Manufacture And Characterization Of MEMS Infrared Source Used In NDIR Gas Sensor

Micro electro mechanical systems (MEMS) infrared source has advantages in volume,power consumption, electrical modulation and cost of production. MEMS infrared source isthe core component of gas sensor based on Non-Dispersive Infra-Red (NDIR). This thesisintroduces the manufacture of a novel MEMS infrared source based on nanomaterial blacksilicon fabricated by plasma process. This MEMS infrared source can be applied to NDIR gassensor.The work of this thesis is composed of following respects. This thesis begins with acomprehensive investigation into the present research situation of MEMS infrared source andthis paper introduces the basic theory of infrared radiation. From the theory of heat transfer,heat transfer model of the infrared source is studied. Based this, the design of structure andsize was completed. Ansys Workbench is used in the thermoelectric simulation of the infraredsource model. TCAD is used to simulate and verify the ion implantation scheme. Criticalprocesses related in the experiments are designed so that main process parameters can bedetermined. Completed process flow for MEMS infrared source is designed rigorously. Thusthe MEMS infrared source can be taped out according to this flow. The MEMS infraredsource is packaged and the performance is tested.Compared with related products, the emissivity of MEMS infrared source is as high as98%at3-5μm because of the almost blackbody characteristic of black silicon. Furthermore, theblack silicon increases the radiation efficiency by40%. DRIE process is used in membranerelease procedure so that smaller size can be achieved, the radiation area reaches1.8×1.8mm,but the device size is only3×3mm. At1.03W input power, the temperature in the radiationzone is between300-440℃. Radiation spectrum of the MEMS infrared source covers2-14μm.When the modulation frequency is40Hz, the modulation depth can reach40%. Test resultsrevealed that radiation characteristic and modulation characteristic of the MEMS infraredsource can meet the demand of NDIR gas sensor. The manufacture of the infrared source issimple, so that good repeatability and high yield can be ensured. Thus the industrialization ofthe MEMS infrared source is easy to be accomplished.