[bluGill]

Tsmc needs to have customers for their products. In theory they could convince my company to build our chips with them (though I think we are happy with whatever process our current suppliers have which is probably in the 60nm range - obviously if I had insight into that side of the business I couldn't talk), but out column is only a few thousand chips a year. They would love to take our money, but they won't build a plant to make chips just for us. However if they think they can get AMD as a customer, that is enough to make a plant for as even worst case there will be enough volumn to pay off the loans (that is break even), and that lets them sell capacity to people like us who might be willing to pay a higher margin.

I would bet that Tsmc was courting amd for years. It is too expensive to build a foundry without some big customers committed. You can build a foundary for someone who won't order for a few years and you have to manage the risks of all the big customers (they might go bankrupt, they might never commit to...), so the more the better.