Researchers claim lower cost lithography technique

According to the team, the approach allows complex shapes to be created and can be carried out using less expensive light sources and conventional chip manufacturing equipment. "The whole optical setup is on a par with what's out there," said Dr Trisha Andrew from MIT's Research Laboratory of Electronics. "We've demonstrated a way to make everything cheaper." The system is said to use a materials approach, combined with sophisticated optics, to get large scale patterning. It builds on stimulated emission depletion imaging, or STED, in which fluorescent materials emit light when illuminated by a laser. If the laser power falls below a certain level, the fluorescence stops, leaving a dark patch. By controlling the laser's power, a dark patch can be created which is much smaller than the wavelength of the laser light. By using these dark areas as a mask, these smaller sizes can be 'locked in' to the surface. However, the MIT and Utah team has combined STED with another technique called absorbance modulation, replacing the fluorescent materials with a polymer whose molecules change shape in response to specific wavelengths of light.