DDR4 memory is starting to trickle out, and Samsung's latest modules are particularly notable. The server-oriented RDIMMs are populated with 3D memory packages that stack multiple dies on top of one another. This so-called TSV memory is different from the firm's 3D V-NAND, which stacks multiple layers of memory cells within a single die. Samsung explains:
To build a 3D TSV DRAM package, the DDR4 dies are ground down as thin as a few dozen micrometers, then pierced to contain hundreds of fine holes. They are vertically connected through electrodes that are passed through the holes
Each TSV chip stacks four 4Gb dies. The dies are built on "20-nanometer class" fabrication technology, which is vague Samsung-speak for a process node between 20 and 30 nm. Samsung expects to be able to stack even more layers in the future, enabling higher-capacity modules. These latest ones weigh in at 64GB each.
Achieving higher densities isn't the only benefit to stacking DRAM dies. Samsung claims its TSV-infused DDR4 module "performs twice as fast as a 64GB module that uses wire bonding packaging, while consuming approximately half the power." Enterprise customers should appreciate both of those attributes.