關止狀態下金氧半電晶體異常能帶間穿隧漏電流特性之深入研究

Abstract

過去幾年來由於金氧半產品縮小化的需要，使得金氧半元件技術演進至次 微米的境界，其不僅在氧化層方面變薄了，更進而使得閘極至汲極重疊區 域下之電場強度增強，使得金氧半元件在關止狀態時產生嚴重的能帶間穿 透，進而造成閘極引致汲極漏電流，而且將主導薄氧化層金氧半電晶體之 汲極漏電流．對於由Ｐ型通道金氧半電晶體所形成的閘控二極體，所觀察 到汲極漏電流的新型異常特性將被提出，本論文將首先提供一個考慮在閘 極至汲極重疊區域下之電子累積的新物理模型，以解決舊有的空乏近似模 型應用在實驗數據上的不確定性，並合理的重新產生此異常汲極漏電流特 性． Owing to the necessity in scaling of MOS products for the past few years, MOS device dimensions have been shrinked to below one micron with oxide thickness reduced such as to cause a high electric field in the gate-to-drain overlap region. This increased electric field can cause seriously the band-to-band tunneling phenomenon in off-state thin oxide MOSFET's. The gate -induced drain leakage current (GIDL) is therefore generated, and will dominate the drain leakage current at off-state condition. For the submicron buried-type p-channel LDD MOSFET' s, a new observation of the anomalous drain leakage current- voltage characteristics measured in a gated-diode configuration have been reported. This thesis first presents a new physical model taking into account the electrons accumulated in the gate- to-drain overlap region, which can eliminate the uncertainties in determining the parameter values when applying the deep depletion approximation theory. The measured anomalous drain leakage current-voltage characteristics have been reasonably reproduced based on this new model.