Conducting Nanocrystal Patterns Using a Silver Organic Complex Blended with Polystyrene as e-Beam Resist

Abstract

With the intention of producing a metal composite consisting of Ag nanoparticles embedded in patterned polystyrene, silver triphenylphosphine nitrate, Ag(PPh 3 ) 3 NO 3 , was chosen as a source of Ag metal as it is soluble in toluene to form a blend with polystyrene, a well-known negative tone e-beam resist. At a constant e-beam dosage of 150 μC cm -2 , the patterns were produced at 5, 10, and 30 keV beam energies while varying the dwell time at a location (pixel) and the number of passes. The presence of Ag in the patterned regions was confirmed by the EDS analysis. TEM showed the formation of small Ag nanoparticles in the embedded matrix of the polymer. The reduction of Ag precursor following exposure to the e beam was monitored by XPS. UV-vis absorption studies showed a broad peak at 464 nm, typical of surface plasmon absorption by Ag nanoparticles. Confocal fluorescence studies showed the embedded Ag nanoparticles in the carbon matrix to have fluorescence property as well. C-AFM measurements have shown that the patterned blend is well conducting due to the interacting Ag nanoparticles, the resistance being two orders less compared to that of polystyrene itself. The higher the beam energy, the lower was the dwell time required to attain a conducting pattern.