Infrared emitter and NDIR sensor

Abstract

An IR source is provided in the form of a micro-hotplate device comprising a CMOS metal layer made of at least one layer of embedded on a dielectric membrane supported by a silicon substrate. The device is formed in a CMOS process followed by a back etching step. The device is advantageous over state of the art devices as it provides a micromachined IR source capable of achieving high temperatures (and thus higher emissions), while at the same time can be fabricated by commercial CMOS processes - thus having low fabrication cost, high reproducibility and reliability and offering the possibility of monolithic integrated circuitry. The device can also be integrated with an IR detector on the same chip and packaged to form a complete NDIR sensor.

Description

technical field [0001] The present invention relates to a thermal infrared (IR) source using a microhotplate fabricated on a microchip. The invention also relates to the integration of an infrared source and an infrared detector to form an NDIR sensor. Background technique [0002] It is known to fabricate thermally effective infrared sources on silicon substrates comprising microheaters formed inside a thin film layer (consisting of an electrically insulating layer) formed by etching part of the substrate. Such devices can be used to provide heat (eg, 600° C.) at low power consumption (typically from a few milliwatts to hundreds of milliwatts) for use as an infrared source / emitter. [0003] For example, "Micro-machined thermal emitter from a commercial CMOS process," by Parameswaran et al., reported in IEEE EDL 1991 that a polysilicon heater for IR applications manufactured with CMOS technology uses front etching to suspend the heater, thereby reducing work consumption. ...

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Problems solved by technology

However, in this case, since the optical path is on the chip, the infrared radiation propagation distance is very small, therefore, the sensor has low sensitivity

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