Micron’s ¥1.5 Trillion Hiroshima Chip Plant: The Full Breakdown of Its HBM Expansion for AI

The total investment is approximately ¥1.5 trillion, reported as $9.3 billion by Bloomberg and $9.6 billion by Nikkei and Reuters . This makes it Micron's largest single investment in Japan to date . Initial commercial shipments of next-generation HBM for AI systems are targeted for around 2028, with some sources specifying a window between June and August 2028 . Full-scale production at maximum capacity is projected for March to May 2030 . The facility is expected to achieve a monthly output of 40,000 high-end DRAM wafers, with a significant portion dedicated to HBM .

Japanese Government Subsidies: A National Strategic Push

Japan's Ministry of Economy, Trade and Industry (METI) is providing massive financial backing for the Hiroshima expansion as part of a national strategy to rebuild domestic semiconductor manufacturing capacity . The key subsidy commitments include:

• September 2025 — ¥536 billion ($3.6 billion) pledge: METI announced a major subsidy of up to ¥536 billion (approximately $3.63 billion) specifically for Micron's Hiroshima DRAM plant, with a focus on HBM and extreme ultraviolet (EUV) lithography . This package includes up to ¥500 billion for capital spending (covering about one-third of total investment) and ¥36 billion over five years for R&D .
• Earlier subsidies in 2022–2023: This builds on an earlier ¥46.5 billion ($320 million) subsidy from 2022 for advanced DRAM production and a ¥192 billion ($1.3 billion) subsidy from 2023 to help install EUV equipment .
• National budget context: Separately, Japan's overall budget for cutting-edge semiconductors and AI has been nearly quadrupled to about ¥1.23 trillion ($7.9 billion) for the coming fiscal year, reflecting the country's strategic focus on the sector .

Micron's HBM Market Share Position: From 2% to 20%

Micron has rapidly emerged as a meaningful third player in a global HBM market historically dominated by SK Hynix and Samsung. According to data from Silicon Analysts, the market share evolution is :

Key data points from multiple sources:

• Micron's HBM market share surged from 9% in Q4 2024 to nearly 20–21% by Q4 2025 . Forbes noted that Micron transformed from a minor player into a significant contender in just one product cycle .
• Counterpoint Research data shows Micron's overall DRAM revenue share fluctuating between 22–26% in 2025 .
• SK Hynix remains the clear leader with an estimated 50–55% share, followed by Samsung at 35–40%, with Micron at 5–10% according to some early 2026 estimates (likely narrower HBM segment definitions) . Other sources focusing on HBM3E or bit shipments place Micron closer to 20% .

The bottom line: There is variance in estimates due to different segment definitions (overall DRAM vs. pure HBM vs. HBM3E), but the consensus is clear: Micron has roughly tripled its HBM share in two years but still trails SK Hynix (leader) and Samsung (strong #2).

Broader Context: The AI Memory Supercycle & Japan's Semiconductor Resurgence

The AI memory supercycle: A global rush to build AI infrastructure is driving an unprecedented boom in memory demand. Nomura Securities has described this as a "super cycle" expected to last through at least 2027, driven by explosive demand for HBM, general-purpose DRAM, and NAND for AI servers . The HBM market was valued at $2.93 billion in 2024 and is projected to reach $16.72 billion by 2033, a compound annual growth rate of roughly 21% . Memory prices have been soaring due to supply shortages .

Japan's semiconductor resurgence: Japan is executing a three-pronged strategy to rebuild its domestic chip manufacturing industry :

1. Strengthening domestic production with subsidies for Micron, TSMC's Kumamoto fab, and Rapidus in Hokkaido.
2. Forming international alliances, attracting foreign leaders like Micron and TSMC to build advanced fabs in Japan.
3. Focusing on advanced nodes, including 2nm GAA (gate-all-around) technology and HBM-specific EUV-based DRAM production .

Japan's semiconductor market was approximately $51.2 billion in 2025 and is projected to reach $89.4 billion by 2030, an 8.9% CAGR . The Micron Hiroshima expansion is a cornerstone of this strategy — anchoring cutting-edge HBM production on Japanese soil, backed by billions in state subsidies, and securing supply for the AI era .