A new write stability metric using extended write butterfly curve for yield estimation in SRAM cells at low supply voltage

A new extended write butterfly curve (BC) is proposed and evaluated through our device-matrix-array test-element-group (DMA-TEG) fabricated by Silicon-on-Thin-BOX (SOTB) technology. A good normality at low supply voltage (VDD), as well as good correlation with word-line method, demonstrates the extended write BC as a good candidate for yield estimation at low VDD. The comparison with conventional write BC is also discussed.