Excimer laser as a source for thin Cu film deposition for use in electronic device fabrication

Abstract

Investigations are carried out to characterize Cu deposition from a solid target using a XeCl, 28 ns pulse width, excimer laser at energies between 2 - 15 J/cm2. Scanning electron microscope (SEM) studies of the target surface revealed sputtering effects, droplet formation and surface waves. Density per unit substrate area of droplet-like-Cu particles transferred from the target is a function of frequency, deposition time, state of the target surface and power density. Mass and charge collected at the substrate are obtained as a function of distance to the target. Mass deposition as a variation of laser beam to target angle, facetting angle at feature edges and grain size as a function of substrate bias were measured. Fill shape evolution of micron size holes are obtained. An energy threshold for Cu-ion generation is extrapolated from the measured ion current vs. energy in.