The effect on tip shape by changing the mask direction is studied

in order to fabricate high aspect ratio nano-silicon-tips. This paper presents the fabrication processes for nano-silicon-tips using an (100) single crystal silicon wafer. The evolution of higher order {411} crystal planes during corner undercutting in anisotropic etching of (100) silicon and the effect on tip shape by the factor of mask direction are discussed

by experiment and the model of {411} crystal planes. Experimental results indicate that the profiles of silicon tip are constituted by {411} crystal planes at 76.37°and silicon tips of octahedron and tetrahedron are fabricated with changing mask directions. Nano-silicon-tips are formed by anisotropic etching in 40% KOH etchant at 78 ℃ and oxidation sharpening technique

high aspect ratio of the tips is greater than 2

as the square masks aligning to <110> direction.