A post-package bit-repair scheme using static latches with bipolar-voltage programmable antifuse circuit for high-density DRAMs

Abstract

The antifuse programming voltages are changed into bipolar voltages of V/sub CC/ and -V/sub CC/, alleviating high-voltage problems such as permanent device breakdown and achieving a smaller layout area for the antifuse circuit than the previous scheme. In addition, an efficient bit-repair scheme is used instead of the conventional line-repair one, reducing a layout area for the redundancy bits. Using the static latches instead of the dynamic memory cells for the redundancy bits eliminates possible defects in the redundancy area, making this bit-repair scheme robust. The yield improvement using the post-package repair reaches as much as 3% for 0.16 /spl mu/m 256 M SDRAM.