Methods of making a monolithic microwave integrated circuit
First Claim
1. A method for forming a monolithic microwave integrated circuit having an input terminal, an output terminal and a reference terminal, the method comprising:
- providing a high resistivity initial semiconductor substrate having an initial thickness between a first surface and an initial second surface, and having a bulk resistivity equal to or greater than 100 Ohm-cm;
forming at least one transistor in and over the initial semiconductor substrate, wherein the at least one transistor has a control terminal, an output terminal, and a source region proximate the first surface;
forming a dielectric layer over the first surface and overlying the source region;
forming one or more conductor filled substrate vias extending through the dielectric layer and into the initial semiconductor substrate through the first surface;
forming an interlayer via in the dielectric layer;
forming electrical interconnections overlying the front surface of the semiconductor substrate to electrically couple the interlayer via with at least some of the multiple conductor filled substrate vias so that at least one of the substrate vias is electrically coupled to the source region of the transistor through the interlayer via and at least one of the electrical interconnections;
forming one or more planar capacitors over the first surface of the initial substrate, each capacitor having first and second terminals;
forming one or more planar inductors over the first surface of the initial substrate, wherein the first terminal or the second terminal of the one or more planar capacitors is coupled to a first terminal or a second terminal of the one or more planar inductors wherein other terminals of the one or more planar inductors are coupled to the substrate vias, to one or more terminals of the transistor or to one or more terminals of the microwave integrated circuit;
reducing the initial thickness, thereby creating a new rear surface of a thinned substrate on which inner ends of the substrate vias are exposed; and
applying a conductor to the new rear surface of the thinned substrate so that the exposed inner ends of the substrate vias are electrically connected to the conductor, and so that the source region is electrically connected to the conductor through the interlayer via, at least one of the electrical interconnections, and at least one of the substrate vias.
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Accused Products
Abstract
Low Q associated with passive components of monolithic integrated circuits (ICs) when operated at microwave frequencies can be avoided or mitigated using high resistivity (e.g., ≧100 Ohm-cm) semiconductor substrates and lower resistance inductors for the IC. This eliminates significant in-substrate electromagnetic coupling losses from planar inductors and interconnections overlying the substrate. The active transistor(s) are formed in the substrate proximate the front face. Planar capacitors are also formed over the front face (63) of the substrate. Various terminals of the transistor(s), capacitor(s) and inductor(s) are coupled to a ground plane on the rear face of the substrate using through-substrate-vias to minimize parasitic resistance. Parasitic resistance associated with the planar inductors and heavy current carrying conductors is minimized by placing them on the outer surface of the IC where they can be made substantially thicker and of lower resistance. The result is a monolithic microwave IC previously unobtainable.
68 Citations
22 Claims
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1. A method for forming a monolithic microwave integrated circuit having an input terminal, an output terminal and a reference terminal, the method comprising:
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providing a high resistivity initial semiconductor substrate having an initial thickness between a first surface and an initial second surface, and having a bulk resistivity equal to or greater than 100 Ohm-cm; forming at least one transistor in and over the initial semiconductor substrate, wherein the at least one transistor has a control terminal, an output terminal, and a source region proximate the first surface; forming a dielectric layer over the first surface and overlying the source region; forming one or more conductor filled substrate vias extending through the dielectric layer and into the initial semiconductor substrate through the first surface; forming an interlayer via in the dielectric layer; forming electrical interconnections overlying the front surface of the semiconductor substrate to electrically couple the interlayer via with at least some of the multiple conductor filled substrate vias so that at least one of the substrate vias is electrically coupled to the source region of the transistor through the interlayer via and at least one of the electrical interconnections; forming one or more planar capacitors over the first surface of the initial substrate, each capacitor having first and second terminals; forming one or more planar inductors over the first surface of the initial substrate, wherein the first terminal or the second terminal of the one or more planar capacitors is coupled to a first terminal or a second terminal of the one or more planar inductors wherein other terminals of the one or more planar inductors are coupled to the substrate vias, to one or more terminals of the transistor or to one or more terminals of the microwave integrated circuit; reducing the initial thickness, thereby creating a new rear surface of a thinned substrate on which inner ends of the substrate vias are exposed; and applying a conductor to the new rear surface of the thinned substrate so that the exposed inner ends of the substrate vias are electrically connected to the conductor, and so that the source region is electrically connected to the conductor through the interlayer via, at least one of the electrical interconnections, and at least one of the substrate vias. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for forming a monolithic microwave integrated circuit, the method comprising:
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forming portions of a transistor at a front surface of a semiconductor substrate, wherein the transistor has a doped common region, and wherein the semiconductor substrate has a bulk resistivity equal to or greater than 100 Ohm-cm; forming multiple conductive through-substrate vias (TSVs) extending from the front surface of the semiconductor substrate at least partially through the semiconductor substrate; forming electrical interconnections overlying the front surface of the semiconductor substrate to electrically couple the transistor with at least some of the multiple conductive TSVs; and forming a reference node supported by a rear surface of the semiconductor substrate and electrically coupled with at least some of the multiple conductive TSVs. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for forming a monolithic microwave integrated circuit, the method comprising:
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forming a Laterally-Diffused-Metal-Oxide-Semiconductor (LDMOS) transistor at a front surface of a semiconductor substrate, wherein the LDMOS transistor has a gate, a drain region, and a source region, and wherein the semiconductor substrate has a bulk resistivity equal to or greater than 100 Ohm-cm; forming multiple conductive through-substrate vias (TSVs) extending from the front surface of the semiconductor substrate to a rear surface of the semiconductor substrate; forming electrical interconnections overlying the front surface of the semiconductor substrate to electrically couple the transistor with at least some of the multiple conductive TSVs; and forming a reference node supported by the rear surface of the semiconductor substrate and electrically coupled with at least some of the multiple conductive TSVs. - View Dependent Claims (17, 18, 19)
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20. A method for forming a monolithic microwave integrated circuit, the method comprising:
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forming a transistor in a semiconductor substrate, wherein the transistor includes a doped common region; forming a first dielectric layer over a front surface of the semiconductor substrate; forming a first through-substrate via (“
TSV”
) extending through the first dielectric layer and the semiconductor substrate, wherein a region of the semiconductor substrate through which the first TSV passes has a bulk resistivity equal to or greater than 1000 Ohm-cm;forming an interlayer via in the first dielectric layer, the first TSV electrically coupled to the doped common region of the transistor through the interlayer via; monolithically forming a passive component over the front surface of the semiconductor substrate; forming planar interconnections overlying the front surface of the semiconductor substrate and coupling the transistor and the passive component; and forming a reference node supported by the rear surface of the semiconductor substrate, which is electrically coupled to the transistor through the first TSV. - View Dependent Claims (21, 22)
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Specification