濺鍍法製備五氧化二鉭薄膜及電性改進之研究

Abstract

本實驗嘗試在不同的濺鍍系統壓力與氣氛下，以射頻磁控濺鍍法製備氧化鉭薄膜，之後再做800°C的退火或氧氮微波電漿表面改質處理表面改質處理探討其形成五氧化二鉭薄膜的行為。場發射電子顯微鏡、原子力顯微鏡被用以觀察薄膜表面的形貌；歐傑能譜儀研究其縱深成分分析；並量測漏電流、可靠度介電崩潰量測、電容值與折射率。實驗結果顯示在成長壓力為6mTorr、成長氣氛中含氧量為14.3％時，經微波電漿表面改質處理過的薄膜，有最佳的崩潰電場8.1MV/cm，崩潰點的電流密度為8×10-4A/cm2，其電容值達729pF，介電常數為30.7。X-Ray繞射實驗之結果顯示薄膜無論做任何處理，其化學結構維持TaO1+x之形態。微波電漿表面處理雖能使薄膜之化學計量比更趨近五氧化二鉭，但改質作用侷限於薄膜表面的部份，並不能對薄膜整體結構進行完全的改質。

Tantalum oxide (TaO1+x) films were prepared by radio frequency (RF) amgnetron sputtering method at different chamber opressure and Ar/O2 ratio. The film was then modified by a 800℃ heat treatment and microwave oxygen oplasma to transform to Ta2O5 The crystallinity, morphology and stoichiometric ratio of the films was investigated by x-ray diffraction, scanning electron microscope (SEM), atomic force microscope (AFM) and Auger electron spoectroscopy (AES), respectively. the electrical and optical properties of the films subjected to different treatment were also measured. the tantalum oxide films with best electrical performance was prepared at 6 mTorr sputtering pressure and 14.3% oxygen ambient followed by microwave oxygen plasma treatment. It had the breakdown current density ８×10-4 A/cm2 at the electric field 8.1 MV/cm. The capacitance of tantalum oxide films was 729 pF and dielectric constant was 30.7. Experimental results indicated taht microwave plasma treatment only modified the structure near film surface. The stochiometry fo the film remained TaO1+x regardless of the following modification process, as indicated by x-ray diffraction study.