CEA-Leti paper co-authored by ST and aveni presented at EPTC
The Electronics Packaging Technology Conference (EPTC) was held in Singapore in December 2015, where Thierry Mourier of CEA-Leti presented the joint paper, “Full 300 mm Electrical Characterization of 3D Integration Using High Aspect Ratio (10:1) Mid-Process Through Silicon Vias.” The paper included work done using aveni’s electrografting seed layer (eG3D Seed) process.
Through silicon vias (TSVs) represent a key element in the 3D IC mid-process integration approach. Current TSV dimensions being used in commercialized products are 5-10 µm diameter with aspect ratio up to 10:1. However, to satisfy requirements for next-generation high-performance computing (HPC) applications, aspect ratios of 10:1 and higher are required, with a reduction of TSV diameter down to 2 µm, and even lower. These dimensions challenge conventional metallization processes for barrier and seed layer deposition.
CEA-Leti is working to develop fine-pitch 3D technologies for HPC applications. In collaboration with aveni, CEA-Leti has been successful in developing alternative seed layer deposition processes.
In the paper presented at EPTC, the focus was on alternative processes for barrier and seed layer of 10:1 aspect ratio TSVs. The solution consisted of depositing, respectively, a diffusion barrier and a seed layer, using two different conformal deposition techniques. The first technique was based on a MOCVD TiN process, and the second used aveni’s copper eG3D Seed layer. A sandwiched copper physical vapor deposition layer was temporarily deposited to fulfill the required properties in order to finalize a viable TSV integration on a double-sided 300 mm design architecture. Complete integration and full electrical characterization were discussed, with excellent yield obtained at 300 mm.
Ongoing work continues between CEA-Leti and aveni to develop an alternative fill step to fill 15:1 HAR TSVs using electrografting, as these dimensions have been shown to improve stress and thermal management.