- 學位論文
The Effect of higher-κ Lanthanum Titanate capping on HfO2 gate oxide via Atomic Layer Deposition
以原子層化學氣相沈積鍍製高介電鈦酸鑭薄膜與覆蓋於二氧化鉿閘極氧化層之影響
摘要
Abstract High-κ materials have attracted great attention for their applications in nano-scaled CMOS structures and memory. However, with the trend of scaling down in International Technology Roadmap for Semiconductors (ITRS), seeking for higher-κ dielectric oxides will be the key to meet the requirement for 22 nm and 15 nm node of CMOS technology. Lanthanum titanate (LTO) had been reported to have high dielectric constant and high crystallization temperature, which is taking the merit of TiO2 in high permittivity and La2O3 in thermal stability. Thus the higher-κ dielectric LTO is expected to have its potential in future high-κ dielectric. The LTO films is deposited on HfO2 in stacks structure via atomic layer deposition (ALD) technique in this study. The precursor systems used for deposition of lanthanum titanates were Tetrakis(dimethylamino) Titanium (TDMAT) + water and tris(N-N’-diisopropylformamidinato) Lanthanum (La(iPr2-FMD)3) + oxygen plasma. The electrical characteristics were measured in C-V and I-V relations, and the microstructure of thin films was inspected by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray reflectivity (XRR) and X-ray photoelectron spectroscopy (XPS). The LTO film is observed to diffuse in HfO2 through heat treatment, and yield in a new high-κ material which exhibits better properties than traditional HfO2 thin film and displays higher permittivity of 34.5 and lower equivalent oxide thickness (EOT) of 0.69 nm with a low leakage current of 10-2 A/cm2.