VIBRATIONAL SIGNATURES OF POLYETHYLENE GLYCOL AND BRIGHTENERS ON COPPER
Brett Baker, Clayton Yang, Lee Richter and
National Institute of Standards and Technology
Gaithersburg, MD 20899
With the use of fourier transform infrared spectroscopy (FTIR) and sum
frequency generation spectroscopy (SFG), the surface coverage and confirmation
of additives often used in copper deposition are identified on copper surfaces.
Ex situ experiments at open circuit and during deposition show an increase
in the adsorption of brighteners such as 3- mercapto-1-propanesulfonic
acid (MPSA) and bis-(3-sulfopropyl)-disulfide (SPS) with time. With an
increase in the surface coverage of these species, a decrease in the surface
coverage of PEG is noted. The trends in surface coverage and adsorption
of these species have been shown for both sulfate- and perchlorate-based
electrolytes. The differences in the kinetics between the adsorption of
MPSA and SPS will be discussed.