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US 8,298,895 B1Granted
Selective threshold voltage implants for long channel devices
AssigneeInternational Business Machines Corporation
InventorEmre Alptekin
Life of this patent
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Abstract
In a replacement metal gate process flow, sacrificial gates are exposed and removed subsequent to the formation of source and drain regions for various transistor devices. Sidewalls formed adjacent to the sacrificial gates remain. By using an angled implant such that, for a short-channel device, the remaining sidewalls shadow and protect the exposed short-channel region, a designer may adjust the threshold voltage on long-channel devices without affecting the threshold voltage of the short-channel device.
Claims8
A method for selectively doping long channel devices, the method comprising the steps of:
- forming a plurality of device regions on a semiconductor substrate where a first device region is designed for a long channel device and a second device region is designed for a short channel device;
- forming a first sacrificial gate and a first set of spacers along the sides thereof, wherein the first sacrificial gate is formed over a channel region for the long channel device on a portion of the semiconductor substrate within the first device region;
- forming a second sacrificial gate and a second set of spacers along the sides thereof, wherein the second sacrificial gate is formed over a channel region for the short channel device on a portion of the semiconductor substrate within the second device region, and wherein the channel region for the long channel device is longer than the channel region for the short channel device;
- removing the first and second sacrificial gates;
- and
- implanting a dopant into the semiconductor substrate at an angle at which a height of the first and second sets of spacers at least partially prevents the dopant from reaching the channel region for the short channel device but allows the dopant to reach the channel region for the long channel device.
3 more elements
Dependencies are inferred from the claim text.