一种围栅金属氧化物半导体场效应管阈值电压模型

针对深亚微米金属氧化物半导体场效应管(MOSFET)多晶硅耗尽效应加剧问题,提出了一种全耗尽圆柱形围栅MOSFET阈值电压解析模型.通过求解多晶硅耗尽层电势泊松方程,得到多晶硅耗尽层上的压降,用以修正沟道区的通用边界条件.然后利用叠加原理求解沟道二维电势泊松方程,建立了圆柱形围栅MOSFET的表面势和阈值电压解析模型,并利用器件数值仿真软件Sen-taurus对解析模型进行了验证.研究结果表明,衬底掺杂原子浓度越高,或多晶硅掺杂原子浓度越低,多晶硅耗尽层上的压降就越大,阈值电压偏移也越显著.与现有模型相比,该解析模型的精确度提高了34%以上.

A Threshold Voltage Model for Surrounding Gate Metal-Oxide-Semiconductor Field-Effect Transistor

An analytical model of threshold voltage for the full depletion cylindrical gate metal-ox-ide-semiconductor field-effect transistor (MOSFET),is proposed to address the issue that polysil-icon depletion effect is aggravated for deep submicron MOSFET. The potential Poisson's equa-tion in the polysilicon depletion layer is solved to get the voltage drop in the polysilicon depletion layer, and the voltage drop is then used to modify the universal boundary conditions of the chan-nel region. Then the 2D potential Poisson's equation in the channel is solved by using the super-position principle to construct the analytical models of surface potential and threshold voltage for the cylindrical gate MOSFET. These models are verified by device simulation software Sentaurus. The results show that the voltage drop in the polysilicon depletion layer would be larger and the corresponding threshold voltage shift would be more significant when the doping density of sub-strate is higher and the doping density of polysilicon is lower. Comparisons with existing models show that the precision of the derived analytical model is improved by more than 34%.