<p>On April 20, a magnitude 7.7 strong earthquake occurred off the coast of northeastern Japan, impacting four semiconductor industrial clusters: Iwate, Aomori, Miyagi, and Fukushima, sparking high market concern over potential supply chain disruptions. Among all affected sectors, risks were most concentrated in the photoresist supply chain, while production conditions at Kioxia's NAND plants remained uncertain.</p>
<p><strong>Kioxia has suspended production at its NAND plant in Kitakami, Iwate Prefecture; preliminary inspections are estimated to take one to three days, and the timeline for full production resumption remains unclear; the two facilities combined account for approximately 5% to 8% of global NAND capacity.</strong> However, according to IC Smart citing internal Kioxia sources, the company has not announced a production halt, and the seismic activity had limited actual impact on the factories, creating a discrepancy between the two accounts.</p>
<p>The photoresist supply chain faces even more severe pressure. Tokyo Ohka Kogyo (TOK) has fully suspended operations at its factory in Koriyama, Fukushima Prefecture, <strong>with the shutdown expected to last four to six weeks</strong>; this facility accounts for about 25% of global advanced photoresist capacity. Additionally, Shin-Etsu Chemical's Shirakawa plant in Fukushima Prefecture announced a production halt, <strong>with equipment recalibration estimated to require four to eight weeks</strong>.</p>
<p>In contrast, the impact on semiconductor equipment and silicon wafer sectors was relatively limited. Tokyo Electron (TEL) confirmed that its affected Northeast factories showed no structural damage after inspection and have resumed normal operations. Shin-Etsu Chemical and SUMCO's 12-inch wafer fabs are expected to resume production gradually starting April 21. Analysts note that the restart timelines for TOK and Shin-Etsu Chemical's photoresist lines will be the core variables observed by the supply chain over the coming weeks.</p>
<h2>Kioxia Iwate Plant: Discrepancies in Halt Reports, Resumption Timeline Pending</h2>
<p>According to media reports, the earthquake's epicenter was located off the Sanriku coast, occurring at 4:53 PM local time on April 20, with a maximum intensity of 5-lower recorded in Tase, Aomori Prefecture—the municipality most severely impacted in this quake. <strong>The affected area covered Iwate, Aomori, Miyagi, and Fukushima prefectures, home to major global semiconductor companies including Kioxia, Tokyo Electron, Shin-Etsu Chemical, and SUMCO.</strong></p>
<p>Currently, no major wafer fabs are located in areas with intensities of 5-lower or higher, but intensity level 4 zones cover the location of Kioxia's Kitakami plant. According to ijiwei, Kioxia's Kitakami Fab 1 and Fab 2 are globally significant NAND flash production bases, estimated to account for 5% to 8% of global capacity combined. No major structural damage has been detected post-quake; inspections are estimated to take one to three days, though the timeline for full production resumption remains unclear.</p>
<p>However, IC Smart cited Kioxia sources stating that the company has not announced a production halt, and the 4-to-5 intensity shaking had limited actual impact on the factories, contradicting ijiwei's report. Notably, EE Times Japan previously reported that Kioxia's K2 plant utilizes base isolation structural design capable of effectively absorbing seismic shocks; this plant is dedicated to producing high-density 218-layer 3D NAND using CBA (CMOS Direct Bonded to Array) technology, with full-scale shipments scheduled to begin in the first half of 2026.</p>
<h2>Photoresist Recalibration Requires 4-8 Weeks, Involving 25% of Global Advanced Capacity</h2>
<p><strong>Among all impacted sectors, the photoresist supply chain carries the highest concentration of risk.</strong> TOK has fully suspended operations at its Koriyama, Fukushima Prefecture factory for comprehensive inspections, with the shutdown expected to last four to six weeks. This facility holds a pivotal position in the global advanced photoresist supply, <strong>accounting for approximately 25% of total global capacity.</strong></p>
<p>Additionally, Shin-Etsu Chemical's factory in Shirakawa, Fukushima Prefecture, announced a production halt, with equipment recalibration estimated to require four to eight weeks. ijiwei points out that advanced photoresist capacity is highly concentrated in a few key facilities; this suspension has fully exposed supply concentration risks, making the restart timing and pace of TOK and Shin-Etsu Chemical's production lines core variables closely tracked by the market.</p>
<h2>TEL and Wafer Makers: Rapid Return to Normal Operations After Inspection Shutdowns</h2>
<p>Tokyo Electron's (TEL) Northeast production and logistics center in Oshu City, Iwate Prefecture, temporarily halted production following the earthquake. Inspection efforts focused on verifying equipment alignment accuracy, mechanical precision, and potential damage to piping and electrical systems. However, TEL announced on April 20 that neither its Northeast factory nor its Miyagi facility sustained structural damage, and both sites have resumed normal operations.</p>
<p>Regarding silicon wafer suppliers, Shin-Etsu Chemical and SUMCO voluntarily suspended production at their respective 12-inch wafer fabs in Miyagi and Fukushima for safety checks. According to EE Times China, both companies expect to gradually resume production starting as early as April 21. Given that global silicon wafer supply remains relatively ample, the actual impact of this suspension on overall supply is expected to be limited.</p>
<h2>Earthquake Impact Scope: Hokkaido Raises Concerns, Kyushu Largely Unaffected</h2>
<p>The earthquake's shockwaves extended northward to Hokkaido, where intensity level 4 was recorded, marking the northernmost reach of this event. In recent years, Hokkaido has emerged as Japan's third-largest semiconductor cluster; government-backed foundry Rapidus is constructing a new fab in Chitose City, targeting mass production of 2-nanometer processes by 2027, generating some market concern regarding subsequent impacts.</p>
<p>In contrast, the Kyushu region was not directly impacted. Only intensity levels of 1 to 2 were recorded in Kyushu, home to Sony, ROHM, and TSMC's Kumamoto plant, leaving production unaffected.</p>
<h2>Supply Chain Comprehensive Assessment: Short-Term NAND Volatility Manageable, Photoresist Under Close Scrutiny</h2>
<p>Overall, according to ijiwei analysis, <strong>Kioxia's brief production halt due to inspections may trigger short-term supply fluctuations in tight-supply niche markets such as AI servers and automotive storage; however, impacts on silicon wafers and semiconductor equipment are expected to be relatively limited.</strong></p>
<p>Photoresists represent the most prominently affected sector, characterized by highly concentrated advanced capacity and limited alternative resources. The resumption progress of TOK and Shin-Etsu Chemical will remain a key focus for supply chain observers and market investors over the coming weeks.</p>

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<p>A magnitude 7.7 earthquake struck northeastern Japan yesterday, affecting four major semiconductor clusters. The photoresist sector faced the heaviest impact: Tokyo Ohka Kogyo and Shin-Etsu Chemical's Fukushima plants suspended operations, with recalibration expected to take 4 to 8 weeks, covering 25% of global advanced capacity and becoming the biggest supply chain variable. Kioxia's Iwate NAND plant suffered no structural damage, but its resumption timeline remains uncertain, potentially triggering short-term volatility in the memory market</p>

- On April 20, a 7.7 magnitude earthquake struck off the coast of northeastern Japan, affecting key semiconductor regions and raising supply chain concerns.  
- Kioxia's NAND factory in Iwate has paused operations for inspections, with uncertain timelines for full recovery, while the photolithography supply chain faces significant pressures with major factories halting production.  
- Analysts emphasize that the recovery of TOK and Shin-Etsu’s production lines will be critical to watch in the coming weeks, as their facilities account for a substantial share of the global advanced photolithography capacity.

Wallstreetcn

Tokyo Ohka Kogyo Co., Ltd.

Shin-Etsu Chemical Co Ltd

Shin-Etsu Chemical Co., Ltd.

iShares Semiconductor ETF

VanEck Semiconductor ETF

TANWAN

AINNOVATION

Nano Labs

Mitsubishi Chemical Holdings Corporation

Tokyo Electron Ltd.

SUMCO

Rapid Micro Biosystems

Rapid7

Rapid Nutrition PLC

Sony Group Corporation

Sony

Rohm Co., Ltd.

GDPD

IMDTECL

Sun Cable

DELISI

Taiwan Semiconductor

Tokyo Electron

Japan Earthquake Shakes Semiconductor Chain: Kioxia NAND Production Halted, Critical Photoresist Plants Idle for 4-8 Weeks