Three-dimensional DIBL for shallow-trench isolated MOSFET's

This work presents a new phenomenon: the three-dimensional (3-D) DIBL effect. The effect is examined by studying the width-dependent punchthrough leakage of deep-submicron shallow-trench isolated (STI) MOSFET's. Different from previous works on STI, where phenomena are investigated in a low V/sub d/ range, the 3-D DIBL is based on analyses in the large V/sub d/ range. For STI process,the effect suppress DIBL and the suppression is more effective as scaling down device width. The phenomenon is a result of the 3-D electrostatic effect, which diverts drain fields away from channel into the gate electrode over field oxide region. The effect reduces the total drain fields penetrating through the channel into the source, and hence suppress the DIBL. A simple dipole theory describing the 3-D DIBL phenomenon is presented to extend the previous DIBL theory, which is based on two-dimensional (2-D) approach. Three-dimensional device simulations are used to obtain insights on electric field and surface potential to illustrate the physical basis for the 3-D DIBL theory.