EXTREMELY SHARP {111}-BOUND, SINGLE-CRYSTALLINE SILICON NANO TIPS

Abstract

This paper presents (111) nano tips made using (111) single crystalline silicon. Many research efforts have reported on the fabrication methods of micro and nano tips in silicon. Most of the developed fabrication methods are based on (100) or (110) silicon. However, (111) silicon will give the sharpest {111}-bounded nano tips, and in addition, (111) silicon has the best mechanical properties compared with other types of silicon. In this paper, we use (111) silicon wafers to fabricate two type of nano tip. One type is the sharpest nano tip that can be fabricated by using only {111} silicon planes. The other type is a high aspect ratio nano tip, which is composed of one {111} plane and two vertical passivation planes. In the first case, the tip height is 5 μm and the total cone angle of the tip is 54.7°, which represents the sharpest angle for a nano tip bounded only by {111} planes on silicon. In the second case, the nano tip height is 15 μm, and the aspect ratio is greater than 3:1. The cone angle of the nano tip is only 19.5°. The tip radius is less then 10 nm, which is of the sharpest {111}-bound, single-crystalline-silicon nano tips.