Front-end processing defect localization by contact-level passive voltage contrast technique and root cause analysis

To keep the evidence of the root cause, focused ion beam (FIB) cross-section and transmission electron microscope (TEM) analysis are the effective techniques for further analysis when a unit is de-processed to contact-level and front-end layers are still intact. To make sure that FIB cross-section hits a defect, it is very important to localize the defect precisely in advance. Since the contacts are the only access to the front-end layers of a semiconductor device, it should be possible to utilize them as probes to pinpoint the defects related to the front-end processes. In this paper, The technique of contact-level passive voltage contrast was employed to identify the contacts with abnormal contrast and thus localize the front-end processing defects.