Samsung ($005930.KS) says HBM5 targets 2x HBM4E performance and zHBM aims for 8x HBM5. See the architecture, shipping data, exposed stocks, and risks.
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Samsung Electronics ($005930.KS) has sketched two very different steps beyond today's HBM. HBM5 targets twice the performance of HBM4E. zHBM then moves the memory above the accelerator and targets roughly 8 times HBM5 performance. The second number is the real news because it changes the package, not just the memory speed.
Key takeaways - HBM5 targets 2x HBM4E performance, 20% better performance per watt, and 20% lower thermal resistance. - zHBM is a concept, not a dated product. Its official target is about 8x HBM5 performance. - Do not turn those ratios into a 16x bandwidth forecast. The company has not published an HBM5 bandwidth specification.
On September 1, 2026, Samsung Electronics ($005930.KS) said HBM5 is being designed for 2 times HBM4E performance, 20% better performance per watt, and 20% lower thermal resistance. The targets came from its Memory Executive Summit keynote at SEMICON Taiwan, as reported by The Asia Business Daily.
Those are development goals, not a shipping data sheet. By contrast, the company's current roadmap already has two concrete markers:
Jangseok Choi, head of memory product planning, described the shorter die-to-die paths as "vertical highways" in The Asia Business Daily's report.
No. Doubling HBM4E's stated 3.6 TB/s produces 7.2 TB/s arithmetically, but Samsung Electronics ($005930.KS) said performance, not bandwidth. It has not disclosed HBM5 pin speed, bus width, stack bandwidth, capacity, layer count, customer qualification, or production timing in the September announcement.
One possible route is a wider interface. HBM4 doubled the bus from 1,024 to 2,048 pins, and a September report suggested that 4,096 bits could help HBM5 reach the target (Tom's Hardware, "Samsung teases new HBM5"). That remains inference, not a specification.
A 2,048-bit bus at 14 Gbps yields about 3.58 TB/s, which rounds to the stated 3.6 TB/s. The advertised 16 Gbps ceiling would imply more than 4 TB/s. Product speed, system speed, and architectural performance are not interchangeable.
zHBM stacks memory directly over the xPU. Samsung Electronics ($005930.KS) says the concept could deliver about 8 times HBM5 performance, more than 10 times its memory density, 3 times its energy efficiency, and over 50% lower thermal resistance (Samsung Semiconductor, "Next-Gen 3D-Memory Vision").
One source conflict matters: the September press report compares zHBM with HBM4E, while the company's August release names HBM5. This analysis uses the first-party baseline and does not multiply the claims.
Today's 2.5D package places an accelerator and HBM stacks beside one another on an interposer. zHBM turns that path vertical and adds an interlayer for customer-specific logic.
| Architecture | Memory placement | Public maturity | What is disclosed |
|---|---|---|---|
| HBM4 | Beside xPU on an interposer | Volume shipping | Up to 3.3 TB/s, 24 to 36 GB; 48 GB planned |
| HBM4E | Beside xPU on an interposer | Customer samples | 3.6 TB/s, 48 GB; 32 and 64 GB variants planned |
| HBM5 | Not yet disclosed | Development target | 2x HBM4E performance, 20% better performance per watt |
| zHBM | Directly above xPU | Concept model | About 8x HBM5 performance, over 10x density, 3x energy efficiency |
The catch is heat. A vertical stack removes distance but puts memory on top of one of the hottest dies in a server. The company's claimed thermal improvement is therefore a requirement, not a bonus. Wafer bonding yield, repairability, and heat removal will decide whether the architecture leaves the show floor.
The near-term HBM trade is still a three-supplier product ramp: Samsung Electronics ($005930.KS), SK Hynix ($000660.KS), and Micron ($MU). The longer-term zHBM trade shifts value toward companies that can co-design memory, logic, bonding, packaging, and cooling as one system.
For the mapped supply chain, see the High Bandwidth Memory trend, the HBM producer category, and our Micron ($MU) memory-supercycle analysis.
The next signal is evidence that HBM5 and zHBM can clear samples, customer qualification, yield, and volume. SEMI expects 300 mm memory-equipment spending to exceed $50 billion in 2026, up 29%, as HBM and DDR5 capacity expands (SEMI, "AI Power Constraints Drive System-Level Integration").
Watch four checkpoints:
Do not treat zHBM as 2027 revenue, and do not assume its ratios can be multiplied. Treat it as a sign that HBM is becoming part of the processor architecture itself. That is a larger opportunity, but it is also a much harder manufacturing problem.
HBM5 is Samsung Electronics ($005930.KS)'s next-generation high-bandwidth memory under development after HBM4E. The company targets twice HBM4E performance, 20% better performance per watt, and 20% lower thermal resistance. It has not published final bandwidth, interface, capacity, customer, or production specifications.
zHBM is a concept architecture that stacks high-bandwidth memory directly above an AI accelerator instead of beside it on an interposer. Samsung Electronics ($005930.KS) targets about 8 times HBM5 performance, over 10 times its density, 3 times its energy efficiency, and more than 50% lower thermal resistance.
Samsung Electronics ($005930.KS) has not announced a sampling or production date for zHBM. Its August 2026 presentation described a concept model. Investors should wait for a named customer, qualification results, thermal data, and a manufacturing schedule before assigning near-term revenue to it. Not investment advice.
HBM5 is Samsung Electronics ($005930.KS)'s next-generation high-bandwidth memory under development after HBM4E. The company targets twice HBM4E performance, 20% better performance per watt, and 20% lower thermal resistance. It has not published final bandwidth, interface, capacity, customer, or production specifications.
zHBM is a concept architecture that stacks high-bandwidth memory directly above an AI accelerator instead of beside it on an interposer. Samsung Electronics ($005930.KS) targets about 8 times HBM5 performance, over 10 times its density, 3 times its energy efficiency, and more than 50% lower thermal resistance.
Samsung Electronics ($005930.KS) has not announced a sampling or production date for zHBM. Its August 2026 presentation described a concept model. Investors should wait for a named customer, qualification results, thermal data, and a manufacturing schedule before assigning near-term revenue to it. Not investment advice.