Study Of Tunneling Gate Current For High-κ Surrounding-gate (SG) MOSFET

With the downscaling of the device, the thickness of oxide becomes thinner, whichleads to greater leakage current. The increased gate current not only increases standbypower consumption but also greatly affects device performance and reliability. So, it isessential to decrease the gate current. Gate dielectrics and device structure are mainlydiscussed in this paper to decrease the tunneling gate current. Firstly, long channelcylindrical surrounding gate MOSFET is adopted. Secondly, high-κ dielectric materialsare discussed.This paper established analytical modeling of direct tunneling gate current inlong-channel cylindrical surrounding-gate MOSFET with high-κ dielectrics andanalytical modeling of direct tunneling current through high-κ gate stacks forlong-channel cylindrical surrounding-gate MOSFET. The results from the previous:direct tunneling gate current is a strong function of gate oxide thickness, but lessaffected by the change of channel radius. Moreover, for the same effective oxidethickness of1nm, the direct tunneling current of an HfO2high-κ dielectric is reduced byfour orders of magnitude compared with a pure SiO2film. The results from the latter: itrevealed that when the thickness of equivalent oxide is constant, the thinner of the firstlayer the smaller of the direct tunneling gate current. Moreover, it is can be seen that thedielectric with higher dielectric constant shows lower tunneling current as expected.In a word, this paper is based on the long-channel cylindrical surrounding-gateMOSFETs structure and established the analytical modeling of direct tunneling gatecurrent. The accuracy of the analytical model is verified by the good agreement of itsresults with those obtained by the three-dimensional numerical device simulator ISE.