Structure of film thermoelectric converter based on bi-material microcantilevel and fabricating method thereof

Abstract

The invention discloses a structure of a film thermoelectric converter based on a bi-material microcantilevel and a fabricating method thereof. The film thermoelectric converter mainly comprises a heating resistor 1, the bi-material microcantilevel 2 and a sealing ring 3. The principle of the bi-material microcantilevel measuring the temperature of the heating resistor 1 is similar to the principle of the traditional bi-metal temperature sensor, and heat of the heating resistor 1 after the temperature rises leads the temperature of the bi-material microcantilevel 2 to rise through ways of convection, radiation, or heat exchange and the like. Because heat expansion coefficients of two materials made into the bi-material microcantilevel 2 are different, the deflexion at the free end or the strain at the root part of the bi-material microcantilevel 2 is changed, and the temperature information of the heating resistor 1 can be obtained after the shape change of the bi-material microcantilevel 2 is detected by a detection element 9. The film thermoelectric converter based on the bi-material microcantilevel 2 has high sensitivity of measuring the heating resistor 1 by using the bi-material microcantilevel 2, little heat of transmitting to an underlayer through a bi-material microcantilevel temperature sensitive element, and small error of converting alternative current and direct current; meanwhile, the heating resistor can be flexibly designed.

Description

technical field [0001] The invention relates to a structure and a manufacturing method of a thermoelectric transducer, in particular to a structure and a manufacturing method of a thin-film thermoelectric transducer based on a dual-material micro-cantilever beam, and belongs to the field of micro-electromechanical systems (MEMS). Background technique [0002] The AC-DC conversion standard is one of the basic electrical standards. Through this standard, the 10Hz-1MHz AC voltage (or current) can be derived from the corresponding DC flow, and traced to the Josephson DC quantum voltage reference (uncertainty better than 10 -8 ). At present, the most accurate AC-DC conversion standard system in the world is realized by thermoelectric converters. A thermoelectric converter consists of a heating resistor and a temperature sensor. AC voltage (or current) and DC voltage (or current) are applied to the heating resistor in turn. The temperature sensor measures the temperature of the ...

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Problems solved by technology

[0007] However, this kind of thermoelectric converter using thermopile as temperature sensitive element has the following disadvantages: (1) From the perspective of improving the sensitivity of thermopile temperature sensor, thermocouple material needs to have high Seebeck coefficient, low resistivity, low thermal conductivity and other characteristics, but according to the Wedman-Franze law, the product of thermal conductivity and resistivity of the material is a constant, it is difficult to reduce thermal conductivity and resistivity at the same time, CuNi widely used at present 44 -Cu, CuNi-NiCr, and Bi-Sb thermocouples have relatively large thermal conductivity, and the heat insulation is not ideal. The heat transferred to the substrate through the thermocouple wire is one of the main sources of AC-DC conversion errors.

(2) The sensitivity of the thermocouple temperature sensitive element is relatively low

In order to improve the temperature measurement sensitivity (or the responsivity of the thermoelectric converter), more than 100 pairs of thermocouples are usually used to form the thermopile sensitive element. The size of the device is very large, and a large-area Si 3 N 4 / SiO 2 / Si 3 N 4 Heat insulation film, the film is easy to wrinkle or break, and it is difficult to achieve stress balance

(3) Thermopile materials with high responsivity (such as Bi, Sb, Bi 2 Te 3 、 Bi 0 5 Sb 1 5 Te 3 , Sb 2 Te 3 ) processes such as deposition, corrosion, and stripping are poorly compatible with standard integrated circuit processes and yields are low

(4) The size of the thermopile composed of a large number of thermocouples is large, which limits the degree of freedom in the design of the heating resistor. Usually, only two-wire heating resistors can be used. When measuring small AC signals, the temperature of the heating resistor is low, so that the thermoelectric converter The response rate is small and the conversion error is large

The disadvantage is that system integration, structural optimization design and necessary electromagnetic shielding measures have not been realized; limited by the packaging structure of commercial infrared detectors, the distance between infrared detectors and heating resistors cannot be approached; the performance is comparable to that of thin-film thermoelectric transducers based on thermopile temperature measurement methods There is still a big gap; the use of photon detectors requires refrigeration equipment, which is costly, while the responsivity and detection rate of thermopile infrared detectors are relatively low

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