Novel integrated gas flow sensor based on porons silicon technology

摘要

We report on aa novel C-MOS compatible silcion gas flow sensor with thermal isolation assured by a htick porous silicon laer. The good thermal isolation, combined with a small device size (of the order of 1.1mm x 1.5mm) lead to very fast resonse with a time constant asf smallf as 1.5ms. The principle of operation is based on heat transfer from a polysilicon resistor to the gas, while two al/polysilcion thermopiles integrated on both sides of the resistor measure the induced temperature differences. The heater and the hot contacts of the thermopiles are thermally isolated. The sensor was tested by measuring nitrogen flo9ws from 0 to 0.4 m/sec. First results showed very good sensor characteristics: sensitivity per heating power 9.8 mV/(m/sec)W, responsivity 1.4V/W, noise equivalent power and minimum detectable velocity 7 10~(-9) W/Hz~(1/2) and 4.1 10~(-3) m/sec respectively.