| Summary: | The aim of this project was to improve the imaging performance of planar
superlenses for evanescent near-field lithography. An experimental investigation
of the performance of superlenses with reduced surface roughness was
proposed. Such an investigation poses significant requirements in regards
to process control in thin film deposition of silver onto dielectric substrates.
Thin film deposition of silver films, onto silicon dioxide substrates, achieved
films with root mean square surface roughness as low as 0.8 nm. While
these experiments provided good understanding of the deposition process,
significant variability of the surface roughness parameter remained an issue.
The diffculty of achieving consistent control of surface roughness led
to a finite element method simulation study where this parameter could be
readily controlled. An improved understanding of how surface roughness
affects superlens imaging performance was obtained from the results of this
investigation. Furthermore, it was shown that in order to conduct an experimental
investigation to verify the simulation results, it would be necessary
to improve the imaging capability of super-resolution lithography protocols
to achieve 3σ line edge roughness (LER) of <20 nm. Resist-scheme optimisation
was identied as an important factor in this regard. Thus, a novel
calixarene-based photoresist was formulated and characterised. The resist
demonstrated superior imaging capabilities through interference lithography
and evanescent near-field optical lithography, capable of resolving 250-nm
period half-pitch line gratings with 3σ LER below 10 nm. The development
of this novel photoresist will enable future lithographical investigations to
be conducted with improved resolution and imaging fidelity.
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