高栅压低漏压条件下FG-pLEDMOS的热载流子退化机理

针对FG-pLEDMOS施加高栅压低漏压的热载流子应力会使器件线性区漏电流发生退化,而阈值电压基本保持不变,使用TCAD软件仿真以及电荷泵测试技术对其进行了详细的分析.结果表明:沟道区的热空穴注入到栅氧化层,热空穴并没有被栅氧化层俘获,而是产生了界面态;栅氧化层电荷没有变化,使阈值电压基本不变,而界面态的增加导致线性区漏电流发生退化.电场和碰撞电离率是热空穴产生的主要原因,较长的p型缓冲区可以改善沟道区的电场分布,降低碰撞电离率,从而有效地减弱热载流子退化效应.

Mechanism of hot-carrier induced degradation in FG-pLEDMOS under high gate voltage low drain voltage stress

No threshold voltage change but linear-region drain current degradation are observed in FG-pLEDMOS(p-type lateral extended drain MOS transistors) stressed under high gate voltage low drain voltage condition.Numerical device simulations by TCAD(technology computer aided design) and charge pumping measurements are used to reveal the degradation mechanism.It is showed that interface traps induced by hot holes injection into the oxide are responsible for the linear-region drain current degradation,and since there are no hot holes trapped in the gate oxide the threshold voltage keeps unchanged as a whole.As electric field and impact ionization are the main cause for the hot holes generation,increasing the length of p-buffer region can decrease hot-carrier induced degradation due to the optimization of the electric field and impact ionization in the channel region.