STED microscopy illumination used in photolithography

In a post last month, I questioned what it would take for microscopy methods that overcome the diffraction limit to gain more use. I may have found a partial answer to my question in a research paper published last week in Science Express.

The key to more powerful computers and increased data storage is patterning smaller details, but the standard photolithography techniques used for this have reached optical limitations. To pattern features without the diffraction-limit constraint of standard techniques, Timothy Scott and colleagues from the University of Colorado at Boulder turned to an irradiation technique similar to one used by stimulated emission-depletion (STED) microscopy.

In simple terms, STED microscopy confines fluorescence emission to a point smaller than the diffraction limit by using a pulsed beam to excite the fluorophore, and overlapping it with the focal point of a pulsed, Gauss-Laguerre (donut-shaped) mode beam. The two sets of pulses must reach the focal plane simultaneously so that the Gauss-Laguerre beam instantly de-excites potentially excited molecules by stimulated emission. 

Similarly, the University of Colorado researchers’ single-photon lithography method uses a central beam that links polymer chains together and a surrounding Gauss-Lagueer mode beam that inhibits action in the surrounding area. The size of patterned features is limited by the contrast between the central beam and the Gauss-Laguerre beam. The technique doesn’t require an expensive laser or come with the speed limitations of two-photon-based alternatives to standard photolithography.

While this may not be a direct use of STED microscopy, it shows how science can cross disciplines, sometimes finding even more practical or important uses. 

Research paper:
Two-Color Single-Photon Photoinitiation and Photoinhibition for Subdiffraction Photolithography, Timothy F. Scott, Benjamin A. Kowalski, Amy C. Sullivan, Christopher N. Bowman, and Robert R. McLeod, Published online April 9 2009; 10.1126/science.1167610 (Science Express Reports)