Work of indentation methods for determining copper film hardness

We have investigated the indentation hardness of sputter deposited copper films on oxidised silicon substrates. The results were initially analysed by the Oliver and Pharr method. AFM imaging of the indenter revealed pile-up material at the edges of the indents, which needs to be accounted for in the hardness calculation. Thus, the hardness is recalculated by measurement of the actual areas and volume by AFM analysis and also by work of indentation methods. A comparison between the results obtained by these methods is made.