Maikap S, Rahaman S Z, Tien T C
Department of Electronic Engineering, Chang Gung University, Tao-Yuan, Taiwan, Republic of China.
Nanotechnology. 2008 Oct 29;19(43):435202. doi: 10.1088/0957-4484/19/43/435202. Epub 2008 Sep 22.
The charge storage characteristics of the high-κ HfAlO nanocrystal memory capacitors prepared by atomic layer deposition in an n-Si/SiO(2)/HfAlO/Al(2)O(3)/Pt structure have been investigated after high-temperature annealing treatment. The high-resolution transmission electron microscopy image shows that the diameter of high-κ HfAlO nanocrystal is<2 nm. The high-κ HfAlO nanocrystals have been also confirmed by x-ray photoelectron spectroscopy measurement. Due to the formation of high-κ HfAlO nanocrystals with the high-temperature (∼900 °C) annealing treatment, a large hysteresis memory window of 3.7 V at a sweeping gate voltage <10 V is observed as compared to that of the as-deposited memory capacitors. A hysteresis memory window of ∼1.7 V with a small sweeping gate voltage of ± 5 V is also observed. A small equivalent oxide thickness (EOT) of 5.6 nm is obtained due to the high-κ memory structure design. A significant memory window of ΔV≈0.7 V at 20 °C and ΔV≈0.6 V at 85 °C is observed after 10(4) s of retention time, due to the charge confinement in the high-κ HfAlO nanocrystals.
对采用原子层沉积法制备的、具有n-Si/SiO(2)/HfAlO/Al(2)O(3)/Pt结构的高κ值HfAlO纳米晶体存储电容器，在高温退火处理后其电荷存储特性进行了研究。高分辨率透射电子显微镜图像显示，高κ值HfAlO纳米晶体的直径<2纳米。X射线光电子能谱测量也证实了高κ值HfAlO纳米晶体的存在。由于经过高温（约900°C）退火处理形成了高κ值HfAlO纳米晶体，与沉积态存储电容器相比，在扫描栅极电压<10 V时观察到了3.7 V的大滞后存储窗口。在扫描栅极电压为±5 V较小时，也观察到了约1.7 V的滞后存储窗口。由于采用了高κ值存储结构设计，获得了5.6 nm的小等效氧化层厚度（EOT）。由于电荷被限制在高κ值HfAlO纳米晶体中，在保持时间为10(4) s后，在20°C时观察到显著的存储窗口ΔV≈0.7 V，在85°C时观察到ΔV≈0.6 V。
