Evaluating an electric field modulated plasma enhanced atomic layer deposition of platinum layers on different substrates

Abstract

Atomic layer deposition is a key technique for preparing large area uniformity, three-dimensional conformal, and ultrathin films due to its sequential self-limiting saturated chemisorption properties. Electric fields of varying magnitudes and directions were applied on Si, Al2O3, Au, and Ni substrates in Pt plasma enhanced atomic layer deposition processes. Studying the influences of electric fields on the initial nucleation and growth of Pt films on different substrates helps to understand the dynamic knowledge and underlying physical mechanisms so as to obtain ultrathin, continuous films and full control over the morphology and distribution of deposited materials. The XPS results reveal that the Pt coverage rate increases on all substrates with applied voltages. The induced dipole moment causes the (MeCp)PtMe3 molecule to rotate in a certain direction resulting in a more compact arrangement, and the energy generated by electric fields also helps the dissociation of methyl, ethyl, Cp, and MeCp ligands, which greatly mitigate the spatial site resistance effect, thus improving initial monolayer chemisorption efficiency and the Pt coverage. We also find that Pt prefers to grow in the (111) direction due to the increase in adsorption of (MeCp)PtMe3 molecules caused by the gradient forces under electric fields. However, applied electric fields can also influence the morphology by inducing surface diffusion and acting on plasma species.