Research on Testing Methods for Micro-fatigue strength of Micro-Nano Devices.

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Micro-and nano-tecnology will play a very important roll in the field of IT, medical technology, biotechnology and so on as a key technology for a new innovation and social development. Though many researches has been done to build in new functions to micro-and nano-devices, a few fundamental studies on mechanical properties of micro-and nano-material has been done for the reliability of micro devices. The purpose of our researches is (1) to make a testing machine for measuring the mechanical properties of micro-material and micro devices, (2) to collect data of mechanical properties of micro-materials and enable to use the materials with high reliability.As a research of first step, we made a fatigue and strength testing machine in bending using micro-machine fabrication technology of Si single crystal photo lythography. The features of the testing machine are as follows. (1) Measuring and control of very small weight loading can be done by voltage control because a comb type actuator of static electricity is applied. (2) The shape of the loading actuator can be a pair of tweezers which enable the test of fluctuating stress of reverse type. (3) The testing machine and the specimen are separate type, which enable the test of any material. (4) The test can be done in a scanning microscope, which enable the test of micro-and nano-material.The performance of the testing machine is as follows. (1)Loading weight is 0.0005N〜0.005N. (2)Loading deflection is 14 micron. (3)Fluctuating frequency is 10KHz.Using the testing machine fatigue test of Si single crystal of 50μ^W×5μ^T were carried out. 8 specimen were tested in repeated stress cycle with maximum stress 0.0025〜0.005N and the frequency 50He〜3KHz. Specimen were failed after fluctuating number 5×10^5〜9×10^5 without any trouble in testing machine.