Resolution enhancement through three color photolithography

Multiphoton absorption polymerization uses nonlinear absorption of laser light to expose a negative-tone photoresist locally, creating three-dimensional structures that can have feature sizes on the sub-100 nm scale. The resolution can be further improved using schemes in which a second beam of light prevents exposure of the photoresist. However, the feature pitch that can be achieved by two-color schemes is limited by the inability to deactivate the photoresist completely. One solution to this problem is to develop a method that instead employs three laser beams. Here we discuss the potential advantages of three-color lithographic schemes and demonstrate new materials that pave the way towards the demonstration of three-color lithography.