Happy Spheres are Clean Spheres and Clean Spheres Come from Trial and Error Solvent Testing

After several attempts at optimizing the SEM for taking images of the polystyrene nanospheres, the layer of contaminant that was affecting the etching process was imaged.  It does not spread throughout the entire sphere layer, but rather is in small areas strewn throughout the monolayers.  The contaminant has been seen previously but only as a lighter (contrast) region of spheres, not the contaminant itself directly.  It was imaged by increasing the power of the beam and taking several images using the backscatter detector to first identify the regions of contamination.  Then switching to the In Lens detector and imaging the previously found areas the "gunk" between and on top of the spheres could be seen.  When looking at samples which have been subjected to solvent-testing, in an effort to remove the contaminant, progress has been seen.  The tested samples show large areas of contaminant free spheres layers.  These layers still have line interruptions throughout them, and their coverage has decreased due to the loss of some spheres during the cleaning process.  Although the decrease in coverage is not ideal, having clean spheres with which to etch was the primary concern, as imaging techniques can later be used to determine the areas where spheres are still present so that when AFM is performed following etching we will know where to probe.  Having clean spheres means that etching can now be performed, and if the results are good we can use smaller spheres and work on shrinking the size of the fabricated pillars!  Moving right along!