Correlation between yield and waiting time: a quantitative study

Using SEMATECH yield modeling techniques, the effect of reductions in cycle time and of improvements in environmental cleanliness is projected to die-per-wafer yield gains in semiconductor wafer fabrication. This study provides a methodology to determine the impact upon the total process yield of the factory as a result of shortening queue times. Modeling a fabrication facility that uses a 0.25 micron high-performance logic (1poly, 4metal) process flow, the methodology is used to determine variations in yield at different concentrations of airborne particles. In turn, the methodology provides guidelines for implementing operational strategies intended to achieve increases in total process yield.