Atomic scale control of high-k dielectric ultrathin film grown by atomic layer-by-layer MOCVD with using in situ spectroscopic ellipsometry monitoring

1.HfO_2超薄膜有望成为未来小型化MOSFET器件的高k栅电介质替代材料，本文采用原子层层偏有机化学气相沉积(MOCVD)方法制备了HfO_2超薄膜。利用直接安装在沉积室中的椭偏仪，对HfO_2薄膜的生长进行了实时椭圆偏振测量，结果表明该方法对超薄膜生长工艺的优化是有用的。2.利用HfO_2、SiO_2和Hf-SiO_2的光学介电常数的计算结果，分析了HfO_2沉积过程中原位椭圆偏振光谱的时间演化。模拟了薄膜生长初期界面层的形成和后续氧化物的形成，这些结果与横截面电子显微镜图像和能谱分析的结果定性一致。3.采用MOCVD方法制备了Pr硅酸盐超薄膜。从角度分辨X射线光电子能谱分析，估算了硅酸盐/Pr硅酸盐界面的价带偏移量和Pr硅酸盐的带隙。结合J-V和C-V测量结果，硅酸盐是下一代EOT小于1.0 nm的MOSFET高k栅介质层的理想材料。

1.HfO_2 ultrathin films which are expected to be alternative high-k gate dielectrics for future miniaturized MOSFET devices are fabricated by the atomic layer-by-layer mete-organic chemical vapor deposition (MOCVD). By using an ellipsometer directly installed to the deposition chamber, we performed in situ real-time ellipsometry monitoring of HfO_2 thin film growth, and showed that this method was useful for process optimization of ultrathin film growth.2.Time evolution of in situ spectroscopic ellipsometry spectra during HfO_2 deposition was analyzed by using the calculated results of optical dielectric constants of HfO_2, SiO_2, and Hf silicate. Formation of interfacial layer at an initial stage of film growth and the following oxide formation are modeled, and these results are qualitatively consistent with the results of cross sectional TEM images and EDX analysis.3.Pr silicate ultrathin films are fabricated by MOCVD. From the angle-resolved X-ray photoelectron spectra analysis, valence band offsets at the Si/Pr silicate interface and band gaps of Pr silicate are estimated. Together with the results of J-V and C-V measurements, we can conclude that Pr silicate is one of suitable materials for high-k gate dielectrics of the MOSFET at the future generation with the EOT of less than 1.0nm.