NPGS : USA & Montana Maps
This is an optical image of a map of the United States which has been written
at a scale of about 28,000,000,000 to 1. The pattern was written in PMMA
on silicon and was sputter coated with Au after development.
Below, the same pattern is shown when scanned in the SEM with an image resolution
of 500 x 400 pixels. Note how the lines look dashed because the pixels in
the digital image are larger than the actual lines of the pattern. When the
beam is in the middle of the exposed line, the pixels appear
black, while the edges of the exposed lines appear white. The scale
bar in this image is 10 microns long.
This is an SEM image of the state of Montana taken at a magnification where
the individual lines can be resolved. The linewidths are ~80 nm. The apparent
roughness of the lines that are nearly horizontal is an artifact that is
caused when the pixel size of the image is comparable to the linewidth.
This is an SEM image of the label at Bozeman taken at a magnification where
the individual lines can clearly be resolved. The linewidths are ~60 nm.
Note that this image and the one immediately above show the very first patterns that were written on two different SEMs and neither microscope used a blanker during the exposure. The slight overexposures in the letters below are the only evidence that a blanker was not used during the pattern writing.