Research & Development Group, Hitachi, Ltd.,1-280 Higashi-Koigakubo, Kokubunji, Tokyo 185,Japan.
Microsc Microanal. 2019 Feb;25(1):105-114. doi: 10.1017/S1431927618016227. Epub 2019 Jan 30.
A scanning ion beam instrument equipped with a gas field ionization source (GFIS) has been commercialized, but only helium and neon are currently available as GFISs. In this study, the characteristics of neon, argon, and krypton ion emissions from a single-atom tip are compared, specifically for faster fabrication by milling of a silicon sample. Although the boiling point of argon is about 87 K, our experiments on characterizing argon ion emission can be carried out at temperatures of about 50 K at an argon gas pressure lower than 0.1 Pa. Argon exhibits ion current characteristics, as a function of tip voltage, between those of neon and krypton. The value obtained by multiplying the ion emission current by the sputtering yield is suitable for a figure of merit (FOM) for faster fabrication. The FOM for argon is the highest among the three ion species. This value must be extensively evaluated from the viewpoint of practical nano-fabrication application. The instabilities of neon, argon, and krypton ion currents (3σ) become as low as 8% in 1 h, which is sufficient for fabrication applications. We conclude that an argon or krypton GFIS ion beam instrument will be a useful tool for nano-fabrication.
一种配备气体场电离源 (GFIS) 的扫描离子束仪器已经商业化，但目前 GFIS 仅可使用氦气和氖气。在这项研究中，我们比较了单个原子针尖发射的氖气、氩气和氪气离子的特性，特别是针对通过硅样品铣磨实现更快制造的特性。尽管氩气的沸点约为 87 K，但我们对氩气离子发射特性的研究可以在低于 0.1 Pa 的氩气压和约 50 K 的温度下进行。氩气的离子电流特性与氖气和氪气之间的关系介于两者之间。将离子发射电流乘以溅射产额的乘积值适合作为更快制造的性能指标 (FOM)。在这三种离子中，氩气的 FOM 最高。从实际纳米制造应用的角度来看，必须对其进行广泛评估。在 1 小时内，氖气、氩气和氪气离子电流（3σ）的不稳定性降低到 8%，足以满足制造应用的要求。我们得出结论，使用氩气或氪气 GFIS 离子束仪器将成为纳米制造的有用工具。
