Micro-machining of metal surfaces by scanning probe microscope

首先，我们构建了一个用于微加工研究的扫描探针显微镜（SPM）系统。SPM系统由SPM单元、气氛控制装置和测量/控制系统组成。SPM单元具有测量侧向力图像和法向力图像的机构。其次，我们研究了空气中纯金属表面的微加工SPM，该SPM在悬臂梁的末端安装了一个非常锋利的金刚石尖端。采用气相沉积或机械抛光法制备了镍、铜、金等纯金属样品。用x-y扫描在0.5-3 μ m x方向宽度和0.5-20 μ m N载荷下对样品表面进行划伤，用同一SPM在小于0.1 μ m N载荷下观察划伤区域的形貌。在Ni表面得到了5 ~ 50nm深度的扁平方形空洞，而在Cu和Au表面则观察到由去除的材料粘附而形成的脊状空洞。此外，在Ni的情况下，随着加载力的增加和划痕重复次数的增加，划痕深度增加。划痕深度也与x方向扫描线的数量密切相关，而与x方向扫描速率和x-y方向扫描宽度关系不大。结果表明，纳米级厚度的材料去除是可控的。金属的塑性、粘接性能和氧化表面等因素决定了微加工的机理。本文提出的方法对各种材料的微加工具有强大的应用价值。

First, we constructed a scanning probe microscope (SPM) system for micromachining studies. The SPM system consists of a SPM unit, an atmosphere control apparatus and a measuring/controlling system. The SPM unit has a mechanism which can measure the lateral force images as well as the normal force images.Secondly, we studied micro-machining of pure metal surfaces in air by the SPM that has a very sharp diamond tip mounted on the end of a cantilever beam. Samples of pure metals, such as Ni, Cu and Au, were prepared by vapor deposition or mechanical polishing of bulk metals. Sample surfaces were scratched with x-y-scanning of 0.5-3 mu m x-direction width and 0.5-20 mu N loading force, and topographies of the scratched area were observed by the same SPM with a loading force of less than 0.1 muN.Flat square hollows of 5-50 nm depth were obtained on Ni, although the ridge caused by the adhesion of removed materials were observed on Cu and Au. In the case of Ni, moreover, the scratched depth is increased with increasing loading force and repetition numbers of scratching. The scratched depth is also strongly dependent on numbers of x direction scan line, but scarcely on x direction scan rate and x-y direction scan width. Results obtained indicate that the nano-scale thickness material removal can be controlled. The mechanism of micro-machining should be determined by several factors such as plasticity, adhesive property and oxide surface of metals. The method presented here will be powerful for micro-machining of various materials.