The chip industry is pushing to quadruple the stack height of 3D NAND flash from 200 layers to 800 layers or more over the next few years, using the additional capacity will help to feed the unending need for more memory of all types. Those additional layers will add new reliability issues a number of incremental reliability challenges, but the NAND flash industry has been steadily increasing the stack height for nearly a decade. In 2015, Toshiba announced the first 16-die stack using through-si...