Mechanisms for the Latchup Window Effect in Integrated Circuits

The latchup window effect has been studied in CMOS and advanced bipolar integrated circuits, using a 1.06 pm laser as a diagnostic tool. An important new finding is the identification of latchup windows in bipolar circuits with oxide-isolated sidewalls. The results show that window behavior is caused by distributed effects rather than the local mechanisms that have been assumed in previous modeling efforts. Lateral substrate currents and distributed resistances in diffused regions and metallization are important in modeling latchup window behavior in MSI devices.