Reliable Antifuse One-Time-Programmable Scheme With Charge Pump for Postpackage Repair of DRAM

Abstract

A reliable antifuse (AF) one-time-programmable (OTP) cell and its sensing plus programming circuits for postpackage repair of dynamic random access memory (DRAM) are presented. The OTP cell was fabricated without any process modifications by utilizing destructive breakdown of thin gate oxide of nMOS capacitor as storage. The measurement results of OTP array fabricated by 0.13- $\mu $ m CMOS process show a tight read current distribution after programming. For pin compatibility with standard DRAM specifications, an internal charge pump is designed to provide high program voltage without any additional pin. Based on the AF cells, a programmable decoder is proposed to store the address of failed bit, decode the input address, and decide whether to access normal bit or redundant one of DRAM. The whole bit-repair scheme uses static latches as redundant cells. By avoiding the uses of address comparator and multiplexer, the proposed scheme shows less access penalty compared with prior scheme.