Study Of CMOS Microbolometer

Infrared detection has broad application prospects in military,meteorology,earth environment,agriculture,medicine and so on.As the core device of infrared detection technology,infrared detectors have been widely studied by the scientific community and the industry.The common room temperature infrared detectors are microbolometer,pyroelectric detector,diode detector and so on.These detectors have many problems,such as complex technology and high processing cost.The microbolometer based on integrated circuit technology has the advantages of low cost,high integration and easy to mass production.It is a new trend of future room temperature infrared detector.In this paper,a microbolometer is designed and fabricated based on integrated circuit technology,and its structure and properties are studied.The main research results are as follows:1?Based on standard integrated circuit technology,A L type microbolometer with detection wavelength of about 10?m is designed.The micro bridge structure mainly consists of infrared absorber made of silicon nitride/silicon dioxide and serpentine aluminum resistance sensor.The CST simulation results show that there are two absorption peaks near 8.4?m and 10?m,and the infrared absorption rate at 10 m is up to 0.73.The increase of the silicon nitride layer on the infrared absorber enhanced the absorption rate at 8.4?m and the absorption rate at 11 ?m?14?m.The simulation results of microbridge thermal performance based on ANSYS software show that when the radiant power P is 20W/m2,the maximum temperature of the bridge reaches 35mK and the thermal time constant is 6.4ms.The effect of the width of the bridge arm and thickness of the bridge deck on the temperature rise and thermal time constant is futher studied.The results show that the smaller the width of the bridge arm is,the higher the temperature of the bridge surface is,butthe the thermal time constant is high.The smaller the thickness of the structure,the higher the temperature of the bridge can reach,and the thermal time constant is small.2?A CMOS microbolometer is fabricated based on 0.18?m integrated circuit technology.The measured results show that the resistance temperature coefficient(TCR)of the thermistor aluminum resistance of the microbolometer is 0.355%,and the effective thermal conductivity is 6.62 X 10-4W/K.After the chip package is completed,a microbolometer response system is built to measure its photoelectric performance.When the bias current is 0.1mA,the voltage response of the unsuspended microbolometer at 8.8?m and 10?m is 0.127 V/W and 0.066V/W.Using Post-CMOS technology to process chips for realizing suspension,the processing technology and improvement plan for the microbolometer are studied.