A thermal detector includes a transducer layer of semiconducting yttrium barium copper oxide which is sensitive at room temperature to radiation and provides detection of infrared radiation. In a gate-insulated transistor embodiment, a layer of ferroelectric semiconducting yttrium barium copper oxide forms a gate insulator layer and increases capacitance of the transistor or latches the transistor according to the polarization direction of the ferroelectric layer. The transducer layer may be formed as an amorphous semiconductor and deposited at room temperature by simple sputtering. The sensitive element can be incorporated into a thermal isolation structure as part of an integrated circuit.
REFERENCES TO RELATED APPLICATIONS
This application claims the benefit of U.S. provisional application 60/000,424 filed Jun. 22, 1995. This application is also a continuation in part of U.S. application Ser. No. 08/382,200 filed Feb. 1, 1995, now U.S. Pat. No. 5,572,060.
A bolometer thin film having a high temperature coefficient of resistance (.vertline.TCR.vertline.) is produced in a simple and easy production process to provide a highly sensitive infrared sensing element. The invention provides a bolometer using a thin film of an oxide represented by Z.sub.y CuO.sub.x, wherein Z is one or more alkaline earth metals, one or more rare earth element selected from yttrium and lanthanide elements, one or more elements belonging to Period 5 or Period 6 of the Periodic Table selected from bismuth, lead, thallium, mercury, and cadmium, or potassium or sodium, y is a number satisfying 0.ltoreq.y.ltoreq.2, and x is a number satisfying 0.5y<x.ltoreq.1.5+2y. The bolometer has a temperature coefficient of resistance (.vertline.TCR.vertline.) higher than that of conventional bolometers. This bolometer is produced by forming a bolometer thin film by sputtering using a mixture of an oxide of Cu such as Cu.sub.2 O, CuO or a mixture of Cu.sub.2 O and CuO with an oxide of any of the elements represented by Z, or a complex oxide of these elements as a target.
A method and structure for forming a capacitor in a semiconductor device using a high dielectric constant, yttrium barium copper oxide layer as the capacitor dielectric layer. The process begins by providing a semiconductor structure having a conductive plug therein and having an opening, with sidewalls, over the conductive plug. The opening is shaped to accomodate a capacitor structure as is known in the art. A first conductive layer is formed on the conductive plug and on the sidewalls of the opening. A yttrium barium copper oxide layer is deposited on the first conductive layer using a sputtering process with a YBa.sub.2 Cu.sub.3 O.sub.7 target. The yttrium barium copper oxide layer can be annealed to control the oxygen content. For example, YBa.sub.2 Cu.sub.3 O.sub.6+X can be controlled at between X=0.2 and X=0.5. A second conductive layer is formed on the yttrium barium copper oxide layer, thereby forming a capacitor comprising the first conductive layer, the yttrium barium copper oxide layer, and the second conductive layer.
The present invention provides a much more optimum design for an infrared pixel microstructure. The configuration of the microstructure itself is designed to optimum operational characteristics including faster speeds than previously available. These faster speeds are achieved by reducing the thermal mass of the pixel itself, thus directly affecting the pixels associated thermal time constant. Thermal mass is reduced by tailoring the cross section of the pixel structure such that protective layers are substantially reduced in areas where they are not necessary. This results in the desired reduction and overall pixel mass and consequently more optimum pixel performance.
A pixel structure is provided that has a substrate and a bolometer disposed upon the substrate that includes a transducer and an absorber that have been spaced apart from each other and from the substrate so as to permit the transducer and the absorber to be separately optimized. For example, the absorption characteristics of the bolometer can be maximized, while concurrently minimizing the thermal loss to the substrate. While the absorber is spaced from the transducer, the absorber is in thermal contact with the transducer such that radiation absorbed by the absorber also heats the transducer. In this regard, the bolometer also includes a thermally conductive post extending from the transducer to the absorber. Since the transducer has an electrical resistance that varies in response to changes in the temperature of the transducer, heating of the transducer in response to the absorption of radiation by the absorber causes the electrical resistance of the transducer to correspondingly vary in a predetermined manner. By measuring the change in electrical resistance of the transducer, such as by passing a known current therethrough, a precise measurement of the radiation absorbed by the absorber can be determined. In addition to the pixel structure, a method is provided for fabricating a pixel structure having a bolometer in which the transducer and absorber are spaced apart so as to likewise facilitate the independent optimization of the characteristics of both the absorber and the transducer.
