On July 1st, Toshiba Corporation's Semiconductor Company and Storage Products Company consolidated to form Semiconductor & Storage Products Company.This page describes reliability information of semiconductor products.

Instruments Used in Failure Analysis

[As of April, 2011]

Failure analysis of semiconductor devices requires highly precise, highly sensitive analytical instruments capable of enabling observation at the nanometer and micrometer level. Such instruments can be used for measuring electrical characteristics, identifying failure locations and analyzing failure mechanisms. Table 1 lists instruments of high applicability that are used in failure analysis.

Table 1 Instruments Used in Failure Analysis
	Instrument	Analytical Application
Measurement of electrical characteristics	Curve tracer	Identification of breakdown voltage, leakage
	Oscilloscope	Identification of functions, AC characteristics
	Tester	Identification of DC and AC characteristics, functions
	Nanoprobe	Evaluation of single device characteristics
Identification of failure location	Liquid crystal analysis (polarization microscope)	Hot spot detection
	Photo emission microscope (PEM)	Luminescent spot detection
	Scanning laser microscope	Operation analysis (OBIC/OBIRCH methods)
	EB tester (strobe SEM)	Operation analysis (Voltage contrast)
Observation	Stereo microscope	Outer appearance
	Metallurgical microscope	Chip inspection
	Infrared microscope	Chip backside inspection
	Scanning probe microscope (SPM)	Surface shape and characteristics inspection
	Scanning capacitance microscope (SCM)	Surface carrier concentration inspection
	Scanning atomic force microscope (AFM)	Surface shape inspection
	Scanning electron microscope (SEM)	Shape inspection
	Transmission electron microscope (TEM)	Minute structure analysis
	X-ray fluoroscopy	Internal inspection
	Scanning acoustic tomography	Delamination and void inspection
Analysis	Electron probe X-ray microanalyzer (EPMA)	Elemental analysis, composition analysis
	Auger electron spectroscope (AES)	Surface elemental analysis, status analysis
	Secondary ion mass analyzer (SIMS)	Elemental identification, surface elemental analysis
	Time-of-flight secondary ion mass analyzer (TOF-SIMS)	Elemental/molecular identification, top surface analysis
	X-ray photoelectron spectroscope (XPS)	Surface elemental analysis, status analysis
	Fluorescent X-ray analyzer	Impurity analysis, composition analysis
	Fluorescence microscope	Fluorescent material analysis
	Fourier transformation infrared spectrometer (FT-IR)	Status analysis
	Electron spin resonance (ESR)	Electron status analysis
	Electron beam diffractometer	Crystallization analysis
	X-ray diffractometer	Crystallization analysis, stress measurement
	Scanning infrared detector	Internal chip temperature distribution measurement
	Thermal analyzer	Material analysis
	Gas mass analyzer	Material analysis
Sample processing	Focused ion beam (FIB)	Sample processing
	Grinder, polisher	Sample processing
	Ion milling system	Sample processing

Measuring Electrical Characteristics

In general, a curve tracer or similar device capable of measuring current-voltage characteristics is used to check for opens, shorts and breakdown voltage degradation. In addition, an oscilloscope is handy for conducting simple A/C characteristics checks.
Testers, such as large general-purpose testers for LSI, memory testers and linear IC testers, are used according to the device tested. Measurements obtained from the device are used to diagnose failures or analyze the circuit failure location based on comparisons with standard values.

Identifying the Failure Location

The first step in failure analysis is critical: identifying the failure location. There are several ways to do this.
A scanning infrared detector is used to find abnormal temperature distributions within the chip, a liquid crystal analysis is used to identify hot spots in order to detect minute leakages, and an emission microscope is used to detect weak luminescence.
The methods used to analyze the operating state of a device include the electron microscope based EBIC method and the scanning laser microscope based OBIC or OBIRCH method for PN junction electrical potential analysis, and the EB tester based voltage contract method for wire electrical potential analysis.

Observing the Failure

In addition to metallurgical and stereo microscopes, the scanning electron microscope (SEM) and transmission electron microscope (TEM) are essential for identifying and inspecting failure locations. An infrared microscope and X-ray inspection system also provide critical information. In addition, the scanning tunnel microscope (STM) and atomic force microscope (AFM), which provide data up to the atomic level, are used.

Analyzing Elements ^{Note 1}

Solid surface analysis is particularly an effective means in semiconductor failure analysis. As shown in Figure 1, the principle generally involves projecting an excitation source, such as an electron beam, ion beam or electromagnetic wave (such as an X-ray) onto a solid surface, and then conducting elemental and chemical state analyses of the surface (or bulk) using the X-ray, secondary ion or Auger electron signals ejected by the excited material as the signal source.
Table 2 summarizes the characteristics of the solid surface analysis methods (systems). Of the equipment listed in the table, the electron probe X-ray microanalyzer (EPMA), Auger electron spectroscope (AES), secondary ion mass spectrometry (SIMS), X-ray photoemission spectroscope or electron spectroscope (XPS or ESCA) and the fluorescence X-ray spectroscope are frequently used. Use is determined by application, taking into consideration the area to be analyzed and sensitivity.

This is [Figure 1 Interaction of Ion, Electron and Photoelectron (X-ray) with Solid Surface].

Figure 1 Interaction of Ion, Electron and Photoelectron (X-ray) with Solid Surface ^{Note 1}

Table 2 Comparison of Physical Surface Analysis Methods ^{Note 1}
Excitation Source	Signal Source	Analysis Technique	Data Obtained	Features/Other
Electron	Reflected primary electron	Low-speed electron energy loss spectroscopy (LEELS)	Adsorption state	Uses low-energy electrons of several eV. Shows vibration state of adsorbed molecule.
	Auger electron	Auger electron spectroscopy (AES)	Elemental analysis, bonding energy, state analysis based on chemical shift	Uses electron beams of about 3 to 20 keV. Surface analysis with beam of several 10nm or less is also possible.
	Ion	Electron impact drift method	Elemental analysis of adsorbed material.	Impact of minute current applied to surface removes adsorbed ions, performing mass separation.
	Characteristic X-ray	X-ray microanalyzer (EPMA)	Elemental analysis of minute area	Commonly used in microanalysis. Detectable depth is about 1 micrometer.
	Light	Cathode luminescence	Electron beam excited electron -electron hole re-coupling luminescence	Measures defects, precipitation, impurity precipitation and carrier diffused layers.
Ion	Reflected ion	Ion-scattering energy spectroscopy (ISS)	Outermost surface layer atomic structure, elements	Performs scattering primary ion energy separation using low-speed ions (100eV to several eV).
	Back-scattered ion	Rutherford backscattering spectroscopy (RBS)	Composition, elemental analysis, depth distribution	Measures energy of back-scattered ions using H⁺ or He⁺ of several hundred eV to several MeV.
	Secondary ion	Secondary ion mass analysis (SIMS)	Microanalysis, depth distribution	Thin film, surface analysis, microanalysis of bulk, concentration depth analysis
	Characteristic X-ray	Particle induced X-ray emission	Elemental analysis	Simultaneous multielement analysis at high sensitivity
X-ray, Ultra-violet ray	Photoelectron	Photoelectron spectroscopy (XPS) Vacuum ultraviolet electron spectroscopy (UPS)	Elemental analysis, electron coupling energy	Conducts electron coupling energy and elemental analysis by measuring photoelectron energy.
X-ray, Soft x-ray	Secondary X-ray	Fluorescence X-ray analysis	Elemental analysis	Enables quick analysis.
X-ray, Soft x-ray	Secondary X-ray	Soft X-ray analysis	Electron state	Measures electron state of atom by irradiating with soft X-ray.

Sample Processing

Surface and cross-sectional observation and analysis of specific locations (failure locations) in the LSI are necessary in failure analysis. These types of observations and analyses require a precision processing method for samples. For this, a focused ion beam (FIB) system and precision polishing equipment capable of polishing in the chip state are utilized.