Substrate temperature and electron fluence effects on metallic films created by electron beam induced deposition

Using three different precursors [MeCpPtMe₃, Pt(PF₃)₄, and W(CO)₆], an ultra-high vacuum surface science approach has been used to identify and rationalize the effects of substrate temperature and electron fluence on the chemical composition and bonding in films created by electron beam induced deposition (EBID). X-ray photoelectron spectroscopy data indicate that the influence of these two processing variables on film properties is determined by the decomposition mechanism of the precursor. For precursors such as MeCpPtMe₃ that decompose during EBID without forming a stable intermediate, the film's chemical composition is independent of substrate temperature or electron fluence. In contrast, for Pt(PF₃)₄ and W(CO)₆, the initial electron stimulated deposition event in EBID creates surface bound intermediates Pt(PF₃)₃ and partially decarbonylated W_x(CO)_y species, respectively. These intermediates can react subsequently by either thermal or electron stimulated processes. Consequently, the chemical composition of EBID films created from either Pt(PF₃)₄ or W(CO)₆ is influenced by both the substrate temperature and the electron fluence. Higher substrate temperatures promote the ejection of intact PF₃ and CO ligands from Pt(PF₃)₃ and W_x(CO)_y intermediates, respectively, improving the film's metal content. However, reactions of Pt(PF₃)₃ and W_x(CO)_y intermediates with electrons involve ligand decomposition, increasing the irreversibly bound phosphorous content in films created from Pt(PF₃)₄ and the degree of tungsten oxidation in films created from W(CO)₆. Independent of temperature effects on chemical composition, elevated substrate temperatures (>25 °C) increased the degree of metallic character within EBID deposits created from MeCpPtMe₃ and Pt(PF₃)₄.