PERFORMANCE OF PMMA FOR NANODOT PATTERNING USING ELECTRON BEAM LITHOGRAPHY

The performance of a positive tone resist, PMMA, for sub 100 nm patterning of nano-dots using electron beam lithography is to be studied. This optimization is done on a JEOL JBX-6000 FS System. The various parameters such as beam current, resist thickness, dose and electron energies are optimized. This patterning involves greater control over beam parameters so as to reduce aberrations that might arise due to astigmatism. In this respect, the optimization of the beam current parameters is very important, as a narrower beam will minimize scattering effects. These structures will be particularly significant for the fabrication of quantum dot based devices. Nano-dot arrays of dimensions 70 nm with equal spacings of 70 nm were obtained at 100 pA beam current at 50 KeV for a dose of 170 μC/cm².