氧氣及氮氣電漿處理後之薄氧化層成長研究

Abstract

在此篇論文中，我們探討了矽以及二氧化矽經由電漿處理後形成的薄膜之特性。熱形成之二氧化矽由於其優越的電性及熱穩定性，使得它四十幾年來成為金氧半場效電晶體中主要的閘極絕緣層。當現今的元件在尺寸上急遽地縮小，二氧化矽的厚度已不可避免的接近其物理極限。使用熱形成之氮氧化矽來取代二氧化矽，在這些年來因為其所增進的效能及可靠性，已受到相當之矚目。另一方面，在現今之深次微米紀元中，由於電漿輔助之氮化及氧化具有較小的熱累積以及較高的產出，也是另一個具吸引力之方法。 本篇論文中，我們探討了經由氮氣及氧氣電漿處理過後，所形成之薄膜的成長率及機制。另外，氮氣電漿處理過之熱形成二氧化矽，以及再氧化之氮氣電漿氮化矽也在本篇論文討論中。我們使用電容法以及電性之量測來探討薄膜的特性。在我們的研究中發現，電漿形成之氮化矽或氧化矽，其成長速度均高於熱形成之氮化矽或氧化矽，這是由於電漿中較高的反應物密度所致。另外，再氧化之氮氣電漿氮化矽 （或可稱氧氣退火後之電漿氮化矽）顯示出比熱形成之二氧化矽更好的可靠性。

Thin-film characteristics of plasma treatment on silicon and silicon dioxide were studied in this thesis. Due to the superior electrical properties and thermal stability, silicon dioxide grown by thermal means has been utilized as the main gate-insulator in the MOSFETs for over 40 years. With the aggressive scaling of the dimension in modern devices, the thickness of the silicon dioxide has inevitably approached its physical limits. Thermally grown oxynitrides (SixOyNz) has been received great attention in these years to replace silicon dioxide because of its improved performance and reliability. Plasma-assisted nitridation and oxidation is another attractive vehicle due to its reduced thermal budget and high throughput, which are important in today's deep-submicron era. In this thesis, we investigated the growth rates and mechanisms of the thin films formed by nitrogen and oxygen plasma applied on the silicon. The thermal oxides that were further nitrided by nitrogen plasma and the oxidized plasma nitrides were studied, too. C-V and electrical measurement were used to characterize the samples. In our study, the growth rates of the plasma nitride and oxide are found to be faster than that of the thermal nitride or oxide, and this were due to the high density of the reactants formed in the plasma; and the oxidized plasma nitride (or alternatively, oxygen-annealed plasma nitride) has demonstrated superior reliability as compared with the thermal oxide. English Abstract ii Acknowledgements iii Contents iv Figures Captions v Chapter One-Introductions 1 1.1 Problems Encountered by Silicon Dioxide 1 1.2 Possible Candidates for Next-Generation Gate Dielectrics 1 1.3 Oxynitrides Grown by Plasma Treatment 2 1.4 Topics of This Thesis 4 Chapter Two-Experimental Procedures 5 2.1 Silicon Wafer Preparation 5 2.2 Plasma Processing 5 2.3 Furnace Oxidation 6 2.4 Device Patterning and Metallization 6 2.5 Measurements 6 Chapter Three-Results and Discussions 8 3.1 Plasma Nitride Growth in N2 Plasma Treatment 8 3.2 Plasma Oxide Growth in O2 Plasma Treatment 12 3.3 Thermal Oxidation After N2 Plasma Treatment 15 3.4 Nitridation of the Thermal Oxide by N2 Plasma 17 Chapter Four-Conclusions 19 References 20 Figures 23