The HBM Stacking Robots — TC Bonders & Hybrid Bonders
Every HBM stack on Earth is built by a single Korean company's bonding machines. The successor technology is owned by a single Dutch company.
An HBM stack is built one DRAM die at a time. The dies must be aligned to each other within fractions of a micron — about 1/200th the width of a human hair — then pressed together under heat to fuse the copper connections. The machine that does this is called a thermo-compression (TC) bonder , and one Korean company, Hanmi Semiconductor , makes 71% of them globally. Each TC bonder costs $3-6M. The next-generation process, used starting in HBM4E and HBM5, is called hybrid bonding — where copper pads are joined directly to copper pads without solder, requiring sub-10-nanometer precision. Two companies in the world make hybrid bonders at scale: BE Semiconductor (Netherlands) and Applied Materials (which has a partnership with BESI). This is the cleanest equipment monopoly in the entire semiconductor industry.
You cannot make HBM without TC bonders. You cannot make HBM4E or beyond without hybrid bonders. There is no third option, and the lead-time to deliver these machines is 12-18 months. Every HBM ramp announcement at SK Hynix, Samsung, and Micron is fundamentally an order announcement for these two equipment names.
2 names on the watchlist
71% global share of TC bonders — the machine that physically stacks every HBM die on Earth.
Korean equipment maker that builds the thermo-compression (TC) bonders that stack HBM DRAM dies layer-by-layer with sub-micron alignment . Per TechInsights' 2025 TC Bonder Market Report, Hanmi holds 71.2% global share (cumulative $247.7M). Over 90% share specifically in HBM3E 12-layer TC bonders. Closest competitors: SEMES (Samsung's in-house, 13.1%), ASMPT (5.6%), Yamaha Robotics (5.6%). They are now expanding into hybrid bonding too.
Co-leader in hybrid bonders. The HBM4E / HBM5 generation runs on BESI's machines.
Dutch maker of hybrid bonders that join copper-to-copper at less than 10 nanometers of precision , required for HBM4E 16-high stacks and beyond. Applied Materials bought a 9% stake in April 2025, creating an effective "AMAT CMP + BESI bonder" alliance. Bernstein expects all three HBM makers (SK Hynix, Samsung, Micron) to adopt BESI for HBM4E/HBM5 from 2027 onward. The FT reports hybrid bonding revenue went from €36M (2023) to €476M projected (2026).
- Bernstein, TrendForce, Counterpoint · May 2026