Columnar porous Si-face 6H-SiC substrates were prepared by a photo-electrochemical etching
method and applied as nanoimprint lithography (NIL) stamps. The diameter of the pores in the
porous region was about 20 nm and the center-to-center separation between pores was about 60 nm.
The columnar porous SiC substrates were subjected to a vapor phase silanization treatment whereby
a monolayer of perfluorooctyltrichlorosilane (FOTS) was deposited in order to keep the stamps
from sticking to the substrates during the imprint step. Subsequently, the porous SiC stamps were
used to imprint polymethylmethacrylate (PMMA) at elevated temperatures and pressures. The
imprinted PMMA could then be used to transfer the nanopattern on the columnar porous SiC to
other substrates for various purposes; e.g. templates for GaN regrowth, catalysts for nanowire
growth by vapor-liquid-solid type methods (VLS), etc. SiC is not typically used for NIL stamps
since etch processing of SiC is less mature than that of Si. However, as demonstrated here, there is
no reason why SiC cannot be used as a material for NIL stamps. The superior mechanical properties
to Si make the use of SiC alluring as a master template for NIL processing.
The effect of ecthing duration on structural properties of porous Si fabricated by a new two-steps alternating current photo-assisted electrochemical etching (ACPEC) technique for MSM photodetector
