Controlling Interfaces toward Area Selective Atomic Layer Deposition

With the growing demands on nanostructure fabrication for advanced electronics, atomic layer deposition (ALD) continues to gain attention as an important method to achieve pattern features at the sub-10 nm length scale. Based on sequential, self-limiting vapor-surface reactions, ALD offers exceptional conformality, thickness control at the Angstrom level, and tunable film composition. Due to the chemical specificity of ALD reactions, several molecular-level system parameters can strongly impact the ALD nucleation and growth rate, including the specific substrate interface as well as the type of ALD precursor. As a result, the substrate interface and precursor selection can be tuned to intentionally control nucleation rates in ALD, which in turn provides a means to achieve selectivity on spatially patterned substrates. The resulting process of area selective atomic layer deposition (AS-ALD) has attracted significant attention in recent years. In this talk, we will provide examples of tuning surface chemistry to achieve AS-ALD. The development of inhibitory layers such as self-assembled monolayers (SAMs) and small molecule inhibitors (SMIs) to alter the native surface reactivity will be described. Some new SMIs include aryl or alkyl thiol, amine, nitro, and sulfonic acid compounds. The inhibition strategies demonstrate good selectivity in the deposition of thin films on a variety of substrate materials, and selectivity in AS-ALD can be further enhanced by choice of ALD precursor. Finally, we will describe the development of carbon-free inhibitor layers for AS-ALD.