應用於砷化銦鎵金氧半元件之複合式介電質材料之研究

Abstract

三五族金氧半場效電晶體近年來已被廣泛的研究。與傳統的矽材料相比，砷化銦鎵具有高電子遷移率和較低的導通電壓，因此成為未來通道材料的首選，以取代傳統以矽為基板的互補式金氧半場效電晶體,作為下一代低功耗、高速度的邏輯應用。然而，高介電質氧化物與三五族半導體之間的界面問題阻礙了三五族元件的發展，因此如何改善界面品質是一項很重要的研究。本論文主要是利用分子束沉積系統沉積高介電質材料(二氧化鋁、二氧化鉿、二氧化鈰、氧化鑭)，以堆疊的方式沉積在高銦含量的砷化銦鎵基板上，並藉由高溫退火的方法改善氧化物與半導體之間的界面品質和元件性能。實驗結果顯示以二氧化鉿為擴散阻擋層，可以有效抑制半導體的鎵、砷元素擴散到氧化層區域，再利用高介電係數的二氧化鈰和高能隙的二氧化鋁以分別改善電容等效厚度值和降低漏電流。而以二氧化鉿和氧化鑭交互堆疊的結構，在5000C的高溫退火後，有優秀的表面缺陷密度值和較高的電容值。

III-V metal-oxide-semiconductor field effect transistors (MOSFETs) have been widely investigated in recent years. InXGa1-XAs material has high electron mobility and the InXGa1-XAs based devices have lower turn on voltage than conventional Si devices. Therefore, InXGa1-XAs material is considered as a potential candidate to replace Si as the channel material for next generation low power, high speed complementary metal-oxide-semiconductor (CMOS) device for logic applications. In this thesis, HfO2 demonstrated good inversion behavior and acts as a diffusion barrier layer between CeO2 and InXGa1-XAs, CeO2 with high dielectric constant was used to enhance the overall capacitance of the composite dielectric layer, and Al2O3 was deposited on CeO2 after post-deposition annealing (PDA) to reduce the lower leakage current. On the other hand, the high k material for the composite structure of La2O3(0.8nm)/HfO2(0.8nm)×5 is investigated for n-InXGa1-XAs MOS capacitor. The device shows higher capacitance, good inversion behavior, excellent interface traps densities (Dit), and lower capacitance equivalent thickness (CET).