| 单晶硅脆塑转变临界厚度的原位实验 |
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| 作者姓名： | 刘冰 徐宗伟 李蕊 何忠杜 |
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| 作者单位： | 1.天津商业大学机械工程学院, 天津 300134 |
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| 基金项目： | 国家自然科学基金资助项目51805371天津市自然科学基金资助项目18JCQNJC75400天津市自然科学基金资助项目17JCZDJC38200 |
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| 摘 要： | 为提高单晶硅纳米切削表面质量的同时, 不影响加工效率, 以扫描电子显微镜高分辨在线观测技术为手段, 在真空环境下开展了单晶硅原位纳米切削实验研究.首先, 利用聚焦离子束对单晶硅材料进行样品制备, 并对金刚石刀具进行纳米级刃口的可控修锐.然后, 利用扫描电子显微镜实时观察裂纹的萌生与扩展, 分析了单晶硅纳米切削脆性去除行为.最后, 分别采用刃口半径为40、50和60 nm的金刚石刀具研究了晶体取向和刃口半径对单晶硅脆塑转变临界厚度的影响.实验结果表明: 在所研究的晶体取向范围内, 在(111)晶面上沿111]晶向进行切削时, 单晶硅最容易以塑性模式被去除, 脆塑转变临界厚度约为80 nm.此外, 刀具刃口半径越小, 单晶硅在纳米切削过程中越容易发生脆性断裂, 当刀具刃口半径为40 nm时, 脆塑转变临界厚度约为40 nm.然而刀具刃口半径减小的同时, 已加工表面质量有所提高, 即刀具越锋利越容易获得表面质量高的塑性表面.
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| 关 键 词： | 单晶硅 脆塑转变 在线观测 晶体取向 刃口半径 |
| 收稿时间： | 2018-02-24 |
In-situ experiment on critical thickness of brittle-ductile transition of single-crystal silicon |
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| Affiliation: | 1.School of Mechanical Engineering, Tianjin University of Commerce, Tianjin 300134, China2.School of Precision Instrument & Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China |
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| Abstract: | Single-crystal silicon is widely used in optoelectronics and micro-electromechanical systems because of its unique physical and chemical properties. Ductile-mode removal of single-crystal silicon can be realized by strictly controlling the cutting parameters, which significantly affect the machining efficiency. To improve the surface quality without reducing the machining efficiency, nanometric cutting experiments were performed using high-resolution scanning electron microscopy (SEM) with online observation. First, the samples were prepared, and the nanometric cutting edge of a diamond cutting tool was fabricated by focused ion beam (FIB) technology. Then, the initiation and propagation of the micro cracks were observed online by scanning electron microscopy to analyze the machining behavior of single-crystal silicon in brittle mode. Finally, using diamond cutting tools with edge radii of 40, 50, and 60 nm, respectively, the effects of crystal orientation and tool edge radius on the critical thickness of brittle-ductile transition of single-crystal silicon were studied. The experimental results show that in the presently studied crystal orientations, single-crystal silicon is most easily removed in the ductile mode along the111] direction on the (111) plane, where the critical thickness of brittle-ductile transition is about 80 nm. In addition, the smaller the tool edge radius is, the more prone is the single-crystal silicon to brittle fracture in the nanocutting process. When the tool edge radius is 40 nm, the critical thickness of brittle-ductile transition is about 40 nm. However, the machined surface quality increases with decrease of the tool edge radius. This indicates that the sharper the cutting tool, the easier it is to obtain a high-quality surface. |
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