JEDEC may relax HBM4 height restrictions

In recent years, the relentless drive of artificial intelligence (AI), high-performance computing (HPC), and personal computing has significantly propelled the research and development of high-performance DRAM products, leading to a swift rise in market demand for HBM-class DRAM. Since the latter half of last year, there have been continuous updates regarding the forthcoming HBM4, with major memory manufacturers like Samsung, SK Hynix, and Micron intensifying their investments to accelerate the pace of development.

According to ZDNet, the JEDEC Solid State Technology Association is contemplating a relaxation of the height requirements for HBM4, specifically, the current maximum limit of 720 micrometers. To alleviate the manufacturing challenges faced by Samsung, SK Hynix, and Micron, rumors suggest that JEDEC may extend the height limit for 12-layer and 16-layer stacked HBM4 to 775 micrometers. This adjustment would mean that memory manufacturers could achieve 16-layer stacking within the bounds of existing bonding technologies, without the necessity to shift to novel hybrid bonding techniques.

Currently, both Samsung‘s TC NCF technology and SK Hynix’s MR-RUF technique rely on microbumps to facilitate interlayer connections. Last month, Samsung announced the development of the industry’s first HBM3E 12H DRAM, elevating from the previous 8-layer stacking to 12 layers, and through optimization of the TC NCF material, has managed to reduce the gap to 7 micrometers. However, to achieve 16-layer stacking, the thickness would inevitably increase, making such a feat challenging with the current technology under the original height constraints.

Hybrid bonding technology, which does not require microbumps and allows for direct bonding between onboard chips and wafers, promises tighter interlayer connections to reduce package thickness. Yet, this technology is still in its infancy and is considerably more expensive compared to existing bonding methods, leading manufacturers to be somewhat reluctant to adopt it at this stage.

With JEDEC’s willingness to relax the height restrictions for HBM4, it not only grants additional development time for hybrid bonding technology but also accelerates the commercialization process of HBM4.