Gauge R&R
Gauge R&R provides an analysis technique for engineers to determine the amount of variability caused by a measurement system. For semiconductor devices to ensure that specifications can be guaranteed the repeatability and reproducibility of measurements need to be small relative to the measured specification tolerances. Primarily product and test engineers use this to assess test equipment. Yet with advanced design-for-test (DFT) based test methods which rely upon on-die circuitry to take a parametric measurement, design engineers should perform a Gauge R & R analysis to understand their on-die measurement variability.
Typically, Gauge R&R studies require engineers to use a group of reference devices for equipment studies. Performing multiple tests on the same equipment measures repeatability. Performing multiple tests on different machines measures reproducibility. By collecting this data into yieldWerx Enterprise the results can be analyzed using various techniques, including ANOVA, to calculate the sources of variance not part of the Reference Devices. Problem tests, sites and equipment can be quickly identified, quantified, and corrected. Often engineers use the final measurements to add guard bands to the test parameters. Guard banding is a common practice used to guarantee outgoing specification quality. Consider the limits set for an IDDQ test (https://en.wikipedia.org/wiki/Iddq_testing). Based upon a Gauge R&R’s reproducibility result an engineer may set the limit tighter. This limit guarantees that no die/units which pass the IDDQ test could fail in a customer system.
Core yieldWerx’s Reporting & Analysis module includes Gauge R&R as a standard report. This report can be part of a checklist for releasing a test solution to production. In addition, the data and reports stored in yieldWerx makes it easy to periodically compare product material with the data from the reference devices to ensure things continue to perform as expected.
Engineering roles that often finding themselves using Gauge R&R analysis include product engineers, test equipment engineers and quality engineers.