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

1.采用原子层-有机化学气相沉积（MOCVD）技术制备了HfO_2超薄膜，有望成为未来小型化MOSFET器件的替代高k栅极介质。利用直接安装在沉积室上的椭偏仪，对HfO_2薄膜生长进行了现场实时椭偏监测，结果表明，该方法可用于超薄膜生长的工艺优化。利用HfO_2、SiO_2和Hf硅酸盐的介电常数计算结果，分析了HfO_2沉积过程中原位椭偏光谱的时间演变。模拟了膜生长初期界面层的形成和随后的氧化物形成，这些结果与横截面TEM图像和EDX分析结果定性一致。采用MOCVD法制备了硅酸镨超薄膜。通过角分辨x射线光电子能谱分析，估计了硅/硅镨界面处的价带偏移和硅镨的带隙。结合J-V和C-V测量结果，我们可以得出结论，硅酸镨是未来一代EOT小于1.0nm的MOSFET高k栅极介质的合适材料之一。

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.