| Summary: | 碩士 === 國立高雄應用科技大學 === 光電與通訊工程研究所 === 102 === The purpose of this dissertation is to fabricate and measure two CMOS Pirani gauges. One of them was fabricated by using CIC TSMC CMOS-MEMS 0.35μm process. The sensor structure consists of a floating membrane and two resistor materials, including aluminum and tungsten silicide. In addition, thermally conductive metal layers were formed on the floating membrane to improve the temperature uniformity of the sensors. The aluminum resistor has a width of 0.5 μm and winds up through the floating membrane to achieve a sensing resistor with high resistance. And the tungsten silicide resistor with low resistance is placed at the center of the floating membrane to be a heater or a sensor. Another Pirani gauge was manufactured by adopting a standard 0.8μm CMOS process. The structure of this gauge also includes a floating membrane, but the sensing materials are a thin aluminum film with a positive temperature coefficient of resistance(PTCR) and a polysilicon layer with a negative temperature coefficient of resistance(NTCR).
The resistance and TCR of the aluminum resistor and the tungsten silicide resistor for aluminum/tungsten silicide Pirani gauge were measured as 6318 Ω and 0.35 %/K, 195 Ω and 0.195 %/K, respectively. The temperature of tungsten silicide sensor drift about 45℃ for Wheatstone bridge circuit in the pressure range of 0.01 Torr to 760 Torr. In the CT circuit operation, temperature of sensor kept at about 30℃. The resistance and TCR of the aluminum resistor and the polysilicon resistor for the aluminum/polysilicon Pirani gauge were measured as 4692 Ω and 0.35 %/K, 4251 Ω and -0.42 %/K, respectively. The sensitivity of the single aluminum sensor, the single polysilicon sensor and the aluminum/polysilicon Pirani sensor were estimated as 0.047897 V/Torr ,0.05598 V/Torr, and 0.1617 V/Torr using the Wheatstone bridge circuit under a bias voltage of 2.2 V in the pressure range of 1 mTorr to 10 Torr.
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