Integrated toroidal coil inductors for IC devices
First Claim
1. A semiconductor structure comprising a solenoidal coil integrated with an integrated circuit (IC) chip, wherein said solenoidal coil is partially embedded inside a cavity formed in a substrate of said IC chip and partially in back-end-of-the-line layers of said IC chip.
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Abstract
A means for fabrication of solenoidal inductors integrated in a semiconductor chip is provided. The solenoidal coil is partially embedded in a deep well etched into the chip substrate. The non-embedded part of the coil is fabricated as part of the BEOL metallization layers. This allows for a large cross-sectional area of the solenoid turns, thus reducing the turn-to-turn capacitive coupling. Because the solenoidal coils of this invention have a large diameter cross-section, the coil can be made with a large inductance value and yet occupy a small area of the chip. The fabrication process includes etching of a deep cavity in the substrate after all the FEOL steps are completed; lining said cavity with a dielectric followed by fabrication of the part of the coil that will be embedded by deposition of a conductive material metal through a mask; deposition of dielectric and planarization of same by CMP. After planarization the fabrication of the remaining part of the solenoidal coil is fabricated as part of the metallization in the BEOL (i.e. as line/vias of the BEOL). To further increase the cross section of the solenoidal coil part of it may be built by electrodeposition through a mask on top of the BEOL layers.
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Citations
33 Claims
- 1. A semiconductor structure comprising a solenoidal coil integrated with an integrated circuit (IC) chip, wherein said solenoidal coil is partially embedded inside a cavity formed in a substrate of said IC chip and partially in back-end-of-the-line layers of said IC chip.
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16. A method of fabricating a semiconductor structure comprising the steps of:
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(a) forming one or more cavities in a substrate of an integrated circuit (IC) chip;
(b) forming a first dielectric material over said substrate including in said one or more cavities;
(c) removing said first dielectric material abutting said one or more cavities, while leaving said first dielectric material in said one or more cavities as a liner;
(d) forming a bottom coil element of a solenoidal coil in said one or more dielectric lined cavities;
(e) forming a second dielectric material over said substrate including said bottom coil element of said solenoidal coil;
(f) removing said second dielectric material over said substrate not containing said one or more cavities; and
(g) forming side coil elements and a top coil element of said solenoidal coil, wherein said top coil element is in electrical contact with said bottom coil element through said side coil elements.
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Specification