Development of Versatile Mechanical Testing Machine for Sub-Micro-Sized Specimens

微（或纳米）机电系统（MEMS/NEMS）有望应用于微光子学和生物医学设备，如用于电光通信的光开关和用于脑外科手术的微导管。在这样的装置中使用的部件的尺寸被认为是亚微米至微米的量级。因此，微尺寸材料的力学性能的评估是必不可少的，这样的MEMS/NEMS器件的实际应用。特别是，断裂和疲劳性能的微尺寸的组件是至关重要的实际MEMS/NEMS设备的结构完整性和长期可靠性。为了评价这种亚微米尺寸试样的断裂和疲劳性能，我们已经开发了一种新型的亚微米尺寸试样的机械试验机，它可以施加少量的静态和循环载荷到试样。利用聚焦离子束加工技术，在薄膜表面制备了悬臂梁型亚微米缺口试样。使用该试验机进行了疲劳裂纹扩展和断裂试验。我们能够测量试样的断裂韧性、疲劳寿命和疲劳裂纹扩展速率。这台试验机对于确定MEMS/NEMS应用中亚微米尺寸试样的断裂和疲劳性能非常有用。

Micro (or nano) electromechanical systems (MEMS/NEMS) are expected to be applied to micro-photonics and bio-medical devices such as optical switches for electro-optical communications and micro-catheters for brain surgery. The size of the components used in such devices is considered to be in the order of submicrons to microns. Therefore, the evaluation of mechanical properties of micro-sized materials are essential for practical applications of such MEMS/NEMS devices. In particular, the fracture and fatigue properties of micro-sized components are of crucial importance to the structural integrity and long-term reliability of actual MEMS/NEMS devices. In order to evaluate fracture and fatigue properties of such submicro-sized specimens, we have developed a new type mechanical testing machine for submicro-sized specimens, which can apply small amount of static and cyclic loads to the specimens. Cantilever beam type submicron-sized specimens with notches were prepared from thin films by focused ion beam machining. Fatigue crack growth and fracture tests were carried out using the testing machine. We were able to measure fracture toughness, fatigue life and fatigue crack growth rate of the specimens. This testing machine is extremely useful for determing fracture and fatigue properties of submicron-sized specimens for MEMS/NEMS applications.