TSMC's advanced packaging technology, chip-on-wafer-on-substrate (CoWoS), has its supply contracts booked through next year, leaving little headroom for additional output. With that bottleneck, global big tech and fabless (semiconductor design) companies are said to be weighing or already adopting Intel's improved embedded multi-die interconnect bridge (EMIB) technology, "EMIB-T." As TSMC's supply crunch drags on, Intel's new technology is drawing attention as an alternative.
◇ Big tech shows interest, including MediaTek, Broadcom and Meta
On the 2nd, industry sources said MediaTek formally said in its recent earnings release that it will develop an extra-large artificial intelligence (AI) application-specific integrated circuit (ASIC) by using CoWoS and EMIB-T in parallel. Broadcom and Meta are also reportedly weighing a switch from CoWoS to EMIB to cut expense, and Google and Nvidia are also said to be showing interest in EMIB-T.
Among Korea's corporations, SK hynix's moves stand out. SK hynix, which has closely collaborated with TSMC to optimize high bandwidth memory (HBM) and CoWoS, recently received a substrate with EMIB applied from Intel and is said to be weighing a method of mounting HBM and system semiconductors together. It is seen as an effort to diversify a packaging supply chain that has been concentrated on TSMC.
Behind these moves is TSMC's severe supply shortage driven by surging AI Semiconductor demand. Reservations for TSMC's CoWoS are already booked through 2027, and some customers are said to be waiting more than a year for their turn. Even when there is no problem in front-end wafer production, bottlenecks in back-end packaging are delaying shipments of finished goods.
◇ No interposer, silicon only where needed… about half the cost
The biggest difference between CoWoS and EMIB is how they connect a compute die such as a graphics processing unit (GPU) with HBM. CoWoS places the compute die and HBM side by side on a large silicon interposer and uses wiring across the entire silicon slab beneath to link the dies. EMIB, by contrast, does not use such a large silicon slab at all. It embeds a small silicon bridge only where the compute die and HBM actually meet, inside the substrate.
What is drawing attention recently is not the original EMIB, but the improved EMIB-T. While EMIB, in mass production since 2017, allowed signals to pass only horizontally between adjacent dies, EMIB-T adds through-silicon vias (TSVs) into the bridge itself so that power and high-speed signals can also flow vertically. Because it uses expensive silicon only where needed, Intel claims manufacturing costs are up to 50% lower than CoWoS.
Some note it is hard to say EMIB outperforms CoWoS across the board. EMIB is advantageous for local consolidation between a compute die and adjacent dies, but for designs that must densely connect multiple HBM stacks and surrounding chiplets with a focus on a single GPU in the center, some analysts say CoWoS, which uses a large interposer, still leads in routing density and scalability.
◇ Diverging views on Production yield, TSMC developing a counter technology
Assessments of EMIB-T's maturity are still divided. Some say EMIB-T's final package Production yield has risen to 98%, on par with CoWoS, while others analyze it remains around 90%. In addition, the manufacturing Production yield of the silicon bridge substrate itself, a pre-assembly stage, is still around 50%, making substrate supply a more fundamental bottleneck for EMIB-T's spread.
TSMC also appears to be responding. After local reports that it is developing an in-house packaging technology similar to EMIB with Taiwanese substrate maker Kinsus, TSMC's American depositary receipts (ADR) rose by more than 7%, and Intel shares climbed by more than 12%.
The industry expects next year, when EMIB-T mass production hits its stride, to be a real watershed. A semiconductor industry official said, "After EMIB-T mass production next year, we will need to see the scale of actual customer volume transfer to gauge whether the landscape will shift," but added, "As long as the CoWoS supply crunch doesn't ease, Intel will likely continue to benefit."