The semiconductor industry’s march toward broader 3D IC integration marked an important milestone this week at the 2013 Electronic Components & Technology Conference (ECTC), with the report of an advanced new temporary bonding solution for 3D Through-Silicon-Via (TSV) semiconductor packaging.
The breakthrough was unveiled during ECTC’s 3D Materials and Processing session, when Ranjith John, materials development and integration engineer at Dow Corning, presented a paper co-authored by Dow Corning, a developer of silicones, silicon-based technology and innovation, and SÜSS MicroTec, a supplier of semiconductor processing equipment.
The paper, titled Low Cost, Room Temperature Debondable Spin on Temporary Bonding Solution: A Key Enabler for 2.5D/3D IC Packaging, details the development of a bi-layer spin-on temporary bonding solution that eliminates the need for specialized equipment for wafer pretreatment to enable bonding or wafer post-treatment for debonding. Thus, it greatly increases the throughput of the temporary bonding/debonding process to help lower the total cost of ownership.
“This advance underscores why Dow Corning values collaborative innovation. Combining our advanced silicone expertise with SÜSS MicroTec’s knowledgeable leadership in processing equipment, we were able to develop a temporary bonding solution that met all critical performance criteria for TSV fabrication processes. Importantly, the spin coat-bond-debond process we detailed in our co-authored paper takes less than 15 minutes, with room for further improvement,” said John. “Based on these results, we are confident that this technology contributes an important step toward high-volume manufacturing of 2.5D and 3D IC stacking.”
Both 2.5D and 3D IC integration offer significant potential for reducing the form factor of microelectronic devices targeting next-generation communication devices, while improving their electrical and thermal performance. Cost-effective temporary bonding solutions are a key enabler for this advanced technology by bonding ultra-thin active device wafers to thicker carrier wafers for subsequent thinning and TSV formation. However, in order to be competitive, candidate temporary bonding solutions must deliver a uniformly thick adhesive coat, and be able to withstand the mechanical, thermal and chemical processes of TSV fabrication. In addition, they must subsequently debond the active and carrier wafers without damaging the high-value fabricated devices.
Through their collaboration, Dow Corning and SÜSS MicroTec were able to develop a temporary bonding solution that met all of these application requirements. Comprising an adhesive and release layer, Dow Corning’s silicon-based material is optimized for simple processing with a bi-layer spin coating and bonding process. Combined with SÜSS MicroTec equipment, the total solution offers the benefits of simple bonding using standard manufacturing methods. In their co-published paper, the collaborators report a solution exhibiting a total thickness variation of less than 2 µm for spin-coated films on either 200- or 300-mm wafers. The bonding material exhibited strong chemical stability when exposed to phosphoric acid, nitric acid, organic solvents and other chemicals familiar to TSV fabrication. In addition, the bonding solution and paired wafers showed good thermal stability when exposed to the 300°C temperatures common to the TSV process.
Dow Corning builds on a long history of silicon-based innovation and collaboration in semiconductor packaging. From die encapsulants for stress relief, to adhesives for sealing and bonding, to thermal interface materials for performance and reliability, Dow Corning’s well-established global infrastructure ensures reliable supply, quality and support, no matter where you are in the world.