IR thermopile detector

Abstract

An IR detector in the form of a thermopile including one or more thermocouples on a dielectric membrane supported by a silicon substrate. Each thermocouple is composed of two materials, at least one of which is p-doped or n-doped single crystal silicon. The device is formed in an SOI process. The device is advantageous as the use of single crystal silicon reduces the noise in the output signal, allows higher reproducibility of the geometrical and physical properties of the layer and in addition, the use of an SOI process allows a temperature sensor, as well as circuitry to be fabricated on the same chip. The detector can also have an IR filter wafer bonded onto it and / or have arrays of thermopiles to increase the sensitivity. The devices can also be integrated with an IR source on the same silicon chip and packaged to form a complete and miniaturised NDIR sensor.

Description

technical field [0001] The invention relates to an infrared (IR) detector based on a thermopile fabricated on a microchip with a film for thermal insulation. A thermopile is made up of several thermocouples placed in series. The invention also relates to integrating an IR detector with an IR source to make a non-dispersive infrared (NDIR) sensor. Background technique [0002] It is known to fabricate thermal IR detectors on silicon substrates consisting of thin film layers (consisting of electrically insulating layers) formed by etching parts of the substrate. Incident IR radiation increases the temperature of the film - which can be measured by any of thermopiles, resistors and diodes. [0003] For example, "Optimized CMOS Infrared Detector Microsystems" by Schneeberger et al., Proc IEEE Tencon 1995, reports the fabrication of thermopile-based CMOS IR detectors. The thermopile consists of several thermocouples connected in series. KOH is used to etch the film and improv...

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