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

This work presents a new phenomenon: the three-dimensional (3-D) DIBL effec t. The effect is examined by studying the width-dependent punchthrough leak age of deep-submicron shallow-trench isolated (STI) MOSFET's, Different fro m previous works on STI, where phenomena are investigated in a low V-d rang e, the 3-D DIBL is based on analyses in the large V-d range. For STI proces s, the effect suppress DIBL and the suppression is more effective as scalin g down device width. The phenomenon is a result of the 3-D electrostatic ef fect, which diverts drain fields away from channel into the gate electrode over field oxide region. The effect reduces the total drain fields penetrat ing through the channel into the source, and hence suppress the DIBL, A sim ple 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 elect ric field and surface potential to illustrate the physical basis for the 3- D DIBL theory.