Improved Yield Estimation for Heterogeneously Integrated Components
Authors: Ferris Andrew , Jordan Matthew 
Published: January 2025

We show the use of a parallelized daisy “field” design for continuity and reliability testing for 2.5D integrated microelectronics. The use of daisy chains for continuity testing of flip-chip integrated microelectronics packaging is well-established, and statistical models are used to estimate the yield and reliability of the interconnects. However, single points of failure make up the basis for these statistical models. This can be a challenge for unknown yield distributions, as longer daisy chain structures provide an accurate probe for high-yielding processes but are of limited use for process development when the yield is lower. More, shorter-length chains are useful in troubleshooting lower-yield situations, at the expense of decreased statistical relevance and increased complexity of data collection due to the necessity of testing a large number of daisy chains. Additionally, information is lost due to a single failure in a daisy chain creating an open circuit that prevents any further failures in a daisy chain from being identified. The new 2D Daisy Field (2DDF) allows for continuous monitoring of emerging failures across a large grid of microbumps for thermocompression flip-chip bonding applications for a wide range of yield/failure rate distributions. The concept is based on failures causing DC resistance changes across a large population of connections, which do not need to be tested individually. The reduced testing complexity allows for continuous monitoring of the entire interconnect population through the resistance across a single pair of connections. Assuming that, at any given time, failures are occurring at single interconnect points (as is frequently the case for fatigue, stress voiding, electromigration-type failures) allows for the determination of the population failure rate in situ. We will present a procedure for eliminating degenerate failure distribution solutions for the resistance from physical principles to determine the unique failure distribution. The technique allows for continuous monitoring of the failure rate, providing yield as a function of an applied parameter: such as temperature, shear, or voltage. Clustering of failures with respect to these parameters provides insight into the onset and mechanisms of failure. Thus, the clear identification of process limits – thermal budgets, mechanical robustness, operating voltages, and so on – for optimizing fabrication can be performed with only a single experiment through the full range of values, rather than a time-consuming guess-and-check process for a number of discrete process parameters until the approximate yield is found. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525. SAND2023-11665A This research was developed with funding from the Defense Advanced Research Projects Agency (DARPA). The views, opinions and/or findings expressed are those of the author and should not be interpreted as representing the official views or policies of the Department of Defense or the U.S. Government. Distribution Statement ““A”” (Approved for Public Release, Distribution Unlimited). If you have any questions, please contact the Public Release Center.