本篇論文主要的目的是對n型通道橫向擴散金氧半場效電晶體(LDMOSFET)之元件特性及熱載子可靠度，做一個初步的研究及探討。
我的研究主要是針對在不同濃度的輕摻雜區域(NDD)下，其元件的直流特性及熱載子可靠度的差異。
高壓元件所追求的兩個主要特性即：低的導通電阻及高的崩潰電壓。由過去的實驗中得知，增加輕摻雜區域的濃度可以降低元件的導通電阻，但也會造成最大橫向電場的提升，進而可能導致較嚴重的熱載子效應。本篇論文將以不同的輕摻雜區域濃度為主軸，將內容分成五個章節進行討論。
首先，第一章將對高壓元件及其運用做基本的描述與介紹，並簡單的介紹何謂熱載子效應。第二章則是介紹實驗中所量測的各個參數，以及量測的方法與步驟，並詳敘stress的方法與其用意。第三章則是討論不同的輕摻雜濃度對元件退化的影響。由實驗中我們發現，隨著輕摻雜區域濃度的增加，導通電阻(Ron)的退化會有大幅變小的現象，而其最大轉移電導(Gmmax)的退化則會有些微上升的趨勢。我們推論，這與熱電子與熱電洞在不同輕摻雜濃度下注入氧化層的位置有關。
在發覺此現象後，第四章則接著討論不同的元件結構對輕摻雜濃度效應的影響。由實驗中發現，當閘極到汲極的距離(Ld)變長的時候，導通電阻退化降低的效應會變小；而當閘極長度(Lg)變短的時候，導通電阻退化降低的效應會變大。最後，當我們將輕摻雜濃度固定時，我們發現閘極長度對生命期(lifetime)的影響比閘極到汲極的距離來的大。
第五章則是將實驗做個總結，並提出論文中尚未完成的研究方向，以待將來做更深入的探討及研究。

In this thesis, the device characteristics and hot-carrier reliability of Lateral Diffused Metal-Oxide-Semiconductor (LDMOS) transistors are investigated. My research will highlight the impact of various n-type drain drift (NDD) implant doses on DC characteristics and hot carrier reliability of 12V n-channel LDMOS transistors processed in a 0.35μm technology.
Two important features of high-voltage (HV) devices are a low on-resistance (Ron) and a high breakdown voltage (VBV). As we all know, increasing NDD dose could lower on-resistance, but it also cause a rise of the maximum lateral electric field (Eymax), which may lead to a more serious hot-carrier effect. We will discuss the effect of NDD dose in the following five chapters.
In Chapter 1, there will be some basic introductions of HV devices and its application, and we also introduce the background of hot-carrier effect. In Chapter 2, we will show all the parameters extracted from my experiments, measurement methodology, and stress methodology. Then, we will discuss the impact of different NDD dose on parameter degradation in Chapter 3. From my experiments, we discover that Ron degradation will dramatically decrease while Gmmax degradation will slightly increase with higher NDD dose. We suppose that it is related to the places in oxides where hot electrons and hot holes are trapped with different NDD doses.
After discovering this phenomenon, we will discuss the effect of NDD dose in different device structures in Chapter 4. We find that when the length from gate edge to drain N+ edge (Ld) becomes longer, the effect of NDD dose will become smaller. On the contrary, when the gate length (Lg) becomes shorter, the effect of NDD dose will become greater. Then we focus on the highest NDD dose, and discover that Lg has a greater influence on Ron degradation than Ld.
In Chapter 5, a conclusion and a future work are presented for further investigation.

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