Fast wafer level reliability monitoring of product wafers

This tutorial gives an overview of the current state of the art of fast wafer level reliability (WLR) monitoring. Fast WLR is an essential tool for a continuous quality control in a production environment to verify the process reliability beyond process qualification on product wafer material. This is in-line testing method, taking a few seconds per test item, guarantees shortest feedback cycles into production to detect process reliability deviations. Of course, it can be also employed before process qualification, during process development. This tutorial describes the main aspect and highlights problem areas of: test structure design for scribe lines, stress and measurement sequence creation, tester hardware, analysis/reporting and sampling. It discusses the controversy between qualitative and predictive fast WLR, how to use fast WLR even without a physical model for the degradation mechanism. The typical areas of dielectric reliability (MOS gate dielectrics, backend of line capacitors, internal dielectrics), device degradation (hot carrier, negative bias temperature instability, mobile ions), metallisation reliability (electromigration, contact and via integrity) and effects of plasma induced damage are covered. Relevant publications of the field are stated for further studies.