COMPANY PROFILE / OPTICAL COMMUNICATIONS & PHOTONICS
UMC
A Taiwanese foundry that came late to volume photonic chips, using mature 12-inch processes and imec's technology
UMC (United Microelectronics Corporation) is a Taiwanese foundry whose mainstay is mature process nodes such as 28 nm and 22 nm. It is a latecomer to optical communications: according to its 20-F, it set up a 12-inch silicon photonics manufacturing line in the first half of 2025, and in December that year it took a licence for a 12-inch silicon photonics process from imec, the Belgian research institute. In July 2026 it then announced that it had shipped its first volume-production wafers from its 12-inch fab in Singapore to SILITH, a photonic chip design company. This profile confines the company-wide figures to a single table and sets out what UMC can now do in optics, whom it works with and when it will open its offering to all customers, using only UMC's U.S. SEC filing, quarterly report and official announcements.
- UMC in 30 seconds, and where it stands in optical communications and photonics
- The logo and how the name is written
- Where the company sits in optical communications and photonics
- Scale (the company as a whole, in brief)
- Resources committed to optical communications and photonics
- Track record so far
- Plans ahead
- What the company is aiming for in optical communications and photonics
- Partnership map
- Technologies, products and services
- The risks this company carries
- Glossary, references and claim-to-source audit
1. UMC in 30 seconds, and where it stands in optical communications and photonics
CorporationIt also has a Chinese-language name; this article uses UMC throughout
NYSE: UMCTraded in the U.S. as ADRs
inside the data centreCPO and optical I/O in view for the future
plus an imec licenceimec's iSiPP300 process. December 2025
Companies involved in optical communications fall into three broad types: optical components & modules, chips & foundries, and network systems & carriers. UMC belongs to chips & foundries and manufactures, under contract, photonic chips designed by its customers Sourced.
What distinguishes UMC among the foundries in this series is that it makes no secret of being a latecomer and has bought time with outside technology. It has experience of volume silicon photonics production on its own 8-inch lines, but for the move to 12-inch it brought in imec's finished process under licence. The July 2026 volume shipment was not of a UMC general-purpose platform but of a single company's product, SILITH's, and the platform UMC will offer to any customer is due to open in 2027. As of September 2026, then, the accurate reading is that UMC is "at the stage of having one volume-production track record".
2. The logo and how the name is written
The UMC logo is a trademark of the company. We have not recreated it with generated imagery;
we obtained the SVG logo served by UMC's official website and, after confirming that its content is identical to the official file, placed it here as img/umc_logo.svg.
A note on names: the legal name is United Microelectronics Corporation, and the company also has a Chinese-language name. The logo and general usage write it in capitals as UMC, and this article does the same. SILITH (SILITH Technology), its volume-production customer, is a fabless photonic chip design company and is not part of the UMC group.
Official site: https://www.umc.com/en3. Where the company sits in optical communications and photonics
The middle box in Fig. 1 says "owns the switches and GPUs", a trait of NVIDIA and Broadcom that does not apply to UMC. UMC owns no end products; it takes manufacturing orders from photonic chip design companies Not yet confirmed. The basics of silicon photonics processes are covered in our explainer on silicon photonics, and the make-up of optical transceivers in our explainer on optical transceivers.
4. Scale (the company as a whole, in brief)
The company as a whole is not the subject here, so we note only its size Sourced.
| Measure (NT$ million) | FY2024 | FY2025 | Q2 2026 |
|---|---|---|---|
| Revenue | 232,303 | 237,553 | 68,730 (quarter) |
| R&D expense | 15,616 | 17,725 | - |
| Employees (31 December 2025) | - | 19,097 (12,337 engineers) | - |
A dash means the relevant passage of the materials used gives no figure. 2025 revenue translates to US$7,573 million (the 20-F's own convenience translation).
The figures above are for the whole company. UMC discloses none of its silicon photonics revenue, investment or dedicated headcount Not yet confirmed. In July 2026 it raised its 2026 capital budget to US$2 billion and approved a cleanroom expansion at its P4 building in Singapore and construction of a new fab in Tainan, but the earnings report explains this only as preparation for future opportunities brought by AI and does not say it is an investment for optics. This article does not treat the US$2 billion as optics investment.
5. Resources committed to optical communications and photonics
As a matter of method, we checked four things: people, money, external investment or acquisitions, and universities or public funding. UMC is a company for which few of these can be confirmed.
| Resource | Details | Category |
|---|---|---|
| People (responsible executives) | In the 20-F's executive biographies, the responsibilities of the vice president for technology development (Steven Hsu) include silicon photonics. In official announcements a senior vice president (GC Hung) comments on the optics business | Sourced |
| People (dedicated staff) | Name and headcount of any dedicated optics organisation | Not disclosed |
| Money (R&D) | NT$17.725 billion company-wide (2025, up 13.5% year on year). No optics breakdown | Company-wide sourced; optics not disclosed |
| Money (line investment) | The 20-F says a 12-inch silicon photonics manufacturing line was configured in the first half of 2025. The investment amount is not stated | Sourced (amount not disclosed) |
| Technology brought in | A licence for imec's iSiPP300 process (December 2025), described as a CPO-capable process. The fee is not disclosed | Sourced |
| Investments, acquisitions and joint ventures | No investments in, acquisitions of or joint ventures with optics-related companies appear in the 20-F or official announcements | Could not be confirmed |
| Research institutes | The 20-F says UMC and imec "have begun close cooperation and have started trial runs" | Sourced |
| Public funding | No government funding for optics R&D or manufacturing is mentioned | Could not be confirmed |
| Sites | Volume shipments come from the 12-inch fab in Singapore (Fab 12i). UMC also describes Singapore as an important technology development base | Sourced |
The 20-F says UMC's 12-inch silicon photonics combines SOI wafer processing, 12-inch immersion lithography, and Ge and SiGe epitaxy Sourced. Optical waveguides are a few hundred nanometres wide; tiny sidewall roughness becomes scattering loss, and tiny linewidth variation shifts the resonant wavelength of micro-rings. 12-inch processes with immersion lithography are generally thought to make it easier to reduce this variation Not yet confirmed. Ge and SiGe epitaxy are the steps used to make germanium photodetectors, which receive light, and GeSi electro-absorption modulators (EAMs). In other words, UMC's move to 12-inch is not just about volume; it is also a transition to making the same devices more uniformly. Better uniformity means more good chips per wafer and a lower cost per chip.
6. Track record so far
| When | What happened | What it means |
|---|---|---|
| Date not disclosed | Experience of volume silicon photonics production on 8-inch lines (the 20-F calls it "our existing 8-inch silicon photonics mass production foundation") | It is not starting from zero in optical processes |
| First half of 2025 | Completes configuration of the manufacturing line needed for a 12-inch silicon photonics process | Begins the move to 12-inch |
| Second half of 2025 | Completes design tape-outs with customers and enters the trial-run stage | Starts running customer designs |
| 8 December 2025 | Announces a licence for imec's iSiPP300 process. Says it is working with several new customers on PICs for optical transceivers, with risk production planned for 2026 to 2027 | Brings in a 12-inch process from outside to speed up the ramp |
| 2025 to 2026 | Works with SILITH to go from development to production readiness in 18 months | Clears a path to volume production with one company's product |
| 14 July 2026 | Ships the first volume-production wafers of SILITH's PICs for 1.6T from its 12-inch fab in Singapore. Announces that the photonics platform has been qualified for volume production by a major cloud operator (name not disclosed) | Its first volume-production track record in optics |
| 29 July 2026 | In the second-quarter earnings report, the CEO calls the first volume shipment a major milestone and says the company is preparing to launch a photonics platform available to all customers in 2027 | The next stage is a general-purpose offering |
7. Plans ahead
In the announcement with SILITH, UMC explains that, following the commercialisation of SILITH's 200G-per-lane products, the two are co-developing an all-silicon platform that reaches 400G per lane using only silicon Mach-Zehnder modulators (MZMs) Sourced. It adds that, for ultra-wide bandwidth beyond that, it is also developing an approach using thin-film lithium niobate (TFLN) with partners, whom it does not name. The imec licence announcement also sets out a plan to extend its offering to CPO and optical I/O by combining the process with a range of advanced packaging technologies (see our explainers on co-packaged optics and on thin-film lithium niobate).
None of the following appears in UMC's 20-F, earnings report or official announcements Not yet confirmed.
Silicon photonics revenue and production capacity / optics-related capital spending / the licence fee paid to imec / the name of the cloud operator that qualified SILITH's product / the names and number of new customers working on the imec-licensed process / the TFLN partners / when volume production for CPO begins / when and at what scale volume optics production began on 8-inch lines.
8. What the company is aiming for in optical communications and photonics
This section includes things the company does not say directly. We set them out as inferences within what the primary sources support, with the evidence for each.
| What the evidence suggests | Primary information it rests on | Category |
|---|---|---|
| A "fast follower" that does not insist on in-house development and buys time with a finished outside process | It licensed its 12-inch process from imec, and the 20-F presents this as "showcasing the results of international cooperation" | Inference |
| First prove volume production with a specific customer's product, then open it up to all | Volume production of SILITH's product came first (2026), with UMC's own general-purpose platform to be offered in 2027 | Sourced |
| For now, aim for the next speed in silicon without introducing new materials | It says 400G per lane will use all-silicon MZMs, keeping the manufacturability, scalability and cost advantages of CMOS compatibility, and positions TFLN as the step beyond | Sourced |
| To make Singapore its core optics base | Volume shipments come from its 12-inch fab in Singapore, which it describes as an important technology development base | Inference |
| To grow optics as a new source of earnings for its mature-process fabs | UMC's mainstay is mature processes such as 22/28 nm, and optical devices do not need leading-edge scaling. The 20-F says it makes optics by combining existing processes such as 12-inch immersion lithography | Inference |
In the imec licence announcement of December 2025, new customers' photonic chips were to enter risk production in 2026 to 2027. Yet in July 2026 a volume shipment for SILITH was announced Sourced. At first glance this looks ahead of plan, but the SILITH announcement says it combined SILITH's own silicon photonics architecture with UMC's process integration, and the same announcement says separately that "UMC's own" 12-inch photonics platform will be offered in 2027. From this we read that SILITH's volume production relies on a process tailored to that customer, and that the general-purpose platform built on imec's technology is still to come Not yet confirmed. How SILITH's process relates to the imec-licensed technology, however, is not stated in any of the materials.
9. Partnership map
10. Technologies, products and services
| Item | What the official materials say | In production or in development |
|---|---|---|
| 8-inch silicon photonics | Described in the 20-F as an existing volume-production foundation. Products and customers are not stated | Volume-production experience (details unknown) |
| 12-inch PICs for SILITH | SILITH's 1.6T silicon photonics products; its 200G-per-lane products are already commercialised. Shown to have high yield and reliability, and qualified for volume production by a major cloud operator | In volume production (first shipment July 2026) |
| 12-inch process from imec | iSiPP300: micro-ring-based filters and modulators, GeSi electro-absorption modulators, a range of low-loss fibre coupling options and 3D packaging modules (as described by imec). A CPO-capable process | Trial runs (risk production 2026 to 2027) |
| UMC's own 12-inch photonics platform | Generally available for customers' product development | Due in 2027 |
| 400G per lane | An all-silicon approach with silicon MZMs, co-developed with SILITH | In development |
| Related packaging technologies | According to the 20-F, it has shipped 2.5D silicon interposers with embedded deep trench capacitors and has begun offering wafer-to-wafer (W2W) hybrid bonding. Not specific to optics | Available (application to optics not disclosed) |
"High yield" and "qualification by a major cloud operator" are claims in the SILITH and UMC announcement; neither yield figures nor the qualifying party have been published Sourced. Nor did the materials we reviewed contain any statement of compliance with standards (IEEE 802.3, OIF or MSAs) Not yet confirmed. For how micro-rings and electro-absorption modulators work, see our explainers on wavelength multiplexing and micro-rings, on optical modulation and modulation formats, and on photodetectors.
11. The risks this company carries
| Risk | Details | Category |
|---|---|---|
| A single volume-production track record | The only disclosed volume optics production is the one for SILITH. The general-purpose platform starts in 2027 | Sourced |
| Scale is invisible | Optics revenue, capacity and investment are all undisclosed, so progress cannot be verified from outside | Sourced |
| Indirect dependence on an end customer | SILITH's product is announced as qualified by one major cloud operator. If that operator's procurement policy changes, UMC's optics volumes will move with it | Inference |
| Dependence on outside technology | The core of its 12-inch process relies on the imec licence. The licence terms (duration, exclusivity, treatment of improvements) are not disclosed | Inference |
| Being a latecomer | Tower Semiconductor (US$1.3 billion of contracts for 2027), GlobalFoundries (the AMF acquisition) and TSMC (COUPE), all covered in this series, have already announced large volumes or investments in optics | Our calculation |
| Materials for the next generation | It aims for 400G per lane in all-silicon, but UMC itself indicates that beyond that new materials such as TFLN may be needed. Processes for new materials would rely on partners | Inference |
12. Glossary
- Silicon photonics
- Building light paths (waveguides), modulators and photodetectors onto a silicon wafer using semiconductor manufacturing processes.
- iSiPP300
- imec's silicon photonics process for 12-inch (300 mm) wafers, licensed by UMC.
- SOI wafer
- A wafer with a thin oxide layer sandwiched within the silicon. The thin silicon layer on top is used for optical waveguides.
- Risk production
- A stage before full volume production in which customers knowingly accept the risk of producing small quantities.
- MZM
- Mach-Zehnder modulator: splits light into two paths, shifts their phase and recombines them to change the light's intensity.
- EAM
- Electro-absorption modulator: switches light on and off using a material whose light absorption changes under an applied voltage.
- TFLN
- Thin-film lithium niobate, a material with a strong electro-optic effect that is being researched for ultra-fast modulators.
- Tape-out
- Completing a design and handing the manufacturing data to the fab.
13. References
- United Microelectronics Corporation Form 20-F for the fiscal year ended December 31, 2025 (filed with the U.S. SEC on 30 April 2026). Configuration of the 12-inch silicon photonics line and trial runs, the imec licence, the 8-inch volume-production foundation, responsible executives, revenue, R&D expense and headcount, and related packaging technologies. https://www.sec.gov/Archives/edgar/data/1033767/000119312526193757/d91630d20f.htm
- UMC Press release, "UMC Licenses imec’s iSiPP300 Technology to Extend Silicon Photonics Capabilities for Next-Generation Connectivity" (8 December 2025). Content of the licence, new customers and the timing of risk production, and plans to extend into CPO and optical I/O. https://www.umc.com/en/News/press_release/Content/technology_related/20251208
- UMC / SILITH Press release, "SILITH and UMC Achieve Mass Production Milestone for Silicon Photonics" (14 July 2026). The first volume shipment, the 18-month ramp, qualification by a major cloud operator, development of 400G per lane and TFLN, and general availability in 2027. https://www.umc.com/en/News/press_release/Content/technology_related/20260714
- UMC Second-quarter 2026 earnings report (29 July 2026). Quarterly revenue, the CEO's remarks on optics, and the 2026 capital budget of US$2 billion. https://www.umc.com/upload/media/08_Investors/Financials/Quarterly_Results/Quarterly_2020-2029_English_pdf/2026/Q2_2026/UMC26Q2_report.pdf
- UMC Official website (source of the company name style and the logo). https://www.umc.com/en
14. Claim-to-source audit
| Claim in the article | Category | Source |
|---|---|---|
| Legal name, headquarters address, revenue and R&D expense (2024 and 2025), headcount | Sourced | Reference 1 https://www.sec.gov/Archives/edgar/data/1033767/000119312526193757/d91630d20f.htm |
| Listing venues (NYSE: UMC, TWSE: 2303) | Sourced | Reference 2 https://www.umc.com/en/News/press_release/Content/technology_related/20251208 |
| 12-inch line configured in the first half of 2025, tape-outs and trial runs in the second half, the 8-inch volume-production foundation, the combination of SOI, immersion lithography and Ge/SiGe epitaxy, trial runs started with imec | Sourced | Reference 1 https://www.sec.gov/Archives/edgar/data/1033767/000119312526193757/d91630d20f.htm |
| Silicon photonics within the responsibilities of the vice president for technology development; 2.5D interposers and W2W bonding | Sourced | Reference 1 https://www.sec.gov/Archives/edgar/data/1033767/000119312526193757/d91630d20f.htm |
| The iSiPP300 licence from imec, new customers and risk production in 2026 to 2027, plans to extend into CPO and optical I/O, the iSiPP300 device set | Sourced | Reference 2 https://www.umc.com/en/News/press_release/Content/technology_related/20251208 |
| First volume shipment for SILITH, the 18-month ramp, qualification by a major cloud operator, commercialisation of 200G per lane, all-silicon MZMs for 400G per lane, TFLN, general availability in 2027, Singapore's role | Sourced | Reference 3 https://www.umc.com/en/News/press_release/Content/technology_related/20260714 |
| Second-quarter 2026 revenue, the CEO's remarks on optics, the US$2 billion capital budget and its explanation | Sourced | Reference 4 https://www.umc.com/upload/media/08_Investors/Financials/Quarterly_Results/Quarterly_2020-2029_English_pdf/2026/Q2_2026/UMC26Q2_report.pdf |
| Not treating the US$2 billion capital budget as optics investment | Our calculation | This article's judgement, because reference 4 does not link it to optics |
| The three types of optical communications company | Our calculation | Our own classification. Example companies drawn from those covered in this series |
| Optics revenue, capacity, investment, licence fee, cloud operator's name, new customers, TFLN partners, CPO volume timing, start of 8-inch volume production | Not yet confirmed | Not stated in references 1 to 4. This article does not estimate them https://www.sec.gov/Archives/edgar/data/1033767/000119312526193757/d91630d20f.htm |
| Optics-related investments, acquisitions and joint ventures; public funding for optics | Not yet confirmed | Not stated in references 1 to 3. This article does not conclude that they do not exist either https://www.sec.gov/Archives/edgar/data/1033767/000119312526193757/d91630d20f.htm |
| Compliance with standards | Not yet confirmed | Not stated in references 1 to 3 https://www.umc.com/en/News/press_release/Content/technology_related/20260714 |
| The readings of a "fast follower" buying time with an outside process, Singapore as its core base, and optics as a new source of earnings for mature-process fabs | Inference | This article's interpretation of references 1 to 3 |
| The reading that SILITH's volume production uses a customer-specific process and that the general-purpose platform is still to come | Inference | This article's interpretation from comparing references 2 and 3 |
| The explanation that 12-inch immersion lithography makes it easier to reduce device variation | Inference | This article's commentary based on the general properties of such devices. Not something UMC has stated |
| The risks of indirect dependence on an end customer, dependence on outside technology, and next-generation materials | Inference | This article's interpretation of references 2 and 3 |
| Other foundries having already announced large volumes or investments in optics | Our calculation | Our own summary, based on the profiles of each company in this series |
Last updated 26 September 2026 / Troy Technical
Every figure in this article comes from the Form 20-F United Microelectronics Corporation has filed with the U.S. Securities and Exchange Commission (SEC) and from the company's earnings report and official announcements. No research-firm estimates or press-based figures have been used. Passages marked "Inference" are this article's interpretation of the primary sources, not statements made by the company.