Reference bolometer and associated fabrication methods
First Claim
1. A reference bolometer disposed upon a substrate, the reference bolometer comprising:
- a thermally conductive layer disposed over a portion of the substrate, said thermally conductive layer comprising a first surface opposite the substrate and a side surface extending between the first surface and the substrate;
a protective coating over at least the side surface of said thermally conductive layer; and
a detector element disposed over the first surface of said thermally conductive layer and at least a portion of said protective coating that is over the side surface of said thermally conductive layer such that said detector element is in thermal communication with the substrate via said thermally conductive layer.
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Accused Products
Abstract
A reference bolometer and the associated methods for fabricating a reference bolometer and for fabricating an array of bolometers are provided. The reference bolometer is fabricated such that a thermally conductive layer underlies the detector element, i.e., the absorber and transducer elements, and is encapsulated by a protective coating. The protective coating serves to prevent the thermally conductive layer underlying the detector element of the reference bolometer from being etched during the process of etching or otherwise removing other portions of the thermally conductive layer that underlie the detector elements of the imaging bolometers. As such, the thermally conductive layer of the reference bolometer maintains the desired thermal communication between the detector element and the substrate such that the output of the reference bolometer is unaffected by incident radiation. Methods for fabricating the reference bolometer are also provided that should increase the reliability and yield, thereby permitting manual inspection of the resulting focal plane array to be reduced.
26 Citations
26 Claims
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1. A reference bolometer disposed upon a substrate, the reference bolometer comprising:
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a thermally conductive layer disposed over a portion of the substrate, said thermally conductive layer comprising a first surface opposite the substrate and a side surface extending between the first surface and the substrate;
a protective coating over at least the side surface of said thermally conductive layer; and
a detector element disposed over the first surface of said thermally conductive layer and at least a portion of said protective coating that is over the side surface of said thermally conductive layer such that said detector element is in thermal communication with the substrate via said thermally conductive layer. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A reference bolometer disposed upon a substrate, the reference bolometer comprising:
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a thermally conductive layer disposed over a portion of the substrate, said thermally conductive layer comprising a first surface opposite the substrate and a side surface extending between the first surface and the substrate; and
a detector element disposed over both the first surface and at least a portion of the side surface of said thermally conductive layer such that said detector element is in thermal communication with the substrate via said thermally conductive layer. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method of fabricating a reference bolometer comprising:
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forming a thermally conductive layer over a portion of a substrate, wherein the thermally conductive layer is formed to have a first surface opposite the substrate and a side surface extending between the first surface and the substrate;
depositing a protective coating over at least the side surface of the thermally conductive layer; and
constructing a detector element over the first surface and at least a portion of the side surface of the thermally conductive layer such that the detector element is in thermal communication with the substrate via the thermally conductive layer. - View Dependent Claims (14, 15, 16, 17, 18, 19)
depositing the thermally conductive layer over the substrate; and
removing the thermally conductive layer from selected portions of the substrate to thereby define a thermally conductive island upon which the protective coating is deposited and the detector element is constructed.
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15. A method according to claim 14 wherein removing the thermally conductive layer from selected portions of the substrate comprises removing the thermally conductive layer from an annular portion over the substrate to thereby define a moat surrounding the thermally conductive island.
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16. A method according to claim 13 further comprising depositing an etch stop layer over a portion of the substrate that surrounds the thermally conductive layer prior to depositing the protective coating.
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17. A method according to claim 16 further comprising depositing a reflector over a portion of the substrate contemporaneously with the deposition of the etch stop layer and prior to forming the thermally conductive layer such that the reflector will subsequently underlie the detector element and will be spaced therefrom by the thermally conductive layer.
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18. A method according to claim 16 wherein depositing the protective coating comprises:
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depositing the protective coating over both the thermally conductive layer and the etch stop layer; and
removing the protective coating deposited over the etch stop layer while preserving the protective coating deposited over the thermally conductive layer such that the protective coating encapsulates both the first surface and the side surface of the thermally conductive layer.
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19. A method according to claim 18 wherein constructing the detector element comprises constructing the detector element over the protective coating that is deposited over the first surface of the thermally conductive layer.
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20. A method of fabricating an array of bolometers comprising at least one reference bolometer and a plurality of imaging bolometers, the method comprising:
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constructing at least one reference bolometer comprising a thermally conductive layer, a detector element disposed over the thermally conductive layer, wherein the detector element and a protective coating are disposed over at least a side surface of the thermally conductive layer;
constructing a plurality of imaging bolometers, each imaging bolometer comprising the thermally conductive layer and a respective detector element disposed over the thermally conductive layer; and
etching exposed portions of the thermally conductive layer to thereby remove the thermally conductive layer underlying the detector element of each imaging bolometer, wherein at least the protective coating prevents etching of the thermally conductive layer underlying the detector element of the reference bolometer. - View Dependent Claims (21, 22, 23, 24, 25, 26)
depositing the thermally conductive layer over a substrate; and
removing the thermally conductive layer from selected portions over the substrate to thereby define a thermally conductive island for supporting the detector element of the at least one reference bolometer.
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22. A method according to claim 21 wherein removing the thermally conductive layer from selected portions over the substrate comprises removing the thermally conductive layer from an annular portion over the substrate to thereby define a moat surrounding the thermally conductive island.
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23. A method according to claim 20 wherein constructing the at least one reference bolometer comprises depositing an etch stop layer over a portion of a substrate that surrounds the thermally conductive layer prior to depositing the protective coating.
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24. A method according to claim 23 wherein constructing the plurality of imaging bolometers comprises depositing a plurality of reflectors over respective portions of the substrate contemporaneously with the deposition of the etch stop layer and prior to forming the thermally conductive layer such that each reflector will subsequently underlie the detector element of a respective imaging bolometer.
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25. A method according to claim 23 wherein constructing the at least one reference bolometer comprises:
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depositing the protective coating over both the thermally conductive layer and the etch stop layer; and
removing the protective coating deposited over the etch stop layer while preserving the protective coating deposited over the thermally conductive layer of the reference bolometer such that the protective coating encapsulates both the first surface and the side surface of the thermally conductive layer.
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26. A method according to claim 20 wherein etching exposed portions of the thermally conductive layer comprises plasma etching exposed portions of the thermally conductive layer.
Specification