Abstract

With the development of Atomic and Close-to-atomic Scale Manufacturing(ACSM), the chemical principal and mechanisms that enable selective atomic layer deposition (ASD) is gaining rapid growing interests to unlock attractive avenues for the development of novel nanostructures by depositing atoms at desired surface locations. It has found versatile applications in emerging fields beyond semiconductor industry. Yet with the continuing downscaling, it is important to expand approaches for selective ALD with atomic scale precision on nanoscale features. In this talk, the inherently selective atomic layer deposition processes will be discussed. Previously, we have demonstrated facet-selective ALD processes, which based on intrinsic differences of precursors chemisorption on terraces or step edges of nanoparticles. To expand the inherently ASD, the acidity and alkaline, surface electronegativity, lattice strains could be exploited to achieve this inhibitor-free selective deposition process. It is demonstrated that the electronegativity differences altering the chemisorption energy barrier, which affects the initial nucleation rate. Oxides ALD was studied on a series of oxide substrates. Although the oxides have -OH groups on the surface and proposed to have similar nucleation sites, there are long nucleation delays on basic oxides. The H-transfer reaction is a key factor to influence the reaction barrier. It is hard to nucleate on basic substrates because the H-transfer reaction is blocked. In addition, an anisotropic growth model with the dynamical competition of expansion and dissociation of the nucleus is proposed to nucleation delay are quantitively predicted and the model provides a practical method to evaluate the selectivity of ALD theoretically. It provides a new strategy for inherently selective ALD, which will expand the selective toolbox of nanofabrication for next-generation nanoelectronic applications.