Investigation into the selectivity of CVD iron from Fe(CO)5 precursor on various metal and dielectric patterned substrates

It has been shown that CVD iron from a Fe(CO)5 precursor deposits selectively on dielectric surfaces over tungsten surfaces. No similar selective CVD mechanism for titanium and aluminium to SiO2 surfaces was observed. It was established that the selectivity between the tungsten surface and the SiO2 surface could be enhanced through the oxidation of the tungsten surface. Depositions carried out on oxidised tungsten (WOX) and SiO2 substrates showed that iron layers up to 0.5 μm thick with a resistivity of 18 μΩcm can be deposited with excellent selectivity. The selective mechanism is attributed to the electrochemical properties of the tungsten or WOX layer, which prevents the reduction of the iron precursor. Selectivity loss was attributed to defects or impurities adsorbed to the tungsten surface.