On October 1, Micron outlined its plan to expand four sites in Taiwan. According to Central News Agency (CNA) coverage of the briefing, the company's cumulative investment in Taiwan had exceeded NT$1.6 trillion as of June 2026, with roughly half of that coming in the past four years. The same day, Taiwanese DRAM maker Nanya Technology also announced that it had received approval to build a 3D wafer packaging and testing plant in Pingtung. Investment in AI-oriented memory is spreading, but each site handles a different process. Separating front-end work, where circuits are made, from back-end work, where chips are stacked and finished into products, shows which part of supply capacity this expansion actually strengthens.
What Does Each of the Four Sites Add, by Process?
The NT$1.6 trillion figure is not a newly decided investment amount. According to CNA, it is the cumulative investment through June 2026 cited by Lu Dong-hui, chairman of Micron Taiwan. Investment over the past four years is roughly equal to the total of the preceding 25 years, he said. That shows investment in Taiwan has risen sharply in recent years, but the NT$1.6 trillion cannot be treated as the budget for the planned four-site expansion. CNA briefing report
In Taiwan, Micron is expanding wafer fabrication in Taoyuan and Tongluo, HBM packaging in Taichung, and wafer testing in Tainan. Combining facility information from Economic Daily News, which covered the October 1 briefing, with Micron's acquisition announcement and latest earnings remarks, the role and progress of each site can be summarized as follows.
| Site | Process or facility being expanded | Confirmed stage | Announced plan and timing |
|---|---|---|---|
| Taoyuan | "Fab 11E," an EUV-capable wafer fabrication building | New building planned; designed with future High-NA EUV in mind | Operations expected around 2028 (Economic Daily News, Oct. 2) |
| Taichung | A second advanced packaging plant converted from an existing facility | Conversion under way since 2025 | HBM production to begin in mid-October 2026 (Economic Daily News, Oct. 2; CNA, Oct. 1) |
| Tainan | A facility converted from AUO's former LCD plant, mainly for front-end wafer testing | Equipment move-in began in early September 2026 | Equipment move-in timing disclosed; Economic Daily News' Oct. 2 report gives no date for mass production or shipments |
| Tongluo | The P5 plant acquired from PSMC, plus an additional fabrication building | P5 acquisition completed March 16, 2026 | Full-scale product shipments expected from mid-2027 (Micron's Sept. 30 earnings remarks) |
Sources: Economic Daily News, CNA, Micron's announcement of the P5 acquisition, Micron's fiscal Q4 2026 prepared remarks. Information confirmed through October 2, 2026, organized by process being expanded and stage of execution. The table does not list every existing function at each site.
Taichung's "production start" and Tongluo's "full-scale product shipments" do not refer to the same stage. Equipment move-in at Tainan should likewise be distinguished from the point at which testing capacity actually supports shipments. Summarizing the four sites' plans as simply "more production in Taiwan" obscures these differences in timing between processes.
Tongluo's schedule is confirmed not only by briefing coverage in Taiwan but also by Micron's latest official remarks. In its September 30 earnings materials, the company said its plan to begin full-scale product shipments from the site in mid-2027 remains on track. Acquiring a building does not by itself increase supply; installing equipment and ramping up take time before shipments follow.
Converting Existing Facilities Links Tongluo and Taichung
The P5 site in Tongluo, which Micron acquired on March 16, includes about 300,000 square feet of existing cleanroom space for 300mm wafers. Micron's announcement of the completed acquisition also states a plan to vertically integrate it with the nearby Taichung site. In Tongluo, the company also plans a second fabrication building with about 270,000 square feet of cleanroom space. The concept is to absorb existing manufacturing facilities while linking processes within Taiwan. Micron's acquisition completion announcement
Cleanroom area alone, however, does not reveal actual shipment capacity. Which equipment is installed, which products are made, and what yields are achieved all change how much supply the same floor space can produce. Micron has indicated it will integrate with Taichung, but it has not disclosed how products will move among the four sites.
Facility conversion is also under way in Taichung and Tainan. According to Economic Daily News, Taichung is converting an existing facility into a second advanced packaging plant. At the former AUO plant in Tainan, an 11-meter-high warehouse is being remodeled into a three-level cleanroom structure, mainly for wafer testing. A building once used to make LCD panels is being reborn as a memory testing facility. The expansion is clearly not all about building plants on new land. Economic Daily News facility report
By contrast, the new building in Taoyuan is being designed around future manufacturing equipment. Economic Daily News reported that Fab 11E will provide the floor load capacity and height needed to install and maintain EUV tools, and will be designed to accommodate future High-NA EUV. High-NA is a technology for forming even finer circuits in EUV lithography. Still, designing a building with future tools in mind is a different stage from actually installing equipment and starting mass production.
The manufacturing capacity at Taoyuan and Tongluo plays a different role from the packaging capacity at Taichung. For its EUV-based DRAM process technology, 1γ (1-gamma), Micron says bit density per wafer rises by more than 30% compared with the 1β generation. That is a technology that increases the memory capacity obtainable from a single wafer; it does not mean total shipments from Taiwan's plants will rise by more than 30%. Micron's explanation of 1γ technology
HBM is memory in which DRAM chips are stacked vertically and connected layer to layer with through-silicon vias (TSVs). It requires both a process that shrinks circuits to raise capacity per wafer and a process that stacks multiple chips and connects them at high speed. Looking only at the expansion of wafer fabrication buildings makes it easy to overlook the role of the packaging capacity being added in Taichung. Micron's explanation of HBM structure
Nanya's Pingtung Plant: TSVs Alone Do Not Mean HBM Mass Production
On October 1, Nanya Technology announced that it had received approval from Taiwan's National Science and Technology Council to establish a 3D wafer packaging and testing plant in Pingtung. Using TSV and wafer-stacking technology, the plant will perform wafer-level packaging and testing for high-performance, high-bandwidth memory, the company said. The Southern Taiwan Science Park Bureau described the same processes and uses on the same day. Nanya's announcement of the approval, Southern Taiwan Science Park Bureau announcement
As of the company's August 14 explanation, it was still evaluating candidate sites and continuing discussions with the authorities. This time the location was named as Pingtung, and the approval needed to establish the plant was obtained. That moves the project from weighing candidate sites to proceeding at a specific location. Approval, however, does not mean the plant is complete or that mass production has begun. Nanya's August 14 explanation
When "AI," "high bandwidth" and "TSV" appear together, it is easy to picture an HBM mass-production plant. But Nanya's announcement does not mention a specific HBM generation. It also does not disclose the number of stacked layers, bandwidth, the start of mass production or the investment amount. The technology used at the plant alone is not enough to conclude which products it will eventually produce in volume.
TSVs are not used only in HBM. In May 2026, Micron announced sampling of a 256GB DDR5 server module and explained that it uses TSVs in a 3DS structure that stacks multiple DRAM chips. In other words, a product can use stacking and TSVs and still be DDR5. This does not indicate that Nanya will make the same DDR5 module, but it is a concrete example showing that "it uses TSVs, so it's HBM" cannot be assumed. Micron's announcement of the 256GB DDR5 module
What can be confirmed from Nanya's plan at this point is a policy of establishing capacity in Pingtung to stack DRAM and perform packaging and testing. Comparisons with specific competing products will have to wait until the memory standard and product specifications are made clear. Even though both are investments in Taiwan, Micron's announced HBM production start and Nanya's new plant approval should not be treated as the same stage.
What to Watch Next: Shipments by Process, Not Investment Totals
In its September 30 earnings remarks, Micron said it had finalized customer agreements for most of its calendar 2027 HBM supply, and that prices have risen substantially from a year earlier. The comment shows strong HBM demand, but it describes Micron's HBM supply as a whole. It does not mean everything to be made at the second Taichung plant is already under contract, nor that the Taiwan expansion will soon push market prices down. Micron's earnings materials
To judge whether investment in Taiwan translates into actual supply growth, it is necessary to track whether each process's plan leads to shipments on schedule. In Taichung, the start of HBM production in mid-October 2026 is the first milestone. Tongluo aims for full-scale product shipments in mid-2027. How much the Tainan testing facility contributes to expanded supply capacity cannot be judged from equipment move-in reports alone. Once production volumes and testing capacity are disclosed, it will be possible to evaluate concretely how much supply capacity has actually grown, rather than counting factories.
For Nanya, key information remains: which memory products the approved Pingtung plant will finish. Once product standards and operating plans are clear, it will be possible to compare which AI uses the company is targeting and in which areas it will compete with established makers. For now, no plan has been shown for Micron and Nanya to share equipment or customers.
What the Taiwan expansion shows is that investment is spreading beyond front-end wafer fabrication to the back-end work of stacking and testing chips. If production starts in Taichung and full-scale shipments from Tongluo proceed as planned, and each process's expansion feeds through to actual product supply, Micron would further strengthen its ability to make DRAM in Taiwan and finish it into products such as HBM. To judge how much the enormous cumulative investment has improved supply capacity, it will be necessary to look past the investment amount itself and confirm actual production and shipments.