Design,Manufacture And Test Of Micro Hot Plate Of Gas Sensor Based On MEMS Process

Micro-electromechanical Systems(MEMS)developed with the progress of semiconductor integrated circuit micro machining technology and ultraprecise machining technology.It can integrate micro sensors,micro actuators,signal processing and control circuits,and even interface,communication and power supply into a whole,characterized by such features as small volume,light weight and practicality of mass production,etc.In recent years,metal oxide semiconductor(MOS)materials have been increasingly applied into gas detection.Nevertheless,since certain temperature is required for MOS materials to react with gas,the power dissipation of sensor is excessive,consequently restraining its further development.In contrast with traditional gas sensor,MOS gas sensor on MEMS technology is equipped with a host of advantages on such aspects as consistency and microminiaturization,which is easier to achieve integration and low power consumption.Meanwhile,MOS gas sensor is compatible with the existing silicon-based processing technology,which is the orientation of development for future gas sensor.Within this type of sensor,the micro heat plate(MHP)made via MEMS technology can provide heat for MOS air-sensitive thin-film materials,and its thermal performance can exert influences on the displaying of sensor's overall performance.Consequently,it is of great necessity to carry out in-depth analysis and research on MHP so that the structure of the sensor can be optimized.Within the traditional MHP gas sensor,the heating electrode and the test electrode are not on the same plane.With such traditional design,the production process is way too complicated,the heat transfer distance between the heating electrode and the test electrode is too long,and a parasitic electric field is likely to take form among the heating layer,insulating layer and testing layer,exerting certain influences on the signal to be tested.In this new design,the heating electrode and the test electrode are placed on the same plane.Compared with traditional devices,the production process has been streamlined,the heating process and heat transfer is optimized,and the parasitic electric field among the "three-layer" structure is avoided.Platinum was used for both heating electrode and test electrode in this design.The resistance of platinum is equipped with such merits as large range of measurement,good stability and anti-oxidation property.Within a certain range of temperature,the resistance-temperature characteristic curve is linear,and the temperature of platinum electrode can be effectively calculated based on the resistance value of platinum.By gradually increasing the voltage at both ends of the heating electrode of MHP and by measuring the resistance value of heating electrode during the heating and heat generation process,the relation curve for voltage and resistance of the heating electrode can be achieved.The relation curve for voltage and resistance can be further calculated by referring to the linearity between resistance and temperature of the platinum resistance.Eventually,regulation of working temperature can be realized by changing the working voltage of platinum electrode.Simulation analysis can be carried out on various structures' temperature distribution in the physical field with Multiphysics module in COMSOL,the finite element simulation software.In this academic paper,a new-type MHP with four pins was designed,and by using finite element analysis method,the temperature distribution of the new-type MHP was simulated;meanwhile,the structure of MHP was optimized via simulation.