Controller reliability challenges in emerging NAND memory

The requirement for ever denser memories is answered by the introduction of new NAND memory technologies. New multi-layer three dimensional stacking (BiCS4) as well as four bits per cell (QLC) technologies are introduced by the NAND memory FAB companies. The introduction of these technologies brings into bear reliability challenges which are answered with new and unique methods. Any memory controller must contend with the variability between the layers in 3D manufacturing technologies as well as the high error rates and stress condition sensitivity introduced by QLC. We answer these challenges with new ECC, DSP and memory management schemes. The high performance, low power and price requirements from storage devices lead to unique solutions that are not available in standard communication systems. In this talk we will introduce some of the challenges and will discuss the principles behind some of the solutions.