In this paper, we analyze the inverse scattering problem by a new deterministic method called "Source and Radiation Field Solution," which has the merit that both the source and the radiation field can be treated at the same time, the effect of which has already shown in ordinary scattering problems.

This paper describes fault-tolerant designs, which have been used to boost the yield of a 286 mm2 256 Mb DRAM with 32 both-ends DQ. The 256 Mb DRAM consists of sixteen 16 Mb units, each containing one 128 Kb row redundancy block. This row redundancy block architecture allows flexible row redundancy replacement, where random faults, clustered faults, and grouped faults can be efficiently repaired. Flexible column redundancy replacement with interchangeable master DQ's(MDQ) is used to allow a 256 b data compression without causing a data conflict, while improving the column access speed by 2 ns. A depletion NMOS bitline-precharge-current-limiter suppresses the current flow which occursas a result of a wordlinebitline short-circuit to only 15 µA per cross fail, avoiding a standby current fail. Consequently, the hardware results show a significant yield enhancement of 16 times relative to the intrablock/segment replacement. Detailed simulation results show that this 256 Mb DRAM allows 275 random faults to be repaired with 5.5% silicon area overhead for 80% chip yield.