EBAC for Isolating Partially-Localized FEOL Electrical Shorts on Test Structures During Sub-14nm Technology Development
EBAC for Isolating Partially-Localized FEOL Electrical Shorts on Test Structures During Sub-14nm Technology Development
Wednesday, November 8, 2017
Summary:
EBAC is a static technique that can be used for isolating partially-localized electrical shorts with the resolution needed for subtle defects in sub-14nm-technology test structures. The technique’s limited success with shorts on entire interconnected test structures can be circumvented by using it in combination with optical localization techniques such as OBIRCH. Once the short is localized to the optical system resolution, the interconnect can be removed and precise isolation can be achieved with EBAC if obvious defects are not found by SEM inspection. BEOL (Back End Of Line) shorts are found by probing the approximate area until a current signal is observed in an additional (shorted) segment. FEOL (Front End of Line) shorts need no comparison to layout if the structures terminate at silicon, since the EBAC signal will also terminate at silicon. The following three case studies are examples of subtle FEOL shorts on a sub 14nm technology that required the resolution of EBAC. For all cases, EBAC’s use in locating shorts saves considerable time over nanoprobing individual structures.
EBAC is a static technique that can be used for isolating partially-localized electrical shorts with the resolution needed for subtle defects in sub-14nm-technology test structures. The technique’s limited success with shorts on entire interconnected test structures can be circumvented by using it in combination with optical localization techniques such as OBIRCH. Once the short is localized to the optical system resolution, the interconnect can be removed and precise isolation can be achieved with EBAC if obvious defects are not found by SEM inspection. BEOL (Back End Of Line) shorts are found by probing the approximate area until a current signal is observed in an additional (shorted) segment. FEOL (Front End of Line) shorts need no comparison to layout if the structures terminate at silicon, since the EBAC signal will also terminate at silicon. The following three case studies are examples of subtle FEOL shorts on a sub 14nm technology that required the resolution of EBAC. For all cases, EBAC’s use in locating shorts saves considerable time over nanoprobing individual structures.