Here's the Google Translation from TechNews Taiwan.
Samsung is currently the main problem facing the problem of low yield in its 20nm manufacturing process, not the title at Apple's demands, the need for an appropriate portion of A8 processor orders to TSMC, but based on recent progress news, Samsung was forced to abandon the orders may be more than just part of A8, A8 processor is probably all be produced by TSMC.
The site says TSMC's 20nm process is the fastest ever production of a manufacturing process and yields have improved to 50-70%.
Apple is still expected to split orders for the A9 processor between Samsung "to avoid excessive concentration of a single vendor."
Read More [via MacRumors]