Towards Quantification of Contaminants in Electrodeposited Cu Films
In this contribution we report on a recently developed quantitative depth profiling technique with sub-nanometer depth resolution based on laser ablation ionization mass spectrometry (LIMS). The high vertical depth resolution, a high dynamic range >108 coupled with a high detection sensitivity of ~ 10 ppb allows the identification/quantification of trace amounts of contaminants localized at grain boundaries of the Cu deposit. Results of the LIMS techniques are compared with complementary 3D atom probe tomography experiments.
To demonstrate the capabilities of these analytical techniques we use copper films electrodeposited in the presence of SPS (bis-(sodium-sulfopropyl)-disulfide) and Imep (polymerizates of imidazole and epichlorohydrin) additives as model system. This approach allows the targeted insertion of grain boundaries into the Cu film perpendicular to the growth (depth profiling) direction.