results suggest that dislocation motion occurred even at low temperatures near 80°C.
Micro-NanoMechatronics and Human Science, 2005 IEEE International Symposium on; 12/2005
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ABSTRACT: The fracture toughness of single-crystal silicon thin films oriented to (100) and (110) was investigated by tensile testing under both 〈100〉 and 〈110〉 loading conditions. The specimen was fabricated from a p-type Czochralski (CZ)-grown wafer and passed through a thermal process during the fabrication of the test device. The measured fracture toughness is dependent on the loading direction in the tensile test and independent of the specimen surface orientation. The test results were 1.94 MPa√m in the 〈100〉 direction and 1.17 MPa√m in the 〈110〉. In these tests, no longitudinal size effect on the fracture stress or fracture toughness was observed. The SEM photographs obtained from the fracture specimens after the tensile test show that the crack initiated from the notch tip and propagated straight in the across-the-width direction on the (110) or (111) cleavage plane.
Fatigue & Fracture of Engineering Materials & Structures 06/2005; 28(8):687 - 694. · 0.85 Impact Factor
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ABSTRACT: This paper presents the dependence of fracture toughness, fracture strength, and fracture behavior, such as crack propagation, on the crystal orientation of single-crystal silicon. We conducted on-chip tensile testing to measure fracture strength and fracture toughness of single-crystal silicon films with [100] and [110] surface in the <100> and <110> loading direction. The loading direction had a significant effect on fracture toughness, which was 2.17 MPa√m in the <100> direction and 1.27 MPa√m in <110>. However, the fracture stress varies with both loading direction and surface orientation. We observed a fracture specimen on which a [111] cleavage plane eventually appeared on any crystal types of the specimen.
Micro Electro Mechanical Systems, 2004. 17th IEEE International Conference on. (MEMS); 02/2004
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ABSTRACT: We developed a method of measuring the fracture toughness,-which is a material constant in the macroscopic domain, of single crystal silicon on a micrometer-scale. We notched the thin film specimen on a single edge and then conducted uniaxial tensile test to failure. The average value of measured fracture toughness of specimens on the (100) plane was 1.58 MPa·m<sup>1</sup>2/ with scatter. This is slightly higher than, but comparable to, the value for bulk silicon. Scanning electron microscope (SEM) observation of the failed specimens revealed that the fracture developed mainly along the [110] cleavage plane.
TRANSDUCERS, Solid-State Sensors, Actuators and Microsystems, 12th International Conference on, 2003; 07/2003
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ABSTRACT: The proposed method for testing the uniaxial tensile
characteristics of thin film materials is integrated onto a silicon
chip. The developed process for fabricating the test chips starts with
SOI wafers whose top silicon layer is prepared for the test materials.
The results of testing single-crystal silicon films having orientations
of 〈100〉, 〈110〉, and 〈111〉 were compared
with those from bending tests of bulk silicon. The measured Young's
moduli and fracture strains clearly showed orientation dependence, and
the measured values were reasonable compared with those of the bulk
materials. The fracture strains varied from 0.4 to 2.2% depending on the
orientation and were the lowest in the 〈111〉 direction
Micromechatronics and Human Science, 1997. Proceedings of the 1997 International Symposium on; 02/1997
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ABSTRACT: Here presented a work for investigating the fracture behavior of single crystal silicon film having a notch of sub-micron-length by tensile test. The specimens are 5 μm thickness, 100 μm length and 50 μm width, with different surface orientations and tensile direction. A focused ion beam (FIB) process was used to form a notch on one edge of the specimen and the notch size ranged from 0.1 to 1.0 μm. The fracture behavior of the specimens showed variety in this test. The fracture toughness, K<sub>IC</sub>, in the plane strain state, was constant for notch length above 0.5 μm, approximately 1.0 and 2.0 MPa·√m for the <110> and <100> tensile axes, respectively. On the other hand, when the notch length is below 0.5 μm, it is scattered and the specimen untidily fractured, indicating size limitation effect of notch. And the preferred fracture orientations also showed anisotropy when notch length is above 0.5 μ, i.e., on {110} plane in the <110> direction, or on {1111} plane in the <112> direction, initiated from notch tips.
Micro-Nanomechatronics and Human Science, 2004 and The Fourth Symposium Micro-Nanomechatronics for Information-Based Society, 2004. Proceedings of the 2004 International Symposium on;
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ABSTRACT: A tensile-testing system that allows tests at elevated temperature was developed. Using this system, we evaluated the mechanical properties of micro-scale single-crystal silicon film at 573 K. The silicon test specimens had a surface orientation of (100), and a tensile direction of <110>, The average measured Young's modulus and fracture stress were 144 GPa and 5.19 GPa, respectively, at 573 K. At room temperature, Young's modulus and fracture stress were 137 GPa and 4.89 GPa. These similar values show that the mechanical properties of single-crystal silicon film hardly change at 573 K compared to room temperature.
Micro-Nanomechatronics and Human Science, 2004 and The Fourth Symposium Micro-Nanomechatronics for Information-Based Society, 2004. Proceedings of the 2004 International Symposium on;
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ABSTRACT: This paper proposes a multifunctional tactile sensor device driven by magnetic force. The device has the advantage that it can detect multiple physical values, such as contact-force and the elastic and damping coefficients of a contacted object. We previously used an external pneumatic system for actuating the device, and confirmed it can measure the elastic-coefficient of an object. This time, we realized hybrid active tactile sensor system by assembling a magnetic driving mechanism for detecting multiple physical values. We also developed a theoretical model of the detection, and experimentally confirmed both elastic and damping coefficient detection by using different types of silicone rubbers as samples.
Micro Electro Mechanical Systems, 2005. MEMS 2005. 18th IEEE International Conference on;
