围栅金属氧化物半导体场效应管电流模型

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

针对深亚微米级围栅金属氧化物半导体场效应管(MOSFET)处于堆积或反型时自由载流子对表面势影响显著的问题,提出了一种全耗尽圆柱形围栅MOSFET表面势和电流解析模型.考虑耗尽电荷和自由载流子的影响,采用逐次沟道近似法求解电势泊松方程,得到围栅MOSFET从堆积到耗尽,再到强反型的表面势模型,最后通过源漏两端的表面势得到了围栅器件从线性区到饱和区的连续电流模型,并利用器件数值仿真软件Sentaurus对表面势和电流模型进行了验证.研究结果表明,表面势在堆积区和强反型区分别趋于饱和,在耗尽区和弱反型区随栅压的增加而增加,同时漏压的增加将使得沟道夹断,此时表面势保持不变.增加掺杂浓度导致平带所需的负偏压变大,表面势增加.与现有的阈值电压模型相比,该模型的精确度提高了16%以上.

A drain current model for the full depletion cylindrical gate metal-oxide-semiconductor field-effect transistor（MOSFET）is proposed to address the issue that free carrier has a significant impact on surface potential when deep submicron MOSFET is in the accumulation or inversion region.Accounting for the effects of depletion charge and free carrier,the potential Poisson＇s equation is solved using the gradual channel approximation to get the analytical model of surface potential which is valid from the accumulation region to depletion region,and to inversion region.The continuous current model from linear region to saturation of cylindrical gate MOSFET is obtained from the surface potentials of source and drain.The surface potential and current model are verified by the device simulation software Sentaurus.The results show that the surface potentials in the accumulation and strong inversion regions tend to be saturated respectively,while the surface potentials in the depletion and weak inversion regions increase as the gate voltage increases.As the drain voltage increases,the channel is pinched-off which leads to the invariability of surface potential.The increase of channel doping density causes both rising the negative bias voltage needed by flat voltage and increasing the surface potential.Comparisons with the threshold-based models show that the precision of the proposed analytical model improves by more than 16%.