用于非破坏性读出铁电存储器的MFIS结构的机理研究

分析了 MFIS FET的工作机理以及影响 MFIS电容的存储窗口特性的因素 ,提出用存储窗口与铁电薄膜正、负矫顽电压的差值来评价存储窗口特性 ,制备了 Au/Cr/PZT/Zr O2 /Si的 MFIS结构并研究了其存储窗口特性 ,存储窗口随 Zr O2 的厚度变化呈现一个极大值 ,甚至会出现 C-V曲线方向的变化 ,而 PZT薄膜的厚度增大会导致窗口增大 ,这是由于界面效应以及在铁电层和介质阻挡层上电压分配关系的不同而造成的 ,这一结果与前面的分析很好地吻合。当 Zr O2 和 PZT的厚度分别为 3 0 nm和 2 5 0 nm、扫描电压从 -5 V到 +5 V变化时 ,存储窗口大小为 2 .5 V,与相应的铁电薄膜的正、负矫顽电压的差值的比为 0 .8。

Mechanism of MFIS of Au/Cr/PZT/ZrO2/Si Structure for NDRO FeRAM Application

Mechanism of MFI S FET and the impact of the process on th e memory window characteristics of MFIS capacitor were analyzed. The ratio of th e memory window width to the D value of ± V c was introduced to evaluate the me mory window property. MFIS structure com posed by Au/Cr/PZT/ZrO 2/Si was prepared and its performance was studied, in whi ch PZT was grown by MOD method. It was f ound that the memory window width has a maximum when the thickness of the ZrO 2 thin film increased while the PZT thickn ess was fixed. It was observed that the C V curve of MFIS capacitor changed in the anti clock direction when the charg e injection effect was severe. When the thickness of PZT thin film increased whi le the ZrO 2 thickness was fixed, the me mory window increased. The above phenome na verified the analysis of mechanism o f MFIS FET. The memory window reached 2. 5 V for the sweep voltage from -5 V to + 5 V under condition of ZrO 2 thickness a nd PZT thickness being 30 nm and 250 nm respectively. The ratio of absolute valu e of memory window to the D value of ± V c was 0.8.