鐵電記憶元件的低溫製程及電流遲滯研究

Abstract

鉭酸鍶鉍具有不疲勞的特性，對於用在非破壞性讀取的鐵電記憶電晶體有相當的好處，但是就其本身的低殘存極化量和較高的製程溫度，則限制了其做為鐵電記憶體的應用。在本篇研究，欲以添加不同高居里溫度的物質來增進殘存極化量及達成降低製程溫度的目的，並藉由金屬有機溶液沈積法沈積該鐵電薄膜，使鐵電記憶元件的製程溫度有效降低至600℃。而且，透過電容和電壓及電流和電壓的量測法，可明顯地看出此方法不僅實現了鐵電記憶元件的低溫製程，同時又保有數十奈米等級的低電流密度和在來回5伏特應用電壓下仍有1.3伏特的記憶體效應的特性。而在另一方面，此種鐵電記憶元件具有電流遲滯效應的現象，原因為極化向量所導致，當然這樣的現象和極化向量對電場及電容對電壓的量測是對等的。除此之外，對於實際操作鐵電記憶電晶體，閘極所面臨的不同漏電流的問題在此篇都將探討。

SrBi2Ta2O9 (SBT) ferroelectric films have been demonstrated to possess the fatigue-free property to apply in the non-destructive MFISFET，but suffer from the issue of the low remanent polarization and high crystallization temperature。In this thesis，the stoichiometric SBT films prepared by using the metal-organic solution deposition (MOD) method was doped with the Bi3TiTaO3 (BTT) and Bi3TiNbO3 (BTN) for promoting the remanent polarization and achieving the goal of decreasing the process temperature below to 600℃。Moreover，the C-V measurement also reveals the broader memory widows of 1.3V as the sweep voltage in the 5V，and the leakage current density is as low as1E-8 A/ 。On the other hand，the hysteresis loop of conducting current in the MFIS structure also reveals the effect of the polarization behavior of ferroelectric film 。Furthermore，the effect of leakage current on the operation of the MFIS structure is discussed。