An iterative diagnosis approach for ECC-based memory repair

Abstract

In modern SoCs embedded memories should be repaired to achieve acceptable yield. They should also be protected by ECC against field failures to achieve acceptable reliability. In technologies affected by high defect densities, conventional repair induce very high costs. To reduce them, we can use ECC to fix words comprising a single faulty cell and repair to fix all other faulty words. However it was shown that, for high defect densities, the diagnosis required for ECC-based repair may induce very large cost. In previous work this issue was fixed by means of new memory test algorithms that exhibit the so-called “single-read double-fault detection” property. As these algorithms are complex and increase test length, we explore a new iterative diagnosis approach, which provides tradeoffs in terms of hardware cost and test length.