Low power mode current is a very important parameter of most microcontrollers. A non-production prototype microcontroller had high current issues with certain SRAM modules which were produced using a new memory compiler. All devices were measuring 100’s μA of low power mode current which was an order of magnitude higher than the requirement. Many failure analysis (FA) techniques had to be used to determine the root cause: Optical Beam Induced Resistance Change (OBIRCh), photo emission microscopy (PEM), microprobing, and nanoprobe device characterization. Transistor models and measurements of probe structures from the effected lots both predicted that the device low power mode current would meet expectations; however, all first silicon samples had elevated low power mode current. A knowledge of low power design methodology was needed to ensure all issues were discovered.

We describe a technique that is used to obtain timing information from laser assisted device alteration (LADA). The technique uses a non-pulsed laser scanning microscope to obtain timing information with a temporal resolution on the order of microseconds. Custom software is used to extract the timing information from the LADA images.