Onto Innovation Inc. (NYSE: ONTO) has closed its acquisition of a 27% minority equity stake in Rigaku Holdings Corporation, purchasing the stake from Atom Investment, L.P., an affiliate of Carlyle, for approximately 113.1 billion yen, or roughly $720 million.

The deal, first announced in April 2026, is intended to deepen a strategic collaboration between the two companies focused on X-ray-based process control technologies for semiconductor manufacturing.

Onto Innovation said it will account for the investment using the fair value option method and will not consolidate Rigaku's financial results into its own. The company will nominate one director to serve on Rigaku's board.

Mike Plisinski, chief executive officer of Onto Innovation, said in a statement: "This investment strengthens our partnership, accelerates innovation, and enhances our ability to provide more holistic process control solutions to support our customers as they introduce the next generation of semiconductor technologies into high-volume production."

Onto Innovation is headquartered in Wilmington, Massachusetts, and provides process control equipment and services to the semiconductor industry.