Micro- and nanomachining technologies are commonly categorized into top-down and bottom-up
approaches. Making nanoscale structures using top-down approach has been facing difficulties due to the
limitation of optical lithography and the low throughput of electron beam and ion beam techniques. Soft lithography
and hot embossing can transfer nanostructures across a large wafer. However, these techniques are
limited to a soft substrate such as polymers only. A recent work by researchers from the Purdue University,
Harvard University, Madrid Institute for Advanced Studies, and the University of California, San Diego
demonstrated a new embossing technology to create wafer-scale smooth three-dimensional nanoshapes on
hard crystalline metal.