Bolometric detector, device for detecting infrared radiation using such a detector and method for producing this detector

A method for producing a bolometric type infrared detector involving, starting with a readout circuit, particularly one produced on a silicon substrate:

• firstly forming a first auxiliary sacrificial layer on said silicon substrate intended to be removed by any known means after producing the detector in order to thermally isolate the readout circuit from the detection module or sensitive part;
• forming a layer of sensitive bolometric material on this auxiliary sacrificial layer;
• depositing a layer made of a dielectric material on this sensitive layer;
• using a lithographic mask and etching to produce linear openings of limited thickness in this layer in order to create areas of contact with the layer of sensitive material;
• depositing a first layer of electrically conductive material;
• using a lithographic mask to produce a first network of conductive tracks, some of which are situated opposite the openings made in the layer of dielectric material and because of this are in electrical contact with the sensitive material;
• producing conductive supports or posts by applying a new lithographic mask intended to protect the entire structure apart from small-sized openings, said openings being etched through the superficial layers in the following order:
• conductive material, dielectric material, bolometric material, then through the sacrificial layer as far as the surface of contacts previously made on the surface of the readout circuit, then by depositing at least one metallic layer, then by etching this/these metallic layer(s) with the aid of a lithographic mask away from posts;
• depositing a second layer of dielectric material on network;
• using a lithographic mask and etching to produce openings in said dielectric layer localised on the conductive tracks of network that are in contact with the sensitive material;
• depositing a second layer of electrically conductive material on the layer of dielectric material;
• using a lithographic mask to produce a second network of conductive tracks substantially oriented at right angles relative to the tracks that constitute the first network;
• using a lithographic mask and etching to define support arms and the peripheral contour of the membrane or sensitive part of the detector;
• and finally, eliminating the sacrificial layer so that the membrane or sensitive part is suspended above the substrate.