Circuit failure identification using focused ion beam and transmission electron microscopy characterisation techniques

In this paper we present the development and improvement of techniques used in CNET Meylan during the last few years for localisation, cross sectioning and observation of circuit failure using focused ion beam, scanning and transmission electron microscopy techniques. Failure analysis examples are given to illustrate the methods used. Defect localisation is carried out using potential contrast and electrical testing. The imaging and ion milling capability of the focused ion beam technique is used for cross sectioning the failure area with an accurate control of the localisation. The physical observation of defects on the cross section is carried out either in situ using scanning ion microscopy or ex situ using electron beams. For higher resolution the defective area is ion milled using the focused ion beam technique to produce a thin lamella containing the defect which can be then observed with sub-nanometer spatial resolution using transmission electron microscopy. Chemical analysis can also be carried out in the transmission electron microscope using electron energy loss spectroscopy and electron energy filtering to complete the failure identification. The high resolution compositional maps give a clear identification of the materials in the defect area and allows us to give some hypothesis about the origin of the circuit failure.