一种FIB刻蚀结合KOH腐蚀的制造纳米梁的新方法

One new method to fabricate nanobeams using focused Ion beam (FIB) and KOH etching

常规的通过干法刻蚀制作纳米梁的方法会不可避免地在梁上引入晶格损伤层。本文提出一种制造无晶格损伤层纳米梁的新工艺方法。在常规光刻后,辅助利用FIB(聚焦离子束)刻蚀修改硅梁中部上方的SiO2掩模。根据单晶硅的材料和工艺特点,通过KOH各向异性腐蚀,硅梁两侧壁与硅片表面垂直,并自停止为(111)面。自停止面自校正地沿<112>晶向自硅梁中部向两端扩展,直至硅梁成型。经过冷冻干燥,最终在(110)SOI硅片上制得了宽度为112nm的单晶硅纳米梁。自校正的腐蚀方式提升了工艺稳定性,并且由于结合利用了湿法腐蚀和FIB技术,此工艺方法具有无晶格损伤层、工艺重复性好、加工精度高等优点。

Conventional method to fabricate nanobeams by dry etching will induce crystal damage inevitably. A new process method is proposed to fabricate nanobeams without surface damage layer. SiO2 masks above the middle of silicon beams are modified by Focused ion beam （FIB） after conventional photolithography. After KOH etching, sidewalls with （111） terminations are all vertical to （110） surface plane, based on the material and process properties of crystal silicon. （ 111 ） Terminations spread from the middle to the ends of beams along with the 〈 112 〉 direction by self-modifying etching, until beams are formed. After freeze drying, one silicon nanobeam with width 122nm is obtained on （110） Silicon- On- Insulator （SOI） substrate finally. Self- modifying etching improves the process repeatability. Besides, due to the combination of wet etching and FIB, this presented process method has some merits such as no surface damage, good repeatability, and high processing resolution.