aveni SA announced that CEA-Leti has successfully fabricated 3D through silicon vias (TSVs) with an unprecedented 12:1 aspect ratio using aveni's Rhea™ copper seed, achieving 100% electrical yield. The 12:1 TSVs used in this study were 120µm high x 10µm in diameter.

“Aveni’s electrografted wet metal deposition technology can produce conformal metal layers of exceptional quality, such as the Rhea copper seed used in this study,” said Frédéric Raynal, Chief Technology Officer at Aveni. “This research was conducted by CEA-Leti as part of the IRT Nanoelec 3D Program. For the TSVs tested in this study, the measured electrical results showed a very high correlation with the theoretical yield, which is very satisfying.”

TSVs are a type of interconnect that vertically connects multiple layers (stacked chips) to create high-density electrical connections. This technology is most commonly used in high-performance applications, such as high-bandwidth memory (HBM) stacks integrated with graphics processing units (GPUs) on silicon interposers. High-density interconnects are critical because they enable greater processing power in smaller device footprints.

The aspect ratio (A/R) refers to the ratio of the height (V) to the diameter (W) of a cylindrical via. Until now, advanced TSVs have generally been limited to 10:1. This is due to the limitations of conventional dry deposition technologies such as PVD (physical vapor deposition). At aspect ratios greater than 10:1, the TSV diameter shrinks, which limits the transport of reactants during the PVD process and slows the deposition rate. This causes incomplete or discontinuous filling within the TSV, which in turn affects electrical yield and reliability.

“This is the first time that TSV technology has achieved perfect electrical yield at a 12:1 aspect ratio,” said Bruno Morel, CEO of aveni. “While there have been several reports demonstrating 10:1 TSVs, no one has demonstrated this perfect electrical yield performance at a 12:1 aspect ratio. This achievement further demonstrates the broad applicability of aveni’s electrograft technology. Our roadmap continues to advance towards smaller diameter TSVs at higher aspect ratios.”