Guiding Area Selective Deposition by a Mechanistic Understanding of Surface Chemistry

With the growing demands on nanostructure fabrication for advanced electronics, area selective deposition is gaining attention as an important method to achieve pattern features at the sub-10 nm length scale. Area selective deposition is a bottom-up patterning process in which material is deposited only where desired, and the process holds great potential for a variety of applications. This talk will describe how control over the substrate surface chemistry can be used to achieve area selective atomic layer deposition (AS-ALD). The technique of ALD relies on self-saturating, layer-by-layer, gas-surface reactions to deposit conformal thin film materials and is an excellent choice for selective deposition because its chemical specificity provides a means to achieve selectivity on a spatially patterned substrate. A deep understanding of the gas-surface chemistry behind ALD can be critical toward developing improved ALD and AS-ALD processes. In this talk, examples of tuning surface chemistry to both enhance and inhibit ALD nucleation will be presented, and mechanistic insights developed through in situ and ex situ measurements will be shared. The development of inhibitory layers such as self-assembled monolayers (SAMs) to alter the native surface reactivity will be described. We will show that the inhibition process provides good selectivity in the deposition of thin films on a variety of substrate materials, including dielectrics and metals such as Cu, Co, W and Ru. The talk will conclude by showing how improved selectivity in AS-ALD can be achieved by combining both nucleation enhancement and inhibition strategies.