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.

This paper describes the investigation of donut-shaped probe marker discolorations found on Al bondpads. Based on SEM/EDS, TEM/EELS, and Auger analysis, the corrosion product is a combination of aluminum, fluorine, and oxygen, implying that the discolorations are due to the presence of fluorine. Highly accelerated stress tests simulating one year of storage in air resulted in no new or worsening discolorations in the affected chips. In order to identify the exact cause of the fluorine-induced corrosion, the authors developed an automated inspection system that scans an entire wafer, recording and quantifying image contrast and brightness variations associated with discolorations. Dark field TEM images reveal thickness variations of up to 5 nm in the corrosion film, and EELS line scan data show the corresponding compositional distributions. The findings indicate that fluorine-containing gases used in upstream processes leave residues behind that are driven in to the Al bondpads by probe-tip forces and activated by the electric field generated during CP testing. The knowledge acquired has proven helpful in managing the problem.

Two case-studies on uncommon metals whiskers, performed at the Reliability Analysis Laboratory (RAL) of Northrop Grumman Innovation Systems, are presented. The components analyzed are an Oven Controlled Crystal Oscillator (OCXO) and an Electromechanical Relay. Investigative techniques were used to determine the chemical and physical makeup of the metal whiskers and develop an understanding of the underlying effects and mechanisms that caused the conditions conducive to whisker growth.

Degradation of contact mating surfaces can produce a wide range of problems including intermittent failures and also full functional failures in all computer systems. This paper discusses the complexity involved with investigating the failure mechanism and root cause for intermittent memory failures on a product from end customers. Also discussed in detail is the approach of fault isolation followed by hypothesis development & physical analysis to arrive at root cause of failure. Fault isolation was achieved through register probing. Three major hypotheses were put forth namely plastic debris, misalignment and contact area issues. The physical analysis data collected through optical inspection, 2D x-ray, cross section and SEM analysis coupled with EDX to prove or disprove the hypotheses, revealed contact area corrosion in the form of nickel oxide. Contributors like gold plating thickness and plating porosity of the mating surfaces was verified to be not an issue in this case. Further analysis on the connector pins, memory modules and the contact area indicated damage to the connector pins leading to nickel exposure. The root cause for damage to the pins was analyzed to be a result of memory modules being inserted at an angle. Further studies are planned to look into design issues of connectors and memory modules to minimize damage to the contact area.