Low power semiconductor transistor structure and method of fabrication thereof
First Claim
1. A method for fabricating an integrated circuit having transistor devices defined on a substrate:
- forming a first screening layer for a first digital device, the first screening layer being positioned below a first gate of the first digital device, the first screening layer having a first dopant concentration between 1×
1018 to 1×
1020 atoms/cm3;
forming a second screening layer for a second device type, the second screening layer being positioned below a second gate of the second device type, the second screening layer having a second dopant concentration between 1×
1018 to 1×
1020 atoms/cm3;
performing an epitaxial deposition to form a common epitaxial layer for the first digital device and the second device type, the common epitaxial layer being positioned above and adjacent to the first screening layer and the second screening layer;
maintaining at least a portion of the common epitaxial layer as a substantially undoped channel region for the first digital device, the substantially undoped channel region of the first digital device having a first dopant concentration less than 5×
10 atoms/cm3; and
performing a shallow trench isolation between the first digital device and the second device type by etching the common epitaxial layer to form a trench and depositing a dielectric within the trench, the shallow trench isolation being performed after forming the common epitaxial layer, wherein the shallow trench isolation extends beyond the first screening layer and the second screening layer.
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Accused Products
Abstract
A structure and method of fabrication thereof relate to a Deeply Depleted Channel (DDC) design, allowing CMOS based devices to have a reduced σVT compared to conventional bulk CMOS and can allow the threshold voltage VT of FETs having dopants in the channel region to be set much more precisely. The DDC design also can have a strong body effect compared to conventional bulk CMOS transistors, which can allow for significant dynamic control of power consumption in DDC transistors. The semiconductor structure includes an analog device and a digital device each having an epitaxial channel layer where a single gate oxidation layer is on the epitaxial channel layer of NMOS and PMOS transistor elements of the digital device and one of a double and triple gate oxidation layer is on the epitaxial channel layer of NMOS and PMOS transistor elements of the analog device.
491 Citations
19 Claims
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1. A method for fabricating an integrated circuit having transistor devices defined on a substrate:
-
forming a first screening layer for a first digital device, the first screening layer being positioned below a first gate of the first digital device, the first screening layer having a first dopant concentration between 1×
1018 to 1×
1020 atoms/cm3;forming a second screening layer for a second device type, the second screening layer being positioned below a second gate of the second device type, the second screening layer having a second dopant concentration between 1×
1018 to 1×
1020 atoms/cm3;performing an epitaxial deposition to form a common epitaxial layer for the first digital device and the second device type, the common epitaxial layer being positioned above and adjacent to the first screening layer and the second screening layer; maintaining at least a portion of the common epitaxial layer as a substantially undoped channel region for the first digital device, the substantially undoped channel region of the first digital device having a first dopant concentration less than 5×
10 atoms/cm3; andperforming a shallow trench isolation between the first digital device and the second device type by etching the common epitaxial layer to form a trench and depositing a dielectric within the trench, the shallow trench isolation being performed after forming the common epitaxial layer, wherein the shallow trench isolation extends beyond the first screening layer and the second screening layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification