| The objective of the thesis work was to investigate the use of indentation microprobing as an adhesion measurement technique for thin films, with the goal of fully qllantitative characterization of the energy associated with delamination. This technique is of importance due to its ability to test films in their as-deposited or as-processed state, without inducing changes in the process of sample preparation. Sample preparation and testing are simple and fast, and data analysis is straightforward. Thorough analysis of the indentation technique for single-layer thin films was developed by Hutchinson, Marshall and Evans in 1984, and has been used by a number of researchers since. Indentation induces a stable delamination (i.e. it arrests at a certain size after testing) of circular geometry. A primary limitation of the method relates to the difficulty of initiating and/or propagating delaminations in thin films that are either strongly bonded or ductile in nature. Such films tend either to not delaminate, or to require excessive indenter tip penetration invalidating the critical assumptions. In order to overcome this limitation, the single-layer analysis was extended to accommodate the use of one or more superlayers. In addition to allowing evaluation of multilayers or microlaminates, the superlayer can be chosen to efficiently store strain energy to minimize the penetration required and promote delamination. The multilayer analysis was then evaluated with four experimental investigations involving assessment of the adhesion of sputtered copper and tungsten thin films on standard single crystal silicon wafers with thermally grown SiO{dollar}sb2{dollar}. Trends associated with film thickness, adhesion-promoting interlayers, annealing, sputtering-process parameters and the influences of superlayers were identified. The observed trends and adhesion energy values measured were consistent with expectations and previous research by other investigators. Additionally, the multilayer technique has been used by other researchers since its inception, and proved useful in the analyses of aluminum films on carbon/sapphire and sapphire substrates using tantalum superlayers. It is concluded that the multilayer analysis is of value to quantitative adhesion assessment, and holds promise for more thorough investigation of processing-performance and structure-micromechanism relations of thin films. |
