SK Hynix Moves Early on Hybrid Bonding, Targeting HBM5
Taylor Wilson
SK Hynix has begun qualifying hybrid-bonding equipment ahead of schedule, targeting HBM5 mass production in 2029–2030. This means the HBM race is shifting from how many layers you can stack to how tightly you can pack them and how well you can cool them — packaging density is becoming the decisive variable in the next round of AI chip competition.
What is hybrid bonding, and why is it arriving now?
Hybrid bonding — joining chips directly through copper and dielectric layers instead of metal bumps — dramatically shrinks the gap and height between stacked dies.
This means → more DRAM layers fit in the same package footprint, and heat escapes more easily. Those are the two hardest constraints facing AI accelerators today.
Current HBM products use thermocompression bonding (TCB), which relies on micro-bumps. TCB works, but its pitch and stack height are reaching physical limits. Hybrid bonding is a replacement, not an upgrade.
HBM4 still uses TCB — why is SK Hynix running two tracks?
Counterpoint Research notes that after JEDEC relaxed its standard, TCB can still support HBM stacks of up to 16 layers. It is not exiting soon.
SK Hynix continues to order TC bonding machines for HBM4: Hanwha Semitech and Hanmi Semiconductor both received orders, with Hanmi disclosing a deal worth ₩44.2 billion.
In plain terms = HBM4 is the last big order book for the old process. Hybrid bonding is still climbing the yield curve, and the line cannot go dark. Running both tracks is a hedge, not hesitation.
Who is competing on equipment?
SK Hynix has adopted the Kynex integrated hybrid-bonding system jointly developed by Applied Materials and BESI. The system reportedly compresses the full process from roughly 10 hours to about 1 hour.
Hanwha Semitech's die-to-wafer (D2W) hybrid-bonding cluster system is already under quality evaluation at SK Hynix, and its second-generation tool, SHB2 Nano, entered the line in April this year.
This means → equipment competition has moved past "can it be done" to "whose cluster is faster and yields higher." Applied Materials + BESI and Hanwha are in direct head-to-head position.
Why is the process called "nanometer-precision"?
Hybrid bonding demands nanometer-level alignment accuracy and is extremely sensitive to particle contamination. It requires ISO Class 3 cleanrooms — no more than 1,000 particles above 0.5 µm per cubic meter.
Cluster systems integrate plasma activation, deionized-water cleaning, metrology, alignment, and bonding into one enclosed flow. The core purpose is to minimize contamination exposure as wafers move between steps.
This reflects a broader reality: hybrid bonding is not just "a different way to stick chips together." It imposes an entirely new standard on line cleanliness and process integration.
Why have thermal management and packaging suddenly become the focal point?
AI accelerators keep demanding more memory bandwidth. HBM stacks must sit right next to the GPU or AI logic die while enduring higher power density.
Stack height, cooling paths, bond pitch, and package layout — these four variables used to be "good enough is fine." Now they are the performance ceiling.
In plain terms = the old race was about how many memory layers you could stack. The new race is about where the heat goes after stacking and how the space is divided. Whether HBM5 can hit mass production on hybrid bonding on schedule is the single most important proof point in this technology contest.
Content is for reference only, not financial advice.