Uncooled microbolometer and preparation method thereof

Abstract

The invention discloses an uncooled microbolometer, which comprises a microbolometer microbridge structure used for an uncooled detector, wherein the thermistor material and the light absorbing material in the microbridge structure are vanadium oxide-carbon nano tube composite membranes, the vanadium oxide-carbon nano tube composite membranes are formed by compounding one-dimensional carbon nano tubes and two-dimensional vanadium oxide membranes, and the microbridge structure is in a three-layer sandwich structure: the bottom layer is provided with an amorphous silicon nitride membrane which is used as the supporting and insulating material of the microbridge, the middle layer is provided with one or more layers of vanadium oxide-carbon nano tube composite membranes which are used as the heat sensitive layer and the light absorbing layer of the microbolometer; and the surface layer is provided with another layer of amorphous silicon nitride membrane which is used as the passivation layer of the heat sensitive membrane and a stress control layer. The microbolometer and the preparation method thereof can overcome the defects of the prior art, improve the working performance of devices, reduce the cost of raw materials, and are suitable for large-scale industrial production.

Description

technical field [0001] The invention relates to the technical fields of uncooled infrared detection and uncooled terahertz detection, in particular to a microbolometer and a preparation method thereof. Background technique [0002] Infrared detectors convert invisible infrared heat radiation into detectable electrical signals to realize the observation of external affairs. Infrared detectors are divided into two categories: quantum detectors and thermal detectors. Thermal detectors, also known as uncooled infrared detectors, can work at room temperature, have the advantages of good stability, high integration, and low price, and have broad application prospects in military, commercial, and civilian fields. Uncooled infrared detectors mainly include three types: pyroelectric, thermocouple, and thermistor. Among them, the microbolometer focal plane detector based on thermistor is a kind of uncooled infrared detector that has developed very rapidly in recent years. Detectors ...

AI Technical Summary

Problems solved by technology

However, since the electronic structure of the vanadium atom is 3d 3 4s 2 , the 4s and 3d orbitals can lose part or all of their electrons. Therefore, the vanadium oxide film prepared by the traditional method has its own insurmountable shortcomings: that is, the valence state of the V element in the vanadium oxide film is complex and the stability of the chemical structure of the film is poor. Wait

Due to the complex composition of the V element, small changes in the preparation process will have a greater impact on the chemical composition of the vanadium oxide film, resulting in significant changes in the electrical, optical, and mechanical properties of the film, which in turn affect the performance of the device.

Therefore, the main disadvantages of the microbolometer based on vanadium oxide film are: the preparation process of vanadium oxide film is difficult, the repeatability and stability of the product are poor, etc.

Chinese patent ZL 200320109976.X, authorized by Liu Junhua et al. on May 4, 2005, describes a carbon nanotube film piezoresistive thermal infrared detector. This invention also uses carbon nanotubes as infrared light absorption and thermal Sensitive materials, when the micromachine is exposed to light radiation, thermal warping or resonance frequency drift will occur, so that the piezoresistive factor of the carbon nanotubes bonded to the micromachine will change. Using the piezoresistive effect of carbon nanotubes, through The drift of the frequency of the resistance change of carbon nanotubes is used to sense the temperature distribution and then measure the radiation intensity. This invention solves the problems of low sensitivity and high cost of pyroelectric detectors

[0008] In short, the conductivity and chemical stability of vanadium oxide films are insufficient and need to be improved.

However, carbon nanotubes also have some shortcomings in terms of electrical and optical properties, so it is not suitable to use simple carbon nanotubes or ordinary carbon nanotube-polymer composite films as infrared or terahertz light absorption and Thermistor materials, directly applied in uncooled infrared detectors, or uncooled terahertz detectors

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