| With the application of smart mobile terminals and wearable devices in the biomedical field,miniaturization and low power consumption are required for gas sensors.However,most of the existing commercial non-dispersive infrared（NDIR）gas sensors are difficult to meet the needs of their applications due to the problems of difficult integration,large size and high power consumption.As one of the key components that determine the performance of NDIR gas sensors,the infrared light source directly restricts its size,power consumption,integration,etc.Therefore,the development of a miniaturized,high integrated and low powered infrared light source is one of the key links to realize the miniature NDIR gas sensor.This paper aims to develop a low powered silicon-based infrared light source which is compatible with complementary metal oxide semiconductor（CMOS）technology and which has excellent performance.The main research contents are as follows.Based on the needs of its applications and the research progress of silicon-based thermal radiation infrared light source,according to the basic theory of infrared thermal radiation and heat transfer,the materials and structures of infrared light source devices are analyzed and designed.The finite element simulation software COMSOL Multiphysics is used to simulate the electrical-thermal-mechanical coupling of infrared light source.The analysis of the simulation results of the temperature distribution,stress distribution,and electrical power consumption of the infrared light source shows that the non-equidistant serpentine heating wire routing method is adopted.And the radiation enhance coating can make the designed silicon-based infrared light source obtain better performance.According to the above optimized design structure,a silicon-based infrared light source chip is fabricated.The preparation of the silicon oxide/silicon nitride multilayer dielectric film with embedded tungsten heating wire was completed by the standard CMOS process which has stable process and high yield.In the Post-CMOS process flow,the manufacture of gold electrodes,the release of thin films and the fabrication of infrared radiation enhance layer were carried out.The manufactured silicon-based infrared light source chip was tested for electrothermal characteristics and infrared radiation characteristics,which verified the accuracy of the simulation results and evaluated the performance and indexes of the infrared light source.When the heating power consumption is 138 m W,the average temperature of the silicon-based infrared light source is about 469°C,and the thermal response time is 41 ms.At the modulation frequency of 40 Hz,its modulation depth is still 58%,which is suitable for high frequency pulse mode with low power consumption.At the same time,the use of the infrared radiation enhance layer has a good enhanced effect on its infrared radiation power and infrared radiation intensity.In addition,in order to test its practical applied performance in NDIR gas sensor,a double-layer gas chamber for improving gas detection sensitivity was innovatively developed,and a set of NDIR gas detection system for CO2 gas detection was developed based on the double-layer gas chamber and the CO2 gas test was carried out.Finally a silicon-based thermal radiation infrared light source that can be used for NDIR gas sensor to detect CO2 gas concentration in human exhalation was realized.The performance and indexes of the developed silicon-based thermal radiation infrared light source in this paper is at a relatively good level in similar designs at home and abroad,with low power consumption,small size,short thermal response time,uniform temperature distribution and high integration. |
