Amkor Technology is expanding its planned investment in a new advanced semiconductor packaging and test campus in Arizona to approximately $12bn, as customer commitments drive the addition of a second phase.
The company said demand has surpassed the 33,000 sqm of cleanroom capacity planned for Phase 1 of the campus.
Phase 2 will add a further 60,000 sqm, bringing the total cleanroom area across the site to around 93,000 sqm.
The project is being developed as a multi-phase semiconductor manufacturing campus in Peoria, Arizona, with capabilities spanning wafer bump, probe, assembly and test.
Amkor said the expansion will increase the scale of advanced packaging manufacturing in the US, with the combined phases expected to support a workforce of more than 3,500 Arizona-based employees.
The campus is intended to become the first US outsourced semiconductor assembly and test (OSAT) production site providing advanced packaging at high volume, offering customers a domestic turnkey manufacturing platform.
Construction of Phase 2 is expected to begin in late 2027, with completion targeted for the end of 2029. The wider campus covers approximately 170 acres, allowing for further expansion in response to customer demand.
Amkor originally broke ground on the Arizona campus in October 2025, when the planned investment stood at $7bn across two phases. The project was initially planned to provide more than 750,000 sq ft of cleanroom space.
The latest expansion follows a series of developments around Amkor’s US advanced packaging strategy.
In June, the company announced a 10-year agreement with TSMC covering advanced packaging and testing services in Arizona, while in July it announced a multi-year partnership with NVIDIA supported by a $1.5bn advanced packaging and development agreement.
“This next phase reflects the confidence our customers have placed in Amkor, the critical role advanced packaging plays in enabling the future of semiconductor innovation, and the strategic importance of our Arizona campus," said Kevin Engel, President and CEO of Amkor Technology.
The Arizona campus will support semiconductor applications including artificial intelligence, data centres, smartphones, automotive and wearable devices.
