A 1.2 V 8 Gb 8-Channel 128 GB/s High-Bandwidth Memory (HBM) Stacked DRAM With Effective I/O Test Circuits

Motivated by a graphics memory system that achieves multiplied bandwidth by the number of memories per system, HBM DRAM adopts a brand new architecture, with many technical changes and challenges. The first main change in the architecture is the stacked memory structure with TSV array, which has independent bandwidth per slice. The second is semi-independent row, column command interface, which enhances effective performance. For supporting high bandwidth, this chip has fine pitch microbump interface. Methods for testing microbump are explained. 8 Gb stacked HBM is fabricated with chip-on-wafer process and tested with high-frequency wafer probing. Using chip-on-wafer test results, 128 GB/s at 1.2 V supply voltage is achieved.