Failure Analysis of Faulty vias or Contacts in Mixed-Signal Integrated Circuits

Faulty vias or contacts could be the main cause of failure for an integrated circuit (IC). Unlike a digital IC, the faulty vias or contacts in an analog or a mixed-signal IC are usually more difficult to identify because of the more complicated circuit structure, the more different devices involved, and larger range of signal levels presented in different parts of the circuit. A quick and accurate localization method will have high technical value for failure analysis (FA) and process improvement. In this paper, we proposed a new method to give a quick localization of faulty vias or contacts for analog and mixed-signal ICs. We combine several FA techniques including photon emission microscopy, microprobing, and lock-in infrared optical beam-induced resistance change analysis in conjunction with the circuit schematic and layout. We demonstrated with several examples that the developed approach can identify the faulty vias or contacts accurately and this method should be useful for the IC designer and process engineer to identify the root causes of IC failure related to faulty vias and contacts.