A Unique Approach to Yield Enhancement / Defect Characterization Using Electrical Comb Monitors

摘要

Comb /serpent defect monitors are typically used to characterize and understand process yields on production by mimicking actual production flow. In contrast, a unique application of comb/serpent defect monitors is discussed. By processing the monitors in a non-standard process flow compared to production wafers, sources of defects can be definitively isolated and then eliminated. Comb/serpent defect monitors are an important supplement to any yield improvement plan because: 1) They definitely pinpoint the source process which is affecting yield. 2) They determine the kill ratio of each defect type. As design rules shrink and semiconductor devices add multiple layers of metal, the detectability of killing defects using inline inspections dimishes, thus does the need increase for type of defect partitioning described herein. Advantages and disadvantages as well as specific examples of the benefits of comb/serpent monitors in a .6μm CMOS process manufacturing environment are discussed. Also discussed is the use of this non-standard process flow material to monitor key yield impact in an integrated process instead of using a PWP monitor.