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US 8,558,289 B2Granted
Transistors having a composite strain structure, integrated circuits, and fabrication methods thereof
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsChun-Fai Cheng, Hsueh-Chang Sung, Kuan-Yu Chen, Hsien-Hsin Lin, Fung Ka Hing
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Abstract
A transistor includes a gate electrode disposed over a substrate. At least one composite strain structure is disposed adjacent to a channel below the gate electrode. The at least one composite strain structure includes a first strain region within the substrate. A second strain region is disposed over the first strain region. At least a portion of the second strain region is disposed within the substrate.
Claims21
A transistor comprising:
- a gate electrode disposed over a substrate;
- at least one composite strain structure disposed adjacent to a channel below the gate electrode, the at least one composite strain structure comprising:
- a first strain region within the substrate, wherein the first strain region is undoped;
- and
- a second strain region at least partially disposed over the first strain region;
- and
- a doped region over the second strain region.
4 more elements
A transistor comprising:
- a gate electrode disposed over a substrate;
- and
- at least one composite strain structure disposed adjacent to a channel below the gate electrode, the at least one composite strain structure comprising:
- a first strain region within the substrate, a bottom portion of the first strain region having a circular shape, wherein the first strain region is undoped;
- and
- a second strain region disposed over the first strain region, at least a portion of the second strain region being disposed within the substrate, wherein the second strain region comprises a facet in a {111} crystallographic plane of the substrate, and an angle between the facet and a horizontal reference line of the substrate is between about 50-degrees and about 60-degrees.
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A method for forming a transistor, the method comprising:
- forming a gate electrode over a substrate;
- forming at least one composite strain structure, disposed adjacent to a channel below the gate electrode, comprising:
- forming a first strain region within the substrate, the first strain region is configured to provide a first stress to the channel;
- and
- forming a second strain region at least partially over the first strain region, the second strain region is configured to provide a second stress to the channel, the second stress being greater than the first stress;
- and
- forming a doped region over the second strain region.
4 more elements
Dependencies are inferred from the claim text.