VARIATION OF MACROSCOPIC SHAPE AND MICROSTRUCTURE OF SILVER NANOPARTICLE SUSPENSION DROPLETS USING INK-JET PRINTING

摘要

Micro-interconnects of integrated circuit (IC) devices were produced using ink-jet printing of Ag nanoparticle suspensions. The macroscopic shape and microstructure of the Ag micro-dot deposits using ink-jet printing were observed using SEM (Scanning Electron Microscope) and EDS (Energy-Disperse Spectrometers). The well-dispersed suspension of nanoparticle Ag colloids, which was made up of 5–10 nm silver particulates, allows low-temperature sintering of Ag. The 50 wt% Ag suspension had a viscosity of about 7.95 cP at 25 ℃, which is appropriate for printing jobs. A bipolar voltage signal was used to drive a piezo-electric droplet generator and then 50–70 μ m diameter droplets was dispensed on the substrate. Using SEM, a smooth deposition of drying silver dot morphology was observed. Drying the silver dots was improved by using hydrophobic substrates and a slow evaporation rate of suspensions was used to resolve an unexpected ring-shape, because both are able to control the interactions among the self-assembled Ag particles, surface tension, and the evaporation rate of droplets. Finally, thedeposit/substrate composite was processed at 300 ℃ for 60 min under a pure oxygen atmosphere to allow for the complete evaporation of the carrier and for sintering of the nano-particles, thereby yielding a finished circuit interconnect.