影響場效電晶體微縮化的兩大因子: 長距集合式庫倫作用與彈道傳輸

Abstract

近年來，由於電晶體的微縮，使得電子受到各種複雜的散射機制而導致遷移率下降。根據先前的研究，當長度短到奈米尺度時，在高摻雜的源極與汲極中的電漿子與反轉層電子之間的長距集合式庫倫交互作用將會本質地惡化反轉層電子遷移率。在這份論文中，透過實驗量測與電腦輔助設計軟體，我們研究源極與汲極的電漿子共振是如何滲透到通道中影響電子遷移率，並且透過電漿子共振建立其模型。另外，同時考慮了另一個本質上存在的彈道傳輸，萃取出兩個關鍵的通道長度，可以當作區分所有通道長度的傳輸機制的指南。並且在通道長度越來越小時，在彈道傳輸中分離出長距庫倫交互作用。另外，隨著二維反轉層電子氣密度的影響也被考慮在內。此引導指南也說明了隨著通道長度的微縮，電子遷移率也將跟著下降的趨勢。

Recently, owing to the scaling of transistors, electrons suffer more from complicated scattering mechanisms, thus resulting in mobility degradation. According to previous studies, when the channel length is reduced to the nanometer dimension, long-range collective Coulomb interactions between plasmons in high-doping region (source and drain) and electrons in the inversion-layer will be intrinsically degrade the inversion-layer electron mobility. In this thesis, we use both experiments and TCAD to investigate how source/drain plasmons penetrate into the channel, and establish its model via the plasmon resonance. Additionally, we consider another intrinsic factor, namely the ballistic transport. As a result, two critical channel lengths are created, which can serve as a guidelines to distinguish transport mechanisms for all lengths. When dealing with shorter channels, we can separate long-range Coulomb interactions from ballistic transport. Moreover, the effect of two-dimensional electron gas density is taken into account. These guidelines can help elucidate the observed decreasing trend of inversion-layer effective moility with the decreased channel length.