Monolithic microwave circuit with thick conductors
First Claim
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1. A method of making a monolithic microwave integrated circuit including thick metallic conductors, said method comprising the steps of:
- a. forming at least one insulating layer onto an insulating silicon substrate;
b. depositing onto the at least one insulating layer a predetermined pattern of a conductive etch-stop material which is convertible to an insulating material, said pattern including at least one area that is to remain conductive and at least one area that is to be converted to insulating material;
c. depositing onto the pattern of etch-stop material, and onto any exposed areas of the at least one insulating layer, a first layer of low-temperature oxide material having a thickness corresponding to the thickness of the thick metallic conductors;
d. etching through the first layer of LTO material in a first sub-pattern corresponding to the at least one area that is to be converted to insulating material to form at least one cavity that corresponds to and exposes the at least one area;
e. converting the exposed at least one area of the conductive etch-stop material to an insulating material;
f. etching through the first layer of LTO material in a second sub-pattern corresponding to at least one portion of the at least one area of the conductive etch-stop material which is to remain conductive to form at least one cavity that corresponds to and exposes the at least one portion; and
g. filling the cavities corresponding to the at least one area and to the at least one portion with a metallic conductor material forming respective thick conductors.
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Abstract
A monolithic microwave integrated circuit (MMIC) is produced by a method which forms multilevel conductive members, including thick low-loss metallic members. The low-loss metallic members are particularly useful for forming inductors and interconnecting circuit components. The MMIC is formed on a thick oxide layer of a silicon-on-insulator structure having a high-resistivity silicon substrate to inhibit RF interaction with the substrate.
16 Citations
23 Claims
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1. A method of making a monolithic microwave integrated circuit including thick metallic conductors, said method comprising the steps of:
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a. forming at least one insulating layer onto an insulating silicon substrate; b. depositing onto the at least one insulating layer a predetermined pattern of a conductive etch-stop material which is convertible to an insulating material, said pattern including at least one area that is to remain conductive and at least one area that is to be converted to insulating material; c. depositing onto the pattern of etch-stop material, and onto any exposed areas of the at least one insulating layer, a first layer of low-temperature oxide material having a thickness corresponding to the thickness of the thick metallic conductors; d. etching through the first layer of LTO material in a first sub-pattern corresponding to the at least one area that is to be converted to insulating material to form at least one cavity that corresponds to and exposes the at least one area; e. converting the exposed at least one area of the conductive etch-stop material to an insulating material; f. etching through the first layer of LTO material in a second sub-pattern corresponding to at least one portion of the at least one area of the conductive etch-stop material which is to remain conductive to form at least one cavity that corresponds to and exposes the at least one portion; and g. filling the cavities corresponding to the at least one area and to the at least one portion with a metallic conductor material forming respective thick conductors. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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2. A method of making a monolithic microwave integrated circuit including thick metallic conductors, said method comprising the steps of:
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a. forming a silicon-on-insulator layer structure on an insulating silicon substrate; b. doping the silicon layer, in at least one predetermined area, to form a layer of a conductive material; c. depositing an insulating layer onto at least the conductive material; d. depositing onto the insulating layer, in a predetermined pattern of areas, a layer of a conductive etch-stop material which is convertible to an insulating material, said pattern including at least one area which is to remain conductive and at least one area which is to be converted to insulating material; e. depositing onto the layer of conductive etch-stop material, and onto any exposed areas of the insulating layer, a first layer of LTO material having a thickness corresponding to the thickness of the thick metallic conductors; f. etching through the first layer of LTO material, in a first sub-pattern corresponding to the at least one area of the conductive etch-stop material which is to be converted to said insulating material, to expose said at least one area and to form at least one cavity in the LTO material corresponding to said at least one area; g. converting the exposed at least one area of the conductive etch-stop material to an insulating material; h. etching through the first layer of LTO material, in a second sub-pattern corresponding to at least one portion of the at least one area of the conductive etch-stop material which is to remain conductive, to expose said portion and to form at least one cavity in the LTO material corresponding to said portion;
p1 i. depositing an adhesion layer onto walls defining the cavities formed in the layer of LTO material and onto the exposed at least one portion;j. filling the cavities corresponding to the at least one area and to the at least one portion with a metallic conductor material for adhering to the thin adhesion layer and forming respective thick conductors. - View Dependent Claims (11, 12, 13, 14)
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Specification