複晶矽鍺閘極之負偏壓溫度不穩定性研究

Abstract

本論文中，主要是將氮離子佈植利用在複晶矽鍺閘極PMOS元件中，來探討對於硼穿透與閘極空乏現象，及不同劑量氮離子佈值對P型金氧半電晶體中負偏壓溫度不穩定性NBTI (Negative Bias Temperature Instabilities) 的影響。 在第一部份，為了改善複晶矽鍺閘極氧化層的品質，利用N2O氧化層處理的方法。從研究中發現，這個方法可以有效抑制硼穿透效應並改善氧化層的可靠度，推究其原因是SiO2/Si介面堆積了許多氮原子，形成矽氮強鍵來取代矽氧弱鍵結。另外探討複晶矽鍺閘極在不同離子佈植劑量下，對於硼穿透、閘極空乏與阻值的關係。 第二部份主要是研究不同的濃度氮離子佈值對NBTI的影響。我們發現在閘極佈值氮離子劑量的越高，會造成較嚴重的NBTI。此外本論文中也會探討動態NBTI與Substrate Hot Hole，經過研究較大劑量的氮離子佈值，也會造成較嚴重的基板熱載子效應。DNBTI在閘極加正偏壓時，發生回復(recovery)，這個現象指出其實NBTI 所造成的傷害是可以部分回復的。

In this study, the effects of poly-SixGe1-x gate MOSFET’s with nitrogen co-implantation process are investigated. The subject is focus on NBTI (Negative Bias Temperature Instabilities) of different nitrogen dosages, boron penetration, and gate depletion of the pMOSFET. First, for the reliability and electrical properties concern, N2O oxynitride was used for gate dielectric. Boron penetration was suppressed effectively, due to nitrogen atoms at Si/SiO2 interface. In addition, boron penetration and gate depletion were discussed simultaneously under different dosage of nitrogen co-implantation. Furthermore, the influence of different dosages of nitrogen implantation on NBTI was also investigated. High nitrogen dose implantation in the gate leads to serious NBTI degradation. Then both the dynamic NBTI effects and substrate hot holes effects were also discussed in this study. Larger nitrogen dose not only results in serious NBTI effects but also serious substrate hot holes. As DNBTI was measured, the reduction of ΔVTH after positive gate bias stressing is related with the recovery of interface states.