Monocrystalline Silicon Self-stop Etching Technology Research

Heavy boron-diffusion and self-stopped etch technique is a universal means to control the thickness accurately in micromachining. It is widely used in the micromachining process of inertial devices, such as gyroscope and micro-accelerometer. Heavy boron-diffusion and self-stopped etch technique is studied, which includes boron-diffusion and etch technics. The stress after diffusion is also analyzed. The main contents are as follows:1. Design and analysis of technical parameters of diffusion process.Some technical parameters are analyzed by the testing of sheet resistance and concentration grads, such as direction and flux of airflow, diffusion temperature, diffusion time, type of silicon substrate, clearance between source and silicon wafer. The proper technical parameters are fixed.2. Choice and analysis of etchant.The silicon is etched in KOH and EPW. It proves that EPW is better than KOH. The composition of EPW is comfirmed, as well as the etching temperature. Otherwise, some research is done about etchant of BSG and isotropic etchant, and the cantilever is made successfully.3. Analysis of stress resulted from diffusion.Some cantilevers of different dimensions are made, and the deflection curve of cantilevers is analysed. The stress is estimated and the distributing is also obtained.