Effects of Adsorbed Moisture in SiO₂ Substrates on the Formation of a Mn Oxide Layer by Chemical Vapor Deposition

Manganese oxide formed by a chemical vapor deposition (CVD) method is a promising candidate for an ultrathin diffusion barrier layer in the interconnect structure of advanced semiconductor devices. This study placed emphasis on the adsorbed moisture in a hydrophilic SiO 2 substrate and investigated the effects of the adsorbed moisture on the formation behavior, structure and composition of the CVD Mn oxide layer. The SiO 2 substrates were preannealed at 150 to 500 °C for 1 h to control the type and amount of the residual adsorbed moisture. A Mn oxide layer was subsequently deposited by thermal CVD of bis(ethylcyclopentadienyl)Mn at 200 °C for 30 min. The Mn oxide layer deposited on an as-received substrate was composed of the bilayer of crystalline MnO x and amorphous MnSi x O y . The Mn oxide layer deposited on a preannealed substrate was composed of the single layer of amorphous MnSi x O y . The crystalline MnO x layer was formed by the reaction of the Mn precursor with physisorbed moisture on the as-received SiO 2 . The amorphous MnSi x O y was due to the reaction with chemisorbed moisture on both the as-received and the preannealed SiO 2 . Results of the present work indicate the importance of controlling the adsorbed moisture of the substrates in order to obtain a Mn oxide layer with desired structure and thickness as a diffusion barrier layer.