Thermal type infrared imaging device and fabrication method thereof

A fabrication method of a thermal type infrared ray imaging device comprising a plurality of cells arranged on an SOI (Silicon On Insulator) substrate consisted of a single crystal silicon substrate, an embedded oxide film and a single crystal silicon layer,

• each of said plurality of cells having a photothermal conversion part which converts an infrared ray into heat, and cell thermoelectric conversion part which is provided below said photothermal conversion part and which converts the heat generated by said photothermal conversion part into an electric signal;
• a selection part which selects some cells among said plurality of cells;
• and
• an output part which outputs the electric signal generated by said cell thermoelectric conversion part of each of the selected cells,
• wherein said photothermal conversion part includes:
• a first photothermal conversion layer;
• and
• a second photothermal conversion layer provided over and apart from said first photothermal conversion layer, which converts an infrared ray within a waveband different from a waveband of said first photothermal conversion layer into heat,
• wherein said cell thermoelectric conversion part includes:
• a first thermoelectric conversion part which converts the heat generated by said first photothermal conversion layer into the electric signal;
• and
• a second thermoelectric conversion part which is thermally separated from said first thermoelectric conversion part, and which converts the heat generated by said second photothermal conversion layer into the electric signal, the fabrication method comprising:
• forming a plurality of diodes in said single crystal silicon layer as said first and second thermoelectric conversion parts constituting said cell thermoelectric conversion part separated from each other;
• forming input and output wirings to be connected to said plurality of cells;
• covering a top surface of said SOI substrate including said input and output wirings with a first insulation film, and then forming a plurality of opening portions which expose said single crystal silicon substrate;
• forming a first sacrifice layer inside said plurality of opening portions and the top surface of said first insulation film;
• removing selectively said first sacrifice layer by etching;
• forming a second insulation film as a material of said first photothermal conversion layer constituting a portion of said photothermal conversion part on said first sacrifice layer remained by etching and said first insulation layer exposed by removing said first sacrifice layer by etching;
• forming said first photothermal conversion layer by removing a portion of said second insulation layer by etching;
• forming a second sacrifice layer on said first photothermal conversion layer and said first insulation layer exposed by removing said second insulation film by etching;
• removing selectively said second sacrifice layer;
• forming a third insulation film as a material of said second photothermal conversion film constituting a portion of said photothermal conversion part on said second sacrifice layer remained by etching and said first insulation layer exposed by removing said second sacrifice layer by etching;
• removing selectively said third insulation film by etching;
• removing selectively materials of said first and second sacrifice layers by etching;
• and
• removing selectively a portion of said single crystal silicon substrate via said plurality of opening portions.