We used atomic force microscopy (AFM) for the indentation test evaluating the indentation hardness of materials in nanometer range. BK7, fused silica, and silicon single crystal were used as test sample materials. The data analysis processes to determine the contact area were important to evaluate the indentation hardness of materials. Comparing the results of AFM with those of Nanoindenter and micro-Vickers tests, the direct measurement of the size of the residual hardness impression was useful to evaluate the contact area even in nanometer region. The results led us to conclude that AFM indentation with a sharp indenter is powerful tool to estimate the indentation hardness in nanometer range.
