Onto Innovation Inc. has closed its acquisition of a 27 percent minority equity stake in Rigaku Holdings Corporation, paying roughly $720 million to acquire the shares from Atom Investment, L.P., an affiliate of Carlyle. The deal deepens a strategic collaboration between the two companies aimed at advancing X-ray-based process control technology for semiconductor manufacturing.
The purchase price came to ¥113.08 billion. Onto Innovation will account for the investment under the fair value option method and will not consolidate Rigaku's financial results into its own books. As part of the agreement, Onto Innovation will nominate a director to sit on Rigaku's board.
The partnership itself was first announced in April 2026, and this investment formalizes it with an equity stake rather than just a joint development agreement. "As semiconductor innovation advances rely increasingly on more complex 3D architectures and exotic materials, our customers face growing challenges in understanding and controlling their most critical manufacturing processes," said Mike Plisinski, chief executive officer of Onto Innovation.
What's new here is the move from technology partner to equity holder, giving Onto Innovation a board seat and direct visibility into Rigaku's roadmap. Engineers working on process control for advanced packaging and complex 3D chip architectures will care about how that changes tool development priorities, since Onto's existing portfolio already spans unpatterned wafer inspection, 3D metrology, and metal interconnect composition analysis alongside lithography for advanced semiconductor packaging.
Onto Innovation has not disclosed a timeline for jointly developed X-ray tools reaching the market, or which applications will get priority. The Rigaku stake will next surface publicly in Onto Innovation's upcoming Form 10-K filing, reported as a fair-value investment rather than a consolidated subsidiary.
