Study on Performance Increase and Fluctuation Suppression in Thin Film SOI MOSFET by utilizing quantum effects

本研究的目的是利用量子效应来提高规模化MOSFET的性能并抑制其波动。我们制作了超窄沟道MOSFET，观察到了量子效应引起的阈值电压升高，数值模拟证实了这一点。在实验中，为了对电子进行纵向和横向的限制，采用电子束光刻和干法刻蚀技术制作了极窄的硅沟道。沟道宽度从2 nm到100 nm不等。沟道宽度非常均匀，其分布小于2 nm。还研究了沟道取向和载流子极性的依赖关系。在NMOS和PMOS中，当沟道宽度均小于10 nm时，阈值电压迅速增大。为了阐明这些现象的原因，用有限元方法求解了薛定谔方程，得到了窄沟道中的电子态。结果表明，阈值电压的升高是由量子限制引起的。我们将这种效应称为量子力学窄通道效应。这种效应可以用来抑制起伏和控制阈值电压。

The purpose of this study is to increase the performance and suppress the fluctuations in scaled MOSFETs by utilizing the quantum effects. We fabricated ultra-narrow channel MOSFETS and observed the threshold voltage increase by the quantum effect, which is confirmed by the numerical simulations. In the experiments, in order to confine electrons not only vertically but also laterally, extremely narrow silicon channels are fabricated by the electron beam lithography and dry etching technique. The channel width is varied from 2nm to 100nm. The channel width is very uniform and its distribution is less than 2nm. The dependences on channel orientation and polarity of carriers are also investigated. The threshold voltane rapidly increases when the channel width is less than 10 nm both in NMOS and PMOS.In order to clarify the origin of these phenomena, the Schrodinger equations are solved by the finite element method and the electron states in narrow channels are obtained. The results show that the threshold voltage increase is caused by the quantum confinement. We refer to this effect as the quantum mechanical narrow channel effect. This effect can be utilized to suppress the fluctuations and control the threshold voltage.