Porous low-k thin films




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The integration of Cu with porous, low-k ILDs has attracted significant interest since the combination will lead to additional performance improvement and potential cost reduction.  However, the successful integration of Cu/Low-k systems is very challenging.  The material properties such as interconnected mesoporosity and low mechanical strength in the promising low-k films definitely open up the possibility of many integration problems. 


 Diffusion barrier is required

  • To prevent intermixing between Cu and low-k dielectrics

  • To improve the adherence of Cu to low-k films

Diffusion barrier criteria

  • Stable to Cu and low-k

  • Continuous and thin

  • Able to conformally cover the surrounding surfaces

In addition, porous low-dielectric constant thin films will inevitably be exposed to reactive plasmas in integration processes to produce the desirable trench and via structure before further treatment, including deposition of barrier materials and inlaying of Cu.    Common concerns include:

  • Will the integration procedures introduce any structural change to the porous low-k films?  

  • Will the resulting structure and dielectric properties still be feasible for the device applications? 

We have focused on investigating the above key issues in the porous low-k/Cu integration using beam-PALS.  Specific studies included probing Metal interdiffusion, Diffusion barrier integrity and porous low-k compatibility to Plasma treatment.