Neon Focussed-Ion-Beam Nanofabrication

我们的愿景是创建一个国家的最先进的三维纳米加工设施的电子，光子和纳米流体设备的发展，基于氖聚焦离子束（FIB）仪器。它将通过提供特征尺寸低于10 nm的设备的快速原型设计，改变英国科学和工程界的纳米制造能力。通过使用氖作为主要离子种类，与传统的镓离子FIB相比，采样中毒效应将从根本上降低。氖束还允许硅的高质量纳米级加工，这对于最近引入的氦离子FIB是不可能的。此外，溅射速率（最终限制产量）比氦离子高一个数量级，允许在实验室时间尺度内加工大量材料。在过去的二十年中，FIB已成为研究实验室的主要纳米制造工具。它特别适合于研究环境，因为原型设备可以非常快速地创建，而无需进行广泛的工艺开发。然而，商业FIB系统的阿喀琉斯之踵是（直到最近）它们都使用镓离子。这些镓离子一旦被（可移除地）注入到纳米制造的样品中，其反应性和高迁移率通常导致有害的样品中毒效应。例如，功能氧化物中的相关电子系统的性质密切依赖于氧的化学计量和顺序;在大多数氧化物中，这些不可逆地被Ga离子扰动。类似地，等离子体纳米孔中的光学损耗受到对Ga离子研磨的电介质造成的损伤的限制。此外，纳米电子器件的电学性能也直接受到Ga注入的影响。卡尔蔡司认识到这些限制，五年前发布了一种新的FIB显微镜，其中Ga源被氦气场离子源（GFIS）取代。相对于Ga的主要优点是离子种类现在是惰性气体，从而一举消除了样品中毒问题。因此，氦GFIS FIB显微镜是场发射扫描电子显微镜成像应用的竞争对手。然而，使用氦的明显缺点是，对于He离子，溅射产率（即，通过入射离子去除材料的速率）通常比对于Ga离子小30倍。这大大增加了制造时间，使得He离子不适合许多应用。这自然意味着在GFIS中使用较重的惰性气体，卡尔蔡司现在正在通过其新的氖GFIS FIB系统实现这一机会。(This产品计划于2012年9月发布。）氖离子的溅射产率通常是He离子的10倍。对于纳米纤维应用，氖的使用代表了快速制造和最小中毒的理想组合。在卡尔蔡司的开发实验室展示的纳米纤维显示加工分辨率优于10纳米。这可与现有技术的电子束光刻技术相媲美，具有快速原型制作的附加优势和三维纳米图案化的可能性（因为FIB是一种无抗蚀剂技术，允许光束相对于样品表面以任意角度对准）。

Our vision is to create a state-of-the-art three-dimensional nanofabrication facility for development of electron, photonic and nanofluidic devices, based on the neon focussed-ion-beam (FIB) instrument. It will transform the nanofabrication capabilities of the UK science and engineering community by offering rapid prototyping of devices with feature sizes below 10 nm. By using neon as the primary ion species, sampling poisoning effects will be radically reduced by comparison with conventional gallium-ion FIB. Neon beams also permit high-quality nanoscale machining of silicon, which is not possible with the recently-introduced helium-ion FIB. Furthermore sputtering rates (which ultimate limit throughput) are an order of magnitude higher than with helium ions, allowing significant volumes of material to be machined within laboratory timescales.Over the last twenty years, FIB has become a dominant nanofabrication tool for research labs. It is particularly well suited to the research environment since prototype devices can very quickly be created without the need for extensive process development. The Achilles heel of commercial FIB systems, however, is that (until recently) they all use gallium ions. The reactivity and high mobility of these gallium ions once they have been (unavoidably) implanted into a nanofabricated sample often leads to deleterious sample poisoning effects. For example, the properties of correlated electron systems in functional oxides intimately depend upon the oxygen stoichiometry and order; in most oxides these are irreversibly perturbed by Ga ions. Similarly the optical losses in plasmonic nano-apertures are limited by the damage done to the Ga-ion-milled dielectric. Furthermore, the electrical properties of nanoelectronic devices are also directly affected by Ga implantation. Recognising these limitations, Carl Zeiss released a new FIB microscope five years ago in which the Ga source is replaced by a helium gas field-ion source (GFIS). The main advantage over Ga is that the ion species is now an inert gas, thereby removing the sample poisoning problem at a stroke. The helium GFIS FIB microscope is therefore a rival to the field-emission scanning electron microscope for imaging applications. The obvious disadvantage of using helium, however, is that the sputter yield (i.e. the rate at which material is removed by incident ions) is typically 30 times smaller for He ions than for Ga ions. This greatly increases the fabrication time, rendering He ions unsuitable for many applications.This naturally suggests the use of heavier inert gases in the GFIS, an opportunity which Carl Zeiss are now realising with its new neon GFIS FIB system. (This product is scheduled to be released in September 2012.) The sputter yield for neon ions is typically ten times greater than that for He ions. For nanofabrication applications the use of neon represents an ideal combination of rapid fabrication and minimal poisoning. Demonstrations of neon-ion nanofabrication at Carl Zeiss's development laboratory show machined resolution better than 10 nm. This rivals that obtainable with state of the art electron-beam lithography, with the added advantages of rapid prototyping and the possibility (since FIB is a resist-less technique, allowing the beam to be aligned at an arbitrary angle with respect to the sample surface) of three-dimensional nanopatterning.