電阻式記憶體（RRAM）除了具有高密度、低成本、低耗能、操作速度快、保存資料能力佳等優點外，構造簡單也是它的一大特色，一般以金屬/絕緣層/金屬的MIM結構為主。而本實驗更進一步簡化了製程，發展出金屬/絕緣層/半導體的MIS結構。 本實驗使用MOCVD方式沉積不同厚度的HfO2，藉由鍍製不同上電極（TiN/Ti, Ni）於HfO2薄膜上，分別得到bipolar及nonpolar兩種不同的電阻轉換特性。由此可知，電阻轉換特性受電極影響而有不同。以TiN/Ti為上電極之元件，在HfO2厚度大於50 nm以上，可得到bipolar的電阻轉換特性，而以Ni為上電極之元件，在HfO2厚度介於10 nm ~ 50 nm間皆可得到nonpolar的電阻轉換特性。藉由電性量測及物性分析等方式，得到以TiN/Ti為上電極bipolar特性的元件，主要是以氧空缺方式形成filament進行傳導，而以Ni為上電極nonpolar特性的元件，則主要是以Ni金屬形成filament進行傳導。除此之外，我們更進一步的建立其電阻轉換機制。 The resistance switching random access memory (RRAM) has the advantages of high density, low cost, low energy operation, fast operating speed, good retention, and simple structure. In general, RRAM is characterized with a metal-insulator-metal (MIM) structure. Here we develop a metal-insulator-semiconductor (MIS) structure, which is more compatible with silicon process than MIM structure. MOCVD is used to deposit different thickness of the insulator layer HfO2. With different electrodes (TiN/Ti, Ni) on the HfO2, we observed different resistance switching characteristics, bipolar and nonpolar switchings, which suggests that the resistance switching characteristic depends on the electrode materials strongly. According to the electrical and structural characterizations, oxygen vacancy plays a role of conducting filament in HfO2 for bipolar resistive-switching when using TiN/Ti electrode. On the other hand, Ni filament contributes to the nonpolar switching with Ni electrode. We also established the possible resistance switching mechanism in detail.
