射頻磁控濺鍍法製作之氧化亞錫薄膜特性之研究

Abstract

本論文討論在不同生長條件與不同退火環境下，氧化亞錫薄膜的晶相、結晶度、穿透度、表面粗糙度與電特性的分析。並且探討氮氧混合氣與水氣退火，不同退火環境之下的特性變化，從調變不同氧含量比例開始探討，進而調變不同鍍膜工作壓力、不同退火溫度，找出最佳的製程條件。 本實驗使用射頻磁控濺鍍系統在室溫下成長氧化亞錫薄膜，以純度99.999%的金屬錫為靶材，並調控濺鍍時的工作壓力與氧含量比例。在薄膜的晶相分析中，氧化亞錫薄膜的主要峰值位置會受到工作壓力與氧含量比例影響，高工作壓力或高氧含量比例主峰位置會出現在(101)上，低工作壓力或低氧含量比例主峰位置會出現在(110)上，而且薄膜的主峰位置在鍍膜的時候就已經決定好了，在退火溫度205°C~265°C範圍之內，薄膜的主要峰值位置不受退火環境影響。在電子能譜分析中，退火環境氮氧混合氣的氧氣量增加或是退火溫度增加，薄膜內氧鍵結的比例也會增加，通入水氣之後，氧氣的鍵結比例增加更明顯。 由實驗的結果，要減少常溫濺鍍所產成的缺陷，比較可行的溫度位在225°C~245°C之間，在此溫度範圍內有較低的載子濃度，如果要有較高的載子遷移率，溫度範圍必須控制在225°C附近，因為退火溫度提高也使得載子濃度增加，不利載子的傳遞。整體而言，通入水氣之後薄膜的載子遷移率會略降，因為水氣會促進薄膜氧化，除了減少薄膜內金屬錫的含量，也增加了薄膜內的缺陷，以至於載子濃度增加。

This thesis reports the experimental results regarding the tin monoxide (SnO) thin films were deposited by RF-sputtering technique. We investigated the crystallinity, optical transmittance, surface morphology and electrical properties of tin monoxide thin film under various deposition conditions and annealing atmospheres. SnO thin films were sputter-deposited on glass substrates under various O2/Ar flow ratios and sputtering pressures at room temperature. First, we investigated the influence of O2/Ar flow ratios on the films' properties. Higher oxygen reduced the content of β–Sn phase, leading to higher purity of tin monoxide. From the analysis of the crystal phases of SnO thin films, the main peak position was influenced by the O2/Ar flow ratios and pressure. As the O2/Ar flow ratios and pressure increased, the main peak position was shifted from (110) to (101), but the main peak positions were not influenced by annealing conditions. The proportion of oxygen in the films was increased with the annealing temperature or the oxygen content of the atmosphere. Compared to other annealing conditions, water vapor annealing can much effectively increase the oxygen content in the films. Overall, the Hall mobility decreased slightly after annealing in water vapor environment, because the water vapor promoted the oxidation of SnO films, not only reducing the metal tin content of SnO films, but also increasing the defects of SnO films. Therefore, the bulk carrier concentration increased, and hall mobility was decreased.