Self aligned channel implantation
AssigneesInfineon Technologies North America Corp., International Business Machines Corporation
InventorsHiroyuki Akatsu, Yujun Li, Jochen Beintner
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Abstract
A short channel insulated gate field effect transistor has within the semiconductor body that houses the transistor a buried layer of the same conductivity type as the body but of higher impurity concentration. The buried layer is below the channel region and essentially extends only the distance between the drain and source regions of the transistor. The process to form the device provides high concentration in the region under the gate to suppress lateral depletion region expansion, while keeping a gradual junction in the vertical direction.
Claims1
A semiconductor body that includes a plurality of field effect transistors in accordance with claim 1 whose gates are to be interconnected, and which are electrically isolated from one another by a surrounding trench that is filled with silicon oxide and in which a continuous conductive layer overlies the body and interconnects the gates of transistors, to be interconnected characterized in that:
- each transistor comprises a portion of the semiconductor body that is of a first conductivity type and source and drain regions of the opposite conductivity type, each of which has a portion that is on the surface of the semiconductive body and which are separated by a portion of the semiconductor body in which a channel is selectively formed during operation of the transistor, each said transistor further comprising a dielectric layer overlying the surface of the semiconductive body between the source and drain regions and suitable for serving as the gate dielectric, a conductor overlying the gate, and a buried layer that is of the first conductivity type and of higher concentration than that of the semiconductive body, and that is located essentially entirely between the source and drain regions displaced from the surface of the body and aligned with and opposite the gate.