A Novel Thermopile-Based Gas Flow Sensor Fabricated with a Single-Wafer-Based Front-Sided Bulk-Micromachining Technique

This paper presents a novel p
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Si/Au thermopile-based micro flow sensor, which is fabricated only from the front- side of (111) silicon wafer for high-yield and low-cost volume production. Benefited from the MIS (Micro-openings Interetch & Sealing) micromachining process and the developed patterned technique of single-crystalline silicon (SC-Si) layer under thin-film, the p
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Si/Au thermocouple with significantly high Seebeck-coefficient can be employed to construct the thermopile-based gas flow sensor, and the 0.65mm×0.65mm tiny-sized MEMS gas flow sensor is achieved. The testing results show that the sensor has an ultra-high normalized sensitivity of 0.158mV/(SLM)/mW (Output without any amplification) for nitrogen gas flow and the short response time of 3.0ms. Besides, the minimum detectable flow rate is estimated at about 9.0 sccm.