The Effect of High-K Gate Dielectrics on Deep Submicrometer CMOS Device and Circuit Performance

The potential impact of high permittivity gate dielectrics on device short channel and circuit performance is studied over a wide range of dielectric permittivities ( gate) using two-dimensional (2-D) device and Monte Carlo simulations. The gate-to-channel capacitance and parasitic fringe capacitances are extracted using a highly accurate three-dimensional (3-D) capacitance extractor. It is observed that there is a decrease in parasitic outer fringe capacitance and gate-to-channel capacitance in addition to an increase in internal fringe capacitance, when the conventional silicon dioxide is replaced by a highgate dielectric. The lower parasitic outer fringe capacitance is beneficial for the circuit performance, while the increase in internal fringe capacitance and the decrease in the gate-to-channel capacitance will degrade the short channel performance contributing to higher DIBL, drain leakage, and lower noise margin. It is shown that using lowgate sidewalls with highgate insulators can decrease the fringing-induced barrier lowering. Also, from the circuit point of view, for the 70-nm technology generation, the presence of an optimum gate for different target subthreshold leakage currents has been identified.