Research On Fabrication Technology Of Thin Film Thermoelectric Converter Based On The Temperature Sensing Mechanism Of The Micro-bridge Resonator

The thermoelectric converter is the benchmark measurement instrument used in the transmission of national AC voltage(current)value.It undertakes the comparison between the AC voltage(current)reference value in China and the international AC voltage(current)reference value or standard value.High measurement accuracy AC voltage and current reference are the basis of AC power and electrical energy measurement,so it has important research significance.For the larger output impedance of the thermopile temperature measurement,part of the heat generated by the heating resistor is conducted to the substrate through a thermocouple with good thermal conductivity and other problems,this paper presents a new temperature measurement method of the thin film thermoelectric transducer—measure the temperature of heating resistance by the high sensitivity of the resonant frequency of the microbridge to the axial thermal stress.The heat of the radiation after temperature rise because of heating resistance increases the average temperature of the microbridge,so that the axial compressive stress increases(or the axial tensile stress decreases),and the resonant frequency decreases,the temperature information of the heating resistance is obtained by measuring the variation of the resonant frequency of the microbridge.The paper mainly completed the manufacturing of thin film thermoelectric converter based on electrothermal excitation-pressure resistance detection microbridge resonator and thin film thermoelectric converter based on electrostatic excitation-capacitance detection microbridge resonator.The influence of the PECVD electrode and the plate structure on the performance of the silicon nitride film has been emphatically studied.A thin film of silicon nitride with a small residual stress was prepared and used as a passivation film for the heating resistor.The process parameters of dry etching were optimized,the ratio of lateral etching to vertical etching was improved,and the frontal release of the electrostatic excitation-capacitance detection micro-bridge resonator was simplified,which simplified the device structure.Gold-amorphous silicon bonding process was studied to heat the bonding between resistance chip and bridge resonator chip.Eventually we developed two new resonant thin film thermoelectric converters.Finally,the resonant characteristics of the micro-bridge resonator with electrothermal excitation and piezoresistive detection are tested,and the thermoelectric conversion error of the thermoelectric converter is measured based on the Fast-reversed DC method.The thermoelectric transfer difference less than 5.4ppm at frequency range between 10 Hz and 100 kHz.