Initial growth of chemical-vapor-deposited Ru from bis(hexafluoroacetylacetonate)dicarbonyl ruthenium

Abstract

Deposition of ruthenium (Ru) was done using chemical vapor deposition with bis(hexafluoroacetylacetonate)dicarbonyl ruthenium (Ru(hfac) 2(CO) 2) as the precursor, at temperatures, T, ranging from 548≤ T≤623 K. The initial growth behavior on Si (100) surfaces was investigated using atomic force microscopy and X-ray photoelectron spectroscopy. Three-dimensional nucleus growth was observed. For T=573 K and a precursor partial pressure of 1.3×10 −1 Pa, after 5 min deposition, the nuclei density observed on an H-terminated Si surface of 4.7×10 9 cm −2 was about three times that observed on an SiO 2 surface. Kinetic analysis of nucleation showed a lower activation energy on an H-terminated surface (5 kcal/mole) than that on an oxide surface (11 kcal/mol). As predicted by quantum chemical calculations, the much larger dissociation energy of Ru-hfac (241 kcal/mol) than of Ru–CO (57 kcal/mol) suggests that the deposition is mainly controlled by the hfac dissociation step. Moreover, the existence of adsorbed H was demonstrated to facilitate Ru deposition by removing hfac ligands through the formation of volatile H(hfac).