A Novel Prediction-Based Two-Tiered ECC for Mitigating SWD Errors in HBM

Errors emerge as a major issue in the reliability of dynamic random access memory (DRAM). To enhance reliability, a two-tiered error correction code (ECC) architecture that comprises on-die ECC (OD-ECC) and system ECC (S-ECC) is adopted as a part of the standard for state-of-the-art high-bandwidth memory (HBM). However, conventional ECCs are insufficient to mitigate malfunctions of subwordline drivers (SWDs), a primary cause of errors. Moreover, the efficient co-design of two-tiered ECCs has not been sufficiently studied. To address these issues without increasing the size of check bits, this article proposes a two-tiered ECC architecture comprising an OD-ECC based on prediction and an S-ECC with data deinterleaving. The proposed OD-ECC predicts the SWD errors by leveraging the detection capabilities of two interleaved Reed-Solomon (RS) engines. In addition, the proposed S-ECC not only preserves strong error detection capability but also masks the misprediction effect of OD-ECC, where data deinterleaving renders additional errors caused by misprediction of OD-ECC to be bounded in the detectable range of the employed cyclic redundancy check (CRC). The experimental results demonstrate that the proposed two-tiered ECC can significantly enhance the error correction capability for SWD errors while maintaining the correction capability for other types of errors.