An improved photon-emission-microscope (PEM) instrumentation system has been developed for use in diagnosing failure conditions in semiconductor devices, including complex integrated circuits. This system is designed primarily to image areas that emit photons, at wavelengths from 400 to 1,100 nm, associated with device failures caused by leakage of electric current through SiO2 and other dielectric materials used in multilayer semiconductor structures. In addition, the system is sensitive enough to image areas that emit photons during normal operation. This system supplants a prior PEM system based on a photon-intensified, gated, charge-coupled-device (CCD) camera.
This system includes an optical microscope fitted with a low-light-level imaging subsystem based on a state-of-the-art high-resolution (1,024 × 1,024 pixel), cooled, back-illumination CCD camera in a light-proof enclosure. Another major subsystem is a computer running the latest in Windows-based image-processing software, which can facilitate generation of test reports and research papers by putting out image files in popular formats, including tagged image file (TIF), bit map (BMP), and Joint Photographic Experts Group (JPG) formats.
A device under test (DUT) is placed on a translation stage under the microscope. This stage enables movement of the DUT along both axes perpendicular to the optical axis, as well as along the optical axis for focusing. Any of several microscope objective lenses affording different magnifications (5×, 20×, 50×, and 100× with extra long working distance) can be selected. The exposure time is programmable between 5 milliseconds and 2 hours. Provisions for setups of external equipment, including the power supply for the DUT and digital multimeters, can be incorporated into custom software.
In operation, the system integrates the photons emitted from the DUT, and the resulting bright spots (showing the locations of substantial emission of photons) are displayed superimposed on an image of the DUT that was acquired previously under visible light. Failure-analysis engineers can use the information in this display to locate failure sites on the DUT.
This work was done by Duc Vu of Caltech for NASA’s Jet Propulsion Laboratory. NPO-42121
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Improved Photon-Emission-Microscope System
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Overview
The document outlines the capabilities and applications of the Improved Photon-Emission Microscope (PEM), a sophisticated analytical tool developed for failure analysis in semiconductor devices. The PEM is designed to detect photon emissions in the 400 to 1100 nm range, which are associated with device failures due to current leakage through dielectric isolation films in multi-layered semiconductor structures, including integrated circuits (ICs), very-large-scale integration (VLSI), application-specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs).
The PEM system integrates advanced optical microscopy with cutting-edge computer image processing and cooled back-illumination CCD camera technology. This combination allows for the detection of extremely faint light emissions, significantly improving the sensitivity and speed of failure analysis compared to older systems. The microscope is equipped with a low light-level imaging system housed in a light-proof enclosure, and it features a movable stage for precise positioning of the device under test (DUT) in three dimensions. Various optical lenses (5X, 20X, 50X, and 100X) are available to optimize imaging.
In operation, the PEM captures and integrates the emitted photons from the DUT, displaying defects as bright spots on a CRT screen, which helps engineers pinpoint the exact location of failures. The system is capable of detecting leakage currents as low as 0.5 micro-amps, making it a powerful tool for identifying dielectric defects. The nondestructive nature of the PEM allows for the observation of photon emissions through glass passivation and, in some cases, under metallization.
The document also lists various types of failures that can be identified using PEM, including process-induced failures, random failures, electrostatic discharge (ESD) damage, latch-up conditions, hot electron injection impacts, and optoelectronic failures. Additionally, it invites users to explore custom applications and software integration for specific needs.
For further inquiries or to schedule an appointment, the document provides contact information for the Failure Analysis Group at NASA's Jet Propulsion Laboratory. Overall, the PEM represents a significant advancement in failure analysis technology, offering enhanced sensitivity and efficiency for semiconductor device testing and diagnostics.
