Massimo Perucca, PhD - Diad Group: Writing nanopatterns with light
The challenge of bridging from nano- to milli-meter scale has been realized, indeed a very fast way of creating nanometer-sized features over large surface areas is now available. US researchers at Northwestern University in Chicago proved that the optical nanolithography technique could be used to rapidly prototype miniature devices, such as photomasks, circuits and photonic components. The new technique developed by Chad Mirkin and colleagues is called beam pen lithography (BPL). BPL delivers beams of light to a surface coated with a light-sensitive material through an array of around 200 tiny pyramid-shaped pens; each pen has a square base that measures several tens of microns long made from PDMS polymer. The light-pens, are manufactured starting from an array of pyramid-shaped polymer tips that are coated with a thin layer of gold, which is removed at the apex of each tip to leave behind an opening that exposes the PDMS inside. When light is shone onto the underside of the pyramids it is channeled through them to the tips and a fine beam of light emerges from the point where the gold was removed. The light pens can then be used to print highly precise patterns onto a silicon substrate pre-coated with a layer of photoresist. One major advantage of the new tips is that their diameters can be varied from 5 to 500 nm. Another advantage is that some pens can be "shut off" while others are "turned on", allowing different patterns to be printed. " The next step in the BPL system development is to build structures where each pen can be individually addressed using light modulators.