Three-layer microbridge structure, three-layer uncooled microbolometer and preparation method thereof

Abstract

The invention provides a three-layer micro-bridge structure, which includes a bridge deck, a second-layer micro-bridge, a first-layer micro-bridge, and left and right aluminum electrodes. The uppermost bridge deck of the micro-bridge structure is covered with a light-absorbing material and a thermistor film And the passivation layer, the upper optical resonant cavity is formed between the bridge surface and the second layer of micro-bridges, the middle optical resonant cavity is formed between the two layers of micro-bridges, and the lower optical resonant cavity is formed between the first layer of micro-bridges and the underlying silicon substrate. Resonant cavity, the present invention also provides a three-layer uncooled microbolometer comprising the microbridge structure and its preparation method, the microbridge structure of the present invention has three resonant cavities, and the optical absorption efficiency is greatly improved; During the simulation process, under the same stress conditions, the deformation of the three-layer S-type microbridge structure is smaller than that of the single-layer L-type and double-layer S-type structures, which ensures the good mechanical stability of the microbridge structure. At the same time, the growth of the bridge legs also increases the overall temperature rise of the device.

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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