Study On Fabrication Of Silicon Micro Cantilever Probe

With MEMS and nanotechnology developing, the cantilever probe was used more and more in SPM, tunnel sensors, micro-nano-processing and high-density data storage. The curvature radius of the micro-nano-tip and the performance of the cantilever determine the sensitivity of the sensors. The Fabrication of silicon micro cantilever probe is regarded as the research object in this thesis. Using single crystal silicon and combining with wet etching and dry etching techniques, the fabrication procedures of silicon micro cantilever probe are studied.In order to fabricate high aspect ratio nano-silicon tips, wet anisotropic etching and dry etching techniques are used to produce silicon tip respectively. The characteristics of the two methods are studied, and different-shaped silicon tips are produced. The tetrahedral silicon tips of aspect ratio about 1.1 are made by dry etching method. Different aspect ratio tips from 0.52～2.1 are formed using KOH solution with anisotropic wet etching method. The effects on silicon tip shape by the solution concentration, additives (IPA), and mask direction are studied. And based on the intersection model of crystal planes, this paper puts forward the identification method for crystal planes and discusses two crystal planes{411} and {331} which appear in the experiment. Through analyzing the effect on the rapid etched crystal planes {331} and {411} by solution concentration and additive and discussing the effect on tip shape by the factor of mask direction, the process parameters to get high aspect ratio nano-silicon-tips are achieved. Nano-silicon-tips are formed by anisotropic etching in 40% KOH etchant at 78℃and 3 hours dry oxidation sharpening at 980℃, as the square masks aligning to <110> direction. The high aspect ratio of the tips is greater than 2, and the profiles of silicon tips are constituted by {411} crystal planes that intersect (100) crystal planes at 76.37°.Three fabrication processes of silicon micro cantilever probe are designed, and the best processe is chose to take an experiment. The structure and experimental mask layout of the silicon cantilever probe are designed, and the process and chromic mask layout are optimized. By using wet anisotropic etching technique the size of 450μm×50μm of silicon micro cantilever probes are fabricated. The curvature radius of apex is less than 50nm, the height of the silicon tips is about 10μm, and the aspect ratio of is about 2. By using dry etching method the size of 230μm×40μm of the silicon micro cantilever probes are fabricated. The height of the silicon tips is about 14μm, the aspect ratio of is about 1.1. The integration of silicon tip and cantilever is realized by the two techniques. This work lays a good foundation for the micro cantilever probe applying in the sensing fields.