Method and structure for increasing the threshold voltage of a corner device

摘要

A structure for increasing the threshold voltage of a corner device, particularly for shallow trench isolation having narrow devices. An FET comprises a substrate having a channel formed therein under a gate between spaced source and drain regions. A trench isolation region is formed in the substrate around the transistor and on opposite sides of the channel to isolate the transistor from other devices formed in the substrate, with the trench isolation region forming first and second junction corner devices with opposite sides of the channel. A first dielectric layer is formed under the gate and over the channel of the field effect transistor to form a gate insulator for the transistor. A second corner edge dielectric layer is formed under the gate structure and over the first and second corner devices, such that the corner edge dielectric layer increases the thickness of dielectric over each corner device and thus increases the threshold voltage (Vt) and edge dielectric breakdown and decreases MOSFET corner gate-induced drain leakage.