TiO_2/Al_2O_3堆栈结构high-k薄膜的制备及性能

Preparation and Properties of TiO_2/Al_2O_3 Stacked High k Gate Dielectric Films

采用磁控溅射法制备了TiO_2/Al_2O_3堆栈结构高k栅介质薄膜,研究了不同后处理条件对等效氧化物厚度,界面电荷和界面扩散的影响。实验结果表明:400℃退火后,TiO_2已经结晶,退火可以降低漏电流密度和介电层中的电荷密度。同时,退火使Ti进一步向Al_2O3层扩散,形成TiO_2和Al_2O_3的混合层,Al_2O_3层过薄时不能有效阻挡TiO_2的扩散。

TiO2/Al2O3 stacked high k dielectric films were deposited by RF-magneton sputtering. The effect of post-anneal on the morphology, equivalent oxide thickness, fixed charge density and the interfacial diffusion of the films were studied by atomic force microscopy, X-ray diffraction, precise impedance analyzer, picoammeter and Auger electron spectroscopy. The TiO2 film crystallized upon annealing above 400 ℃. The post-annealing improved the surface roughness, decreased the leakage current and the fixed charge density of the stacked films. Moreover, the post-annealing enhanced the diffusion of Ti to Al2O3 layer. The very thin Al2O3 layer could not block Ti from diffusion through the Al2O3 layer to the substrate.