Thermopile-type infrared sensor and process for producing the same

摘要

An inexpensive thermopile-type infrared sensor is provided, in which the S/N ratio, i.e. ratio of output voltage to Johnson noise, is increased, a flat and rigid membrane structure is formed therein, and an absorption characteristic as well as a production yield thereof are improved. In the thermopile-type infrared sensor according to the present invention, thermoelectric elements are formed on a single crystalline silicon substrate containing a cavity therein. The thermopile-type infrared sensor contains a first dielectric film covering the cavity, a plurality of n-type polycrystalline silicon layers formed on the first dielectric film, extending radially from the vicinity of a chip center, and metal film layers formed in contact with the n-type polycrystalline silicon layers, wherein hot junctions are formed at the chip central side and that cold junctions at the chip peripheral side of the n-type polycrystalline silicon layers, respectively, by contacting the n-type polycrystalline silicon layer and the metal film layer, and at least one series of thermoelectric elements is formed on the first dielectric film by connecting alternately and successively, by the metal film layer, said hot junction and cold junction of the neighboring n-type polycrystalline silicon layer.