Chemical vapor deposited RuOx films: interfacial adhesion study

RuOx films were deposited by chemical vapor deposition (CVD) with different oxygen flow rates on seed-Ru/SiO2/Si stack. The seed Ru film deposited by sputtering strongly adheres to the SiO2/Si substrate. After CVD-RuOx film deposition at a low oxygen flow, peeling occurs at the seed Ru/SiO2 interface, while for films deposited at a high oxygen flow, adherence is maintained. A post deposition rapid thermal annealing in N2 ambient (RTA(N2)) improves the adhesion of the films that fail. Our analysis shows that incorporation of organic impurities from the CVD precursors is not responsible for the poor adhesion of these films. Diffusion of oxygen to the Ru/SiO2 interface results in the formation of an interfacial ruthenium oxide layer. We suggest that the formation of this layer, either during RTA(N2) for low O2 flow samples or during the CVD-RuOx process for the high oxygen cases, enhances adhesion. In addition, the RTA(N2) treatment increases the tensile stress of the films. Formation of interfacial layer enhances the film adhesion by increasing the work of adhesion, altering the critical forces at the interfaces and reducing thermal mismatch-induced stress.