Multiple semiconductor-on-insulator threshold voltage circuit
AssigneeAdvanced Micro Devices, Inc.
InventorsQi Xiang, Bin Yu
Life of this patent
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Abstract
An ultra-large-scale integrated (ULSI) circuit includes MOSFETs which have different threshold voltages and yet have the same channel characteristics. The MOSFETs are provided on an SOI substrate. The thickness of a thin film on the substrate is varied to adjust the threshold voltage. The threshold voltage can be varied by roughly 240 mV. The thickness of the thin film can be adjusted through a LOCOS process.
Claims20
A method of manufacturing an integrated circuit including a plurality of transistors, the plurality of transistors including a first transistor having a first threshold voltage and a second transistor having a second threshold voltage, the first threshold voltage being different than the second threshold voltage, the method comprising:
- forming an oxidation structure at a first location on a substrate, the oxidation structure consuming the portion of the substrate;
- removing the oxidation structure, thereby leaving a first recessed portion at the first location on the substrate;
- providing a first gate associated with the first transistor at the first location;
- providing a second gate associated with the second transistor at a second location on the substrate;
- forming a second oxidation structure at a third location on the substrate;
- removing the second oxidation structure, thereby leaving a second recessed portion at the third location on the substrate, the second recessed portion being deeper than the first recessed portion;
- and
- providing a third gate associated with a third transistor at the third location;
- wherein the third transistor has a third threshold voltage, the third threshold voltage being different than the first threshold voltage and the second threshold voltage.
A method of manufacturing an integrated circuit including a plurality of transistors, the method comprising:
- providing a LOCOS structure at a first location on a substrate;
- removing the LOCOS structure, thereby leaving a recessed portion at the first location on the substrate;
- providing at least one of the transistors above the recessed portion at the first location on the substrate;
- providing at least one of the transistors at a second location, the second location being outside the recessed portion, whereby the transistor at the first location has a lower threshold voltage than the transistor at the second location;
- providing another LOCOS structure at a third location on a substrate;
- removing the LOCOS structure at the third location, thereby leaving a recessed portion at the third location on the substrate;
- and
- providing at least one of the transistors above the recessed portion at the third location on the substrate.
A method of manufacturing a ULSI circuit on a semiconductor-on-insulator substrate, the substrate including a semiconductor film, the method comprising:
- selectively oxidizing the semiconductor film to form a first structure at a first location;
- etching the structure to remove the first structure from the semiconductor film;
- forming a first transistor at the first location;
- selectively oxidizing the semiconductor film a second time to form a second structure at a second location;
- etching the second structure to remove the second structure from the semiconductor film;
- forming a second transistor at the second location;
- forming a third transistor at third location outside of the first location and the second location, wherein the first transistor has a first threshold voltage, the second transistor has a second threshold voltage and the third transistor has a third threshold voltage.
Dependencies are inferred from the claim text.