Application of atomic force probing on the polysilicon patterning issue

As the semiconductor technology keeps scaling down, Poly silicon gate pattern becomes more and more critical. If the Poly silicon variation is too big or some mismatch, it will induce severe logic parametric fail or even functional fail, which is difficult for the failure analysis. For the analog device, it ca n induce functional fail. In this case, a function related failure was analyzed an d the level shift circuit was identified. No visible defect was found until contact level by physical FA (PFA) on the structure. Atomic force probing was applied on the device level analysis. After the preliminary probing, an in-depth nanoprobing experiment was designed in order to narrow down the root cause of defect. Based on the electrical analysis, PFA was performed and systematic Poly shrink was found in the specific location which correlates with the process issue.