NPGS Template Stripped Nanostructures

NPGS: Template Stripped Nanostructures

This image shows aluminum double Archimedean spirals written by Tiago Ramos, a grad student in the McPeak Lab at Louisiana State University. They are investigating enhancements in chiral electromagnetic near fields.

The linewidths of the spirals are quite uniform at ~40 nm.

While this image looks like it could be the result of a typical evaporation and liftoff, the processing steps are quite different:

1) Expose and develop PMMA (as shown below) on Si substrate..

2) Using the PMMA as an etch mask, etch ~40 nm into the Si substrate.

3) Remove the PMMA and evaporate ~100 nm of aluminum onto the etched Si surface.

4) Strip off the thin patterned aluminum film using epoxy and a second substrate.

5) The image above is looking down onto the aluminum film which is now epoxied to a different substrate. The spirals are raised ~40 nm above the background which was the depth of the etch.

This is an SEM image of double Archimedean spirals written in PMMA. The image shows the resist after development and metallization.

Note how the linewidths appear narrower at the ends and especially near the center of each double spiral. This is a common effect which results when the resist shifts either before or during the imaging. The image of a similar finished device above shows that the linewidths were actually quite uniform after the development.

Images courtesy of Louisiana State University.