NPGS : Free Standing
The strips are free-standing aluminum that is ~100 nm thick. First, ~0.5 um of negative resist was spun onto a silicon substrate. The negative resist was then patterned to have a strip 15 um wide with registration marks spaced around it. (Note that the registration marks simply consisted of the patterned negative resist.) After developing the negative resist, ~0.5 um of PMMA was spun on. The NPGS alignment feature was used to accurately align to the registration marks made of negative resist that were under 0.5 um of PMMA! The strips shown here were then patterned in the PMMA. After aluminum was evaporated and lifted off, an oxygen plasma was used to remove the negative resist from underneath the aluminum, thus leaving the structures free standing above the silicon surface.
This work was done in Dr. Martin Wybourne's research lab when he was at the University of Oregon.