- 學位論文
氧化鋁/鋁/二氧化矽介電堆疊金氧半電容元件中兩態電流現象
Two-State Current Phenomenon in MOS Device with Al2O3/Al/SiO2 Dielectric Stack Structure
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摘要
在本篇論文中, 我們製作了一個介電堆疊層為 氧化鋁/鋁/二氧化矽 的金氧半電容元件並在此元件中發現了兩態特性。在第二章，我們說明了此兩態特性是源自於暫態電流。而暫態電流的來源是因為在寫入元件時，電荷儲存在内嵌鋁而導致。為了能清楚分辨正負電流，我們會在"最佳讀取電壓"去讀取元件。如此一來，將可以得到一組"對稱"的正負電流對。另外，我們發現當寫入電壓提高時，兩態櫥窗也會跟著變大。最後，我們得到元件的資料保存時間大約是1.1秒。在第三章，我們找到了三個可以影響兩態櫥窗的因素。第一，我們觀察到當二氧化矽的厚度越薄時，元件會呈現更大的兩態櫥窗。第二，當元件經過了後金屬退火處理之後，兩態效應會變得更明顯，而這是因為後金屬退火處理會使二氧化矽的厚度局部變薄。第三，內嵌鋁的氧化時間也是一個很重要的因素。當內嵌鋁的氧化時間很長時，二氧化矽厚度會變厚而且中間的內嵌鋁會全部被氧化。基於上述兩個原因，兩態櫥窗幾乎消失不見。
並列摘要
In this thesis, a MOS capacitor with Al2O3/Al/SiO2 dielectric stack structure was fabricated and it is observed that there is a two-state characteristic in this device. In chapter 2, it is shown that the two-state characteristic results from the two-state transient currents and the two-state transient currents are caused by the charges stored in the embedded aluminum. In order to distinguish the two states clearly, it is suggested to read the device at the "best read voltage". This "best read voltage" would lead to a "symmetrical" two-state current pair. It is also noticeable that the two-state window would be larger if the writing voltages are larger and the retention time of our device is about 1.1s. In chapter 3, three factors that could influence the two-state window are discussed. First, it is observed that the two-state window would be larger if the thickness of SiO2 is smaller. Second, it is found out that after post metallization annealing, the two-state window would be larger, which results from the local thickness reduction of SiO2 after PMA. Third, the oxidation time of embedded aluminum is also an important factor. If the oxidation time of embedded aluminum is very long, the thickness of SiO2 would be larger and the embedded aluminum would be totally oxidized. Owing to the thick SiO2 and the absence of embedded aluminum, the two-state window almost disappears.
參考文獻
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