According to tech columnist Tim Culpan, TSMC first began production of the Apple S9 chip near Phoenix, Arizona, at its Fab 21 plant. Last year, the company also began production of the A16 Bionic chip for the iPhone 15 and iPhone 15 Plus at the same facility.

The S9 chip will debut in the Apple Watch Series 9 in late 2023, based on data processing features taken from the A16 Bionic. Both products are manufactured using TSMC’s 4-nm process technology known as N4. With a common technology base, TSMC was able to efficiently adapt its Arizona production line to produce both the S9 and A16 chip.

Although the Apple Watch Series 9 is no longer in production, the S9 chip is still used in the Apple Watch Ultra 2, which was introduced at the same time.

The A16 Bionic has been produced at Fab 21 since September 2024, and the addition of the S9 chip to production signals an accelerated capacity expansion. This fab is TSMC’s first major semiconductor manufacturing site outside of Taiwan, although the facility is still in the early stages of development.

At the current stage (Phase 1A), the fab produces about 10,000 wafers per month. These wafers are distributed among Apple’s A16 and S9 chips, as well as other customers such as AMD. Each wafer can contain hundreds of chips, depending on the crystal size, design, and production efficiency. Completion of Phase 1B will increase the fab’s capacity to 24,000 wafers per month early this year.