EV Group unveils process to improve 3D-IC / TSV packaging reliability
EV Group (EVG), a supplier of wafer bonding and lithography equipment for the MEMS, nanotechnology and semiconductor markets, has developed a new polymer via-filling process for 3D-IC/through-silicon-via (TSV) semiconductor packaging applications.
Available on the EVG100 series of resist processing systems, the new NanoFill process provides void-free via filling of very deep trenches and high-aspect ratio structures, and is suitable for all common polymeric dielectrics-offering a highly flexible, low-cost and production-ready via-fill platform for interposer development for 3D-integrated image sensors and other device types.
TSV interconnects are critical to the development of 3D-ICs since they enable through-chip communication between the vertically stacked device layers. Currently, most TSVs employ a solid copper via structure. However, the mismatch in coefficient thermal expansion (CTE) between the copper via and the surrounding silicon can create a high amount of stress on the via structure, which results in long-term reliability issues.
Replacing copper as the conducting material is not practical due to the general ease of use of the process. Also, the tooling infrastructure for copper is already well established.
However, replacing the solid copper via with a partial copper-plated via that is filled with a polymeric dielectric has been demonstrated to reduce CTE mismatch and stress, thus minimising reliability issues.
EVG's proprietary process and system enable simultaneous void-free via filling and dielectric redistribution layer (RDL) formation utilising a field-proven process technology that is compatible with all standard polymeric materials.
The EVG150 automated resist processing system is shown in the picture at the top of this story.
"3D packaging represents a fundamental change in the semiconductor industry that paves the way for continued advances in device performance and cost reduction through 'More than Moore' approaches," states Markus Wimplinger, corporate technology development and IP director at EV Group.
"EV Group has made significant investments in our portfolio of wafer-level manufacturing solutions to add new products and capabilities, such as our NanoFill solution, to help our customers accelerate the commercialization of 3D-integrated devices."
EVG's new NanoFill via-filling solution provides numerous advantages over traditional spin coating and dry lamination techniques, including providing complete via filling for permanent passivation and planarisation without forming voids or cavities. The solution's ability to use all common polymeric materials provides customers with a high degree of flexibility. In addition, a sidewall passivation option is available that provides cost and throughput benefits for selected applications.
