Three-layer micro-bridge structure, three-layer uncooled micro-bolometer and preparation method thereof

Abstract

A three-layer micro-bridge structure provided by the present invention comprises a bridge surface, a second-layer micro bridge, a first-layer micro bridge and left and right aluminum electrodes, and a light absorption material, a thermistor thin film and a passivation layer are laid on the uppermost bridge surface of the micro-bridge structure. An upper-layer optical resonant cavity is formed between the bridge surface and the second-layer micro bridge, an intermediate-layer optical resonant cavity is formed between the two layers of micro bridge, and a lower-layer optical resonant cavity is formed between the first-layer micro bridge and a bottom-layer silicon substrate. The present invention also provides a three-layer uncooled micro-bolometer containing the micro-bridge structure and a preparation method of the three-layer uncooled micro-bolometer. The micro-bridge structure of the present invention has three resonant cavities, so that the optical absorption efficiency is improved greatly. Secondly, during a simulation process, on a same stress condition, the deformation amount of a three-layer S-shaped micro-bridge structure is smaller than the deformation amounts of a single-layer S-shaped micro-bridge structure and a double-layer S-shaped micro-bridge structure, thereby guaranteeing the good mechanical stability of the micro-bridge structure. Meanwhile, the increase in the lengths of the bridge legs also enables the overall temperature rise of a device to be improved.

Description

technical field [0001] The invention relates to the field of infrared detectors, in particular to a three-layer microbridge structure, a three-layer uncooled microbolometer comprising the microbridge structure and a preparation method thereof. Background technique [0002] Infrared radiation has a wide range of applications, including communications, medical treatment, chemistry, biology, warfare and many other fields. According to the different wavelength ranges of infrared radiation, corresponding to different sources, propagation paths and detectors, the entire infrared spectral region can be divided into four bands according to the band size, which are: near infrared (NIR: 0.75 ~ 3μm), Chinese and foreign Red (MIR: 3-6μm), far-infrared (FIR: 6-15μm) and extreme far-infrared (15-1000μm). And in the atmosphere, the mid-infrared band and the long-wave infrared band have two atmospheric windows of 3-5 μm and 8-14 μm; infrared light is invisible light, and we can convert inv...

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Problems solved by technology

[0010] In the traditional single-layer L-shaped micro-bridge structure, the length of the bridge legs is not enough, which leads to poor heat insulation effect of the whole device. To increase the heat insulation effect of the device, the bridge legs must be increased, and the size of the pixel cannot be reduced, otherwise the device The thermal and electrical properties will be greatly affected, and because the single-layer micro-bridge structure has only one resonant cavity, there is still insufficient optical absorption; although the new S-type double-layer micro-bridge structure designed in the United States has two resonant cavities, The optical absorption effect of the device is better, but the mechanical stability of the S-shaped bridge legs is not as good as the single-layer L-shaped structure

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