A Strategy to Analyze Soft Reliability Issues Detected by Iddq Measurements

1. Introduction As the types of defects that are causing small leakage currents are more and more difficult to find with decreasing feature size, more advanced analysis strategies have to be developed to meet reliability demands. A method based on a delta Iddq test has been developed to sort out parts with potential reliability issues. Those parts are fully functional, but show small Iddq variations indicating weak parametric problems. This paper first explains how this algorithm is applied to reject as many suspicious parts as possible and not throwing away any good parts at the same time. The most interesting question for the failure analyst will be answered in the main part: What kind of defects, if any, can be found on the rejected (but functional) chips, that could have an impact on reliability? The failure analysis flow based on devices failing the delta IDDQ test is shown and a variety of physical defects that can be found with this method is presented. In addition the benefit for physical failure analysis will be explained.