以伸張應力陽極氧化技術成長高品質超薄氧化層

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，此時矽氧化層因為太薄而易生大量漏流，因而有高介電質材料做為金氧半元件絕緣層之考慮。然而，基於高介電質金氧半元件仍有穩定度不佳等問題，因此，如何能夠改善矽氧化層品質仍是重要課題。本論文係討論應變矽之金氧半電容元件，並致力於在經過伸張應力下生長氧化層之金氧半元件的電特性研究以及穩定度測試。 在第一章中，我們介紹實驗及分析工具，並比較快速熱氧化之矽氧化層、陽極氧化之矽氧化層以及化學成長矽氧化層，得知陽極氧化之矽氧化層可獲致較佳之電特性，並可於室溫製備。因此，本實驗係採用伸張應力下生長氧化層之傾斜陰極之陽極氧化系統。 在第二章中，我們研究金氧半元件在經過伸張應力之後電特性之改變，其中探討關於伸張應力對於樣品所造成的各種效應。而實驗結果顯示出經過適當的伸張應力下生長氧化層可以產生高品質的金氧半電容元件。 在第三章，我們對所有經過伸張應力生長氧化層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之氧化層在經過適合的伸張應力下生長可以展現改善的崩潰忍受度以及變化少的SILC。在附錄中，我們提到有關於溫度引起的伸張應力現象，並做簡單的討論。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. The ultra-thin gate silicon dioxide is too leaky; therefore, high-k films are introduced. However, due to poor reliability problems, silicon dioxide is still the main stream is the near future. Thus, it is still crucial to improve the oxide quality. In this thesis, we will focus on the effects of mechanical tensile stress during oxidation on oxide quality and reliability issues of MOS capacitors via the study of the electrical characteristics. In chapter 1, we introduced experimental and analysis tools, and also compared the thermal oxides, chemical oxides, and anodized oxides. We realize that anodized oxides exhibiting better electrical characteristics, and could be prepared at room temperature. Thus, the anodized oxides are adopted. In chapter 2, we investigate the effects and electrical characteristics of the MOS capacitors after applying mechanical tensile stress during anodization process. From the experimental results, we could acquire high quality MOS capacitors after applying suitable tensile stress during anodization process. In chapter 3, the reliability properties of the Non-Stress and Tensile-Stress 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 suitable tensile stress during oxidation exhibit the improved breakdown endurance and the reduced SILC. Finally, a conclusion and some other suggestions were given.