本篇論文主要目的是對不同元件尺寸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，做一個初步的研究與探討。本論文使用的元件主要有三個尺寸參數：L (通道長度)、b (閘極控制的漂移區長度)、S1(漂移區長度)。
對元件特性來說，通道長度和閘極控制漂移區長度的影響比漂移區長度來的重要。接著我們選擇一個典型的元件尺寸(L/b/S1=0.5/0.7/0.4微米)，進行定電壓的熱載子stress實驗並討論熱載子退化現象和退化機制。藉由TCAD模擬以及charge pumping的分析，在不同stress條件下之退化機制可被完整的討論和統整，其中包括退化原因(接面陷阱(Nit)或是電荷捕陷(Not))以及元件退化的位置(通道或是漂移區部分)。
此外，元件尺寸對於元件熱載子可靠度的影響也會討論。根據我們的研究，經由TCAD模擬得知的電子和電洞injection機率大小是用來判定退化趨勢的重要指標。對元件生命期(lifetime)來說，漂移區長度(S1)的影響很微小，而不管是增加通道長度(L)或是閘極控制的漂移區長度(b)，都會使元件生命期增大。
最後，我們可以對於元件效能(performance)做ㄧ些簡單的結論。元件生命期的增加會導致線性電流(Id(lin))和飽和電流(Id(sat))的降低，其中線性電流降的比飽和電流還多，此外生命期增加也會同時提高off breakdown電壓和on breakdown電壓，但是對導通電壓(Vt)來說沒有什麼影響。因此，根據我們對原件的不同需求，必須選擇一個適當的元件尺寸來達到我們設定的目標。

In this thesis, device characteristics and hot carrier reliability of n-type LDMOS transistors with different device dimension are investigated. The device used in this thesis has three main layout parameters L, b, and S1, which corresponds to channel length, length of drift region inside gate, and length of drift region outside gate, respectively.
As for device characteristics, the effect of parameters of L and b is more significant than that of parameter S1. Then we choose a typical device dimension L/b/S1=0.5μm/0.7μm/0.4μm to perform constant voltage hot carrier stress and discuss the hot carrier degradation phenomenon and mechanism. By means of TCAD simulation and charge pumping analysis, device degradation mechanisms are discussed and summarized, including trap properties (interface traps (Nit) and/or oxide traps (Not)) and damage location (channel and/or drift region) under various stress conditions.
Besides, effects of device dimension (L, b, and S1) on hot carrier reliability are investigated. According to our research, TCAD simulation suggests electron and hole injection are good indicators to estimate the trend of device degradation. As for devices lifetime, the effect of parameter S1 is little and the longer parameters of L or b are, the higher lifetime is.
Finally, we can make simple conclusions about device performance as following. Improvement in lifetime causes more decreases of Id(lin) than Id(sat) on performance and results in increases of off-breakdown voltage (Vbd_dss) and on-breakdown voltage (Vbd_on) but has little effect on VT. Therefore, based on the purpose of a device, we should choose a specific device dimension so as to meet our expectation.

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