形變溫度施壓處理對超薄閘極氧化層金氧半元件
特性影響之研究

當金氧半元件的尺寸日漸縮小，矽氧化層的厚度也隨之變的更薄，但是卻被要求提供更高的抵擋電流的能力，因此，如何提升二氧化矽介電層的品質，已經演變成一個重要的課題。然而，大量增加的功率密度及電流密度造成了熱效應和應力的問題更加嚴重。在這篇論文中，我們研究在金氧半元件處在高溫的環境中受到機械應力之後，對其電子特性的影響，並且探討在不同的厚度及不同的生長機制下，形變溫度施壓對氧化層所造成的影響，希望藉由這些測試，來改善二氧化矽超薄閘極氧化層的品質。經由實驗我們發現，適當的伸張形變以及熱效應，會增進金氧半元件的氧化層的品質，如漏電流密度及崩潰電壓…等電特性在經過伸張形變溫度施壓之後都獲得了改善，而我們認為，此一改善是由於伸張形變溫度施壓減少了矽分子和二氧化矽分子之間晶格的不匹配，而造成矽基板和二氧化矽之間的界面鍵結更加完美，才能使其電特性得到這麼大的改善。透過觀察 N 型基版的金氧半電容元件，我們發現其閘極電容值在低頻率測量時會出現負值，在此篇論文中，我們也對此一現象做出種種的分析，並根據這些分析，我們推測負值電容的發生原因是和閘極的漏電流有關。而透過上述的形變溫度施壓處理，元件的漏電流減小了，同樣的，負電容值再經過形變溫度處理後也被大幅的縮小。

關鍵字

金氧半元件；超薄氧化層；應力

並列摘要

With the scaling of MOS devices, the thickness of oxides becomes thinner. Nevertheless, dielectrics are requested to have higher ability to withstand the current. Therefore, it becomes an important topic to promote the quality of silicon-dioxide dielectrics. However, the increasing of power densities cause thermal and stress issue more seriously. In this thesis, we studied the effects of strain-temperature stress on the electrical characteristics of MOS devices with gate oxides grown by different techniques, and tried to promote the oxide quality by the proposed method. From the experimental results, we found that suitable tensile strain-temperature stress would promote the quality of MOS gate oxides. The electrical characteristics on tensile strain-temperature stress are investigated. While observing the C-V characteristics of MOS (n) capacitors, we found that the gate capacitance came to negative at low measured frequency. We infer the phenomenon is related to the gate leakage current by kinds of analyses. Thus, after tensile strain-temperature stress, the negative capacitance phenomenon can be reduced.

並列關鍵字

MOS capacitors ； Ultra-thin oxides ； stress

參考文獻

[1] International Technology Roadmap for Semiconductor, 2004 Update

[2] International Technology Roadmap for Semiconductor, 2004 Update

Semiconductor Industry Association.

Two-frequency Capacitance Measurement Technique for the Thickness Extraction

S. C. Chen, C. H. Yu, and M. S. Liang, “Determination of Deep Ultrathin

國際替代計量

形變溫度施壓處理對超薄閘極氧化層金氧半元件特性影響之研究

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