本研究使用金屬鉿(Hf)靶材，利用反應性磁控濺鍍法在Ar + O2及Ar + N2的氣氛環境下，分別濺鍍HfOx及HfOxNy薄膜，並在氮氣氛700 ℃下退火15分鐘，以作為閘極介電層。實驗中將分析兩種介電薄膜(HfOx、HfOxNy)之材料性質，以及其作為金屬/氧化物/半導體電容結構中之介電層時的電性質，並探討材料性質與電性表現之間的關係，藉以評估其作為積體電路閘極介電層之可行性。此外，本研究中也使用N2O及NH3兩種氣氛，在薄膜沈積前對矽基材施以低溫(450 ℃)電漿氮化處理，並探討此基材氮化前處理步驟對MOS電容器電性表現造成的影響。

　　本實驗利用拉塞福背向散射分析儀對薄膜進行組成成份及密度鑑定；使用低掠角X光繞射儀針對薄膜結構及結晶性進行分析；使用高解析穿透式電子顯微鏡觀察薄膜截面影像，以判斷薄膜及中介層厚度與其微結構；X光光電子能量分析儀則被用來對電漿處理矽基材表面，及介電薄膜進行表面化學鍵結態分析；MOS結構電容器的I-V曲線乃使用直流電壓源/微安培計量儀(HP4140B)量得，C-V曲線則以電感電容電阻計量儀(HP4284)進行量測；此外，也藉由橢圓偏光儀的光學量測，來得到有關薄膜折射率及孔隙率的資訊。

　　實驗結果顯示，在Ar + O2環境下所濺鍍厚度約90 nm的HfOx薄膜，初鍍時將含有過量氧(x > 2)；而初鍍HfN薄膜，即使其乃採用Ar + N2氣氛濺鍍而不通入O2，亦將含有氧，故稱之為HfOxNy；兩薄膜經退火後皆趨近Hf：O = 1：2之計量比。就閘極介電層應用所需的極薄厚度(< 10 nm)而言，兩種介電薄膜即使經過700 ℃退火後，皆仍呈現非晶態，將可避免漏電流經由晶界傳導。此外，無論基材有無經過電漿氮化處理，兩薄膜系統皆存在結構類似SiO2的中介層，但HfOxNy薄膜因濺鍍時不通入氧氣氛，明顯較能抑制中介層的成長；同時HfOxNy也因摻入氮原子而擁有較緻密的薄膜結構。

　　除了電漿氮化的步驟能夠在中介層中引入氮原子，在HfOxNy系統中，氮原子亦能在濺鍍製程中被引入於中介層內，且此效應較N2O或NH3電漿處理造成中介層的含氮量更為明顯。薄膜沈積前的基材氮化，雖然對於抑制中介層於退火時繼續成長的效果並不明顯，但卻能使MOS電容器的平帶電壓偏移量(ΔVFB)減少，且以N2O電漿處理之效果較佳。若就介電層材料來說，經700 ℃退火後的HfOxNy薄膜較退火後的HfOx薄膜更為緻密，且擁有較高的光學折射率，因而呈現極小的遲滯C-V曲線寬度(ΔVh)，顯示氧化層捕獲電荷(Qot)數量明顯地因氮原子存在，使結構更為緻密而被減少；同時，HfOxNy薄膜對漏電流的阻障能力也較HfOx更佳。

　Hafnium oxide (HfOx) and hafnium oxynitride (HfOxNy) gate dielectrics were prepared by reactive magnetron sputtering from Hf target, following by postdeposition annealing at 700 ℃ in N2 ambient. We investigated the material and electrical characteristics to establish the feasibility of applying sputtered HfOx and HfOxNy as the gate oxide. In addition, low-temperature (450 ℃) N2O or NH3 plasma nitridation on Si surface was also carried out. The influence of surface nitridation on the interface quality and electrical properties is also discussed.

　Rutherford backscattering spectrometry (RBS) was utilized to examine the composition and density of the thin films. The crystal structure of the thin films was identified by glacing incident angle x-ray diffraction (GIAXRD). X-ray photoelectron spectroscopy (XPS) was applied for surface chemical bonding analysis of nitrided Si and the dielectric films. The thicknesses of films were determined by high-resolution transmission electron microscopy (HRTEM), and the microstructure was also characterized. For electrical properties, picoampere meter/DC voltage source (HP4140B) was used to measure the I-V curves, and the C-V curves were obtained by LCR meter (HP4284). For optical properties, ellipsometry was used not only to estimate the refractive index of the thin films, but also to simulate the percentage of void in the films.

　Based on RBS analysis, as-deposited HfOx film possesses excess oxygen atoms, and both HfOx and HfOxNy films transform to HfO2 after annealing at 700 ℃. According to the results of GIAXRD and HRTEM, ultra-thin HfOx and HfOxNy films are amorphous even after annealing at 700 ℃ in N2 ambient for 15 minutes. From HRTEM images and XP spectra, there exist apparent interfacial layers with the structure close to SiO2 at the HfOx/Si and HfOxNy/Si interfaces. However, HfOxNy shows a thinner interlayer during deposition because of the nearly oxygen-free ambient. Besides, HfOxNy film also presents a denser structure than the HfOx film does.

　Nitrogen atoms are introduced into the interfacial layers by plsma nitridation on Si before dielectrics deposition. For HfOxNy dielectrics system, the nitrogen-doped process in interfacial layers also occurs during sputtering, and the effects are more significant than surface nitridation treatment. For both HfOx and HfOxNy dielectrics systems, interfacial layers will still further grow during post-annealing process even if Si substrates have been passivated through surface nitridation. Nevertheless, ΔVFB is reduced by plasma nitridation, indicating that the number of fixed oxide charges are effectly decreased, especially via N2O plasma.

　In comparison to HfOx, MOS stacks with HfOxNy dielectics present smaller hysteresis loops, higher refractive index, and less percentage of voids, which expresses that the number of oxide trapped charges are evidently decreased due to nitrogen incorporation in the dielectrics. Furthermore, HfOxNy dielectrics also show higher ability to suppress leakage current than HfOx.

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