Conductive-AFM for Inline Voltage Contrast Defect Characterization at Advanced Technology Nodes

Abstract

Abstract Voltage contrast (VC) mode inline E-beam inspection (EBI) at post contact layer provides electrical readout of critical yield signals at an early stage, which could be months before a wafer reaches functional test. Similar to the passive voltage contrast (PVC) technique that is widely used in failure analysis labs, inline VC scanning is based on scanning electron microscopy, where a low keV electron beam scans across the wafer. Conductive atomic force microscopy (CAFM) was successfully implemented as a characterization method for inline VC defects. In this paper, three challenging VC defect analysis case studies are considered: bright voltage contrast (BVC) gate to active short, BVC Junction leakage, and Dark Voltage Contrast gate contact open. Defects exhibiting a hard electrical short, junctional leakage, and open gate contact are used to illustrate how CAFM provides a powerful and comprehensive solution for in-depth characterization of the inline VC defects.