- 學位論文
熱載子導致高壓P型通道橫向擴散金氧半場效電晶體元件特性退化之可靠度研究
Hot-carrier Induced Reliability Degradation in High Voltage P-LDMOS Transistors
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摘要
本篇論文是採用0.5 μm 2p3m 高壓製程製作，並針對P通道橫向擴散金氧半場效電晶體元件(LDMOS transistor) 進行可靠度研究。主要採用charge pumping方法量測表面缺陷，並結合電腦模擬軟體(TCAD)，對各元件特性參數的退化來做更進一步的分析討論。 首先介紹高壓元件的原理及設計概念，charge pumping理論和量測設置，以及熱退化實驗各參數的萃取。並且利用元件結構參數的變化，charge pumping量測確定從模擬得到的參數(VT, cp)。量測發現長通道和短通道元件在電流密度上的不同，使克爾克效應(Kirk effect)易發生於短通道元件，進而影響可靠度。 由於克爾克效應的發生，基板電流(bulk current)會產生兩個峰值，對元件加壓在最大基板電流進行可靠度分析。根據熱載子實驗結果，發現不論是在長通道或是短通道元件，加壓在第一個峰值的測試，都只在P型漂移區產生較大的傷害。但當短通道元件加壓在第二個峰值，元件可靠度大幅下降，且經由模擬的輔助，發現電場的移動造成整個元件的傷害，使得導通電阻退化和臨界電壓偏移。
並列摘要
In this thesis, the p-type lateral diffused MOS (LDMOS) transistor used in this work is implemented with a 0.5 μm 2p3m high-voltage process. To investigate the reliability issue, charge pumping method is used to detect the interface states of the device. And to combine TCAD (Technology Computer Aided Design) simulation supports the analysis of the device. First, we have background review, which contains the introduction of the high-voltage device, the mechanism of hot-carrier degradation, and the methodology of charge pumping. Then the measurement set-up and the characteristic parameters extraction for the virgin devices are discussed. According to measurement result, we observe that Kirk effect will degrade the reliability in short channel (L = 1 μm) device. Due to Kirk effect, it produces a specific double-hump bulk current in short channel device. The hot-carrier degradation experiment is performed in long channel (L = 5 μm) and short channel (L = 1 μm) devices respectively. Both two channel lengths have mainly damage in the P-well region when stresses at the first peak. And when stressed at the second peak, there has serious degradation in whole device. The shift of electric field makes the degradation of on-resistance (Ron) and the shift of threshold voltage (VT, on). The simulation can give the reasonable explanation.
參考文獻
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