Intricacies in the Failure Analysis of Integrated Capacitors

Abstract Integrated capacitors use metal plates such as in Metal-Insulator-Metal (MIM) and Metal-Oxide-Metal (MOM) capacitors while Polysilicon and Silicon (Si) substrate for metal-oxide-semiconductor (MOS) capacitors. Three major challenges and solutions were discussed in this technical paper. First, the failure site localization of a subtle defect in the capacitor plates. To determine the specific location of the defect site, Electron Beam Induced Current (EBIC) analysis was performed while the part was biased using a nano-probe set-up under Scanning Electron Microscopy (SEM) environment. Second, Failure Mechanism contentions between Electrically Induced Physical Damage (EIPD) or Fabrication process defect particularly, for damage site that is not at the edge of the capacitor and without obvious manifestations of Fabrication process anomalies such as bulging, void, unetched material or shifts in the planarity of the die layers. To further understand the defect site, Scanning Transmission Electron Microscopy (STEM) coupled with Energy-Dispersive X-ray Spectroscopy (EDS) were utilized to obtain high magnification imaging and elemental area mapping. Third, misled conclusion to be an EIPD site manifested by burnt and reflowed metallization. The EIPD site was only a secondary effect of a capacitor dielectric breakdown. This has been uncovered after understanding the circuit connectivity, inspections of the capacitors connected to the EIPD site, fault isolation and further physical failure analysis were performed. As results of the Failure Analysis (FA), Customer and Analog Devices Incorporated (ADI) manufacturing hold lots were accurately dispositioned and related corrective actions were precisely identified and implemented.