The continued dominance of copper in microelectronic manufacturing is due in part to the techniques that have kept pace with the relentless trend towards smaller feature sizes. Pure and defect-free copper features can be created at these and smaller scales using gas phase deposition methods such as chemical vapor deposition (CVD) and atomic layer deposition (ALD). Here we review the deposition processes and in particular surface chemistry for depositing copper metal by CVD and ALD. A summary of known processes is given, and new trends in copper film deposition research are discussed. As well, process parameters and properties of copper films deposited from precursors using key ligand systems such as aminoalkoxides, amidinates, guanidinates, betadiketonates and betaketoiminates are presented. Surface chemistry is examined from the point of view of the similarities of CVD and ALD, considering precursors that can be used in both types of processes. This serves to highlight trends in decomposition mechanisms and illuminates some interesting similarities in process temperature and other parameters.

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Volatile metal complexes are important for chemical vapour deposition (CVD) and atomic layer deposition (ALD) to deliver metal components to growing thin films. Compounds that are thermally stable enough to volatilize but that can also react with a specific substrate are uncommon and remain unknown for many metal centres. Guanidinate ligands, as discussed in this review, have proven their utility for CVD and ALD precursors for a broad range of metal centres. Guanidinate complexes have been used to deposit metal oxides, metal nitrides and pure metal films by tuning process parameters. Our review highlights use of guanidinate ligands for CVD and ALD of thin films over the past five years, design trends for precursors, promising precursor candidates and discusses the future outlook of these ligands.

We report the passivation of angle-independent plasmonic colors on bulk silver by atomic layer deposition (ALD) of thin films of aluminum oxide. The colors are rendered by silver nanoparticles produced by laser ablation and redeposition on silver. We then apply a two-step approach to aluminum oxide conformal film formation via ALD. In the first step, a low-density film is deposited at low temperature to preserve and pin the silver nanoparticles. In the second step, a second denser film is deposited at a higher temperature to provide tarnish protection. This approach successfully protects the silver and plasmonic colors against tarnishing, humidity, and temperature, as demonstrated by aggressive exposure trials. The processing time associated with deposition of the conformal passivation layers meets industry requirements, and the approach is compatible with mass manufacturing.

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