Scanning probe tip geometry optimized for metrology by focused ion beam ion milling
Scanning probe tip geometry optimized for metrology by focused ion beam ion milling
复制标题
通过聚焦离子束离子铣削优化扫描探针尖端几何形状以进行计量
DOI：
10.1116/1.585846
复制
发表时间：
1991
影响因子：
1.4
通讯作者：
P. Russell
中科院分区：
文献类型：
--
作者：
M. Vasile;D. Grigg;J. Griffith;E. Fitzgerald;P. Russell
我们已经开发出一种新的技术，用于生产尖端扫描探针显微镜。尖端的形状针对高纵横比表面形貌是标准的应用进行了优化，如集成电路结构。该技术涉及聚焦离子束（FIB）铣削的尖端，这是以前的形状，以标称几何形状的电化学蚀刻。离子铣削图案是环形的，并且离子束与尖端的轴线共线。该过程允许使用20 keV Ga+的离子铣削剂量的控制与亚微米控制的环形图案。结果是一个窄的锥形结构，长度约为20 μm，当晶粒主导溅射过程时，其终止于曲率半径在30和50 nm之间的点，当没有晶粒结构效应的证据时，曲率半径约为3-4 nm。该微结构在基部处的直径为3 μm，并且其从宏观结构的柄部的直径为约15 μm的部分突出。我们对溅射过程有足够的控制，以产生最终的尖端长度、锥度和半径。通过正确选择环和离子剂量，可以常规地实现从顶点开始的前两微米的12°和15°之间的锥角。溅射模拟预测最终尖端轮廓的正确形状，并示出了改变离子束焦点、剂量以及内外环半径的效果。具有所需几何形状的尖端已由多晶钨、铱和铂铱制成。在扫描尖端显微镜（STM）图像的显着改善已经一致地观察到这些FIB研磨尖端。
We have developed a novel technique for producing tips for scanning probe microscopy. The shape of the tip is optimized for applications where high aspect ratio surfacetopography is the norm, as with integrated circuit structures. The technique involves focused ion beam(FIB)milling of a tip which was previously shaped to a nominal geometry by electrochemical etching. The ion milling pattern is annular, and the ion beam is collinear with the axis of the tip. The process allows control of the ion milling dose using 20 keV Ga+ with submicron control of the annular patterns. The result is a narrow, tapered structure approximately 20 μm in length which ends in a point with a radius of curvature between 30 and 50 nm when grains dominate the sputter process, and radii of about 3–4 nm when there is no evidence of grain structure effects. This microstructure is 3 μm in diameter at the base and it protrudes from a portion of the shank of the macrostructure where the diameter is about 15 μm. We have sufficient control over the sputter process to yield the final tip length, taper, and radius. Cone angles between 12° and 15° over the first two microns from the apex can be achieved routinely, by the correct choice of annulus and ion dose. Sputter simulations predict the correct shape of the final tip profile, and show the effect of varying the ion beam focus, dose, and inner and outer annulus radii. Tips with the desired geometry have been produced in polycrystalline tungsten, iridium, and platinum‐iridium. Significant improvements in scanning tip microscopy(STM) images have been consistently observed with these FIB milled tips.