Quantitative Analysis of Tunneling Current through Ultrathin Gate Oxides

Abstract
The tunneling current through ultrathin (3.0-6.0 nm) gate oxides has been measured as a function of the voltage across SiO2, V OX, and compared with results of existing theories utilizing the WKB approximation. The electron effective mass in the Fowler-Nordheim tunneling region (V OX≥3.25 V) is obtained to be (0.34±0.04)m 0 and that in the direct tunneling region (V OXm 0. It is also shown that the charge-to-breakdown for electron injection from n+poly-Si gates is not significantly degraded by decreasing the oxide thickness and is even dramatically improved for the case of a 3.0 nm-thick gate oxide.