Localization and physical analysis of a complex SRAM failure in 90nm technology

In this paper the analysis process of a complex SRAM failure in 90nm technology is introduced in detail. Using a correlation method, it could be traced back to a failure with an increased supply current. With the help of MCT emission microscopy and thermal laser stimulation (TLS) the defects were localized at both edges of every failing SRAM block. Further inspection by passive voltage contrast (PVC) and atomic force prober (AFP) current imaging led to a localization down to contact level. In the TEM analysis high angle annular dark field scanning TEM (HAADF STEM) was used to obtain better material contrast. CoSi residues were found at the wall of spacers of the failing FETs. Further surface parallel TEM inspection confirmed the hypothesis of a new type of bridging defect, i.e. CoSi stringers along word lines in SRAM cells, which has not been observed before to our knowledge. The process adjustment in the fab to avoid this failure led to a significant yield improvement. The abstract should be 75-200 words long, summarizing the work and placing it in an appropriate context.