Sang Jin Byeon

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.

An exact measurement and repair circuit of TSV connections for 128GB/s high-bandwidth memory(HBM) stacked DRAM

For the heterogeneous-structured high bandwidth memory (HBM) DRAM, it is important to guarantee the reliability of TSV connections. An exact TSV current scan and repair method is proposed, that uses similar to the correlated double sampling method. The register-based pre-repair method improves testability. The measurement results for thousands of TSV shows impedance distribution under 0.1 ohm. Methods are integrated in 8Gb HBM stacked DRAM using 29nm process.