Yield improvement via automatic analysis of wafer-processing order

摘要

Abstract: Manufacturing tools may process wafers in differentfashions: by group of lots, by lot, by group of wafers,one- by-one in single or multichamber tools,... Theorder sequence in which wafers are processed in a givenstep of the manufacturing routing can be used as avaluable source for yield improvement. Within thisscope we published on SPIE's 1996 MicroelectronicManufacturing an Advanced Software System to correlateorder-sequences versus any yield related metric. Sincethen we have developed a new generation of Softwarenamed POSISCAN which automates the analysis anddetection of 'order patterns', that is, footprints ofthe yield being impacted by the order in which thewafers were processed in a specific tool. Yielddegradation induced on each process can have a kind offootprint. We have accumulated a wealth of thesefootprints and developed a very fine knowledge-basedalgorithm to automatically detect them on every lot.The effectiveness of this automated POSISCAN tool isremarkably high and is having a big impact on time todetection/analysis/root-cause of yield loss. !11