本論文討論氮摻雜碳化矽(nitrogen-doped silicon carbide, SiCN)薄膜的材料基本特性以及紫外光後處理對其性質改良之研究。目前在新研發材料中，氮摻雜碳化矽薄膜因具有低的介電常數(k= ~4.9)及較低的漏電流密度，用來取代傳統具高介電常數的氮化矽 (silicon nitride) (k= ~8)，作為新一代的介電阻障層材料。紫外光照射處理為目前受矚目的薄膜改質後處理，在超低介電(ultra low-k)薄膜製程中，應用紫外光後處理使薄膜結構改變，並使介電常數下降。
本研究動機起因於若可應用紫外光改善介電阻障層性質，則可與超低介電薄膜做製程整合，以減少後段製程的步驟。此實驗利用電漿輔助化學氣相沈積法(PECVD)沈積氮摻雜碳化矽薄膜，並利用紫外光照射系統對薄膜做後處理，另外利用MIS(metal-insulator-semiconductor)結構，量測薄膜之電性質的部分。紫外光後處理實驗分為兩個部分，包括照射時基板溫度及照射時間，分別探討對薄膜物理性質與電性質的影響。
研究結果顯示，紫外光與薄膜內部鍵結產生光化學反應，打斷Si-H鍵結，使得Si*自由基增多，並與薄膜內未鍵結C形成Si-C以及Si-(CHn)-Si鍵結，而此鍵結變化造成薄膜性質的改變。紫外光照射時其基板溫350℃，時間三分鐘，可使介電常數下降至4.63，並使其殘留應力減少至-25.69MP，薄膜厚度沒有明顯變化，漏電流密度在電場1MV/cm並沒有明顯上升，故可得知紫外光後處理能有效改良SiCN薄膜介電阻障層性質，有利於半導體後段製程應用。

In this thesis, the basic material properties of nitrogen-doped silicon carbide and the improvement of the dielectric barrier properties by ultraviolet (UV) treatment will be investigated. Nitrogen-doped silicon carbide (SiCN) with lower dielectric constant (k~4.9) and lower leakage current is a promising dielectric barrier material to replace the typical use of silicon nitride (SixNy) (k~8). Recently, a newly-developed post treatment (UV treatment) has attained much attention and was used to change the structure of ultra low-k films in order to decrease the dielectric constant.

In this study, the UV treatment will be used to improve the property of SiCN films for the combination of the back-end-of-line process with ultra low-k films and dielectric barrier. The SiCN film was deposited by plasma-enhanced chemical vapor deposition (PECVD), and the post treatment was used by UV system. The metal-insulator-semiconductor (MIS) structure was used to measure the electrical property of the film. The experiment’ parameters of UV treatment have included the substrate temperature and the curing time during UV treatment. And the effects of the parameters on the physical properties and electrical properties will be investigated.

After UV curing, it could be observed that the Si-H bonds was broken and the Si* free radical increased. The recombination of unsatisfied bonds on silicon and carbon atoms was promoted, enhancing the Si-C and Si-(CHn)-Si bonds. The dielectric constant decreased to 4.63 after UV curing at 350℃ for three minutes. And the residual stress decreased to -25.69MPa. The leakage current did not change obviously at the electrical field of 1 MV/cm. In consequently, UV treatment is effective to improve the SiCN films property and has extremely potential to the back-end-of-line application.

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