Integrated capacitors such as in metal-insulator-metal and metal-oxide-metal capacitors use metal as top and bottom plates while the metal-oxide-semiconductor capacitors utilize polysilicon layer as top plate and silicon substrate as bottom plate (Utmel Electronics, 2021, What is the Difference between MOM, MIM and MOS Capacitors?. https://www.utmel.com/blog/categories/capacitors/). There are three (3) major challenges and solutions were discussed in this technical paper. First is 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 nanoprobe setup under scanning electron microscopy (SEM) environment. Second is the failure mechanism that resulted to contentions between an electrically induced physical damage (EIPD) or a fabrication process defects, particularly for damage sites that are not at the edge of the capacitor and without obvious manifestations of fabrication process anomalies such as bulging, voids, unetched material or shifts in the planarity of the die layers. To further understand the defect site, scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy were utilized to obtain high magnification imaging and elemental area mapping. Third is the 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 refers to the root cause (capacitor dielectric breakdown) that was successfully uncovered after the thorough review on the die circuit schematic, inspection of the capacitors connected to the EIPD sites, review of the fault isolation results and pursuing the further physical failure analysis. As a result of the failure analysis, customer and Analog Devices Incorporated manufacturing hold lots were accurately dispositioned and related corrective actions were precisely identified and implemented.
