A Coupled Electromagnetic and Thermal Model for Picosecond and Nanometer Scale Plasmonic Lithography Process

Plasmonic lithography may become a mainstream nanofabrication technique in the future. Experimental results show that feature size with 22 nm resolution can be achieved by plasmonic lithography. In the experiment, a plasmonic lens (PL) is used to focus the laser energy with resolution much higher than the diffraction limit and features are created in the thermally sensitive phase-change material (PCM) layer. The energy transport mechanisms are still not fully understood in the lithography process. In order to predict the lithography resolution and explore the energy transport mechanisms involved in the process, customized electromagnetic wave (EMW) and heat transfer (HT) models were developed in comsol. Parametric studies on both operating parameters and material properties were performed to optimize the lithography process. The parametric studies show that the lithography process can be improved by either reducing the thickness of the phase-change material layer or using a material with smaller real refractive index for that layer.