High SRAM standby current due to the printing of spurious images

Photoemission microscopy of a 2 Mbit SRAM identified a physical pattern of quiescent current (IDDq) failures on the regular array of this circuit. The pattern of IDDq failures correlated almost exactly with identifying marks on the edge of the SRAM gate reticle. This discovery led to the detection of contamination of the photolithographic imaging optics that resulted in ghost images.