Reliability challenges accompanied with interconnect downscaling and ultra low-k dielectrics

The continuous downscaling of interconnect dimensions in combination with the introduction of porous low-k materials has increased the number of integration challenges tremendously. The paper focuses mainly on the impact of porous low-k dielectrics on interconnect reliability. Numerous reliability issues are induced by their porosity compared to dense low-k materials. The impact of these mechanically inferior materials on packaging is well known. However, on top of the mechanical reliability, ultra low-k materials are extremely vulnerable to processing (especially to plasmas), due to their inherent porosity. Additionally, it is difficult to deposit a continuous, thin barrier on porous low-k interfaces. The inferior properties of porous low-k materials as compared to their dense equivalents are thought to induce numerous reliability issues, which are in addition to the ones caused by the continuous downscaling of metal lines and dielectric spacings. All of this together has an enormous impact on the reliability of the end product.