Infrared imager using room temperature capacitance sensor
First Claim
Patent Images
1. A transducer formed on a monolithic semiconductor integrated circuit substrate comprising:
- a first electrically conductive plate formed on the substrate substantially parallel to a second electrically conductive plate along the xy plane;
a dielectric layer formed on the first plate, the first and second electrically conductive plates and the dielectric layer forming a capacitor;
a bi-material element comprising a top layer and a bottom layer;
an absorber element formed on a portion of the second electrically conductive plate;
a thermal conduction layer connecting the second electrically conductive plate and the bi-material element; and
a thermal isolation support element having a first side which is coupled to said bi-material element and a second side which is coupled to the substrate, the thermal isolation support element anchoring the bi-material element, the absorber element, the second electrically conductive plate and the thermal conduction layer to the substrate,wherein the bi-material element, the absorber element, the second electrically conductive plate and the thermal conduction layer form a deflectable member.
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Abstract
An infrared imager includes an array of capacitance sensors that operate at room temperature. Each infrared capacitance sensor includes a deflectable first plate which expands due to absorbed thermal radiation relative to a non-deflectable second plate. In one embodiment each infrared capacitance sensor is composed of a bi-material strip which changes the position of one plate of a sensing capacitor in response to temperature changes due to absorbed incident thermal radiation. The bi-material strip is composed of two materials with a large difference in thermal expansion coefficients.
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Citations
33 Claims
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1. A transducer formed on a monolithic semiconductor integrated circuit substrate comprising:
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a first electrically conductive plate formed on the substrate substantially parallel to a second electrically conductive plate along the xy plane; a dielectric layer formed on the first plate, the first and second electrically conductive plates and the dielectric layer forming a capacitor; a bi-material element comprising a top layer and a bottom layer; an absorber element formed on a portion of the second electrically conductive plate; a thermal conduction layer connecting the second electrically conductive plate and the bi-material element; and a thermal isolation support element having a first side which is coupled to said bi-material element and a second side which is coupled to the substrate, the thermal isolation support element anchoring the bi-material element, the absorber element, the second electrically conductive plate and the thermal conduction layer to the substrate, wherein the bi-material element, the absorber element, the second electrically conductive plate and the thermal conduction layer form a deflectable member. - View Dependent Claims (2)
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3. An infrared sensor formed on a monolithic semiconductor integrated circuit substrate comprising:
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a reference capacitor comprising a top electrically conductive plate and a bottom electrically conductive plate; a dielectric layer formed on the top electrically conductive plate of the reference capacitor; a sense capacitor comprising a top electrically conductive plate and a bottom electrically conductive plate, said top electrically conductive plate being formed above said dielectric layer and said bottom electrically conductive plate being the top electrically conductive plate of the reference capacitor; a bi-material element comprising a top layer and a bottom layer; an absorber element formed on a portion of the top electrically conductive plate of the sense capacitor; a thermal conduction layer connecting the top electrically conductive plate of the sense capacitor and the bi-material element; and a thermal isolation support element having a first side which is coupled to said bi-material element and a second side which is coupled to the substrate for anchoring the bi-material element, the absorber element, the top electrically conductive plate of the sense capacitor and the thermal conduction layer to the substrate, wherein the bi-material element, the absorber element, the top electrically conductive plate of the sense capacitor and the thermal conduction layer form a deflectable member. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An infrared imager array including a monolithic semiconductor integrated circuit substrate, comprising:
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a plurality of transducers arranged in rows and columns, each of said transducers separately comprising; a first electrically conductive plate formed on the substrate substantially parallel to a second electrically conductive plate along the xy plane; a dielectric layer formed on the first plate, the first and second electrically conductive plates and the dielectric layer forming a capacitor; a bi-material element comprising a top layer and a bottom layer; an absorber element formed on a portion of the second electrically conductive plate; a thermal conduction layer connecting the second electrically conductive plate and the bi-material element; and a thermal isolation support element having a first side coupled is to the bi-material element and a second side coupled to the substrate for anchoring the bi-material element, the absorber element, the second electrically conductive plate and the thermal conduction layer to the substrate, wherein the bi-material element, the absorber element, the second electrically conductive plate and the thermal conduction layer form a deflectable member; and a readout circuit comprising a plurality of source follower amplifiers, each source follower amplifier respectively coupled to the second electrically conductive plate of each transducer. - View Dependent Claims (14, 15, 16, 17)
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18. An infrared imager array including a monolithic semiconductor integrated circuit substrate, comprising:
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a plurality of infrared sensors arranged in rows and columns, each of said infrared sensors separately comprising; a reference capacitor comprising a top electrically conductive plate and a bottom electrically conductive plate; a dielectric layer formed on the top electrically conductive plate of the reference capacitor; a sense capacitor comprising a top electrically conductive plate and a bottom electrically conductive plate, said top electrically conductive plate being formed above said dielectric layer and said bottom electrically conductive plate being the top electrically conductive plate of the reference capacitor; a bi-material element comprising a top layer and a bottom layer; an absorber element formed on a portion of the top electrically conductive plate of the sense capacitor; a thermal conduction layer connecting the top electrically conductive plate of the sense capacitor and the bi-material element; and a thermal isolation support element, a first side contacting the bi-material element and a second side contacting the substrate for anchoring the bi-material element, the absorber element, the top electrically conductive plate of the sense capacitor and the thermal conduction layer to the substrate, wherein the bi-material element, the absorber element, the top electrically conductive plate of the sense capacitor and the thermal conduction layer form a deflectable member; and a readout circuit comprising at least a plurality of source follower amplifiers, each source follower amplifier respectively coupled to the top electrically conductive plate of each sense capacitor. - View Dependent Claims (19, 20, 21)
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22. A method of fabricating a transducer on a monolithic semiconductor integrated circuit substrate comprising the steps of:
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forming a first electrically conductive plate on the surface of the integrated circuit substrate; depositing a dielectric layer; depositing a release layer over the dielectric layer; forming a connection layer over a first portion of the release layer; forming a bi-material element over a portion of the connection layer and over a second portion of the release layer; forming a second electrically conductive plate over a third portion of the release layer; forming a via through the release layer and the dielectric layer, said via contacting the connection layer and avoiding contact with the bi-material element; forming an absorber layer over the second electrically conductive plate; forming a thermal conduction layer between the second electrically conductive plate and the bi-material element; forming a thermal isolation support element over the connection layer and the via and contacting the bi-material element; and chemically removing the release layer.
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23. A method of fabricating an infrared sensor on a monolithic semiconductor integrated circuit substrate comprising the steps of:
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forming a first capacitive electrically conductive plate on the surface of the integrated circuit substrate; forming an insulating layer over the first capacitive electrically conductive plate; forming a second capacitive electrically conductive plate over the insulating layer; depositing a dielectric layer; depositing a release layer over the dielectric layer; forming a connection layer over a first portion of the release layer; forming a bi-material element over a portion of the connection layer and over a second portion of the release layer; forming a third capacitive electrically conductive plate over a third portion of the release layer; forming a via through the release layer and the dielectric layer, said via contacting the connection layer and avoiding contact with the bi-material element; forming an absorber layer over the third capacitive electrically conductive plate; forming a thermal conduction layer between the third capacitive electrically conductive plate and the bi-material element; forming a thermal isolation support element over the connection layer and the via and contacting the bi-material element; and chemically removing the release layer.
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24. A method of reading an output signal provided by an infrared imager array which comprises a plurality of infrared capacitance sensors, each capacitance sensor comprising a sense capacitor and a reference capacitor coupled to a source follower amplifier, the method comprising the steps of:
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clamping a top electrically conductive plate of each reference capacitor to a reset potential; providing a load current to each source follower amplifier; selecting, using a horizontal scanning shift register and a vertical scanning shift register, one capacitance sensor from the plurality of capacitance sensors to be read out; and driving the sense capacitor of the selected capacitance sensor with a first potential and driving the reference capacitor of the selected capacitance sensor with a second potential, said first potential differing in polarity from said second potential; reading a difference in potential between said sense capacitor and said reference capacitor as said output signal. - View Dependent Claims (25, 26)
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27. A infrared sensor formed on a monolithic semiconductor integrated circuit substrate comprising:
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a reference capacitor comprising a top electrically conductive plate and a bottom electrically conductive plate; a dielectric layer formed on the top electrically conductive plate of the reference capacitor; a sense capacitor comprising a top electrically conductive plate and a bottom electrically conductive plate, said top electrically conductive plate being formed above said dielectric layer and said bottom electrically conductive plate being the top electrically conductive plate of the reference capacitor; an absorber element formed on a portion of the top electrically conductive plate of the sense capacitor; a thermal conduction layer connecting the top electrically conductive plate of the sense capacitor to the absorber element, a thermal isolation support element having a first side which is coupled to said thermal conduction layer and a second side which is coupled to the substrate for anchoring the absorber element, the second electrically conductive plate and the thermal conduction layer to the substrate, wherein the absorber element, the second electrically conductive plate and the thermal conduction layer form a deflectable member. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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Specification