超薄介電層在超大型積體電路上的應用

Abstract

本論文提出三種新型的超薄介電層應用於超大型積體電路技術。在閘極介 電層上，我們提出一種新的製程利用氨氣在非常低壓下 (約0.1 Torr)氮 化氧化層。不僅擁有傳統氮化氧化層的優點，且因不須額外的再氧化步驟 ，使得製程能夠簡化。再加上氨氣能與氧化層在較低溫反應，因此這技術 較其他氮化方法較有潛能。在穿透介電層技術上，本論文再引進一種全新 的超薄介電層。其製造方法是先在矽基板沈積一層非常薄的粗糙複晶矽( rugged poly-Si)再經高溫氧化形成具粗糙界面的氧化層。 經由此法製造 的超薄介電層具有相當高的可靠度，而且能在非常低的電壓下工作，完全 符合快閃記憶元件的要求。在儲存電容器的介電層上本論文將非常薄的氮 化矽，在傳統的低壓高溫爐管，在低壓下通入氧氣加以高溫氧化。使得傳 統以氮化矽為主的堆疊介電層進一步降低它的等效氧化層厚度。 In this thesis, we propose three novel ultrathin dielectrics for ULSI applications. For gate dielectrics, a novel technique to fabricate ultrathin gate dielectrics by nitridizing SiO2 only in NH3 at very low pressure (about 0.1 Torr) has been proposed. This dielectrics not only possesses the merits of the conventional nitrided oxides but also have a simple process without the need of re- oxidation. In addition, NH3 can react with SiO2 at low temperature. Hence, this method is promising for the future. An all-new tunneling dielectrics fabricated by oxidizing ultrathin rugged poly-Si has been proposed for the flash memories. This dielectrics possesses high reliability and can be applied for low voltage application. For the dielectrics of the storage capacitors, a novel and simple method is proposed and makes the effective-oxide-thickness of the nitride- based stacked dielectrics be futher scaled down. This dielectrics are constructed by oxidizing very thin nitride at low pressure in a conventional low-pressure- chemical-vapor- deposited (LPCVD) system.