超薄栅介质MOSFET直接隧穿电流自洽解模型

Self-consistent Model on Direct-tunneling Current of Ultra-thin Gate Dielectric MOSFET

采用自洽解方法求解一维薛定谔方程和二维泊松方程,得到电子的量子化能级和相应的浓度分布,利用MWKB方法计算电子隧穿几率,从而得到不同栅偏置下超薄栅介质MOSFET的直接隧穿电流模型。一维模拟结果与实验数据十分吻合,表明了模型的准确性和实用性。二维模拟结果表明,低栅压下,沟道边缘隧穿电流远大于沟道中心隧穿电流,沟道各处的隧穿电流均大于一维模拟结果;高栅压下,隧穿电流在沟道的分布趋于一致,且逼近一维模拟结果。

Quantized energy levels and electron density distribution are calculated by solving the one-dimensional Schrodinger equations and two-dimensional Poisson equation self-consistently. Tunneling probability of electrons through the gate oxide is obtained through the modified WKB（MWKB） method. The gate direct tunneling current in ultra-thin oxide is computed with different device parameters. Comparison of 1-D simulation results with experiment data verifies the validity and extensive applicability of this model. 2-D simulation results indicate that, for lower gate voltages, the direct tunneling current from the channel edges is much lager than that from the channel center, and the direct tunneling current from the whole channel is larger than 1- D simulation results. For higher gate voltages, the tunneling current from all the positions of channel trend to be the same and approach to 1-D simulation results.