Failure analysis of 65nm technology node SRAM soft failure

In this paper, a real case of 65 nm technology node SRAM failure was studied. The failure of the SRAM is soft failure, so the traditional method was failed to localize the exact position of the failed transistor. To find the root cause, the biased current image-Atom Force Microscopy combined with Atom Force Probing was used to probe the failed cell of the SRAM to find one abnormal pass-gate transistor. Theoretical analysis combined with the probing result was performed to find the failure location. Then current image was used to confirm the failure location. According to the AFP result, TEM and EDX were performed along the active of the pass-gate. Incomplete silicidation was observed under the active contact which correlated well to the electrical analysis result.