With the widespread adoption of AI servers, HBM (High Bandwidth Memory) has become a key player in the semiconductor industry. Industry insiders and outsiders are closely watching the evolution of the "base die." Previously manufactured using DRAM processes, these base dies are now being manufactured using foundry processes, starting with HBM4. Samsung Electronics, SK Hynix, and Micron Technology have each developed distinct strategies to prepare for the HBM4 era.

Base Die, the "brain" of HBM

According to a Memory Industry report on the 28th, the world's three largest memory companies are reportedly significantly improving their base die structures in preparation for mass production of the next-generation HBM4. This is because, with the exponential growth in AI computing power, the base die's role is becoming increasingly crucial. It goes beyond simple memory stacking and also determines signal processing and power efficiency.

HBM is a memory device that maximizes bandwidth by stacking multiple DRAM chips using TSV (through-silicon via) interconnect technology. The bottom die receives signals from the bottom layer and performs logic functions, determining the overall performance and stability of the HBM. It can be considered the "brain" and "signal control center" of the HBM.

Prior to HBM3E, this base die was manufactured using DRAM processes. DRAM manufacturers directly designed the logic circuits and produced them on their own DRAM production lines. However, DRAM processes based on planar transistors lag behind the foundry's FinFET processes in terms of speed, signal integrity, and power efficiency.

Against this backdrop, these limitations are becoming apparent as the performance demands of AI servers continue to grow. Therefore, Samsung Electronics and SK Hynix have reportedly decided to transition their HBM4 substrate chips to a foundry process. This move aims to address heat generation and signal latency issues encountered during high-performance computing, while also improving energy efficiency. Compared to traditional DRAM processes, using a foundry process allows for finer line widths and more complex transistor structures, resulting in substrate chips suitable for high-speed computing.

Meanwhile, Micron has chosen a different path. Its strategy is to continue using existing DRAM processes to produce its base chips until HBM4 reaches mass production, but to utilize TSMC's foundry for HBM4E. While this decision appears to be based on immediate production efficiency and cost considerations, avoiding the transition to a foundry process could, in the long term, lead to lags.

Why choose a different strategy?

Industry insiders believe Samsung Electronics and SK Hynix's rapid shift to foundry technology stems from a belief that DRAM processes have outpaced the needs of major GPU customers like NVIDIA and AMD. To maintain technological leadership, they must aggressively adopt foundry processes to ensure performance and stability.

Micron appears to be adopting a relatively conservative strategy, aiming to maintain cost competitiveness by maximizing its existing DRAM process infrastructure while leveraging TSMC's foundry capabilities to ensure a smooth transition when HBM4E is introduced. While this may benefit short-term cost savings, it could be detrimental to competition with performance-focused customers like NVIDIA.

An industry insider stated, "HBM was launched to overcome the physical limitations of stacked DRAM, but it has now reached a stage where the logical performance of the underlying chip determines overall system performance." He added, "Samsung and Hynix's transfer of their underlying chip processes to foundries is not simply a change in manufacturing methods, but a strategic shift that will redefine the competitive landscape for HBM."

Another official stated, "Micron's decision to stick with its DRAM process and shift to foundry later is to minimize costs and risks," adding, "Ultimately, market trust will inevitably go to the company that proves itself first."

Source: Content compiled from m.ddaily

View more at EASELINK