I do not have the answers for your questions (and I don't think anyone can share actual failure rates), but I would direct you this video which goes over a lot

I do not have the answers for your questions (and I don't think anyone can share actual failure rates), but I would direct you this video which goes over a lot of modern chip fabrication techniques, circa 2009: https://www.youtube.com/watch?v=NGFhc8R_uO4 https://www.youtube.com/watch?v=NGFhc8R_uO4 It's crazy stuff. There are wafer test machines which will interface with the wafer directly and do some testing (which are $$$$), JTAG type tests, which access parts of the chip out of band, and functional testing. Some products, like SD Cards actually have a microcontroller on board that will provide the test routines and error correction without the need of an expensive machine. Design for test is extremely important. I'm by no means an expert however, I mostly deal with JTAG and functional tests.