二维量子力学效应对阈值电压的影响

在亚50nm的MOSFET中,沿沟道方向的量子力学效应严重影响了器件性能.基于WKB理论,考虑MOSFET中该效应对垂直沟道方向上能级的影响,引入了其时阈值电压的修正.继而对沟道方向的子带作了抛物线近似并进行了数值拟合,从而建立了一个考虑量子力学效应的全解析模型.由此模型可以得到二维量子力学修正和沟道长度以及其它器件参数的关系.与数值模拟结构比较可以得出如下结论:在亚50nm的MOSFET中,量子力学效应引入了阈值电压的修正是不可忽略的.且此全解析模型精度令人满意.

Impact of 2D Quantum Mechanical Effects on Threshold Voltage

In sub-50-nanometer MOSFETs, the Quantum Mechanical effects along the channel have a significant impact on device characteristics. Based on the WKB theory, the QM effects in the transport direction of a MOSFET are taken into account to revise the energy levels in the carrier confinement direction. This semi-analytical scheme introduces a threshold voltage shift, which is then used to develop a fully analytical 2-D QM charge model with a parabolic approximation to subband edge profiles and numerical fitting .The relation of 2-D QM corrections with channel lengths and other device parameters is ascertained. Compared with the numerical 2-D QM simulation, the correction can not be ignored in sub-50 nm MOSFETs and the fully-analytical charge model is valid.