Improving nucleation of ALD films via the ion implantation pretreatment approach: Calculation and experiments

As a highly recommended approach, the atomic layer deposition (ALD) is widely applied to prepare the nanoscale thin films. To enable the development of ALD in high-quality films, overcoming the non-uniform film growth caused by heterogeneous distribution of reactive sites become vital and attractive nowadays. In this work, efforts for improving the nucleation of iridium (Ir) films on the rhenium (Re) substrates have been made using the pretreatment of plasma immersion ion implantation (PIII) combining with the magnetron sputtering. The related theories of this novel pretreatment method have been studied using the density functional theory (DFT) calculation. The ALD films prepared on the pretreated surfaces were characterized to investigate effects of pretreatment on the microstructure and elemental distribution for nucleation uniformity and film quality. Calculation and experimental results demonstrate that the ion implantation pretreatment on the Re substrate effectively modifies the surface microstructure, increases the density of active sites, and contributes to a well-modulated surface with enhanced homogeneity and affinity. The films deposited on the pretreated surface exhibit more uniform grain size, higher nucleation density, shorter grain spacing and thinner thickness. Our results may pave the way for the deposition of high-quality ALD films on low affinity surfaces.