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

微纳技术作为一种新的创新和社会发展的关键技术，将在信息技术、医疗技术、生物技术等领域发挥非常重要的作用。虽然人们已经做了很多研究来为微纳米器件增加新的功能，但对微纳米材料的力学性能的研究很少，这是为了提高微器件的可靠性。本课题的研究目的是：（1）研制一台用于测量微材料和微器件力学性能的试验机;（2）收集微材料的力学性能数据，使材料具有较高的可靠性。作为第一步的研究，我们利用硅单晶光刻的微机械加工技术研制了弯曲疲劳强度试验机。试验机的特点如下。(1)由于采用了梳齿式静电执行器，因此可以通过电压控制来完成非常小重量负载的测量和控制。(2)加载致动器的形状可以是一对镊子，其能够测试反向类型的波动应力。(3)试验机和试样是分离式的，可以对任何材料进行试验。(4)该试验机可在扫描显微镜下进行，使微纳米材料的测试成为可能。（1）加载重量为0.0005N <$0.005N。（2）加载挠度为14微米。（3）采用10 KHz的脉动频率，对50μ^W×5μ^T的硅单晶进行了疲劳试验。对8个试件进行了最大应力0.0025 ~ 0.005N、频率50 He ~ 3 KHz的重复应力循环试验。试样在试验机上连续波动5×10^5 ~ 9×10^5次后失效，无任何故障。

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.