The dissolution of naphthalene, phenanthrene, and pyrene
from viscous organic phases into water was studied in
continuous-flow systems for time periods ranging from several
months to more than 1 year. By selecting nonaqueous
phases ranging from low viscosity to semisolid, i.e., from
a light lubricating oil to paraffin, the governance of mass
transfer was shown to vary from water phase control to
nonaqueous phase control. An advancing depleted-zone
model is proposed to explain the dissolution of PAHs from
a viscous organic phase wherein the formation of a
depleted zone within the organic phase increases the
organic phase resistance to the dissolution of PAHs. The
experimental data suggest the formation of a depleted zone
within the organic phase for systems comprising a high-viscosity oil (∼1000 cP at 40 °C), petrolatum (petroleum jelly),
and paraffin. Organic phase resistance to naphthalene
dissolution became dominant over aqueous phase resistance
after flushing for several days. Such effects were not
evident for low viscosity lubricating oil (86 cP at 40 °C).
The transition from aqueous-phase dissolution control to
nonaqueous-phase dissolution control appears predictable,
and this provides a more rational framework to assess long-term release of HOCs from viscous nonaqueous phase
liquids and semisolids.
Articles you may be interested inGrain structure analysis and effect on electromigration reliability in nanoscale Cu interconnects Appl. Phys. Lett. 102, 131907 (2013) Abstract. This paper combined experiments and simulation to investigate the grain size and cap layer effects on electromigration (EM) reliability of Cu interconnects. First the statistical distribution of EM lifetime and failure modes were examined for in laid Cu interconnects of large and small grain structures with two different cap layers of SiCN vs. CoWP. The CoWP cap was found to significantly improve the EM lifetime due to the suppression of the interfacial mass transport as a result of strengthening of the Cu/cap interface bonding. In addition, the grain size was observed to affect the EM reliability significantly, particularly for the CoWP capped structures. Resistance traces and failure analysis revealed two distinct failure modes: mode I with voids formed near the cathode via corner and mode II with voids formed in the trench several microns away from the cathode via. It was found that large grain size and strong cap interface reduced the mass transport rate and the void diffusion in the Cu line, leading to a longer EM lifetime and a higher proportion of mode II failures. A statistical simulation of EM lifetimes was also applied to Cu interconnects with grain structures generated by the Monte Carlo method. The simulation results for different grain sizes and cap interfaces are in good agreement with the experimental observations.
Continuous scaling of Cu interconnect structures can significantly impact reliability-limiting processes such as electromigration and stress-induced voiding. Prior to the 65 nm technology node, mass transport under electromigration is dominated by diffusion along the Cu/dielectric cap interface and the electromigration lifetime will degrade by about half for every generation, even with the same current density. Beyond the 65 nm node, small grains were found to mix with bamboo grains in the 90 nm Cu damascene lines and the contribution of the grain boundary transport degraded the electromigration lifetime. The scaling effects on microstructure and electromigration reliability are examined in this paper with the objective of identifying the key issues and exploring potential solutions for sub-100 nm Cu interconnects. We discuss first the scaling effect on electromigration lifetime and the effect due to the small grains on electromigration lifetime and statistics. This is followed by a discussion on grain growth studies focusing on the formation of small grains and a recent simulation study on small grain effect on electromigration reliability. This paper concludes with a discussion of some recent developments in analytical techniques to investigate grain structure and electromigration reliability in sub-100 nm Cu lines
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