Approaches for the repair of VLSI/WSI RRAMs by row/column deletion

The authors present two approaches for the repair of large random access memory (RAM) in which redundant rows and columns have been added as spares. These devices, referred to as redundant RAMs, are repaired to achieve acceptable yields at production time. The first approach, namely, the faulty-line-covering technique, is a refinement of the fault-driven approach. This approach finds the optimal repair-solution within a smaller number of iterations than the fault-driven algorithm. Simulation results show that the faulty-line-covering technique will execute much faster under all fault distributions. The second approach uses a heuristic criterion in the generation of the repair-solution. This heuristic criterion permits a very fast repair. The criterion is based on the calculation of efficient coefficients for the rows and columns of the memory. Two techniques for coefficient selection are proposed.<>