Micron breaks ground on $9.3B Hiroshima HBM plant expansion

The interesting thing here is what specifically is getting built. Micron broke ground on Saturday on a factory in Hiroshima that will make high-bandwidth memory, the chip that sits next to Nvidia GPUs and is currently the tightest link in AI accelerator supply. According to Bloomberg, the total commitment is ¥1.5 trillion, roughly $9.3 billion, with first shipments targeted for around summer 2028.

Putting that capacity in Japan matters because Japan is willing to underwrite a large share of it. METI has allocated up to ¥500 billion, described in the reporting as covering roughly one-third of the capital cost, with a further ¥36 billion earmarked over five years for R&D. That takes total government support for Micron in Hiroshima to as much as ¥774.5 billion, and the project marks Micron's first major expansion at the site since 2019.

The honest caveat is that the reporting is thin on the details a customer would actually care about. There is no mention of which HBM generation the fab is built for, no wafer-per-month or capacity figure, and no named customer contract beyond the general reference to Nvidia's AI processors as the archetype of who buys HBM. Two years is also a long window: Micron's earlier plans for an additional DRAM fab on this same campus have already been reported as slipping to 2027, so summer 2028 as a shipment date is the number to actually watch, not the $9.3 billion headline.

If it lands on schedule, Nvidia and its hyperscaler customers get another serious HBM source outside the current dominant suppliers, and Japan gets another anchor of its domestic chip stack. If it slips, 2028 is the point at which the announcement stops being a signal about supply and starts being a story about missed timing.