Research on Micro Machining Using AFM Diamond Tip
Research on Micro Machining Using AFM Diamond Tip
复制标题
DOI：
10.4028/www.scientific.net/kem.259-260.577
复制
发表时间：
2003-12
期刊：
影响因子：
--
通讯作者：
T. Sun;Yongda Yan;J. Xia;S. Dong;Yingchun Liang;K. Cheng
中科院分区：
文献类型：
--
作者：
T. Sun;Yongda Yan;J. Xia;S. Dong;Yingchun Liang;K. Cheng
本文采用AFM金刚石针尖进行微加工，该针尖类似于单个磨粒，具有高精度的加工阶段。采用机械划伤的方法，在单晶铜表面加工微结构。在此基础上进行了实验研究，分析了加工速度、作用力、进给量等参数对微加工过程的影响。研究了金刚石尖端状态对微加工的影响。采用优化的工艺参数和适当的加工工艺，对其进行了微结构加工。该方法是一种新颖的非常规微加工技术。它可以应用于微机械加工领域，如：MEMS微器件的加工、光刻掩模的加工、微零件的微加工以及其他方法加工的微零件的加工或修整。自1986年以来，STM作为一种重要的地面观测仪器被广泛使用。但随着扫描探针显微镜（SPM）研究的发展，SPM（包括AFM和STM）在表面改性方面的应用已经非常局限。特别是，AFM由于能够控制尖端与样品表面之间的力而受到许多研究者的研究。目前利用AFM普通量头进行微加工主要有两种方法：氧化和机械划伤。李文彬，戴宏杰，等。氧化法加工纳米线[1-2]。Hideki， S. Tegen和H. F. Chen使用机械划痕加工二维图形[3-5]。大多数研究人员使用金刚石尖端来研究微磨损。Ti Miyamoto， G. J. Zhao和R. Kaneko使用该方法研究了不同材料的微磨损特性[6-8]。在这些实验中，只加工了简单的形状，如方孔，以了解材料和划痕参数对磨损过程的影响。AFM金刚石针尖作为一种新型的加工方式，在纳米切削机构和微结构加工等领域得到了广泛的应用。T. Sumomogi和他的同事们用金刚石尖在Ni、Au和Cu表面进行了微加工实验。他们发现了影响金属材料在纳米尺度上微加工的几个因素。Jae-Mo Lee和他的同事开发了一个类似于AFM的系统。在此系统的基础上，他们使用金刚石尖进行了微加工。他们认为这种方法可以作为蚀刻前的工序，也可以作为微型零件模具加工的新方法。我们团队的Q. L. Zhao也进行了类似的研究。建立了金刚石尖端的理论模型。实验结果表明，采用该方法加工的表面替代层比常规抛光和磨削加工的表面替代层少[11-12]。本文采用AFM金刚石针尖和精密工作台进行微加工。进行了实验研究，分析了加工速度、作用力、进给量等参数对微加工过程的影响。研究了两种二维微结构的制备方法。研究了金刚石尖端状态对微加工的影响。最后，采用最优的加工参数和适当的加工工艺，加工出微结构。关键工程材料在线：2004-03-15 ISSN: 1662-9795， vol .259-260, pp 577-581 doi:10.4028/www.scientific.net/KEM.259-260.577©2004 Trans Tech Publications Ltd， Switzerland版权所有。未经Trans Tech Publications Ltd， www.scientific.net的书面许可，不得以任何形式或任何方式复制或传播本文的部分内容。[参考文献]磨削磨料加工技术的研究进展本文的微加工系统由AFM（3100尺寸）、高精度工作台和外接计算机组成。金刚石的尖端类似于单一的磨料。AFM可以精确地控制刀尖的状态，工作台的精度很高。因此，该系统可以进行微加工。AFM控制系统可以通过一些参数来调节针尖的状态。为了使AFM与舞台结合在一起，必须合理设置参数。设置为：扫描尺寸：0nm，扫描速率：1Hz，比例增益：2.0，积分增益：2.0，设定点：1.5 V， AFM处于接触模式。尖端保持在0纳米扫描尺寸。设定点决定垂直载荷。舞台在外部计算机的控制下移动。这两个部分配合合理，可以加工出规则的组织。工艺流程如下：首先，AFM对样品表面进行扫描，找到一个平坦的区域。在正确设置AFM参数后，由计算机控制工作台进行微加工。微加工后，通过减小设定值可以对加工区域进行成像。该系统的优点之一是能在微加工后及时成像。实验与讨论由于铜的硬度比大多数金属材料都要低，所以我们使用的材料是沉积在单晶硅表面的单晶铜（Cu）膜。而且金刚石尖端与铜之间的磨损很小。实验是在大气中进行的。首先研究了垂直载荷对加工深度的影响。在载荷作用下，如果尖端与表面的接触力大于材料的压缩屈服力，则试样表面会发生塑性变形。因此，施加在表面上的载荷必须大于产生塑性变形的载荷。我们在不同负载下加工方形口袋，进料量相同：100nm。测量深度。结果如图1所示。我们可以发现，当力大于65 μN时，深度与载荷成线性关系。当载荷过小时，金刚石尖不再使表面发生塑性变形。因此，在接下来的实验中，我们将垂直载荷设置为大于65 μN，以有效地进行微加工操作。通过实验，我们发现垂直于悬臂梁的进给量，也会影响方袋的深度。为了研究这一现象，我们做了以下实验：在相同垂直载荷（约100 μN）下，用不同的进给量加工方形袋。然后测量深度。结果如图2所示。我们可以发现，随着进给量的增加，深度减小。当进给量大于170 nm时，从三维图中我们可以看到没有口袋，只有浅槽。下面，我们将分析这一现象。在试样表面划痕一行时的针尖状态如图3所示。尖端的力平衡方程为：F= Fi。尖端承受来自两个切割刃和尖端底部的力。从这三个方向加入力平衡与0 20 40 60 80 100 120 140 66 80 95 109 124 138加载(联合国)M c h在g d e p th (n M)图1负载之间的关系和加工深度0 20 40 60 80 100 120 140 70 90 110 130 150 170饲料量纳米M c h在g d e p th (n M)图2饲料数量之间的关系和加工深度578磨削和研磨过程的进步
In this paper, micro machining is performed using AFM diamond tip, which is similar to a single abrasive particle, and a high precision stage. Using mechanical scratching, microstructures are machined on the surface of single crystal copper. Based on the system, some experiments are carried out: Parameters such as velocity of machining, applied force and amount of feed, which will influence process of micro machining, are analyzed. The diamond tip states influence on micro machining is also studied. And using the optimum parameters and proper machining technique, the microstructures are machined. This approach is a novel unconventional micro machining technology. It can be applied in some micro machining fields such as: MEMS micro devices fabrication, mask fabrication of lithography, micro-parts micro machining, and machining or dressing on the micro-parts fabricated by other ways. Introduction Since 1986, STM has been used as an important apparatus for surface observation. But with the development of Scanning Probe Microscope (SPM) research, SPM (including AFM and STM) has been applied in surface modification on a very localized region. Particularly, AFM is studied by many researchers because of its ability of controlling the force between the tip and the sample surface. Recently micro machining using AFM ordinary measuring tips has two main methods: oxidation and mechanical scratching. Won Bane Lee and H. Dai machined nano lines by oxidation [1-2]. Hideki, S. Tegen, and H. F. Chen machined two-dimensional figures using mechanical scratching [3-5]. Using diamond tip, most researchers investigated micro wear. Ti Miyamoto, G. J. Zhao and R. Kaneko investigated micro wear characteristics of different materials using this method [6-8]. Only simple figures such as square holes are machined in these experiments to find out the influence of material and scratching parameters on wear process. As a novel machining way, AFM diamond tip has been used as a cutting tool and it has been applied in the fields of nano cutting mechanism and microstructures fabrication. T. Sumomogi and his coworkers carried out the micro machining experiments using the diamond tip on surface of Ni, Au and Cu. They found out several factors influencing micro machining of metal materials on nano meter scale [9]. Jae-Mo Lee and his coworkers developed a system which is similar to AFM. Based on this system, they performed micro machining using diamond tip. And they thought that this way may be used as the procedure before etching or as a new method to machine moulds of micro parts [10]. Similar studies are also conducted by Q. L. Zhao of our team. The diamond tips theoretical model was established. And experiment results showed that the surface alterative layer using this method was less than that of surface machined by conventional polish and grinding [11-12]. In this paper, micro machining is performed using an AFM diamond tip and precision stage. Some experiments are carried out: Parameters such as velocity of machining, applied force and amount of feed, which will influence process of micro machining, are analyzed. Two fabrication methods of two-dimensional microstructures are investigated. The diamond tip states influence on micro machining is studied. Finally using the optimum parameters and proper machining technique, microstructures are machined. Experimental Setup Key Engineering Materials Online: 2004-03-15 ISSN: 1662-9795, Vols. 259-260, pp 577-581 doi:10.4028/www.scientific.net/KEM.259-260.577 © 2004 Trans Tech Publications Ltd, Switzerland All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications Ltd, www.scientific.net. (Semanticscholar.org-13/03/20,19:03:47) 578 Advances in Grinding and Abrasive Processes The micro machining system in this paper includes AFM (Dimension 3100), high precision stage and an external computer. The diamond tip resembles the single abrasive. AFM can control the tips state accurately and the stages precision is very high. So this system can perform micro machining. AFM control system can regulate the tips state through some parameters. In order to combine AFM with stage together, the parameters should be set properly. They are set as follows: scan size: 0nm, scan rate: 1Hz, proportional gain: 2.0, integral gain: 2.0, set point: 1.5 V, AFM is in contact mode. The tip is kept still by 0nm scan size. The set point decides the perpendicular load. The stage moves under the control of the external computer. These two parts cooperate reasonably and the regular microstructures can be machined. The process procedure is as follows: First, AFM scans on the surface of sample and finds a flat area. After setting AFM parameters properly, the stage is controlled by the computer to perform micro machining. After micro machining we can image the machined area by decreasing the set point value. One of advantages of this system is to image timely after micro machining. Experiments and Discussions The material we used is single crystal copper (Cu) film deposited on surface of single crystal silicon, because the coppers hardness is less than most metal materials. And wear between diamond tip and copper is very small. Experiments are carried out in atmosphere. First we investigate the influence of perpendicular loads on machining depth. Under the load, if the contact force between the tip and the surface is bigger than the materials compressive yield force, the surface of sample will deform plastically. So the load exerted on the surface must be bigger than the load which can make plastic deformation happen. We machine the square pockets under different loads with the same feed amount: 100nm. The depth is measured. The results are shown in Fig.1. We can find that when the force is bigger than about 65 μN, the depth is linear in respect to the load. If the load is too small, the diamond tip cant deform the surface plastically any more. So in following experiments, we set the perpendicular load bigger than 65 μN to perform micro machining operation effectively. Through experiments, we find that the feed amount perpendicular to the cantilever, also influences the depth of the square pocket. We do the following experiments to investigate this phenomenon: Under the same perpendicular load (about 100 μN), square pockets are machined with different feed amount. And then the depth is measured. The results are shown in Fig.2. We can find that the depth decreases as the feed amount increasing. When the feed amount is bigger than 170 nm, from the three-dimensional figure, we can find that no pockets but only shallow grooves can be seen. Below, we will analyze this phenomenon. The tip state during scratching one line on the surface of sample is shown in Fig.3. The force balance equation of the tip is: F= Fi. The tip bears the force from two cutting edges and the bottom of the tip. The join force from these three directions balances with the 0 20 40 60 80 100 120 140 50 66 80 95 109 124 138 Loads( uN) M a c h in in g d e p th ( n m ) Fig.1 Relation between load and machining depth 0 20 40 60 80 100 120 140 50 70 90 110 130 150 170 Feed amount nm M a c h in in g d e p th ( n m ) Fig.2 Relation between feed amount and machining depth 578 Advances in Grinding and Abrasive Processes