单轴应变硅UTBB NMOSFET电子能谷占有率解析模型

Analytical Model for Uniaxial Strained Si UTBB NMOSFET Electron Valley Occupancy

超薄体和隐埋氧化层(UTBB)全耗尽绝缘体上硅(FDSOI)(UTBB FDSOI简称为UTBB)金属氧化物半导体场效应晶体管(MOSFET)沟道硅膜厚度小于体硅最大耗尽层宽度,基于传统三角形势阱近似的器件建模方法已不再适用,必须重新建立基于矩形势阱近似的器件模型。基于有限高度的矩形势阱近似模型求解沟道薛定谔方程,建立了单轴应变硅UTBB NMOSFET电子能谷占有率解析模型。结果表明,应变对UTBB NMOSFET电子能谷占有率影响较大;UTBB NMOSFET电子能谷占有率随沟道载流子浓度的变化趋势与常规NMOSFET器件不同;随着器件沟道硅膜厚度的增加,无限高度的矩形势阱近似计算误差较大。所建解析模型能直接用于硅基应变UTBB MOSFET迁移率、电流等参数计算,为器件及电路设计人员提供理论依据。

The devices modeling method based on the traditional triangular potential well approximation cannot be used for ultra-thin body and buried oxide(UTBB)fully depleted silicon-on-insulator(FDSOI)(UTBB for short)metal oxide semiconductor field effect transistor(MOSFET). Because the thickness of Si film in the channel of UTBB is less than the maximum depletion layer width of the bulk Si,the model based on rectangular potential well approximation must be rebuilt. According to the model of rectangular potential well approximation with finite height, an analytical model about uniaxial strained Si UTBB NMOSFET electron valley occupancy was built by solving Schr?dinger equation approximately. The results show that the strain has a great influence on the electron valley occupancy of UTBB NMOSFET. The change trend of electron valley occupancy of UTBB NMOSFET with carrier concentration in the channel is different from that of traditional MOSFET devices. With the increase of the thickness of silicon film in device channel, the calculation error of infinite height rectangular potential well approximation is larger. The proposed model can be used to calculate the mobility and current for UTBB MOSFET, which provides theoretical basis for device and circuit designers.