微型机电系统（MEMS）是面向21世纪的关键技术，微型机械的设计与制造在很大程度上取决于材料问题的解决。影响微型机械装置功能和可靠性的薄膜材料力学性能需要精确的评价。利用电磁力驱动，设计了一种微拉伸装置，从而精确地测定了长度为100-660μm，宽度为20-200μm，厚度为2.4μm的多晶硅薄膜的力学性能。结果表明，测得的平均弹性模量为164 GPa±1.2 GPa，与理论计算值相当。平均拉伸强度为1.36 GPa±0.14 GPa，其威布尔分布参量为10.4-11.7。统计分析表明，由于微结构和尺寸的约束使得多晶硅薄膜的拉伸强度表现出对微构件长度、表面积和体积的尺寸效应。拉伸强度随表面积与体积之比值增加而增加，这一比值可作为尺寸效应的控制参量。测试数据解释了微构件力学性能参量的离散性，并可用于多晶硅微机械的可靠性设计。最后，提出了应变设计准则，允许应变为0.0057。

The nanoindentation fracture of multilayer hard coatings of TiNrTi C,N.rTiC, Al2O3rTiCrTi C,N.rTiC, TiNrTi C,N.rTiCrTi C,N.rTiC and TiNrTi C,N.rTiCrTi C,N.rTiCrTi C,N.rTiC, deposited on cemented carbide using a CVD technique was studied. Based on an analysis of the energy released in cracking, the calculated fracture toughness values of these coatings were 2.18, 1.74, 3.40 and 3.90 MPa m1r2, respectively. Both load-penetration depth and loadl penetration depth squared plots have been demonstrated to be necessary if a more complete understanding of the coating system behaviour is to be gained. The interfacial failure and the critical load of interfacial failure of these coatings were also discussed. A step was found in the forcel displacement curves at the onset of coating fracture. A straight line segment in the oad-penetration depth squared curves was discussed. The hardness, fracture toughness and anti-wearability of these coatings were compared. The results show that the fracture toughness and anti-wearability are getting higher with the layers increasing.

Mechanical stability and sticking are troublesome problems in microfabrication and operation processes when the separations of components in microelectromechanical systems are in the sub-micrometre regime. Some hitherto neglected mechanical effects, including the quantum mechanical effect, should be taken into account for solving the problems. The magnitude of the Casimir force is significant when the membranes work in vacuum without the effect of capillary forces. In this paper, an analysis is presented of the influence of the Casimir effect with surface roughness, conductivity and temperature corrected on the deformation of a membrane strip structure. With nothing other than the Casimir force loading the strip, a stable static equilibrium state and an unstable static equilibrium state exist, depending on the value of a dimensionless constant K. The membrane strip will collapse if the value of K is larger than the critical value of KC. The critical value of KC varies with the value of wo. This provides a way to check if a system with given dimensions and material properties will be in a stable equilibrium. This also provides a way of designing a membrane strip with high resistance to collapse.

The validity of a novel, direct and convenient method for micromechanical property measurements by beam bending using a nanoindenter has been demonstrated. In the deflection of microbeams, the influence of the indenter tip pushing into the top of the microbeams and the curvature across its width must be considered. The elastic deflection of a polysilicon microcantilever beam will vary linearly with the force. Thus, Young's modulus of the beam determined from the slope of this linear relation is 156 Gpa 92.9-6.3%. The size effects of the manufactured component on Young's modulus and strength of polysilicon microcantilever beams were measured. This result shows that the rupture strengths of polysilicon beams show size effect on the effective volume and surface area of the specimens. The rupture strength of each sample decreased with increasing the specimen effective volume and surface area, but increased with increasing the surface-to-volume ratio. The defect that initiates fracture is often on the surface of the specimen. In such cases the size effect can be traced back to a surface-to-volume ratio as the governing parameter.

Mechanical stability and sticking are the troublesome problems in microfabrication and operation processes when separations of components in MEMS are in the sub-micrometer regime. Some mechanical effect, including quantum mechanical effect should be taken into account for solving the problems. The influence of capillary forces on sticking of a surface micromachined microcantilever in ambient environment or the rinse liquid and the influence of quantum mechanical effect such as the Casimir effect on sticking and stability of a micro membrane strip cavity structure in vacuum were investigated. A factual rough model theory about sticking problem under the Casimir effect was suggested for the first time. The study on the design of anti-sticking structures under different forces shows that sticking and stability of microcantilevers and micro membrane strip cavities has something to do with Young's modulus of materials, surface properties, length of structures, thickness of structures and separation between the fixed surface and the deflecting component. But, it is independent of width of structures. The map of the size design of anti-sticking structures was put forward for the first time. This also provides a way to design a MEMS structure with high resistance to collapse.