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.

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.

Description of a New High Resolution Scanning Transmission EM

1972 ◽  
Vol 30 ◽  
pp. 418-419
Author(s):  
Michael Beer ◽  
J. W. Wiggins ◽  
David Woodruff ◽  
Jon Zubin
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Energy Dispersive Spectrometer ◽  
Scanning Transmission Electron Microscope ◽  
Objective Lens ◽  
Condenser Lens ◽  
Transmission Electron ◽  
Pattern Size ◽  
Scanning Transmission ◽  
Under Construction

A high resolution scanning transmission electron microscope of the type developed by A. V. Crewe is under construction in this laboratory. The basic design is completed and construction is under way with completion expected by the end of this year.The optical column of the microscope will consist of a field emission electron source, an accelerating lens, condenser lens, objective lens, diffraction lens, an energy dispersive spectrometer, and three electron detectors. For any accelerating voltage the condenser lens function to provide a parallel beam at the entrance of the objective lens. The diffraction lens is weak and its current will be controlled by the objective lens current to give an electron diffraction pattern size which is independent of small changes in the objective lens current made to achieve focus at the specimen. The objective lens demagnifies the image of the field emission source so that its Gaussian size is small compared to the aberration limit.

Dual Stage SEM with thermal field-emission gun

1989 ◽  
Vol 47 ◽  
pp. 94-95
Author(s):  
S. Yamazaki ◽  
T. Sato ◽  
S. Aota ◽  
R. Buchanan
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Thermal Field ◽  
Objective Lens ◽  
Wide Field ◽  
Operating Voltage ◽  
High Brightness ◽  
Voltage Range ◽  
Optical Configuration ◽  
Working Distance

Resolution improvement is an on-going goal in scanning electron microscope development. High resolution is required at both high and low accelerating voltages in a wide field of applications, including, but not exclusive to, semiconductors and new materials development. Two approaches which result in improved resolution through-out the operating voltage range of the SEM are 1) the adoption of low aberration objective lenses, and 2) the use of high brightness electron sources.The DS-130F SEM which is described here uses a high brightness thermal field emission gun (TFEG) in conjunction with a modified DS-130 column. The electron optical configuration is quite unique, as it includes two independent stages. The top stage places the sample within a high field strength low aberration objective lens, resulting in ultra high resolution on samples up to 18 x 8 mm. The bottom stage accommodates 6” samples and uses a second dedicated conical objective lens allowing a short working distance to be maintained on tilted samples.

Field Emission SEM Equipped With Noise Compensator

1973 ◽  
Vol 31 ◽  
pp. 302-303
Author(s):  
S. Saito ◽  
H. Todokoro ◽  
S. Nomura ◽  
T. Komoda
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Low Contrast ◽  
Probe Current ◽  
High Resolution Images ◽  
Scanning Electron

Field emission scanning electron microscope (FESEM) features extremely high resolution images, and offers many valuable information. But, for a specimen which gives low contrast images, lateral stripes appear in images. These stripes are resulted from signal fluctuations caused by probe current noises. In order to obtain good images without stripes, the fluctuations should be less than 1%, especially for low contrast images. For this purpose, the authors realized a noise compensator, and applied this to the FESEM.Fig. 1 shows an outline of FESEM equipped with a noise compensator. Two apertures are provided gust under the field emission gun.

A Field Emission System For Transmission Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 298-299
Author(s):  
Michel Troyonal ◽  
Huei Pei Kuoal ◽  
Benjamin M. Siegelal
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Optical System ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Objective Lens ◽  
Electron Optical System ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Emission System

A field emission system for our experimental ultra high vacuum electron microscope has been designed, constructed and tested. The electron optical system is based on the prototype whose performance has already been reported. A cross-sectional schematic illustrating the field emission source, preaccelerator lens and accelerator is given in Fig. 1. This field emission system is designed to be used with an electron microscope operated at 100-150kV in the conventional transmission mode. The electron optical system used to control the imaging of the field emission beam on the specimen consists of a weak condenser lens and the pre-field of a strong objective lens. The pre-accelerator lens is an einzel lens and is operated together with the accelerator in the constant angular magnification mode (CAM).

Rocking Beam Microarea Diffraction Applied to Metallic thin Films

1976 ◽  
Vol 34 ◽  
pp. 396-397
Author(s):  
R. H. Geiss
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Small Area ◽  
Objective Lens ◽  
Electron Optics ◽  
Metallic Thin Films ◽  
Transmission Electron Diffraction ◽  
Transmission Electron ◽  
Sample Height ◽  
Scanning Transmission

The theory and practical limitations of micro area scanning transmission electron diffraction (MASTED) will be presented. It has been demonstrated that MASTED patterns of metallic thin films from areas as small as 30 Åin diameter may be obtained with the standard STEM unit available for the Philips 301 TEM. The key to the successful application of MASTED to very small area diffraction is the proper use of the electron optics of the STEM unit. First the objective lens current must be adjusted such that the image of the C2 aperture is quasi-stationary under the action of the rocking beam (obtained with 40-80-160 SEM settings of the P301). Second, the sample must be elevated to coincide with the C2 aperture image and its image also be quasi-stationary. This sample height adjustment must be entirely mechanical after the objective lens current has been fixed in the first step.

Electron holography of p-n junctions

1996 ◽  
Vol 54 ◽  
pp. 974-975
Author(s):  
B.G. Frost ◽  
D.C. Joy ◽  
L.F. Allard ◽  
E. Voelkl
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Field Emission ◽  
Ccd Camera ◽  
Image Plane ◽  
Reference Wave ◽  
Field Of View ◽  
Control Mode ◽  
Objective Lens ◽  
Electron Holography

A wide holographic field of view (up to 15 μm in the Hitachi-HF2000) is achieved in a TEM by switching off the objective lens and imaging the sample by the first intermediate lens. Fig.1 shows the corresponding ray diagram for low magnification image plane off-axis holography. A coherent electron beam modulated by the sample in its amplitude and its phase is superimposed on a plane reference wave by a negatively biased Möllenstedt-type biprism.Our holograms are acquired utilizing a Hitachi HF-2000 field emission electron microscope at 200 kV. Essential for holography are a field emission gun and an electron biprism. At low magnification, the excitation of each lens must be appropriately adjusted by the free lens control mode of the microscope. The holograms are acquired by a 1024 by 1024 slow-scan CCD-camera and processed by the “Holoworks” software. The hologram fringes indicate positively and negatively charged areas in a sample by the direction of the fringe bending (Fig.2).

Comparison of freeze-fractured yeast replicas using conventional TEM and low-voltage field-emission SEM

1989 ◽  
Vol 47 ◽  
pp. 74-75
Author(s):  
William P. Wergin ◽  
Eric F. Erbe ◽  
Terrence W. Reilly
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Low Voltage ◽  
Objective Lens ◽  
Specimen Preparation ◽  
Lens System ◽  
Air Drying ◽  
Preparation Techniques ◽  
Scanning Electron

Although the first commercial scanning electron microscope (SEM) was introduced in 1965, the limited resolution and the lack of preparation techniques initially confined biological observations to relatively low magnification images showing anatomical surface features of samples that withstood the artifacts associated with air drying. As the design of instrumentation improved and the techniques for specimen preparation developed, the SEM allowed biologists to gain additional insights not only on the external features of samples but on the internal structure of tissues as well. By 1985, the resolution of the conventional SEM had reached 3 - 5 nm; however most biological samples still required a conductive coating of 20 - 30 nm that prevented investigators from approaching the level of information that was available with various TEM techniques. Recently, a new SEM design combined a condenser-objective lens system with a field emission electron source.

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