Samsung was a bigger foundry than TSMC until the 2010’s when Apple provided TSMC with billions in interest free loans in exchange for getting first dibs on new fab processes.
Samsung's custom foundry started sometime in 2000's with Apple as their anchor client. TSMC really singlehandledly created the custom foundry industry in the late 1980's and is the largest by far. TSMC has always been the market leader -- though it had local competitors like UMC in Taiwan -- and Samsung the late comer. Samsung managed to come out with the first 14nm ahead of TSMC's 16nm in 2012 and made all Apple's A SOCs in Austin, TX, but Apple went ahead and outsourced everything to TSMC in Taiwan in their China/Taiwan-first strategy anyway; this is in spite of TSMC's higher cost and marginal performance difference.
> this is in spite of TSMC's higher cost and marginal performance difference
Do you have references for this? Specifically the marginal performance difference. My understanding is that Apple had bigger fab contacts with Samsung than TSMC but were dissatisfied with Samsung’s roadmap execution. That was supposedly the motivation for them to finance TSMC’s new fabs at low interest. I could be wrong, I’m going off memory of various comments I’ve read on this forum over the years.
South Korea is the largest memory chip maker in the world -- between Samsung and Hynix they have 75% of the market share. Micron has about 20%. Samsung also makes logic chips for internal use and external customers -- their foundry business is #2 in the industry. You alo have to remember that TSMC's meteotic rise on the other hand is fairly recent. Intel and Samsung were the largest producer/money-maker in the chip business until very lately.