Nanometer-scale processing and creation of novel functional materials using low energy high flux neutral beams

我们开发了一种高性能中性束（NB）系统。首次利用负离子实现了高中和效率和高通量。采用NB体系建立了50 nm宽的金属氧化物半导体（MOS）栅极刻蚀工艺。中性束蚀刻的MOS电容器的氧化物泄漏电流比传统等离子体蚀刻的低一个数量级。采用NB体系实现了多孔甲基-硅氧烷（多孔MSQ， k-2.2）膜的高选择性、低损伤损伤降解工艺。使用SF_6或CF_4中性光束可以使多孔MSQ蚀刻具有比传统等离子体更高的光阻选择性。这被认为是因为中性光束消除了紫外线（UV）光的暴露，从而增强了抗蚀刻的能力。采用脉冲时间调制的N_2 - NB制备超薄氮化氧膜。利用脉冲N_2 NB在2nm SiO_2薄膜上有效地形成了SiO-N键，并产生了更浅、更锐利、密度更高的N浓度分布。利用NB系统成功制备了具有无损伤光滑侧壁的翅片型垂直mosfet。与传统的反应离子蚀刻相比，所制备的finfet实现了更高的电子迁移率。原子平面很好地解释了迁移率的提高。采用低能中性束和铁蛋白铁芯掩膜制备纳米柱结构。铁蛋白中的铁核直径为7 nm，与蚀刻的纳米柱相同。这表明中性束蚀刻将铁芯的结构和尺寸转移到了硅衬底上。这些结果表明NB可以进行无机和有机材料的原子无损伤刻蚀和表面改性。该技术有望成为未来纳米器件的实用制造技术。

We have developed a high-performance neutral beam (NB) system. It achieved high neutralization efficiency and high flux by utilizing negative ions for the first time.A 50-nm-width metal-oxide-semiconductor (MOS) gate etching process was established using the NB system. The oxide leakage current achieved for a MOS capacitor etched by the neutral beam was one order of magnitude lower than that achieved by conventional plasma etching.A highly selective and low-damage damascene process for porous methyl-silsesquioxane (porous MSQ, k-2.2) films has been realized using the NB system. Use of a SF_6 or CF_4 neutral beam enables etching of porous MSQ with higher selectivity to the photoresist than what can be obtained in a conventional plasma. This is considered to be because the neutral beam eliminates exposure to ultraviolet (UV) light which enhances the resist etching.Pulse-time-modulated N_2 NB was used to form ultrathin oxynitride films. SiO-N bonds were effectively formed and a shallower, sharper, and higher density N concentration profile in a thin 2 nm SiO_2 film was produced using a pulsed N_2 NB.Fin-type vertical MOSFETs with damage-less smooth sidewalls were successfully fabricated using the NB system. The fabricated FinFETs realized higher electron mobility than that using a conventional reactive ion etching. The improved mobility is well explained by the atomically-flat surface.We fabricated nanocolumn structure by using a low energy neutral beam and a ferritin iron-core mask. The iron core in the ferritin was 7 nm in diameter, which was identical to that of the etched nanocolumn. This indicates that neutral-beam etching transferred the structure and size of the iron core to the silicon substrate.These results indicate that the NB can perform atomically damage-free etching and surface modification of inorganic and organic materials. This technique is a promising candidate for the practical fabrication technology for future nano-devices.