Research On The Detection Theory And Fabricating Technology Of New Resonant Infrared Detectors

The infrared detection technology can be widely used in military and civilian area The uncooled infrared detector based on micro-fabrication technologies is an important direction of infrared detector.The analog signal that the traditional uncooled infrared detector output is easy to be disturbed by the outside interference.This paper put forward a kind of new uncooled infrared detector based on Micro-bridge resonator which realized the electrothermally driven and piezoresistive detection by the polysilicon resistance.The new detector's output signal is frequency which is low sensitivity to the electromagnetic interference and has a strong anti-jamming ability.It is a new direction for uncooled infrared detector's developmentThe single and double film's infrared absorption characteristics were respectively calculated and simulated by Matlab.The result shows that moderatly increasing the film thickness and improving film extinction coefficient of the film both can improve the film's infrared absorption rate.Based on above analysis and Micro-bridge stress balance,Micro-bridge in this paper chooses the double layer material which consists of PECVD silicon nitride and thermal oxidation silicon dioxide as the structure layer.The temperature distribution of the Micro-bridge was calculated respectively which is caused by the heating radiation,the working electrothermal excitation.The distribution of temperature field which was caused by electrothermal excitation and detection resistance was simulated by finite element analysis(FEA)software ANSYS.This paper designed the process of resonant infrared detector based on MEMS process.Some key processes were researched such as the preparation of poly resistance,negative type photoresist technology,research of the PECVD silicon nitride materials' properties,sputtering aluminium wire,aluminum wire protection technology,wire bonding technology,etc.Through summing up experience constantly in the process,the resonant infrared detector chip was made out successfully.Device uses ceramic packaging and metal packaging.The device was tested through the open-loop and closed-loop system and the relative response rate of the detector can reach-1.03ppm/?.W,realizing the infrared detection purpose.But there is still a gap with the theoretical value,which is mainly because the structure of device has not been perfectly optimized that will be perfected in the future.