IN Brief:
- Onto Innovation has completed the acquisition of a 27% minority stake in Rigaku Holdings for approximately $720 million.
- The companies are combining Onto optical metrology and analysis software with Rigaku CD-SAXS X-ray technology.
- Initial work targets advanced V-NAND, DRAM, logic, and other structures that increasingly require complementary measurement techniques.
Onto Innovation has completed its acquisition of a 27% minority stake in Rigaku Holdings for approximately $720 million, strengthening a semiconductor process-control partnership centred on X-ray and optical metrology.
The shares were acquired from Atom Investment, an affiliate of Carlyle. Onto will account for the holding under the fair value option rather than consolidating Rigaku’s financial results, and the transaction gives Onto the right to nominate one director to Rigaku’s board.
The strategic value lies less in the ownership structure than in the companies’ overlapping measurement technologies. Onto supplies optical metrology, inspection, lithography, factory analytics, and other semiconductor process-control systems, while Rigaku has extensive X-ray instrumentation capability. Their collaboration is intended to combine those methods as semiconductor structures become harder to characterise with a single measurement technique.
The companies began working together on a system that pairs Onto’s Ai Diffract analysis software with Rigaku critical-dimension small-angle X-ray scattering, or CD-SAXS. Onto said when the partnership was announced that systems had already been delivered for advanced V-NAND and DRAM metrology and that two customers had selected the combined approach.
CD-SAXS derives structural information from the way X-rays scatter through semiconductor features. It becomes useful where structures extend deeply into a device or where buried dimensions are difficult to characterise optically. That is increasingly relevant in three-dimensional NAND, advanced logic, and complex packaging, where conventional line-of-sight or surface measurements do not always provide enough information on their own.
Optical critical-dimension metrology remains valuable because it can provide high measurement speed across a wide range of process steps. The argument for combining the two techniques is therefore not that X-ray measurement replaces optics, but that each supplies information the other may struggle to resolve. Correlating those datasets can give process engineers a more complete picture of the geometry and materials being produced.
That requirement is growing as semiconductor manufacturers add vertical complexity. V-NAND devices use increasingly tall stacks, while leading-edge logic technologies are moving through more complicated transistor, contact, and interconnect structures. Advanced packaging adds further measurement demands through chiplets, redistribution layers, hybrid bonding, and other structures that have to be controlled across relatively large areas while maintaining very small dimensional tolerances.
Onto said earlier this year that adoption of its Atlas optical critical-dimension platform was increasing as manufacturers moved towards 1nm-class process technology. At the same time, it identified additional opportunities for X-ray measurement where deeper structures or material information required complementary data.
The Rigaku investment therefore extends an existing process-control strategy rather than moving Onto into an unrelated equipment market. A closer commercial relationship gives the companies stronger incentives to develop shared intellectual property, integrate software and hardware more tightly, and coordinate customer support around systems that use both techniques.
Rigaku, meanwhile, gains a deeper connection to a semiconductor equipment supplier with an established customer base across wafer fabrication and advanced packaging. X-ray tools have long been used in semiconductor research and analysis, but the larger commercial opportunity depends on making them useful enough, fast enough, and repeatable enough for routine high-volume manufacturing.
That transition is demanding. Semiconductor metrology tools have to demonstrate that the information they provide improves process control, yield, or device performance enough to justify additional equipment, floor space, measurement time, and integration work. A technically impressive measurement can remain a specialist laboratory technique if it cannot fit into manufacturing cycle times.
Onto has cited external estimates suggesting the semiconductor X-ray process-control market could exceed $1 billion within five years. That figure remains a forecast, but the $720 million investment indicates that Onto expects X-ray measurement to occupy a larger part of the process-control stack as device structures become more difficult to inspect using established methods alone.
The transaction removes the closing uncertainty that remained after the investment was first announced. Onto now holds the 27% stake, has a route to board representation, and is already working with Rigaku on deployed semiconductor metrology systems. The next test is whether those early applications can expand into repeatable production use across logic, memory, and advanced packaging.
