陽極氧化法製備氧化鉭薄膜及其電性研究

Abstract

本實驗嘗試在玻璃基板上，以直流濺鍍的方式製備鉭薄膜，之後利用陽極氧化法製備氧化鉭薄膜。在陽極氧化過程中，改變不同之電壓、電流值，並以電腦記錄氧化過程中電壓、電流對時間之變化。在氧化二氮氣氛下，以不同之溫度熱處理氧化鉭薄膜。以穿透式電子顯微鏡觀察薄膜厚度和微觀結構，拉塞福背向分析儀分析薄膜之組成比，原子力顯微鏡分析表面平均粗糙度；並以HP 4156B、HP 4194A、HP 4280A等電性量測儀器量測漏電流對電壓之關係、電容值對頻率之關係、電容對電壓之關係。以探討這些變數對成長氧化鉭薄膜及其性質之影響。實驗中發現氧化膜中鉭與氧之計量比約為2：3，且高定電壓條件下氧化，可獲得高介電常數之薄膜，在50 V之定電壓條件下，可得最大之介電常數值為76，而其漏電流密度在0.7 MV/cm時約為10-4A/cm2。

Tantalum films were deposited on glass substrates by D.C. sputtering method and then were anodized to form tantalum oxide. Effects of anodizing voltages, and currents were evaluated during the anodizing processes. The oxide films were annealed in N2O ambient at various temperatures. The relations of anodizing voltage, current versus time were recorded by a personal computer, the thickness and microstructure were observed by cross-sectional transmission electron microscope (XTEM), the composition were analyzed by Rutherford backscattering spectrometer (RBS), the roughness of the oxide films were analyzed by atomic force microscope (AFM), the leakage current versus voltage, capacitance versus frequency, and the relationships between capacitance and voltage were measured by the instruments including HP 4156B, HP 4194A, and HP 4280A. The best value of dielectric constant obtained in this work was 76 at the anodized condition of 50 V and 3 mA. At 0.7 MV/cm, the leakage current was 10-4A/cm2.