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Strength Evaluation of Single Crystal Silicon Microelements and Related Micromaterials

单晶硅微元及相关微材料的强度评价

基本信息

批准号：
12555025
负责人：
MINOSHIMA Kohji
金额：
$ 8.64万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12555025/
关键词：
Micro Materials Microelements Fracture Fatigue Water Environment Notch Environmental Strength Environmental Strength under Dynamic Loading Conditions 微小材料引張試験結晶方位 Si単結晶

项目摘要

In order to develop a reliable micromachine in a service operation, much care must be taken to micro mechanical evaluation, i.e., mechanical properties of μm-sized microelements. However, the evaluation method has not been well established. In this research project, the fracture behavior is investigated in the micromaterials for the micromachines and micro-electro mechanical system, including single crystal silicon. This will help us establish design criteria and life assessment methods for micromachines. The materials investigated were single-crystal silicon, poly-silicon film, and high-purity vitreous silica fiber. In this investigation, micro-mechanical testing machine is newly developed, and tensile testing of micro samples is thereby possible. The tensile strength of the poly-silicon films is about 0.9 GPa for the width of 10 μm, whereas the strength of the microsample with 5 μm is about 3.7 GPa, which are very strong compared with the structural materials for the ordinary sized machines and structures. Single-crystal silicon is immune to fatigue fracture and stress corrosion in laboratory air. However, the fracture behavior is sensitive to the water environment, and the synergistic effects of water environment and the dynamic stress caused a decrease in strength. Nanoscopic observation of the crack initiation site shows that the nanometric crack is formed on the surface owing to water and the dynamic loading, and the crack nucleation mechanisms are discussed. On the other hand, the influence of water environments on the fracture behavior is investigated in a high-purity vitreous silica fiber. Silica fiber is reported to be sensitive to water, and the static strength is decreases when the tests are conducted in water. However, when the impurity elements are decreased, the static strength is not influenced by water environment, indicating that the resistance to water environment is increased by a decrease in the impurity element in the vitreous silica fiber.

为了在服务操作中开发可靠的微机械，必须非常注意微机械评估，即，微米尺寸的微元件的机械性能。然而，评价方法尚未很好地确立。本研究计画主要针对微机械与微机电系统所需之微材料，包括单晶硅，探讨其断裂行为。这将有助于我们建立微机械的设计标准和寿命评估方法。所研究的材料是单晶硅、多晶硅薄膜和高纯石英玻璃纤维。本研究开发了一种新型的微机械试验机，使微试样的拉伸试验成为可能。对于10 μm的宽度，多晶硅薄膜的抗拉强度约为0.9GPa，而5 μm的微样品的抗拉强度约为3.7GPa，与普通尺寸的机器和结构的结构材料相比，这是非常强的。单晶硅在实验室空气中不受疲劳断裂和应力腐蚀的影响。但其断裂行为对水环境较为敏感，水环境和动应力的协同作用导致强度下降。对裂纹萌生位置的纳米观察表明，由于水和动载荷的作用，裂纹在表面形成纳米尺度的裂纹，并对裂纹的成核机制进行了讨论。另一方面，在高纯度玻璃石英纤维中研究了水环境对断裂行为的影响。石英纤维对水敏感，在水中测试时，其静强度降低。然而，当杂质元素减少时，静强度不受水环境的影响，这表明通过玻璃石英纤维中杂质元素的减少而提高了对水环境的耐性。