四氟化碳及氨之雙重電漿處理於氧化鉿金屬-絕緣層-半導體薄膜電晶體電特性之改善研究

Abstract

二氧化矽在過去40年已經被普遍地應用在積體電路製程技術上。隨著元件的微縮，閘極氧化層厚度也不斷縮小，導致閘極直接穿隧漏電流增加。傳統使用二氧化矽當作閘極介電層將面臨到物理和電性的限制。因高介電常數材料能有效降低漏電流與提升元件效能，所以近年來已被廣泛研究。二氧化鉿有高介電常數(25~ 30)、足夠大的能帶而且和多晶矽有很好的熱穩定性等優點，使用氧化鉿是目前以及未來最為推廣的材料。近年來低溫多晶矽薄膜電晶體由於在主動陣列顯示器的應用而吸引很多注意。我們將二氧化鉿用在低溫多晶矽薄膜電晶體上當作是對照組，而再外雙重電漿處理的實驗組(沉積前氟電漿處理以及沉積後安電漿處理的製程)。我們不僅討論二氧化鉿用於低溫多晶矽薄膜電晶體的基本電性外，更進一步深入探討可靠度的問題。可能是四氟化碳電漿的前處理可以修補介面品質而氮電漿的後處理可以修補二氧化鉿閘極的內部缺陷。而在結果中不管是用哪一種方法量測二氧化鉿用於低溫多晶矽薄膜電晶體的可靠度，雙重電漿處理的觀察片皆比沒電漿處理的對照片特性要好。

Silicon dioxide has been applied popularly in the integrated circuit process technology in the past 40 years. However the continuing scaling down of device has significantly reduced the thickness of gate dielectric film. The aggressive scaling of MOS devices is almost reaching the fundamental and electric limits of convention SiO2 as the gate insulator. Therefore, high-k gate dielectric material has been extensively studied in recent year, which could effectively reduce leakage current and improve device performance. Hafnium oxide (HfO2) is considered one of the promising high-k gate material due to its high permittivity (25~ 30), wide energy bandgap and thermal stability with poly-Si. The oxide of using Hafnium-based is a most promising material for future MOSFET gate oxide applications. High performance low-temperature polycrystalline-silicon thin-film transistors (LTPS-TFTs) have been attracted much attention due to the increasing applications in active matrix display (AMLCDs) in recent years. The HfO2 LTPS-TFTs were used as without treatment as a control group and combined with dual plasma treatment, which pre-deposition plasma fluorination and post-deposition plasma Ammonia of the experimental group. It might be that fluorine incorporation can improve the interface quality and nitrogen also can repair defects at bulk dielectric to decrease the leakage current. No matter how the stress mechanism applies, the dual plasma treatment LTPS-TFTs exhibits a superior performance than without treatment.