Porous low-k thin films

As the feature size in Si-based integrated circuits has been reduced below the sub-micron level, the inherent interconnect RC (wire resistance R and capacitance C) time delay has become the major factor limiting the improvement in device speed.

Copper has replaced aluminum in interconnect conducting lines.
Low dielectric constant (k) materials are being intensively investigated as a replacement for silicon dioxide (k ~ 4.0).

Depth-profiled positronium annihilation lifetime spectroscopy (PALS), as a unique, non-destructive technique, has been used to probe important issues related to the novel porous low-dielectric constant (k) thin films and their integration with Cu.

Taken together, we have used beam-PALS, a valuable technique to further our understanding of many aspects of low-k thin films, including both the films' porous structure and their integration behavior. Related publications are provided for details. These understandings are critical to material identification, processing and application of these materials in advanced integrated circuits.