The industry standard interconnect technology for fine-pitch 2.5D assembly and 3D stacking is thermocompression bonding of solder capped μbumps. This technology has several challenges which have limited widespread adoption in high-volume production. While the implementation of the technology at 40μm pitch is already challenging, the likelihood of extending this technology to 10μm pitch is slim, due to pattern processing complexity, stacking alignment accuracy and instability of the solder material. Alternative interconnect approaches such as solid metal connection without solder reflow, and direct copper to copper (Cu to Cu) bonding, are considered to be more feasible at current state-of-the-art and future fine pitch applications.
This presentation presents the latest development in Direct Bond Interconnect DBI®, a Cu-Cu interconnect technology for both die-to-wafer (D2W) and die-to-die (D2D) stacking. Daisy chain dies were prepared with similar dimensions and interconnect pitch to a typical high bandwidth memory (HBM) die. The daisy chain dies were DBI® bonded onto a host wafer that represents the controller in an HBM stack. Process development is discussed and preliminary electrical testing results are presented.
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This was presented as part of the 2016 International Wafer-level Packaging Conference, October 18-20, 2016