In this research a relatively large area of nano-hole arrays is
reconstructed in 3D and the surface properties computed from
the DEM are analysed as shown in Table 1. The results show that
two kinds of imperfections make the surface different from the
ideal shape. First, the surface has a wavy shape with peaks and valleys
which cannot be detected using a single SEM image. Valleys
are due to the embedment of nanospheres to the photoresist by
dozens of nanometres. This is obtained from the comparison of nanosphere’s diameter and the height difference between top surface
of nanospheres and the bottom surface, which is presented in
Fig. 5. In addition to the waviness of the surface, some areas are up
and down which could be a result of uneven UV exposure in the
fabrication process. These ups and downs are illustrated in Fig. 6.
These two kinds of imperfections are likely to have influence to
subsequent nano-manufacturing processes, especially to nanoimprinting.
In nano-imprinting, an uneven surface will cause uneven pressure and result in uneven patterns. The irregularities
of the master will also be copied to the subsequent products. These
problems will effectively compromise the quality of subsequent
fabrication.