Thermal Sensitivity Mapping with OBIRCH

In this paper, a fault isolation technique using Hamamatsu iPhemos 1340nm continuous wave laser to alter the property of a transistor when the device under test (DUT) is in functional state is discussed. Our technique relies on thermal stimulation of transistors within sensitive analog circuitry whilst the circuit output is monitored with an OBIRCH amplifier. This overcomes multiple difficulties in fault isolation by microprobing and is able to pinpoint the failure to a single failing transistor. One particular case is documented here, detailing the fault isolation technique used.