Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore, Singapore.
Department of Physics, National University of Singapore, 117551, Singapore, Singapore.
Sci Rep. 2017 May 12;7(1):1835. doi: 10.1038/s41598-017-01449-1.
We developed a new digital etch process that allows precise etching of Germanium or Germanium-tin (Ge Sn ) materials. The digital etch approach consists of Ge Sn oxide formation by plasma oxidation and oxide removal in diluted hydrochloric acid at room temperature. The first step is a self-limiting process, as the thickness of oxide layer grows logarithmically with the oxidation time and saturates fast. Consistent etch rates in each cycle were found on the Ge Sn samples, with the surfaces remaining smooth after etch. The digital etch process parameters were tuned to achieve various etch rates. By reducing the radio frequency power to 70 W, etch rate of sub-1.2 nm was obtained on a GeSn sample. The digital etch process was employed to fabricate the Ge Sn fin structures. Extremely scaled GeSn fins with 5 nm fin width were realized. The side walls of the GeSn fins are smooth, and no crystal damage can be observed. This technique provides an option to realize aggressively scaled nanostructure devices based on Ge Sn materials with high-precision control.
我们开发了一种新的数字刻蚀工艺，可实现锗或锗锡（GeSn）材料的精确刻蚀。数字刻蚀方法包括通过等离子体氧化形成 GeSn 氧化物，以及在室温下用稀盐酸去除氧化物。第一步是一个自限制过程，因为氧化层的厚度随氧化时间呈对数增长，并迅速饱和。在 GeSn 样品上发现每个循环的蚀刻速率都一致，蚀刻后表面仍然保持光滑。调整数字刻蚀工艺参数以实现各种蚀刻速率。通过将射频功率降低到 70W，在 GeSn 样品上获得了亚 1.2nm 的蚀刻速率。数字刻蚀工艺用于制造 GeSn 鳍片结构。实现了极其细窄的 5nm 鳍宽的 GeSn 鳍片。GeSn 鳍片的侧壁光滑，没有观察到晶体损伤。该技术为基于 GeSn 材料的高精密控制的激进尺度纳米结构器件提供了一种实现选项。
