Scanning Magnetoresistive Microscopy for Die-Level Sub-Micron Current Density Mapping

Author(s):  
B. D. Schrag ◽  
X. Y. Liu ◽  
M. J. Carter ◽  
Gang Xiao

Abstract In this paper, we will present a new technique for fault isolation and failure analysis in integrated circuits based on a scanning magnetoresistive imaging system. By detecting the stray magnetic fields at the surface of a chip using magnetic sensors with sub-micron spatial resolution, we are able to obtain a full map of in-plane current densities, resolving features smaller than 100 nanometers. We will briefly discuss the capabilities and limitations of the technique and will present results on a variety of frontside and backside samples.

Author(s):  
Ravikumar Venkat Krishnan ◽  
Lua Winson ◽  
Vasanth Somasundaram ◽  
Phoa Angeline ◽  
Pey Kin Leong ◽  
...  

Abstract Short wavelength probing (SWP) uses wavelengths of light shorter than 1100 nm or energies higher than silicon bandgap for laser probing applications. While SWP allows a significant improvement to spatial resolution, there are aberrations to the collected laser probing waveforms which result in difficulties in signal interpretations. In this work, we assess the signals collected through SWP (785 nm) and introduce a photodiode model to explain the observations. We also present a successful case study using 785 nm for failure analysis in sub-20 nm FinFET technology.


Author(s):  
Steve Wang ◽  
Frederick Duewer ◽  
Shashidar Kamath ◽  
Christopher Kelly ◽  
Alan Lyon ◽  
...  

Abstract Xradia has developed a laboratory table-top transmission x-ray microscope, TXM 54-80, that uses 5.4 keV x-ray radiation to nondestructively image buried submicron structures in integrated circuits with at better than 80 nm 2D resolution. With an integrated tomographic imaging system, a series of x-ray projections through a full IC stack, which may include tens of micrometers of silicon substrate and several layers of Cu interconnects, can be collected and reconstructed to produce a 3D image of the IC structure at 100 nm resolution, thereby allowing the user to detect, localize, and characterize buried defects without having to conduct layer by layer deprocessing and inspection that are typical of conventional destructive failure analysis. In addition to being a powerful tool for both failure analysis and IC process development, the TXM may also facilitate or supplant investigations using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and focused ion beam (FIB) tools, which generally require destructive sample preparation and a vacuum environment.


Author(s):  
George Ontko

Abstract Bridging faults are a common failure mechanism in integrated circuits and scan-based diagnosis does a good job of isolating these defects. Diagnosis, however, can sometimes result in large search areas. Typically, these areas are caused by long repeater nets. When this happens, physical failure analysis will become difficult or impossible. This paper concerns itself with using a bridging fault analysis as a means of reducing these large search areas.


2007 ◽  
Vol 998 ◽  
Author(s):  
Thais Cavalheri dos Santos ◽  
Marcelo Mulato

ABSTRACTNife alloys are potential candidates for the development of planar fluxgate magnetic microsensors. In this work, electrodeposition was used to produce NiFe thin films on top of copper substrates. When using this technique the variation of the electric potential, and thus the current density, alters the final stoichiometry of the deposited films, while the final thickness is determined by the total deposition time. We used current densities varying from 4.0 mA/cm2 to 28 mA/cm2, with steps of 4.0 mA/cm2. For each current density, total deposition times of 10, 20, 30 and 40 minutes were used. The morphology was characterized using scanning electron microscopy, structure was characterized using X-ray diffraction experiments, and the composition of the films were determined using energy dispersive spectroscopy. The magnetic properties were investigated evaluating the materials hysteresis cycle. The materials were optimized aiming for lowest coercivity values, and the final result was about 0.215 kA/m.


Author(s):  
Seth J. Prejean ◽  
Joseph Shannon

Abstract This paper describes improvements in backside deprocessing of CMOS (Complimentary Metal Oxide Semiconductor) SOI (Silicon On Insulator) integrated circuits. The deprocessing techniques described here have been adapted from a previous research publication on backside deprocessing of bulk CMOS integrated circuits [1]. The focus of these improvements was to provide a repeatable and reliable methodology of deprocessing CMOS devices from the backside. We describe a repeatable and efficient technique to deprocess flip chip packaged devices and unpackaged die from the backside. While this technique has been demonstrated on SOI and bulk devices, this paper will focus on the latest SOI technology. The technique is useful for quick and easy access to the transistor level while preserving the metal interconnects for further analysis. It is also useful for deprocessing already thinned or polished die without removing them from the package. Removing a thin die from a package is very difficult and could potentially damage the device. This is especially beneficial when performing physical failure analysis of samples that have been back thinned for the purpose of fault isolation and defect localization techniques such as: LIVA (Laser Induced Voltage Alteration), TIVA (Thermally Induce Voltage Alteration), SDL [2] (Soft Defect Localization), and TRE (Time Resolved Emission) analysis. An important fundamental advantage of deprocessing SOI devices is that the BOX (Buried Oxide) layer acts as a chemical etch stop when etching the backside or bulk silicon. This leaves the transistor active silicon intact for analysis. Further delayering allows for the inspection of the active silicon, gate oxide, silicide, spacers, and poly. After deprocessing the transistor level, the metal layers are still intact and, in most cases, still electrically connected to the outside world. This can provide additional failure analysis opportunities.


Author(s):  
Hong Zheng ◽  
Joe Patterson ◽  
G. P. Li

Abstract This paper describes a new technique for identifying defects on integrated circuit. This technique detects the noise content in light emitted from defect sites. The purpose of this technique is to determine which of many light emission sites represent a defect and which represent normal devices. It reports the first phase of studies to evaluate the feasibility and potential effectiveness of this technique. The feasibility of this technique has been demonstrated by simultaneously monitoring electrical noise and the noise in the light emitted from a gallium arsenide light emission diode (LED) and a bipolar transistor. The paper will present the methodology and apparatus used to detect and analyze the noise in light emission.


Author(s):  
Frederick S. Felt

Abstract SQUID and MR magnetic sensors have separately been used for fault isolation of shorts and resistive opens in integrated circuits and packages. These two technologies were once considered to be mutually exclusive, although recent studies [1] rather pointed to their complementary character. This paper shows, for the first time, the use of these two sensors together to isolate a low resistance short in a Quad-NAND gate microcircuit. Electrical test confirmed low resistance shorts between three of the device pins. However, internal optical inspection found no evidence of failure. The low resistance of the shorts was deemed insufficient for liquid crystal analysis. Magnetic current imaging with a SQUID sensor confirmed current flow through the package lead frame and isolated the defect to the microcircuit. Due to package design and the resulting distance of the scan plane, the SQUID was unable to resolve the current path on the microcircuit. In parallel with the SQUID, a magnetoresistive (MR) probe was employed to fit inside the device cavity, make direct contact with the microcircuit, and map high-resolution current images. Two sites with high-current density were accurately identified by MCI in input transistors. Subsequent deprocessing revealed that the defects were located under a broad sheet of aluminum metallization which blocked optical detection, and rendered detection by thermal emission difficult.


Author(s):  
Paul Hubert P. Llamera ◽  
Camille Joyce G. Garcia-Awitan

Abstract Lock-in thermography (LIT), known as a powerful nondestructive fault localization technique, can also be used for microscopic failure analysis of integrated circuits (ICs). The dynamic characteristic of LIT in terms of measurement, imaging and sensitivity, is a distinct advantage compared to other thermal fault localization methods as well as other fault isolation techniques like emission microscopy. In this study, LIT is utilized for failure localization of units exhibiting functional failure. Results showed that LIT was able to point defects with emissions in the mid-wave infra-red (MWIR) range that Photo Emission Microscopy (PEM) with near infrared (NIR) to short- wave infra-red (SWIR) detection wavelength sensitivity cannot to detect.


Author(s):  
Soon Lim ◽  
Jian Hua Bi ◽  
Lian Choo Goh ◽  
Soh Ping Neo ◽  
Sudhindra Tatti

Abstract The progress of modern day integrated circuit fabrication technology and packaging has made fault isolation using conventional emission microscopy via the top of the integrated circuit more difficult, if not impossible. This is primarily due to the use of increased levels and density of metal-interconnect, and the advent of new packaging technology, e.g. flip-chip, ball-grid array and lead-on-chip, etc. Backside photon emission microscopy, i.e. performing photon emission microscopy through the bulk of the silicon via the back of the integrated circuit is a solution to this problem. This paper outlines the failure analysis of sub-micron silicon integrated circuits using backside photon emission microscopy. Sample preparation, practical difficulties encountered and case histories will be discussed.


Author(s):  
V.K. Ravikumar ◽  
R. Wampler ◽  
M.Y. Ho ◽  
J. Christensen ◽  
S.L. Phoa

Abstract Laser voltage probing is the newest generation of tools that perform timing analysis for electrical fault isolation in advanced failure analysis facilities. This paper uses failure analysis case studies on SOI to showcase the implementation of laser voltage probing in the failure analysis flow and highlight its significance in root-cause identification.


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