Comprehensive Overview of Next-Generation HBM Architecture: HBM4 to HBM8 Featuring Up to 64 TB/s Bandwidth, 240 GB Capacity per 24-Hi Stack, and Embedded Cooling

The evolution of High Bandwidth Memory (HBM) standards has seen remarkable advancements with HBM4 through HBM8, driving the innovations needed to meet the increasing demands for artificial intelligence (AI) and data center performance.

Expanding HBM Standards Aim to Meet AI and Data Center Demands

A recent presentation from Korea Advanced Institute of Science and Technology (KAIST) and Tera (Terabyte Interconnection and Package Laboratory) has shed light on the ambitious roadmap for HBM technologies. With technologies such as HBM4, HBM5, HBM6, HBM7, and HBM8, substantial improvements are ahead, promising bandwidths reaching up to 64 TB/s.

Starting with HBM4, this standard is poised to support upcoming AI GPU initiatives and data center technologies slated for launch in 2026. Confirmations from notable players like AMD and NVIDIA regarding their integration of HBM into products like the MI400 and Rubin series signify its importance.

NVIDIA’s upcoming GPU roadmap, detailed by the research firms involved, provides crucial insights, especially given Tera’s expertise in interconnection and HBM packaging. HBM4 memory is strategically designed for NVIDIA’s Rubin and AMD’s MI500 GPUs.

NVIDIA’s Rubin and AMD’s MI500 GPUs: A Closer Look at HBM4

NVIDIA’s Rubin series is set to utilize HBM4 and HBM4e technologies, with the Rubin featuring eight HBM4 sites, while the Rubin Ultra is built with 16 sites. Each variant showcases different die cross-sections, with the Ultra providing twice the compute density.

According to analysis, the Rubin GPU will boast a die area of 728 mm², consuming around 800W. Its interposer measures 2194 mm² and supports a memory capacity of 288 to 384 GB, delivering an impressive bandwidth ranging from 16 to 32 TB/s, with a total power requirement of about 2200W—nearly double that observed in previous Blackwell B200 GPUs.

Key Features of the HBM4 Standard

Data Rate: Approximately 8 Gbps
IO Count: 2048 (up to 4096)
Total Bandwidth: 2.0 TB/s
Die Stacks: 12/16-Hi
Capacity per Die: 24 Gb
Capacity per HBM: Up to 36/48 GB
Power per HBM Package: 75W
Packaging Method: Microbump (MR-MUF)
Cooling Method: Direct-To-Chip (D2C) Liquid Cooling
Custom HBM Base Die Architecture
NMC Processor + LPDDR in Base Die
Supported Platforms: NVIDIA Rubin & Instinct MI400

AMD is also raising the bar with their Instinct MI400, packing a substantial 432 GB of HBM4 alongside bandwidth capabilities reaching 19.6 TB/s—a notable leap beyond NVIDIA’s offerings.

In terms of specifications for HBM4, the technology is set to deliver an 8 Gbps data rate, 2048-bit IO, and a bandwidth of 2.0 TB/s per stack, alongside a maximum memory capacity of 48 GB. It is designed with a 75W per stack power package and utilizes liquid cooling for optimal performance.

Advancements with HBM5, HBM6, HBM7, and HBM8

On the horizon, HBM5 targets a release around 2029 and is expected to maintain an 8 Gbps data rate while expanding IO lanes to 4096. With total bandwidth estimated at 4 TB/s, this standard will leverage 16-Hi stacks offering a capacity of up to 80 GB.

Key Features of the HBM5 Standard

Data Rate: 8 Gbps
IO Count: 4096
Total Bandwidth: 4.0 TB/s
Die Stacks: 16-Hi
Capacity per Die: 40 Gb
Capacity per HBM: 80 GB
Power per HBM Package: 100W
Packaging Method: Microbump (MR-MUF)
Cooling Method: Immersion Cooling, Thermal Via (TTV)
Special Features: Custom HBM Base Die with 3D NMC-HBM & Stacked Cache

NVIDIA’s Feynman is projected to be the first GPU to make use of HBM5, with an official release price target of 2029, allowing for adequate production setup.

The Feynman GPU will reportedly feature a 750 mm² die with a power consumption of 900W, and it is anticipated to package four GPUs with 400 to 500 GB of HBM5 memory, achieving a total thermal design power (TDP) of 4400W.

Next-Gen Innovations with HBM6 and Beyond

Following HBM5, the next leap appears with HBM6, anticipated to debut after the Feynman architecture. This version is predicted to implement a significant upgrade of 16 Gbps data rates alongside 4096-bit IO lanes, allowing for remarkable advancements in bandwidth and memory capacities.

Key Features of the HBM6 Standard

Data Rate: 16 Gbps
IO Count: 4096
Total Bandwidth: 8.0 TB/s
Die Stacks: up to 20-Hi
Capacity per Die: 48 Gb
Capacity per HBM: 96/120 GB
Power per HBM Package: 120W
Packaging Method: Bump-less Cu-Cu Direct Bonding
Cooling Method: Immersion Cooling
Advanced Features: Custom Multi-Tower HBM architecture

With HBM6, we expect gains in both bandwidth and power efficiency, paving the way for potential GPU packaging of up to 6014 mm², providing phenomenal memory bandwidth and capacity capabilities.

HBM7 and HBM8: The Future of High-Bandwidth Memory

Looking further into the future, HBM7 and HBM8 are projected to redefine memory technology. HBM7 could boast a data rate of 24 Gbps and an impressive 8192 IO count, advancing bandwidth capabilities dramatically to 24 TB/s.

Key Features of the HBM7 Standard

Data Rate: 24 Gbps
IO Count: 8192
Total Bandwidth: 24.0 TB/s
Die Stacks: 20/24-Hi
Capacity per Die: 64 Gb
Capacity per HBM: 160/192 GB
Power per HBM Package: 160W
Packaging Method: Bump-Less Cu-Cu Direct Bonding
Cooling Method: Embedded Cooling
Architecture: Hybrid HBM Architecture with Buffer dies

Finally, HBM8 will elevate standards beyond our current understanding, promising data rates that reach 32 Gbps with enhanced capacity, set for release around 2038. As we look ahead, HBM7 and HBM8 standards are poised to usher in an era of unprecedented computing capabilities.

Innovative Cooling Solutions Meets HBM Architecture

Adaptations, like the High-Bandwidth Flash (HBF) architecture, aim to optimize memory-intensive applications such as large language model generation. This innovation employs advanced NAND configurations and interconnect strategies, offering seamless integration with HBM stacks for enhanced performance.

As we transition into an era defined by data-intensive applications, the intricate interplay of innovative architecture and specialized cooling solutions will provide the backbone needed for next-generation computing. The HBM future looks promising with substantial developments in sight, and the upcoming years will provide an exciting glimpse into the evolution of memory technology.

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