Research On Silicon-based Nanoporous Alumina Humidity Sensor

Based on microelectronic process and electrochemical anodization method,a silicon-based nanoporous aluminum oxide humidity sensor is proposed in this paper.The structure is composed of silicon substrate,porous aluminum oxide film and electrode.Based on humidity-sensitive mechanism and the adsorption-desorption mechanism,the sensor can detect the humidity.On the basis of this,the simulation models of humidity sensor with parallel-plate electrode structure or interdigitated electrode structure were constructed,simulated and analyzed by COMSOL simulation software.In this paper,a nanoporous anodic aluminum oxide(NP-AAO)film was prepared by adopting electrochemical anodization method and using an electrochemical anodization system composed of DC power supply(IT6874A),low temperature constant temperature reaction bath(DFY-5/10?)and computer.The microstructure of NP-AAO films was characterized by scanning electron microscopy(SEM S-3400N).The influence factors of the microstructure of the films were studied,such as anodization voltage,the concentration of oxalic acid solution and anodization time,and so on.The Finally,the interdigitated electrode masks were designed,then interdigitated electrodes were fabricated on the surface of the porous aluminum oxide film based on the microelectronic process and completed the production of the sensor.At room temperature,the characteristics of the silicon-based nanoporous aluminum oxide sensor were studied by using the testing system of the sensor composed of the impedance analyzer(LCR-TH2819A),saturated salt solution and computer.The influence factors of the sensor were discussed and analyzed.The results show that the sensitivity of the sensor sample HS1 is 70.4pF/%RH when the power frequency is 1KHz and the voltage is 1.0V at room temperature 25?.The response time and recovery time of the sensor sample HS1 are about 6s and 3s,Respectively.And the influence of external magnetic field,electrode,frequency and different anodization conditions on the humidity-sensitive characteristics of the sensor was analyzed.The silicon-based sensor can achieve the measurement of environmental humidity,which treats nanoporous aluminum oxide as a sensitive material.