DDR4 May Use 3D Stacking Technology
Micron Technology, one of the biggest DRAM companies, has announced that it's working the JEDEC standards organization for computer memory, to standardize a new DRAM interface and die-stacking technology called three-dimensional stacking, or 3DS, which may be incorporated into the upcoming DDR4 standard. X-bit labs has a nice summary of how 3DS works:
The idea behind 3DS is to use specially designed and manufactured master-and-slave DRAM die, with only the master die interfacing with the external memory controller. 3DS technology uses optimized DRAM die, single DLL per stack, reduced active logic, single shared external I/O, improved timing, and reduced load to the external world. This combination of features can improve timing, bus speeds, and signal integrity while lowering both power consumption and system overhead for next-generation modules, according to Micron.