New strategy for the deposition of metals by CVD and ALD: mechanistic and kinetic investigation for the growth of cobalt as model system

比勒费尔德团队最近开发了一种无氢金属化学气相沉积(CVD)方法，它使用脉冲喷雾蒸发(PSE)传递简单的、商业上可用的醇中的金属-有机前体。这一方法被证明对一些与催化、光子、磁性和电子应用有关的过渡金属的生长是成功的。除了众多的技术优势外，它还具有工作在液体注入原子层沉积(Li-ALD)区域的能力。尽管技术实现简单，但无污染的高质量薄膜的生长依赖于前驱体、表面和酒精之间的复杂相互作用，而这又取决于各种参数。因此，要充分发挥这一新办法的潜力，就必须彻底确定和了解所有相关的基本机制。这一目标将通过项目伙伴之间的密切合作来实现，这些合作伙伴具有互补的专业知识，允许将宏观增长行为与分子规模的过程联系起来。不同工艺条件下的化学和动力学的详细原位表征结果将与在超高真空(UHV)条件下研究的表面化学相关联。由于在前期工作中观察到了丰富的化学成分，因此作为一个模型系统，钴薄膜的生长将被研究。这样，将为将来扩大和优化生长纯金属薄膜的高效和高选择性方法的工艺奠定基础。

The Bielefeld team has recently developed a hydrogen-free approach to metal-chemical vapor deposition (CVD), which uses pulsed-spray evaporation (PSE) delivery of simple and commercially available metal-organic precursors in alcohols. This approach was demonstrated to be successful for the growth of a number of transition metals that are relevant in catalytic, photonic, magnetic and electronic applications. Besides the numerous technical advantages, it has the capability to operate in the liquid-injection atomic layer deposition (LI-ALD) regime as well. Notwithstanding the simplicity of the technical realization, the growth of high-quality thin films without contaminations is dependent on the complex interplay between the precursor, the surface and the alcohol which in turn depends on a variety of parameters. Thus, to fully exploit the potential of this new approach, a thorough identification and understanding of all relevant fundamental mechanisms is essential. This goal will be achieved by an intense collaboration between the project partners with complementary expertise which allow connecting the macroscopic growth behavior with the processes on the molecular scale. Results of a detailed in-situ characterization of the chemistry and the kinetics under different process conditions will be correlated with the surface chemistry investigated under ultra-high vacuum (UHV) conditions. As a model system, the growth of Co films will be studied because of the exhibited rich chemistry observed in preliminary work. In this way, the foundations shall be laid for future upscaling and optimization of the processes towards efficient and highly selective methods for the growth of pure metallic thin films.