Will ST eventually sell its R3 wafer fab to Tower?
I applaud Jean-Marc Chery, CEO of ST, and Russell Ellwanger, CEO of Tower, for coming up with a relatively unusual way to ramp up production rapidly at the R3 wafer fab in Agrate Brianza near Milan in Italy.

But the invitation from ST for Tower to occupy a third of the cleanroom (see ST, Tower agree to share 300mm analog, power fab) raises questions about how long the arrangement is contracted to last, and what happens if and when ST wants to reclaim the rest of its cleanroom.

The R3 wafer fab is somewhat late in arriving. It was previously expected to receive chip making equipment in 2020 with volume production starting in 2021. When it was first billed in January 2019 it was described as an R&D pilot line for power technologies that would be capable of expansion to volume production on demand. At the time Chery said: “This new fab is designed to be expandable, of course, according to demand, to start volume production starting from 2021. It will be focused on supporting our growth ambitions and leadership in BCD, IGBT and power technologies.”

Well since then we have had a year of global pandemic but demand for semiconductor components has increased. Which may tell most of the story. ST may have touched the brake on R3 and now wishes to get up to maximum output as quickly as possible. ST has also been pushing hard on developing its own capabilities in two power semiconductor processes – silicon-carbide and gallium-nitride on silicon. The GaN-on-silicon development is focused at a 200mm wafer fab in Tours, France. This may leave silicon-based power, including BCD and vanilla IGBT, looking somewhat mature.

And partnering with specialty foundry is an interesting choice, especially one that is proficient in analog, power and MEMS and regularly expands by seeking facilities, legacy processes to adopt and legacy contracts to fulfil.