Deactivation wavelength effect on super-resolution in 3 color lithography thin films*

The 3 color lithography (3CL) technique has the potential to rival current and emerging lithographic methods by using overlapped beams of visible wavelengths to attain high-resolution features. 3CL uses one beam to excite photoinitiator molecules to a chemically inactive state and a donut-shaped beam to deactivate molecules. The molecules in the dark center of the deactivation beam remain in the chemically inactive excited state. A third beam further excites the molecules that are not deactivated to a different excited state that initiates polymerization.
Previous work has demonstrated 3CL behavior with different photoinitiators in 60 micron films. To better suit industrial applications, we have adapted our technique to 40 nm thin films. We strive to adapt 3CL for a wider range of applications that require different photoresist formulations. In this work, we show the effect of optimizing the deactivation wavelength on features in thin films. The deactivation wavelength must be optimized for the photoresist as a whole because physical and chemical properties of the monomers affect the behavior of the photoinitiator. Because of these complicating factors, we use 2-Beam Initiation Threshold experiments to quickly guide us to the optimal deactivation wavelength.