In-Line Voltage Contrast Inspection of Ungrounded Chain Test Structures for Timely and Detailed Characterization of Contact and Via Yield Loss

This paper shows that in-line voltage contrast inspection can be used to monitor and debug mechanisms causing via and contact opens using ungrounded chain test structures. This opens up a large number of new opportunities to the benefits of in-line VC inspection. A theory explaining the VC appearance of a broken chain is proposed and experimentally verified. The methodology used at IBM’s 300mm fab to apply this phenomenon is described along with some use cases.