Solid-state mass storage has experienced recently an explosive growth, mainly related to digital consumer application (digital cameras, MP3 players, USB keys). The demand is not expected to slow down in the near future. Present storage technology is based on NAND Flash, and it appears that there is still margin to scale it down at least to the 45 nm node. The likely appearance of physical limits to scalability is pushing for the investigation of alternative storage technologies, and several solutions have been proposed. However, any kind of memory needs a selection mechanism, and related parasitic effects can be a severe limitation to scaling. Scaling challenges of select devices (mostly CMOS), and their impact on memory scaling will be investigated, and alternatives proposed.