TEM/FIB Technical Solutions to Electron Beam Induced Radiation Damage to Low K/Ultra Low K Dielectrics in Semiconductor Failure Analysis

2012 ◽  
Author(s):  
Liu Binghai ◽  
Chen Ye ◽  
Mo Zhiqiang ◽  
Zhao Si Ping ◽  
Wang Chue Yuin ◽  
...  
Keyword(s):  
Electron Beam ◽  
Sample Preparation ◽  
Failure Analysis ◽  
Radiation Damage ◽  
Low Dose ◽  
Imaging Techniques ◽  
Single Beam ◽  
Electron Microscopes ◽  
Technical Solutions ◽  
Low K

Abstract Electron-beam induced radiation damage can give rise to large structural collapse and deformation of low k and ultra low k IMD in semiconductor devices, posing great challenges for failure analysis by electron microscopes. Such radiation damage has been frequently observed during both sample preparation by dual-beam FIB and TEM imaging. To minimize radiation damage, in this work we performed systematic studies on every possible failure analysis step that could introduce radiation damage, i.e., pre-FIB sample preparation, FIB milling, and TEM imaging. Based on these studies, we utilized comprehensive technical solutions to radiation damage by each failure analysis step, i.e., low-dose/low-kV FIB and low-dose TEM techniques. We propose and utilize the low-dose TEM imaging techniques on conventional TEM tools without using low-dose imaging control interface/software. With these new methodologies or techniques, the electron-beam induced radiation damage to ultra low k IMD has been successfully minimized, and the combination of single-beam FIB milling and low-dose TEM imaging techniques can reduce structure collapse and shrinkage to almost zero.

The role of radiation damage to the analysis of composition in electron microscopes

1983 ◽  
Vol 41 ◽  
pp. 380-381
Author(s):  
D. K. McElfresh ◽  
D. G. Howitt
Keyword(s):  
Electron Beam ◽  
Radiation Damage ◽  
Vacancy Concentration ◽  
Analytical Electron Microscopy ◽  
Extreme Case ◽  
Binding Energies ◽  
Local Composition ◽  
Damage Process ◽  
High Concentrations ◽  
Electron Microscopes

The effect of the illuminating electron beam on the local composition of beam sensitive specimens is an important consideration when applying the techniques of analytical electron microscopy (AEM). The decrease in the signal from certain elements is often attributed to their volitalization under beam heating, however, radiation damage to the material by the electron beam is another mechanism which can contribute to compositional changes.The ionization and displacement processes that occur within the region of the specimen irradiated by the electron beam can lead to relatively high concentrations of interstitials. The surrounding material is virtually devoid of these species and so these elements will diffuse down the concentration gradient that is generated and so reduce the X-ray or electron loss signal as the region within the probe is depleted.The radiation damage process will continue as long as the electron beam impinges on the specimen and the presence of high vacancy concentration could induce the displacement of other species as the local binding energies are reduced. In the extreme case one might expect to observe tunnels of condensed vacancies arising from the diffusion process.

The Role of Temperature in Limiting Radiation Damage to Organic Materials in Electron Microscopes

1990 ◽  
Vol 48 (2) ◽  
pp. 404-405
Author(s):  
M.K. Lamvik
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Electron Microscope ◽  
Radiation Damage ◽  
Organic Materials ◽  
Charged Particles ◽  
High Flux ◽  
Electron Sources ◽  
Electron Microscopes

The intensity of the electron beam in an electron microscope is at once the basis for progress as well as the ultimate limitation in electron microscopy of organic materials. Gabor noted that the highest intensity available for light optics comes from sunlight, which produces an energy density of 2,000 watts/cm2-steradian. The electron sources in early microscopes could produce a million times that amount, and modern sources even more. While the high intensity made good images possible (because numerical apertures used for electron microscopes are less than 1% of the size used in light microscopy) early microscopists feared that such a high flux of charged particles would destroy most specimens, especially organic ones. Although it was soon found that biological specimens could survive observation by electron microscopy, the introduction of double-condenser illumination systems revealed the problem of specimen contamination. In time it became clear that radiation damage was more fundamental than the gross increases or decreases in specimen mass observed in contamination and etching.

A Study of the Radiation Damage at the Opened/Un-Opened Contact of a Deep Trench Capacitor DRAM

2004 ◽  
Author(s):  
Jen-Lang Lue ◽  
Michael Hsieh ◽  
Danny Kao
Keyword(s):  
Electron Beam ◽  
Sample Preparation ◽  
Radiation Damage ◽  
Ion Beam ◽  
Damage Zone ◽  
Metal Deposition ◽  
Normal Sample ◽  
Si Substrate ◽  
Cross Sectional ◽  
Deep Trench

Abstract This paper studies the effects of an electron beam and an ion beam in sample preparation at the borderless bit-line contact (CB) between a transistor and a bit line in a deep trench capacitor DRAM [1] using the Transmission Electron Microscope (TEM) and the Electron Energy Loss Spectroscope (EELS). An abnormal region in the Si substrate was observed using cross-sectional TEM (XTEM) analysis at both the opened and un-opened CB contacts when normal sample preparation procedures were applied. CBED (Convergent Beam Electron Diffraction) in the TEM verifies this region is a structure of amorphous Si. The EELS spectrum shows the relative thickness (t/λ) of the TEM sample at this amorphous region is similar to that of the single crystal Si substrate. Experimental results demonstrated that this region was the result of radiation damage caused by either the ion-beam scan or the ion-beam Pt metal deposition required for sample preparation in the Focused Ion Beam (FIB) system. This radiation damage was not caused by inline wafer processing. However, the radiation damage zone for an un-opened contact is smaller than that for an opened contact. The size of the radiation damage zone increases relative to the time of the ion beam exposure. Using electron-beam scan and electron-beam Pt metal deposition can prevent this radiation damage from occurring.

Atom Displacement Radiation Damage in Electron Microscopes

1978 ◽  
Vol 36 (3) ◽  
pp. 330-342
Author(s):  
M.J. Makin
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Radiation Damage ◽  
Forming Process ◽  
Electron Dose ◽  
Electron Atom ◽  
Atom Displacement ◽  
Electron Microscopes ◽  
Great Economy ◽  
Electron Interactions

There are inevitably two important aspects of the interaction between a specimen and the electron beam which are fundamental to all electron microscopy. The first of these, the alteration to the beam produced by the specimen, is the image forming process which is the basis of the instrument. The second aspect is the alteration to the specimen produced by the beam, which is termed 'radiation damage'. This effect, which can be severe and undesirable in some cases, can also be exploited to obtain much information difficult to obtain in other ways. The unique advantage of the study of radiation damage in electron microscopes is that both aspects mentioned above can be used simultaneously to continuously monitor the effects as a function of electron dose. This results in a great economy of effort compared with the use of other sources of radiation. Radiation damage in electron microscopes can be broadly divided into two types, that arising from electron-electron interactions, and from electron-atom interactions.

scholarly journals TEM Sample Preparation Using Focused Ion Beam - Capabilities And Limits

2003 ◽  
Vol 11 (2) ◽  
pp. 22-25 ◽  
Author(s):  
H.J. Engelmann ◽  
B. Volkmann ◽  
Y. Ritz ◽  
H. Saage ◽  
H Stegmann ◽  
...  
Keyword(s):  
Electron Beam ◽  
Sample Preparation ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Sample Handling ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Preparation Techniques ◽  
Scanning Electron

TEM sample preparation using Focused Ion Beam (FIB) methods becomes more and more interesting for microscopists because the technique allows for reliable and very efficient sample preparation. The first application of TEM sample preparation by FIB-cutting was reported more than 10 years ago. Meanwhile, a lot of experience has been gathered that allows one to discuss the capabilities and limits of the FIB technique in detail.Several TEM sample preparation techniques are known that all include FIB-cutting but differ in sample pre-preparation, sample handling,etc. This paper focuses on the actual FIB process, FIB tools are closely related to Scanning Electron Microscopes, but instead of an electron beam an ion beam (mostly Ga+ions) is used to remove and deposit material.

Optimization of SEM Analytical Conditions for Low K and Ultra Low K Dielectric Materials

2008 ◽  
Author(s):  
Liu Binghai ◽  
Mo Zhiqiang ◽  
Hua Younan ◽  
Teong Jennifer
Keyword(s):  
Electron Beam ◽  
Radiation Damage ◽  
Decisive Role ◽  
Dielectric Materials ◽  
Condenser Lens ◽  
Probe Current ◽  
Lens Aperture ◽  
Electron Microscopy Analysis ◽  
Damage Process ◽  
Low K

Abstract Electron beam induced radiation damage presents great challenges for the electron microscopy analysis of low k and ultra low k dielectrics due to their beam sensitive nature. In order to minimize the radiation damage, it is necessary to understand the mechanisms behind the damage. This work presents detailed studies regarding the mechanisms behind the effects of probe currents, accelerating voltage and anticharging coating layers on the radiation damage to low/ultralow K dielectrics. The results indicate that the probe current shows a stronger dependence on the size of the condenser lens aperture than the accelerating voltage. Therefore, in terms of the probe current, the condenser lens aperture plays a decisive role in affecting the radiation damage process. In order to minimize the radiation damage, SEM imaging should be conducted with not only a low accelerating voltage but also a small condenser lens aperture to reduce probe current. Based on simulation results, the effects of a coating layer and accelerating voltage are related to the interaction volume and the penetration depth of the electron beam. Pt coating can act as not only an anti-charging layer, but also an effective barrier layer for reducing electron flux that interacts with the low/ultra-low dielectrics.

Modification of the Electron Microscope for Investigation of Fully Hydrated Biological Specimens

1969 ◽  
Vol 27 ◽  
pp. 418-419 ◽  
Author(s):  
R. C. Moretz ◽  
D. F. Parsons
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Structural Damage ◽  
Lower Percentage ◽  
Vacuum Drying ◽  
Total Removal ◽  
Total Absence ◽  
Biological Studies ◽  
Electron Microscopes ◽  
Beam Damage

Short lifetime or total absence of electron diffraction of ordered biological specimens is an indication that the specimen undergoes extensive molecular structural damage in the electron microscope. The specimen damage is due to the interaction of the electron beam (40-100 kV) with the specimen and the total removal of water from the structure by vacuum drying. The lower percentage of inelastic scattering at 1 MeV makes it possible to minimize the beam damage to the specimen. The elimination of vacuum drying by modification of the electron microscope is expected to allow more meaningful investigations of biological specimens at 100 kV until 1 MeV electron microscopes become more readily available. One modification, two-film microchambers, has been explored for both biological and non-biological studies.

Reduction of Specimen Contamination in Electron-Beam Instruments

1976 ◽  
Vol 34 ◽  
pp. 576-577
Author(s):  
G. Lehmpfuhl ◽  
P. J. Smith
Keyword(s):  
Electron Beam ◽  
Cold Trap ◽  
Beam Diameter ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Hydrocarbon Molecules ◽  
Electron Microscopes ◽  
Combination Of Methods ◽  
Convergent Beam ◽  
Very High

Specimens being observed with electron-beam instruments are subject to contamination, which is due to polymerization of hydrocarbon molecules by the beam. This effect becomes more important as the size of the beam is reduced. In convergent-beam studies with a beam diameter of 100 Å, contamination was observed to grow on samples at very high rates. Within a few seconds needles began forming under the beam on both the top and the underside of the sample, at growth rates of 400-500 Å/s, severely limiting the time available for observation. Such contamination could cause serious difficulty in examining a sample with the new scanning transmission electron microscopes, in which the beam is focused to a few angstroms.We have been able to reduce the rate of contamination buildup by a combination of methods: placing an anticontamination cold trap in the sample region, preheating the sample before observation, and irradiating the sample with a large beam before observing it with a small beam.

A theory of contamination in electron microscopes by surface diffusion

1978 ◽  
Vol 36 (1) ◽  
pp. 116-117
Author(s):  
J.T. Fourie
Keyword(s):  
Electron Beam ◽  
Surface Diffusion ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Physical Parameters ◽  
Carbon Compounds ◽  
Hydrocarbon Molecules ◽  
Electron Microscopes ◽  
Primary Electrons ◽  
Long Chain

Contamination in electron microscopes can be a serious problem in STEM or in situations where a number of high resolution micrographs are required of the same area in TEM. In modern instruments the environment around the specimen can be made free of the hydrocarbon molecules, which are responsible for contamination, by means of either ultra-high vacuum or cryo-pumping techniques. However, these techniques are not effective against hydrocarbon molecules adsorbed on the specimen surface before or during its introduction into the microscope. The present paper is concerned with a theory of how certain physical parameters can influence the surface diffusion of these adsorbed molecules into the electron beam where they are deposited in the form of long chain carbon compounds by interaction with the primary electrons.

A New High Intensity Grid Cap for RCA-EMU-3 Electron Microscopes

1968 ◽  
Vol 26 ◽  
pp. 316-317
Author(s):  
George Christov ◽  
Bolivar J. Lloyd
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Voltage ◽  
High Intensity ◽  
Electron Gun ◽  
Tungsten Filament ◽  
Fluorescent Screen ◽  
Electron Microscopes ◽  
Pass Through ◽  
Ground Potential

A new high intensity grid cap has been designed for the RCA-EMU-3 electron microscope. Various parameters of the new grid cap were investigated to determine its characteristics. The increase in illumination produced provides ease of focusing on the fluorescent screen at magnifications from 1500 to 50,000 times using an accelerating voltage of 50 KV.The EMU-3 type electron gun assembly consists of a V-shaped tungsten filament for a cathode with a thin metal threaded cathode shield and an anode with a central aperture to permit the beam to course the length of the column. The cathode shield is negatively biased at a potential of several hundred volts with respect to the filament. The electron beam is formed by electrons emitted from the tip of the filament which pass through an aperture of 0.1 inch diameter in the cap and then it is accelerated by the negative high voltage through a 0.625 inch diameter aperture in the anode which is at ground potential.

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