The identification and analysis of systematic yield loss

With increasing expectations for yield and learning rates, a refined method of yield excursion determination is required. This need is met through the use of yield trend box plots with overlaid wafer map composites by quartile. It was found that this method quickly identifies excursion lots based on spatial non-randomness in addition to yield and its variation. Once identified, lots or wafers with spatial anomalies can be further studied using correlation utilities, time line studies, commonality analysis, and spatial signature matching.