Advanced small pixel high fill factor uncooled focal plane array

An uncooled microbolometer detector element for a focal plane array, said microbolometer comprising:

• integrated readout circuitry;
• a dielectric layer on said readout circuitry, said dielectric layer including a via for providing electrical access to said readout circuitry;
• a thermally isolating bridge structure having a planar surface extending between downwardly projecting legs, said downwardly projecting legs being coupled to said dielectric layer for supporting said planar surface in spaced relation to said dielectric layer so as to form a thermal cavity therebetween;
• an optically absorptive material layer including a planar member extending between downwardly projecting legs, said downwardly projecting legs being coupled to said thermally isolating bridge structure so as to form an optical cavity therebetween, said optically absorptive material layer being characterized by an electrical resistivity that varies as a function of its temperature, said readout circuitry being connected to said optically absorptive material layer to sense its electrical resistivity;
• and
• said planar surface of thermally isolating bridge structure having a serpentine configuration meandering between said downwardly projecting legs.

A method of producing an uncooled microbolometer detector element for a focal plane array, said method comprising:

• providing integrated readout circuitry having a dielectric layer deposited thereon, said dielectric layer including first vias for providing electrical access to said readout circuitry;
• depositing a first sacrificial layer having a preselected thickness on said dielectric layer, said first sacrificial layer including second vias adjacent said first vias for providing electrical access to said readout circuitry;
• depositing a thermal isolation layer on said first sacrificial layer, said thermal isolation layer including a conductive layer electrically coupled to said readout circuitry through said first and second vias, said thermal isolation layer further including recesses for providing electrical access to said conductive layer, wherein said step of depositing said thermal isolation layer includes forming leg members in said first and second vias and forming a serpentine-like planar surface meandering between said leg members on a surface of said first sacrificial layer;
• depositing a second sacrificial layer having a predetermined thickness on said thermal isolation layer, said second sacrificial layer including third vias adjacent said recesses for providing electrical access to said conductive layer;
• depositing an optically absorptive material layer on said second sacrificial layer, said optically absorptive material layer including a semiconductive layer electrically coupled to said conductive layer through said third vias and said recesses;
• and
• removing said first and second sacrificial layers to form a thermal cavity between said dielectric layer and said thermal isolation layer and an optical cavity between said thermal isolation layer and said optically absorptive material layer.