形變溫度施壓對超薄閘極氧化層金氧半元件之效應

Abstract

當金氧半元件縮小至深次微米區域，矽氧化層的厚度也隨之變薄。根據ITRS的預測，在2013年時，元件的等效氧化層厚度將會是0.6nm，雖然縮小化與增加功率密度在現今的電子系統是一種趨勢，但是熱效應的問題是要被考慮的。當晶片經過封裝後，它常常會受到跟封裝有關的應力影響。許多元件大都是因為在高溫操作下受到熱效應與機械應力的施壓而壞掉。在這篇論文，我們將致力研究於經過熱效應與機械應力的施壓後的氧化層穩定度，而且，當金氧半元件在經過承受不同的機械應力同時在升溫的環境後，我們將分析它的電子特性與穩定度。 在第二章中，我們研究金氧半元件在經過承受不同的機械應力同時在攝氏100度的環境加熱5分鐘後的電特性。當中有探討關於對拉伸溫度(tensile-temperature)的樣品去改變烘烤元件時間或改變施加應力的強度的詳細電特性。而實驗結果顯示出金氧半元件經過長時間的拉伸溫度施壓(tensile-temperature stress)或承受適合的拉伸應力可以展現最好的介面品質。 在第三章，我們對所有經過形變溫度施壓的元件去測試它們的穩定度，包括TDDB和SILC。經過這些測試，我們知道金氧半元件經過長時間的拉伸溫度施壓(tensile-temperature stress)或承受適合的拉伸應力可以展現改善的崩潰忍受度以及變化少的SILC。最後，我們對這篇論文給予結論和建議未來的研究方向。

As MOS devices are scaled down to the deep-submicrometer region, the thickness of silicon oxide also scales down. Based on the International Technology Roadmap for Semiconductor (ITRS), the equivalent oxide thickness (EOT) should be 0.6 nm in 2013. Although miniaturization and increasing power density are the trends in modern electronic system, the issue of thermal stress is of concern. After packing up in system, chips often suffer from the package-related stress. Many device failures are caused by the thermal-mechanical stress occurs during high temperature operations. In this thesis, we will focus on the effect of thermal-mechanical stress on oxide reliability. We will analyze the electrical characteristics and reliability of the MOS structure after receiving various mechanical stresses under an elevated temperature. In chapter 2, we studied the electrical characteristics of MOS structures after receiving thermal treatments at 100 oC for 5 minutes with various mechanical stresses applied on the substrate. The detailed electrical characteristics on tensile-temperature samples by changing the baking time and the strength of mechanical stress are investigated. The experimental result shows the samples after long-time tensile-temperature stress and under suitable tensile stress have the best interface quality. In chapter 3, the reliability properties of the strain-temperature samples, including time-dependent-dielectric-breakdown (TDDB) and the stress-induced-leakage current (SILC) are examined. After these tests, we find that the samples after long-time tensile-temperature stress and suitable tensile stress exhibit the improved breakdown endurance and the reduced SILC. Finally, conclusions and some other suggestions about this thesis were given.