Variable probe current using a condenser lens in a miniature electron beam column

2009 ◽  
Author(s):  
C. S. Silver ◽  
J. P. Spallas ◽  
L. P. Muray
Keyword(s):  
Electron Beam ◽  
Condenser Lens ◽  
Probe Current

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.

Development of Multi-Purpose Thermal Field Emission SEM

2001 ◽  
Vol 7 (S2) ◽  
pp. 876-877
Author(s):  
M. Mita ◽  
T. Nokuo ◽  
T. Yanagihara ◽  
K. Ogura ◽  
M. Iwatsuki ◽  
...  
Keyword(s):  
Field Emission ◽  
Thermal Field ◽  
Ebsd Analysis ◽  
Objective Lens ◽  
Electron Optics ◽  
Condenser Lens ◽  
Probe Current ◽  
The Past ◽  
The Magnetic Field ◽  
Immersion Type

Past FE-SEM could obtain a high resolution image, however its probe current was not sufficiently strong enough for analytical purpose.We have developed a multi-purpose thermal field emission scanning electron microscope (JSM- 6500F), in which a new designed “In-Lens Thermal FEG” is installed.Fig. 1 shows a cross section images of the In-Lens Thermal FEG, comparing with the past FEG. The In-Lens Thermal FEG consists of the thermal FEG and the 1st condenser lens. The emitter is located in the magnetic field produced by the 1st condenser lens, so that electrons emitted from the emitter are condensed effectively to produced a high probe current. The maximum probe current of 200 nA is attainable at the accelerating voltage of 15 kV, ten times larger than the maximum probe current of ordinary FE-SEMs. Therefore the WDS analysis can be performed by this newly FE-SEM.The “aperture angle control lens” has been installed in the electron optics system, for improving the resolution at a large probe current. The resolution of 3.0nm at the analytical condition (at probe current 5nA, accelerating voltage 15kV, WD 10mm: fig.2).The ultimate resolution of the microscope is 1.5nm at 15kV and 5nm at lkV. The objective lens is not an immersion type and does not leak magnetic fields on the specimen surface, therefore this equipment was suitable for observing or analyzing magnetic materials, and also suitable for the EBSD analysis. Fig.3 shows an example of the EBSD analysis.

Annular Focused Electron/Ion Beams for Combining High Spatial Resolution with High Probe Current

2016 ◽  
Vol 22 (5) ◽  
pp. 948-954 ◽  
Author(s):  
Anjam Khursheed ◽  
Wei Kean Ang
Keyword(s):  
Electron Beam ◽  
Ion Beam ◽  
Current Mode ◽  
Spot Size ◽  
Beam Current ◽  
Ion Beams ◽  
Second Order ◽  
Primary Beam ◽  
Objective Lens ◽  
Probe Current

AbstractThis paper presents a proposal for reducing the final probe size of focused electron/ion beam columns that are operated in a high primary beam current mode where relatively large final apertures are used, typically required in applications such as electron beam lithography, focused ion beams, and electron beam spectroscopy. An annular aperture together with a lens corrector unit is used to replace the conventional final hole-aperture, creating an annular ring-shaped primary beam. The corrector unit is designed to eliminate the first- and second-order geometric aberrations of the objective lens, and for the same probe current, the final geometric aberration limited spot size is predicted to be around a factor of 50 times smaller than that of the corresponding conventional hole-aperture beam. Direct ray tracing simulation is used to illustrate how a three-stage core lens corrector can be used to eliminate the first- and second-order geometric aberrations of an electric Einzel objective lens.

Dynamic Focusing Techniques for Enhancing SEM Images

1972 ◽  
Vol 30 ◽  
pp. 378-379
Author(s):  
Nelson C. Yew
Keyword(s):  
Electron Beam ◽  
Spherical Surface ◽  
Sem Images ◽  
Condenser Lens ◽  
Sem Image ◽  
Collector System ◽  
Electron Collection ◽  
Effective Depth ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes

There are two major areas where Dynamic Focusing techniques can be used to enhance SEM image qualify and micrograph information content. When used in conjunction with the final condenser lens in the electron-optical column, it increases the effective depth of focus associated with an inclined specimen in the SEM. When used with an ultra-high resolution recording cathode ray tube it provides exceptional corner-to-corner sharpness on the micrograph.Most commercial scanning electron microscopes use a tilted specimen positioned close to the final condenser lens with the secondary electron collector system located in the tilting direction to facilitate efficient electron collection. electron beam pivoting through the center of the principle plane of this lens to minimize distortion and off-axis aberration problems. As a result, the final electron beam is truly focused only along a portion of the spherical surface with its center located at the pivoting point.

Development of a New Digital Fe SEM

1990 ◽  
Vol 48 (1) ◽  
pp. 432-433
Author(s):  
M. Ohi ◽  
K. Harasawa ◽  
T. Niikura ◽  
H. Okazaki ◽  
Y. Ishimori ◽  
...  
Keyword(s):  
Field Emission ◽  
Emission Current ◽  
Objective Lens ◽  
Condenser Lens ◽  
Probe Current ◽  
Current Fluctuation ◽  
Adsorbed Gas ◽  
Noise Cancelling ◽  
Backscattered Electron ◽  
Video Amplifier

By combining a conical type field emission gun and an auto gain controlled noise cancelling system, we have developed three types of digital FESEMs equipped with a digital imaging processor and three different sized specimen chambers each with a stage.It is known that when a cold field emission gun (C-FEG) with a W (310) single crystal tip is used at a vacuum pressure of 10-10 torr, the emission current constantly fluctuates by 5 to 10% due to the adsorbed gas, etc. on the tip surface.Since the probe current in an FESEM equipped with this C-FEG fluctuates to the same extent, the noise caused by emission current fluctuation (emission noise) appears on secondary electron images (SEI) and backscattered electron images (BEI).In order to eliminate emission noise, an aperture (noise cancelling aperture or N/C aperture) installed under the C-FEG detects emission current fluctuation and inputs it to the differential amplifier of the video amplifier system for SEI or BEI on conventional FESEMs.With FESEMs, however, when the accelerating voltage is change in the range from 0.5 to 30 kV, the virtual source of an FEG using Butler type electrodes moves several tens of centimeters on the optical axis. Moreover, the probe current is changed from 10-13 to 10-10 A by changing the excitation current of the condenser lens. For these two reasons, there have been adopted such methods as installing an N/C aperture in two positions (under the C-FEG and at the objective lens aperture position) and controlling the amplifier value of the noise cancelling system and condenser lens excitation by ROM data.

X-Ray Microanalysis of Metallic Thin Films

2005 ◽  
Author(s):  
F. L. Ng ◽  
J. Wei
Keyword(s):  
Electron Beam ◽  
Beam Energy ◽  
Atomic Weight ◽  
Metallic Thin Films ◽  
Electron Beam Energy ◽  
Si Substrate ◽  
X Ray ◽  
Probe Current ◽  
Au Film ◽  
Critical Excitation

Nickel and gold films are widely used for microsystems fabrication and packaging, as well as under bump metallization. In this paper, x-ray microanalysis was used to measure the thickness of Ni and Au films. Au and Ni films with varied thicknesses were deposited on silicon (Si) substrate by magnetron sputtering method. Incremental electron beam energy ranging from 4 keV to 30 keV was applied while other parameters were kept constant to determine the electron beam energy required to penetrate the metallic films. The effects of probe current at a fixed electron beam energy on the penetration depth were investigated too. With higher energy applied, the electron beam can penetrate deeper and more Si signal can be detected. The Ni and Au film thicknesses almost have linear relationship with the required penetration electron beam energy. The probe current has minimal effect on the specimen once it has reached the critical excitation probe current. For Ni and Au films with same thickness, higher energy or probe current is needed to penetrate the Au film to reach Si substrate due to the higher Au atomic weight.

Electron-Beam-induced transformations in zirconia-alumina nanolaminates: An In situ high-resolution Electron–Microscopy study

1996 ◽  
Vol 54 ◽  
pp. 690-691
Author(s):  
M.A. Schofield ◽  
M. Gajdardziska-Josifovska ◽  
R. Whig ◽  
C.R. Aita
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
High Resolution ◽  
Tetragonal Zirconia ◽  
High Resolution Electron Microscopy ◽  
Microscopy Study ◽  
Irradiation Condition ◽  
Transformation Toughening ◽  
Condenser Lens

Composite systems containing zirconia have been used extensively as transformation-toughening materials based on a stress induced martensitic transformation of the metastable tetragonal phase of zirconia to the monoclinic phase. Recently it has been shown that tetragonal zirconia can be stabilized in zirconia-alumina nanolaminates grown by reactive sputter deposition, when the zirconia layer is less than 6 nm thick. Cross-section high resolution transmission electron microscopy (HRTEM) of these nanolaminates revealed localized tetragonal-to-monoclinic transformation caused by sample preparation. In this study, quantitative HRTEM is used to analyze the zirconia nanocrystallite transformation in situ, by controlled exposure of the sample to the electron beam of the microscope.The irradiation conditions used in this study to induce the zirconia transformation are summarized in Table 1. The mildest irradiation condition corresponds to normal imaging illumination used in this study to obtain high resolution images. Under these normal illumination conditions, the first condenser lens (CI) is used to form a 0.1 μm sized probe which is over focused on the sample by the second condenser lens (C2).

scholarly journals Electron Beam Current Loss at the High-Vacuum– High-Pressure Boundary in the Environmental Scanning Electron Microscope

2001 ◽  
Vol 7 (5) ◽  
pp. 397-406 ◽  
Author(s):  
Gerasimos D. Danilatos ◽  
Matthew R. Phillips ◽  
John V. Nailon
Keyword(s):  
High Pressure ◽  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Electron Probe ◽  
High Vacuum ◽  
Environmental Scanning ◽  
Probe Current ◽  
Prototype Instrument ◽  
Scanning Electron

AbstractA significant loss in electron probe current can occur before the electron beam enters the specimen chamber of an environmental scanning electron microscope (ESEM). This loss results from electron scattering in a gaseous jet formed inside and downstream (above) the pressure-limiting aperture (PLA), which separates the high-pressure and high-vacuum regions of the microscope. The electron beam loss above the PLA has been calculated for three different ESEMs, each with a different PLA geometry: an ElectroScan E3, a Philips XL30 ESEM, and a prototype instrument. The mass thickness of gas above the PLA in each case has been determined by Monte Carlo simulation of the gas density variation in the gas jet. It has been found that the PLA configurations used in the commercial instruments produce considerable loss in the electron probe current that dramatically degrades their performance at high chamber pressure and low accelerating voltage. These detrimental effects are minimized in the prototype instrument, which has an optimized thin-foil PLA design.

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