Core Body Of Silicon Micro-resonant Pressure Sensor Design And Production Process

Miniature silicon resonant pressure sensor based on MEMS, which has the highest precision for frequency output, measures pressure by detecting the natural frequency of some object. It has strong antijamming capability and excellent stability as the accuracy is determined by its structure. With the potential advantages of quick response, wide frequency band, compact conformation, low consumption, small size, low weight and batch yield, it has been the research focus of many countrys.This paper presents the whole scheme and structure design of the sensor electrostatically excited and capacitively detected based on systematic study of various miniature silicon resonant pressure sensor. The performance of the sensor has also been analysised and simulated, which gives the voltage excited, capacitance detected, the relationship between pressure and natural frequency, the relationship between temperature and natural frequency, strength verification, interference factor analysis and overall simulation.Moreover novel islands arrangement and resonator shape are introduced, which ensures the fabricablity, avoids the stress concentration at the base of the islands during diaphragm distorting, decreases the restriction of resonator shape, reduces the difficulty of detection for the resonator size increasing.On this basis, the fabrication of the sensor has been studied thoroughly, the main contents are as follows: Reactive ion etching (RIE) and KOH etchant etching have been done in different conditions, the etching parameters of Si₃N₄ and silicon together with the best condition for resonator undercutting have been gotten; P+ etch-stop has been carried out, which shows the effective depth of diffusion and etching ratio have met the requirement of resonator etch stop; Technologies of making through holes in glass wafer and anodic bonding have been studied, the improvements for anodic bonding have been present, and through holes array has also been achieved. Besides SCREAM process has been chosen for resonator undercutting and islands forming to avoide deep-step coating of photoresist, and the experiment of silicon island compensation has also been accomplished.