Research On CMOS Intgrated Two-Dimensional Themal Wind Sensor

Flow sensors are wildly used in many fields. High sensitivity, cheap, portable flow sensors are often needed. With the development of technology of CMOS MEMS, sensors and their processing circuits can be fabricated on one chip, which would make the large-scale fabricated sensors meet those demands. In this thesis,a novel CMOS compatible two-dimensional wind sensor based on thermal theory is presented. Thermal sensing elements are formed by two pairs of Aluminum/n-type polysilicon thermopiles. And it can convert the temperature difference to electric signal without extra electric energy. The classification based on the operation principle is introduced firstly, and detailed analysis on the theory used here is given as follows. And we design the Al structure used for heat dispersion in order to achieve high sensitivity without micromachining, then the resolution of the wind sensor could be optimized. When we design the thermal sensing elements, the equivalent circuits of thermopiles are being used, which make it convenient to simulate the thermopiles with circuits. The system simulation including the FEM simulation of the thermal field and equivalent circuits of the thermopiles is utilized here to optimize the coupling of the controlling circuits, sensors and the condition circuits. Several experimental structures according to the aforementioned analysis are designed and fabricated, and the test results of sensor performance parameters of those structures are compared for the convenience of further design. An improved TMAH Si-etching method without attacking exposed aluminum is reported. And the sensor has the reduced chip area, high sensitivity, small weight, improved offset and excellent performance.