SK hynix is close to finalizing a supply deal with Nvidia for its sixth-generation high-bandwidth memory (HBM4), as the two companies gear up for the launch of Nvidia’s next-gen AI accelerator, the Rubin platform, according to people familiar with the matter.

SK hynix plans to begin mass production of 12-layer HBM4 chips in the fourth quarter of 2025, supplying initial volumes to Nvidia once Rubin’s launch timeline and order size are confirmed. Production will take place at SK hynix’s nearly completed M15X fab in Cheongju, where new HBM4-specific equipment is already being installed.

HBM4 represents a major evolution in memory design. It’s the first generation to feature a foundry-grade logic die and double the number of I/O channels, significantly increasing bandwidth. Since SK hynix lacks a foundry business, it’s outsourcing logic die production to TSMC.