Micro Beam IR Characterization of Narrow Width (-100 nm) Low-k Spaces Between Cu Lines Correlated with Valence EELS Evaluation

Low-k materials of 100 nm width (low-k spaces) between Cu lines in 200 nm pitch Cu / Low-k interconnect samples were characterized by a micro beam IR for the first time, and obtained results were verified in comparison with valence electron energy loss spectroscopy (V-EELS) combined with scanning transmission electron microscopy (STEM). The results derived from the IR technique showed that a metallization process onto a low-k trench resulted in a heavier damage compared to a trench formation processes such as dry etch or ash, and Si-CH3 / Si-O bond intensity ratio decreased from a bottom region of a space up to a cap layer interface, namely the top region was more damaged than the bottom region. V-EELS characterization agreed the IR results.