Abstract Short wavelength probing (SWP) uses wavelengths of light shorter than 1100 nm or energies higher than silicon bandgap for laser probing applications. While SWP allows a significant improvement to spatial resolution, there are aberrations to the collected laser probing waveforms which result in difficulties in signal interpretations. In this work, we assess the signals collected through SWP (785 nm) and introduce a photodiode model to explain the observations. We also present a successful case study using 785 nm for failure analysis in sub-20 nm FinFET technology.

Abstract Dynamic Photon Emission Microscopy (D-PEM) is an established technique for isolating short and open failures, where photons emitted by transistors are collected by sensitive infra-red detectors while the device under test is electrically exercised with automated test equipment (ATE). Common tests, such as scan, use patterns that are generated through Automatic Test Pattern Generator (ATPG) in compressed mode. When these patterns are looped for D-PEM, it results in indeterministic states within cells during the load or unload sequences, making interpretation of emission challenging. Moreover, photons are emitted with lower probability and lesser energies for smaller technology nodes such as the FinFET. In this paper, we will discuss executing scan tests in manners that can be used to bring out emission which did not show up in conventional test loops.

Abstract Combinational logic analysis (CLA) using laser voltage probing allows studying standard cells such as NOR or NAND gates as a whole, instead of individual transistors. The process involves building a reference library of laser probing (LP) waveforms and comparing them to signals from the real device. While CLA has greatly increased the success rate and turn-around time for LP, there are difficulties in signal interpretation. This is partly due to the lack of precise understanding of the laser interaction area and probe placement and partly due to difficulties identifying the correct logic states in the waveform. In this work, we have significantly improved the CLA process by first predicting the shape of the waveform based on laser interaction with the target circuitry and second, implementing an automated pattern search algorithm to further increase the speed and reliability of CLA using LP.