高k材料镧前驱体La(tmhd)_(3)和La(tmod)_(3)的热力学及其ALD应用

Thermodynamics and ALD Application of Lanthanide Precursors La(tmhd)_(3) and La(tmod)_(3) for High k Materials

通过同步热分析研究两种不同的前驱体(La(tmhd)_(3)和La(tmod)_(3))在升华过程中的热稳定性。结果表明,具有不对称分子结构的La(tmod)_(3)的挥发性大于La(tmhd)_(3),其可以作为镧前驱体应用于原子层沉积(ALD)技术。将La(tmod)_(3)和O_(3)作为前驱体,通过ALD技术在SiO_(2)基片上实现了LaOx薄膜的制备。实验结果表明,其最佳的ALD工艺参数包括:La(tmod)_(3)和O_(3)的脉冲时间分别为6 s和2 s,O_(3)的清洗时间为5 s,沉积温度为250℃。在制备的薄膜中发现了理想的自限性沉积行为。通过X射线光电子能谱仪(XPS)、扫描电子显微镜(SEM)和原子力显微镜(AFM)证实了生长的薄膜具有良好的纯度和表面形貌,其在250℃的沉积温度下具有稳定的生长速率(约0.16A/cycle,1A=0.1 nm),薄膜的主要成分为La2O_(3)。

The thermal stability of two different precursors(La(tmhd)_(3),and La(tmod)_(3),)during sublimation process was investigated by simultaneous thermal analysis.The result shows that La(tmod),with an asymmetric molecular structure is more volatile than La(tmhd)_(3),and can be applied as a lanthanum precursor for the atomic layer deposition(ALD)technique.La(tmod)_(3) and O,were used as precursors for the preparation of LaO,films on SiO_(2)substrates by ALD technique.The experimental results show that the optimal ALD process parameters are 6 s and 2 s for the pulse time of La(tmod)_(3) and O_(3),respectively,5 s for the purge time of O3,and 250℃for the deposition temperature.Desirable self-limiting deposition behavior is found in the prepared films.By using X-ray photoelectron spectroscopy(XPS),scanning electron microscope(SEM)and atomic force microscope(AFM),it is confirmed that the grown films have good purity and surface morphology,the films have a stable growth rate(about 0.16 A/cycle,1 A=0.1 nm)at a deposition temperature of 250 C,and the main component of the films is La_(2)O_(3).