Department of Micro and Nanosciences, Helsinki University of Technology, FI-02015 TKK, Finland.
Nanotechnology. 2010 Apr 9;21(14):145301. doi: 10.1088/0957-4484/21/14/145301. Epub 2010 Mar 10.
Local gallium implantation of silicon by a focused ion beam (FIB) has been used to create a mask for anisotropic tetramethylammonium hydroxide (TMAH) wet etching. The dependence of the etch stop properties of gallium-doped silicon on the implanted dose has been investigated and a dose of 4 x 10(13) ions cm(- 2) has been determined to be the threshold value for achieving observable etching resistance. Only a thin, approx. 50 nm, surface layer is found to be durable enough to serve as a mask with a high selectivity of at least 2000:1 between implanted and non-implanted areas. The combined FIB-TMAH process has been used to generate various types of 3D nanostructures including nanochannels separated by thin vertical sidewalls with aspect ratios up to 1:30, ultra-narrow (approx. 25 nm) freestanding bridges and cantilevers, and gratings with a resolution of 20 lines microm(- 1).
利用聚焦离子束（FIB）在硅中局部植入镓，可用于制作各向异性四甲基氢氧化铵（TMAH）湿法刻蚀的掩模。研究了掺镓硅的刻蚀停止特性对注入剂量的依赖性，确定 4×10(13)离子/cm(-2)的注入剂量是实现可观测蚀刻阻力的阈值。只有大约 50nm 的薄表面层被发现具有足够的耐久性，可以作为掩模使用，其在植入区和非植入区之间具有至少 2000:1 的高选择性。FIB-TMAH 工艺已被用于生成各种类型的 3D 纳米结构，包括由具有高达 1:30 的纵横比的薄垂直侧壁分隔的纳米通道、超窄（约 25nm）的独立桥和悬臂梁以及分辨率为 20 线微米(-1)的光栅。
