Micromachined thermopile infrared detector

Abstract

The invention relates to the field of an infrared detector, in particular to a micromachined thermopile infrared detector. The manufacturing technique is simplified and the performance and finished product rate are improved. The manufacture of the micromachined thermopile infrared detector comprises the following steps of: (1) depositing silicon nitride film on the both sides of a silicon substrate by an LPCVD method; (2) etching to remove peripheral silicon nitride film on the frontal side of the silicon substrate by lithography; (3) manufacturing a plurality of Poly-Si strips both ends of which are respectively arranged on the silicon nitride film and the silicon substrate by LPCVD method and photolithographic process; (4) manufacturing a plurality of aluminum strips which form a thermocouple with the plurality of Poly-Si strips by sputtering and photolithographic processes; (5) depositing the silicon nitride film on the frontal side of the silicon substrate by PECVD method; (6) manufacturing an infrared absorption layer (a carbonized photoresist layer) covering the hot junction area of the thermopile with photolithographic process; (7) manufacturing a metal reflective layer (a metal layer) covering the cold junction area of the thermopile with lift-off process; and (8) eroding the back side of the silicon substrate to form a square frustum pyramid shaped groove. The micromachined thermopile infrared detector has reasonable structure design, simple manufacturing process, high detector performance, high finished product rate, good development prospect and is easy to realize.

Description

technical field [0001] The invention relates to the field of infrared detectors, in particular to a micromechanical thermopile infrared detector. Background technique [0002] At present, infrared technology is widely used in civilian fields such as infrared temperature measurement, infrared alarm, and infrared detection, as well as military fields such as infrared imaging, infrared guidance, and infrared early warning; the core of infrared technology is infrared detectors. Among them, the thermopile infrared detector, which is an uncooled infrared detector, has many advantages and is widely used. With the development of MEMS microelectromechanical systems, since the 1980s, micromechanical thermopile infrared detectors have emerged as the times require, and after years of research and practice, they have been successfully used in civilian and military fields. [0003] Most of the existing micromechanical thermopile infrared detectors use silicon nitride-silicon oxide compos...

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Problems solved by technology

[0003] Most of the existing micromechanical thermopile infrared detectors use silicon nitride-silicon oxide composite film structure as the dielectric support film to support the thermopile structure. The purpose is to reduce the stress, but the process is relatively complicated; and the existing micromechanical thermopile Stack infrared detectors generally make the hot junction area and cold junction area of ​​the thermopile on the silicon nitride film on the surface of the silicon substrate. Since the silicon nitride film has a certain degree of heat insulation, even if its thickness is very thin, it can To a certain extent, it prevents the heat from the cold junction area of ​​the thermopile from being transferred to the silicon substrate, but the silicon nitride film itself also has a certain absorption effect on infrared radiation. Therefore, the cold junction area of ​​the thermopile will also absorb a certain amount of heat, so that The temperature difference between the hot junction area and the cold junction area of ​​the thermopile is suppressed, and the detection sensitivity of the detector is reduced; in addition, when the thermocouples constituting the thermopile are fabricated on the silicon substrate, the thermocouple pairs are made on different planes On the one hand, it is necessary to deposit silicon nitride film multiple times, which not only complicates the process, but also causes internal stress and low yield

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