Import - Micro Mechanical Pressure Sensor - Agent [Weikewei]

Micro mechanical pressure sensorIt is the earliest and most successful sensor product made using micro machining technology, mainly including piezoresistive and capacitive types. Here, we will focus on introducing capacitive micro mechanical pressure sensors. The principle of operation of capacitive micro mechanical pressure sensors is the same as that of other capacitive pressure sensors. Capacitive micro mechanical pressure sensors also use the principle of capacitance to convert the measured pressure into changes in capacitance for pressure measurement. The structural form is usually variable implicit, and the core component is toPressure sensitive capacitors.

Two types of materials made using bulk silicon and surface silicon micro machining processesMicro mechanical pressure sensorThe basic structure of the sensor is made using bulk silicon technology. The sensor has a two-layer structure, with the upper layer made of silicon. Anisotropic etching technology is used to perform double-sided etching on a silicon wafer several hundred microns thick, forming a pressure sensitive diaphragm dynamic electrode plate. The lower layer is glass coated with a metal film, serving as the fixed plate of the capacitor. The gap between the moving plate and the fixed plate is determined by the etching depth of the silicon wafer, generally ranging from 1 μ m to 5 μ m. Due to the small gap machining, high sensitivity can be achieved. Silicon and glass wafers are bonded together using electrostatic bonding technology to form a silicon capacitor with a certain gapMicro mechanical pressure sensor. When pressure is applied to the silicon film, the silicon film produces displacement, causing the capacitance between the two plates to change with the gap. The measured pressure is obtained by detecting the change in capacitance.

The processing procedure involves depositing a layer of polycrystalline silicon or silicon nitride (Si) with a certain thickness on a silicon wafer₃N₄）By etching the sacrificial layer on the side, a polycrystalline silicon or silicon nitride is formed微型Thin film cavity. By making electrodes, a capacitor that can sense pressure is formed. The gap between the electric valley surface is determined by the thickness of the sacrificial layer and polycrystalline silicon or silicon nitride. At present, thin film deposition technology is relatively mature, and the thickness and quality of the film can be strictly controlled. Compared to using bulk silicon technology传感器Compared to others, the processing technology of surface silicon sensors is relatively simple, eliminating the need for electrostatic bonding processes. Meanwhile, due to the compatibility between surface silicon technology and integrated circuit technology, the sensor's circuit can be processed on the same silicon wafer as the sensor, improving the circuit's anti-interference ability.