High-performance p+ Si/Au Thermopile-based Gas Flow Sensor in （111） Silicon and Its Packaging Technology

doi:10.3901/JME.2023.02.030

Abstract

Abstract: Flow measurement and control plays an important part in biomedicine, agricultural monitoring, automotive electronics, etc.Aim at the shortcoming of the large-size, low-sensitivity and high-fabrication cost of the most of the previously reported thermopile-based gas flow sensor, a front-sided micromachined p⁺ Si/Au thermopile-based gas flow sensor is designed, fabricated and characterized. P⁺ Si/Au materials with high Seebeck coefficient are employed to construct the thermocouple, combined with the "fishbone" thermal insulation membrane and the embedded isolation cavity structure, which maximizes the thermal resistance of the sensor, reduces the heat loss, and improves the sensitivity. At the same time, high heat-conductivity Au-film is used to connect the cold-junction of the thermocouple and silicon-substrate to not only realize the high temperature difference between the hot-junction and cold-junction, but also simplify the complexity of the process. Thanks to the front-side microfabrication process, the size of sensor is as small as 0.65 mm×0.65 mm. In addition, based on the design of gas flow channel packaging and signal processing circuit, a gas flow detection module integrating sensor chip, air flow channel and processing circuit is completed. With 320 times amplification and 1.0 V voltage bias, tested results show that the sensor has a normalized sensitivity of 5.4 mV/sccm/mW and a quick response time of 1.44 ms.

Key words: thermopile-based gas flow sensor, single-side silicon bulk-micromachining, p⁺ Si/Au thermopile, gas flow channel

CLC Number:

TP212

HUANG Tao, WANG Jiachou, LI Xinxin. High-performance p+ Si/Au Thermopile-based Gas Flow Sensor in （111） Silicon and Its Packaging Technology[J]. Journal of Mechanical Engineering, 2023, 59(2): 30-38.

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