Atomic layer deposition (ALD) is a thin film deposition technique which operates via repeated alternating and self-terminating surface-based reactions between a precursor and a co-reactant, separated in time by purge steps. This technique is particularly well-suited to the deposition of highly uniform and conformal thin films, even on surfaces with nano-scale high aspect ratio features. Furthermore, use of a metal precursor and a co-reactant in ALD and the related technique of pulsed-CVD (pulsed-chemical vapour deposition), provides the potential for deposition of materials that may be inaccessible using CVD methods that rely upon the thermal decomposition of a single metal precursor. This review surveys the different classes of co-reactant used for thermal metal ALD/pulsed-CVD with a focus on the reaction chemistries known or proposed to be involved. Parallels are drawn between surface-based metal ALD/pulsed-CVD reactivity and solution-based reactivity including electroless deposition, solution-based nanoparticle synthesis, and the synthesis of zero-valent complexes bearing labile ligands. Also described are applications of solution screening and solution mechanistic studies to the identification of promising new ALD/pulsed-CVD reactivities, and the generation of initial mechanistic hypotheses as to the fundamental reaction steps involved in metal ALD/pulsed-CVD. A primary goal of this review is to provide a unique reactivity-based perspective of metal ALD/pulsed-CVD. In addition, we have endeavoured to illustrate commonalities between solution-based and surface-based reactions relevant to metal deposition, and to highlight beneficial applications of the former to the development of the latter.

中文翻译：

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金属ALD和脉冲CVD：基本反应以及与溶液化学的联系

原子层沉积（ALD）是一种薄膜沉积技术，通过在前驱物和共反应物之间反复进行交替和自终止的基于表面的反应进行操作，并通过吹扫步骤及时将其分开。即使在具有纳米级高长宽比特征的表面上，该技术也特别适合于沉积高度均匀和共形的薄膜。此外，使用金属前体和ALD中的共反应物和脉冲CVD（脉冲化学气相沉积）的相关技术为使用依赖于单个金属前体的热分解的CVD方法沉积的材料提供了潜在的沉积潜力。这篇综述调查了用于热金属ALD /脉冲CVD的不同类别的共反应物，重点是已知或建议涉及的反应化学。在基于表面的金属ALD /脉冲CVD反应性和基于溶液的反应性之间进行了平行绘制，包括化学沉积，基于溶液的纳米粒子合成以及带有不稳定配体的零价络合物的合成。还介绍了溶液筛选和溶液机理研究在鉴定有前途的新ALD /脉冲CVD反应性中的应用，以及有关金属ALD /脉冲CVD的基本反应步骤的初始机制假设的产生。这篇综述的主要目的是为金属ALD /脉冲CVD提供基于反应性的独特视角。此外，我们努力说明了与金属沉积有关的溶液反应和表面反应之间的共性，并强调了前者对后者发展的有益应用。