Architecture and method of coupling electromagnetic energy to thermal detectors

A millimeter-wave radiation sensor comprising, in combination:

• a substrate having first and second opposing surfaces and
• a thermal detector element located above and physically spaced from the first surface of the substrate to provide a gap therebetween, said detector element comprising at least one each of the following:
• (i) a sandwich structure comprising a heater conductive layer, a dielectric film, and a thermoresistive film, in that sequence, and (ii) contact legs extending downward from and connecting the sandwich structure to the substrate in the spaced manner;
• and
• an antenna on the substrate and physically spaced from the thermal detector element, for coupling received mm-wave and microwave radiation to the thermal detector element.

A method for making a radiation sensor, comprising the steps of:

• providing a substrate having first and second opposing surfaces;
• forming a generally planar thin film antenna on the first surface of the substrate;
• depositing a temporary sacrificial layer having an upper horizontally-extending surface and side vertically-extending surfaces on the antenna and the first surface of the substrate;
• forming a thermal detector element having a planar sandwich structure and as located above and physically spaced from the antenna due to the intervening sacrificial layer material by sequentially forming, at least one each of the following:
• a heater conductive layer, a dielectric film, and a thermoresistive film, on a portion of the upper surface of the sacrificial layer
• forming conductive contact legs in contact with the thermoresistive film and continuing along the side surfaces of the sacrificial layer such that the legs extend downward from and connect the sandwich structure to the substrate;
• and
• selectively removing the sacrificial layer to form an air gap between the antenna and the heater metal film of the thermal detector element.