10 nm Si pillars fabricated using electron-beam lithography, reactive ion etching, and HF etching

Abstract

This article reports the fabrication and preliminary photoluminescence (PL) study of free-standing Si pillars with diameters of about 10 nm and aspect ratios greater than 15. The pillars were fabricated using electron-beam lithography, chlorine based reactive ion etching (RIE), and subsequent HF wet etching. Using HF etching offers several advantages: (a) it is a relatively stress independent process and therefore preserves the original shape of the structure; (b) it is a room temperature process; (c) it has a very controllable etch rate, ∼1.9 nm/h; and (d) it can remove RIE damage and passivate the Si surface. PL with a peak at 720 nm was repeatedly observed from an array of nanoscale pillars with ∼20 nm diameters. However, the cause of such PL is still unclear.