AOC herein describes a collection of material degradation features observed in Vertical Cavity Surface Emitting Lasers (VCSELs) that have been intentionally degraded with a range of electrostatic discharge (ESD) stress conditions. Failure analysis techniques employed include emission microscopy, Focused Ion Beam (FIB) microscopy and Transmission Electron Microscopy (TEM). The results have enabled higher confidence in root-cause determination for failed VCSEL devices.

The primary objectives of failure analysis on structurally complex semiconductor devices are often to determine a defect's location and composition. Determining exactly how these defects propagate through a sample in three dimensions, to confirm a failure mode, is often elusive. This paper discusses characterizations of two defect types to illustrate a technique of sequentially imaging whisker type defects from orthogonal orientations using TEM/STEM. The first type is a high resistance short between two metal lines that is best imaged using STEM in order to observe subtle differences in material composition. The second is a crystalline dislocation through an optoelectronic device that is best observed using TEM. Details of resistive short characterization and crystalline defect characterization performed are provided. TEM/STEM has shown to be a practical tool for locating defects prior to cross sectional analysis. This allows defects to be located and characterized in three dimensions.

We present a new failure analysis technique for dark (optically degraded) vertical-cavity surface-emitting lasers. Measurements of spatially and spectrally resolved light emission under reverse bias provide key information on the failure mechanism.

The need for high bandwidth, high speed interconnects with optimum routing through computer backplanes has led to the use of optical interconnects in multiprocessor computing systems [1]. Most of the current commercially available optical interfaces are based upon 850nm vertical-cavity surface-emitting lasers (VCSELs). Extensive studies conducted by the VCSEL manufacturers show that the reliability of these devices continues to improve [2-4]. In order to understand the risks and implications of using VCSELbased modules in computer systems, we have conducted an experiment designed to provide insight into the emission degradation and failure of VCSEL devices. In this paper we briefly describe the experiment and review the results of the subsequent failure analysis on degraded VCSEL arrays.

This paper discusses the requirements, challenges, and capabilities of a fully automated visual inspection tool (AVIT) designed to improve the evaluation of fiber optic endfaces. The FiberQA™-AVIT system is based on the FiberQA™-EFI (Endface Inspection) software from PVI Systems, Inc.

A new via interconnect failure mode found in organic light emitting diode (OLED) displays has been documented. Physical appearance, electrical performance, response to environmental stresses and root cause analyses have been studied using both simplistic and sophisticated failure analysis tools including focused ion beam etching and time of flight secondary ion mass spectroscopy (TOF-SIMS).

Solid-state semiconductor devices such as III-V based photodiodes can suffer damage from electro-static discharge (ESD) events. Electron beam induced current (EBIC) imaging techniques have been used successfully to characterize a wide range of failure modes in many different material systems. This article proposes a technique of superimposing the EBIC image with the secondary electron image which permits the correlation of the recombination center with defects and is a powerful tool to assist in the understanding of the root cause for failure. Further complementing the EBIC and SEM analysis with optical microscopy, DC and AC electrical characterization enhances the understanding of the location, nature and mode of failure. The creation of these defects is very localized and commonly occurs at pre-existing defect sites or along the periphery of the metal guard ring. This is characteristic of ESD-induced failure along with the localized heating and evaporation of material.

A failure analysis case study for oxide confined vertical cavity surface emitting laser (VCSEL) arrays will be presented. The focus of this work is on devices failing with a reduced optical output due to a rapid degradation of the laser diode. The complete analysis flow will be shown, including electrical and optical characterization as well as detailed investigations on a nanometer scale. It is known that these fails are caused by dislocations. An advanced FIB preparation method enabled cross-section and plan view TEM to successfully visualize the complete extent of a dislocation network.

Various detector chips in optocoupler devices have a thin indium tin oxide (ITO) film deposited over the passivation. This transparent, conductive film is found over the photodetecting area of the die. When this film is electrically connected to ground potential through contacts, it acts as a shield to avoid inversion failures by sinking any charge buildup to ground. In order to perform a full electrical failure analysis on these optocoupler detector chips, the ITO layer must be removed. An extensive search found numerous papers on etching this film over glass substrates, but no known technique was found to selectively remove the ITO layer on a packaged die. This paper discusses an approach to remove this film using an argon gas etch technique. The ideal characteristics of any process used to remove this film on a finished die would be to completely etch the ITO layer, electrically isolating it from ground, while leaving the underlying passivation and metallization fully intact. This would allow for further electrical failure analysis of the die without causing additional damage or affecting the failure mechanism. The results of an experiment using various chemical and gas etchants found that an argon gas etch would remove the ITO layer while only slightly etching the phosphosilicate glass (PSG) passivation beneath. Electrical failure analysis of the die continued at this point, and a subsequent buffered oxide etch (BOE) removed the remaining passivation, leaving the exposed metallization and oxide completely intact. This technique has been used successfully on device failures to find passivation contamination shorting the aluminum metallization to the ITO film.