Experimental Methods for Determining Latchup Paths in Integrated Circuits

Methods of determining latchup paths in integrated circuits are discussed and applied to several device technologies. Localized laser irradiation was used to find latchup-sensitive regions with a special experimental configuration that overcomes the dosimetry problems inherent in small area beams. Two infrared imaging methods were used to find current paths after latchup was initiated with the laser. Circuit interaction in one device type caused the power supply current to decrease after latchup, which shows that measurement of power supply current is not always a reliable way to detect latchup in integrated circuits.