Determination of adhesion energy of CNx thin film on silicon from micro-scratch testing

A method for calculating the adhesion energy of CNx thin film on silicon wafer is presented. In the energy-based method, primary concerns are focused on modeling the critical load, friction coefficient, and deformation properties of the film/substrate composite during a continuous micro-scratch testing. By relying less on the geometry (i.e., the area of the debonded film) of the film delamination occurring ahead of the indenter, this method avoids an error source arising from measurements of the parameter, which has been required in published models. Experimental observations show that, for the film/substrate system, the principal failure mode when subjected to a tangential and normal force is the film delamination from its substrate once the critical normal force necessary to cause failure under the sliding indenter is reached. Based on the measured data from the continuous micro-scratch testing along with an AFM, the adhesion energy of the film/substrate system has been determined to be 60 J/m(2). A reasonable agreement is found between the present results and those from earlier models. The value of 60 J/m(2) represents an average of values calculated by various methods. The influence of mechanical properties of the film/substrate combination on the adhesion energy is also discussed.