Comparison of Second Impact Ionization Phenomena Between 0.18um N- and P-channel MOSFET's

The consequence of the second impact ionization phenomena (2II) with the back-bias VB differs significantly between Nand PMOSFET’s where electron or hole emissions are favored in the ionization processes. In PMOS a direct hole gate-current is now observed like the electronic one, as a function of the lateral field due to the first ionization event (II) which are both strongly reduced with VB during 2II effects. This behavior is opposite to the NMOS one where the II and 2II electronic gate-current is easily enhanced at lower field towards the NMOS gate by the conjonction of the thermionicand tunneling emissions. These results are explained by the localization of the emission point under the gate and by the hole energy loss which reduces the hole gate-current.