基于转移矩阵法确定高k介质中泄漏电流共振隧穿机制的存在性

栅隧穿电流已成为制约MOS器件继续缩小的因素之一.为了掌握和控制高k栅栈的栅电流,必须全面了解其中存在的各种隧穿机制.考虑高k介质和二氧化硅间的界面陷阱,建立了高栅栈MOSFET中沟道与栅极交换载流子的双势垒隧穿物理模型.采用量子力学的转移矩阵方法,计算沟道电子通过高栅栈结构的透射系数,模拟得到的透射系数曲线随电子能量变化呈现峰谷振荡的特征.将本文模拟结果与非平衡格林函数及WKB近似方法模拟结果对比,通过论证得出电子能量低于高导带底的透射系数峰为共振隧穿机制所产生,而能量高于高k介质导带底的电子透射系数峰为直接隧穿的结论.

Demonstration of existence of resonant tunneling mechanism in high-k stack dielectrics leakage current based on transform matrix method

Gate tunneling leakage current has become one of the factors which restrict devices to scale down continually. In order to control of high-k gate leakage current, a comprehensive understanding of various kinds of tunneling mechanisms in the high-k gate stack structure is necessary. With interface defects of high-it dielectric and silicon dioxide taken into consideration, physical model of doublebarrier tunneling of carrier exchange between channel and gate is established. Based on transfer matrix method, the transmission coefficient of channel electron tunneling through high-it stack is calculated, and the transmission coefficient appears oscillation property with the change of electron energy. The simulated results are compared with those generated by nonequilibrium Green function and the WKB approximation approach, which demonstrates that, for the electron whose energy is lower or higher than high-k conduction band, the transmission coefficient peak is generated by resonant tunneling mechanism or direct tunneling mechanism, respectively.