AFAIK Intel has never contracted out their fabs to anyone outside of the Intel family.
I can understand why - doing so inevitably leads to process IP leakage. One way it happens is from a customer pushing to get enough information so they can leak to another fab under the guise of "creating a 2nd source 'just in case'..."
Then what is "Intel Custom Foundry"?
https://www.intel.com/content/www/us/en/foundry/overview.htmlEven somebody on this forum tried to manufacture Bitcoin ASIC using the
https://en.wikipedia.org/wiki/Achronix technology, which is another fabless company. And according to the Wikipedia they fabricate at Intel and TSMC. That was when Intel's 22nm process was the state-of-the art.
IIRC that Bitcoin ASIC on Achronix was something obviously stupid, like they wasted chip space on testing logic despite SHA256D being self-testing and PoW mining being a lottery.
Personally, I think the American-headquartered companies with fabs (like Intel, etc...) are just much better at enforcing the legal contracts with their partners about mutual-nondisparagement (or whatever is that legal concept called) in their fab-for-hire business. So there's much less opportunity for some dumb rumors to spread, like the recent "Samsung enters Bitcoin mining business."
I really don't feel like digging back through the history in this forum. But if somebody is interested and they want to verify what I just wrote, then you are free to dig for the actual references to the Achronix Speedster and how quickly the rumors about Intel's involvement in coin mining had gotten quashed.