Logic State PEM Analysis for ATPG SCAN Logic Failure

Abstract

Photon Emission Microscopy (PEM) analysis is one of the most common used FA techniques to identify the root cause of failures within ATPG scan logic due to its ease of setup and less invasive nature. While conducting photon emissions, the device is made to operate in the fail mode by running a production test vector to look for anomalous emissions or hot spots that could narrow down the area of interest (AOI) for subsequent Physical Failure Analysis (PFA). However, if there is no clue from emission analysis in the case of a hard failure with no sensitivity to voltage, frequency, or temperature, FA debug will be challenging. This paper shows how PEM analysis success may be further improved through logic state circuit study using a DFT ATPG diagnostic platform. Logic state truth table and its relative test pattern will be built based on the diagnostic data using in-house scripts, and the test program can then be changed to the required condition of the circuitry. With the altered logic state, new emission data can be collected, which could potentially reveal new clues to the investigation.