Dry Etching Process and Properties of
|摘要:||本論文以兩種電漿組合(Ar/CF4 and Cl2/BCl3)進行溶膠法製備之鈦酸鉛鋯鐵電薄膜的高密度電漿乾式蝕刻研究，並觀察在兩種不同電漿組合及蝕刻參數下對於PZT薄膜之蝕刻率、蝕刻輪廓、微結構、及電性的影響。
使用Cl2電漿及一般光阻為蝕刻阻擋層，用單一步驟蝕刻W/PZT/Pt堆疊結構，可得到良好的極化特性及低漏電流:在100kV/cm下為1.175E-8 A/cm2 。|
High-density plasma dry etching process was used to etch sol-gel derived PZT ferroelectric thin films. Two different kinds of gas mixtures (Ar/CF4 and Cl2/BCl3) were used in this work. Etch properties such as etch rate, profile, microstructure and electrical properties were measured for different gas mixing ratios and plasma conditions. The maximum etch rate of PZT thin films appears under Ar/CF4 of 1. The voltage shift in the hysteresis loop after etching process was observed and could be recovered by thermal treatment at 600oC for 30 min. However, the internal electrical field caused by etching damage cannot be recovered even by thermal treatment. According to XPS analysis, it is suggested that the Pb and Zr atoms of PZT films react with fluorine to form Pb-F and Zr-F that is the cause of the degradation of electrical properties. On the other hand, etching with different mixing ratios of Cl2/BCl3 shows the maximum etch rate can be reached with pure Cl2 plasma. Even though the degradation was not detected, the vibration phenomenon in the hysteresis loop was observed. The vibration is probably related to environmental humidity because it can be recovered by 200oC thermal treatment. Scanning electron microscopy was used to examine etched profiles of PZT thin films. The wall angle of approximately 75 degrees was obtained. In addition, W/PZT/Pt stacked structure by Cl2 plasma was fabricated. PZT films with excellent polarization properties and very low leakage current density of 1.2E-8 A/cm2 at 100kV/cm was derived.
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