Evaluation of carbon-doped low-k multilayer structure by nanoindentation

This paper reports nanoindentation examination of 600 nm thin carbon-doped low-k films spin-coated on silicon wafer. Our results confirm the recently discovered [R.J. Nay, O.L. Warren, D. Yang, T.J. Wyrobek, Microelectron. Eng. 75 (2004) 103] advantages of using sharp cube-corner indenter instead of conventional Berkovich pyramid for low-k films testing. We were able to detect three-layer structure of investigated films and to compare their relative characteristics using exclusively the registered nanoindentation data. This contrasts the previous works that concluded the existence of cap-layer from the microscopic inspection of the indentation impression. The pop-in behaviour is confirmed to be associated with fracture of the low-k film, while the details of the responsible mechanism remain undetermined at the present level of the knowledge in the field.