Fast and trusted intrinsic stress measurement to facilitate improved reliability assessments

A new measurement method for mechanical stresses with microscopic and sub-microscopic spatial resolution is presented. It bases on classical stress relief techniques in experimental mechanics, as for example the familiar hole drilling method. Applicability of the classic method for micro and nano size objects was achieved, using very local stress relief caused by ion milling inside commercial FIB equipment and image correlation algorithms for the determination of corresponding relaxation strains. Approximately 10 years ago, first publications demonstrated the principal feasibility of the approach. Now, this work gives a more detailed view on different measurement variations, their capabilities and limitations. The paper reports on the effort made for qualifying the new method for use under real industrial conditions, which includes validation of techniques, best practice based choice of tools and sufficient automation of the measurement process. Finally an application example from 3D integration in electronics demonstrates practical benefit obtained by the method.