Some observations on the wear of diamond tools in ultra-precision cutting of single-crystal silicon
Some observations on the wear of diamond tools in ultra-precision cutting of single-crystal silicon
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DOI：
10.1016/s0043-1648(03)00076-0
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发表时间：
2003-08-01
期刊：
影响因子：
5
通讯作者：
Tamaki, J
中科院分区：
文献类型：
--
作者：
Yan, JW;Syoji, K;Tamaki, J
单晶硅不仅是制造微电子和微机械元件的主要衬底材料，而且是一种重要的红外光学材料。由于硅是一种名义上的脆性材料，目前它是通过研磨、研磨和化学机械抛光（CMP）来完成的。然而，在高静水压力的影响下，硅在加工过程中会发生塑性变形，产生韧性切屑。因此，另一种方法是在韧性模式下用单点工具加工硅，而不需要后续的抛光。这种方法可以最大限度地减少由于脆性断裂造成的损伤，并可以显著提高复杂形状部件的生产率。这项技术涉及到使用一个极其刚性的、超精密的机床和一个具有高负前角的单晶金刚石工具。然而，延性加工技术在工业应用中存在的问题之一是金刚石刀具的磨损。刀具磨损不仅提高了加工成本，而且降低了产品质量。在加工大半径零件时，刀具磨损问题尤为严重。本文研究了在小于1 μ m的加工规模下，金刚石刀具在单晶硅衬底单点金刚石车削中的性能。利用扫描电子显微镜（SEM）对切削刃、成品表面和切削屑进行了观察，并测量了微切削力。结果表明，刀具的磨损大致可分为微屑磨损和渐进式磨损两种类型，主要的磨损机制取决于未变形的切屑厚度。在韧性模态切削中，侧翼磨损为主，侧翼磨损地以微沟槽和阶梯结构为特征。刀具磨损使加工表面产生微断裂，产生不连续切屑，提高切削力和切削力比。实验结果还表明，采用适当的冷却剂可以延长延性切削距离。(C) 2003 Elsevier Science B.V.版权所有
Single-crystal silicon is not only a dominant substrate material for the fabrication of micro-electro and micro-mechanical components but also an important infrared optical material. Since silicon is a nominally brittle material, currently it is finished by grinding, lapping and chemo-mechanical polishing (CMP). However, silicon can be deformed plastically in machining, yielding ductile chips under the influence of high hydrostatic pressure. Therefore, an alternate approach would be to machine silicon with a single point tool in the ductile mode without the need for subsequent polishing. This way damage due to brittle fracture can be minimized and the productivity of complex-shaped components can be significantly improved. This technology involves the use of an extremely rigid, ultra-precision machine tool and a single-crystal diamond tool with a high negative rake angle. However, one of the problems existing in the industrial application of the ductile machining technology is the wear of diamond tools. Tool wear not only raises the machining cost but also degrades the product quality. The tool wear problem becomes particularly serious when machining large radius components. This paper deals with the performance of diamond cutting tools during single point diamond turning of single-crystal silicon substrates at a machining scale smaller than 1 mum. The cutting edge, the finished surface and the cutting chips were examined by scanning electron microscope (SEM) and the micro-cutting forces were measured. It was found that the tool wear could be generally classified into two types: micro-chippings and gradual wear, the predominant wear mechanism depending on undeformed chip thickness. In ductile mode cutting, flank wear was predominant and the flank wear land was characterized by trailing micro-grooves and step structures. The tool wear causes micro-fracturing on machined surface, yields discontinuous chips and raises cutting forces and force ratio. Experimental results also indicate that it is possible to prolong the ductile cutting distance by using an appropriate coolant. (C) 2003 Elsevier Science B.V. All rights reserved.