Residual Gas Reaction in the Electron Microscope: II The Design of a Gas-Control Chamber for Quantitative Observations

1969 ◽  
Vol 27 ◽  
pp. 82-83
Author(s):  
Chester J. Calbick ◽  
Richard E. Hartman
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Local Environment ◽  
Chamber Pressure ◽  
Objective Lens ◽  
Ion Pump ◽  
Quantitative Studies ◽  
Precise Knowledge ◽  
Differential Pumping ◽  
And Control

Quantitative studies of the phenomenon associated with reactions induced by the electron beam between specimens and gases present in the electron microscope require precise knowledge and control of the local environment experienced by the portion of the specimen in the electron beam. Because of outgassing phenomena, the environment at the irradiated portion of the specimen is very different from that in any place where gas pressures and compositions can be measured. We have found that differential pumping of the specimen chamber by a 4" Orb-Ion pump, following roughing by a zeolite sorption pump, can produce a specimen-chamber pressure 100- to 1000-fold less than that in the region below the objective lens.

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).

Development of 120KV Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 144-145
Author(s):  
S. Suzuki ◽  
S. Mori ◽  
M. Mizuno ◽  
R. Ichikawa ◽  
T. Honda
Keyword(s):  
Electron Microscope ◽  
Biological Study ◽  
Objective Lens ◽  
Lens System ◽  
Beam Position ◽  
Transmission Electron ◽  
Diffraction Mode ◽  
New Ideas ◽  
Imaging Mode ◽  
And Control

A new electron microscope (EM) of 120 kV has been developed. This EM is designed for biological study but it incorporates many new ideas as a new transmission electron microscope. The main features of this new electron microscope are as follows.A. New Lens System and ControlThe illumination lens and imaging lens system and these control methods have been improved in this EM. It has three illumination mode, which are the spot focus mode, the parallel focus mode and the α focus mode. In the parallel focus mode, the cross over point under the specimen is kept on an objective aperture, which is placed in the back focal plane. That makes it possible to set the small objective aperture such as 20 micron without field cut and any sacrifices of specimen tilting angle at very low magnification. The objective lens condition in the diffraction mode is depending on the imaging mode, which are MAG mode and LOW MAG mode. That means it has two diffraction mode, the objective lens is kept on in one mode and off in the other mode corresponding to the imaging mode, MAG and LOW MAG modes. So the beam position is kept exactly on the specified area on the specimen during the changeover between the imaging mode and diffraction mode.

Characterization of a Fixed Beam Electron Microscope with a Field Emission Gun

1976 ◽  
Vol 34 ◽  
pp. 526-527
Author(s):  
Wah Chiu ◽  
Robert M. Glaeser
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Field Emission ◽  
Current Density ◽  
Beam Current ◽  
Beam Current Density ◽  
Objective Lens ◽  
Electron Beam Current ◽  
Beam Electron ◽  
Fixed Beam

One of the objectives of our research program is to obtain a 2.0 Å point to point resolution in a fixed beam bright field electron microscope. The resolution in the fixed beam electron microscope is limited by a number of factors: electron beam coherence, energy spread, objective lens stability, mechanical stability, and specimen stability. This paper presents systematic studies of the mentioned factors in our JEM 100B fixed beam electron microscope equipped with a field emission gun operating at ∼ 1800°K.The most important characteristic of a field emission gun is its high brightness in the emitter source. In order to estimate the brightness at the specimen plane, one needs to measure the electron beam current density and the angle of illumination. The electron beam current density has been measured by means of a lithium-drifted silicon detector located below the normal position of the photographic plates. The angle of illumination can be estimated from the size of the condenser aperture and its distance from the specimen plane.

The influence of the objective lens current in low magnification electron holography

1995 ◽  
Vol 53 ◽  
pp. 614-615
Author(s):  
B.G. Frost ◽  
D.C. Joy ◽  
E. Völkl ◽  
L.F. Allard
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Field Emission ◽  
Focal Plane ◽  
Reference Wave ◽  
Object Wave ◽  
Objective Lens ◽  
Electron Holography ◽  
Emission Electron

In order to align an electron microscope for low magnification holography we usually completely switch off the objective lens and image the sample by the first intermediate lens. In addition, to achieve a highly coherent electron beam we highly excite the condensor lens resulting in a divergent illumination of the sample and the intermediate lens. Now negatively biasing the fiber of a Möllenstedt type biprism placed between the first an second intermediate lenses of our Hitachi HF-2000 field emission electron microscope creates two virtual sources below the back focal plane of the first intermediate lens. These two sources are necessary to form off-axis holograms. Slightly exciting the objective lens and still imaging the sample by the first intermediate lens results in two major changes in our holograms.First: Due to an electron beam less divergent or even convergent illuminating the first intermediate lens when exciting the objective lens (compare Fig. 1 to Fig.2) the angle β at which object wave and reference wave are superimposed decreases.

Design of a 400KV Ultrahigh-Resolution Analytical TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 134-135
Author(s):  
H. Tsuno ◽  
T. Honda ◽  
Y. Kokubo
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Spherical Aberration ◽  
New Technology ◽  
Objective Lens ◽  
Ultrahigh Resolution ◽  
X Ray ◽  
Analytical Tem ◽  
Analytical Electron ◽  
Analytical Electron Microscope

The condenser-objective (C/O) lens proposed by Riecke, which has a very short gap length and small spherical aberration, was utilized for a commercial 200 kV ultrahigh resolution analytical TEM by Yanaka and Kaneyama. Fig. 1 shows the relation between theoretical resolution and objective lens (OL) spherical aberration coefficient (Cs) at accelerating voltages 200-1250 kV. It was reported that the Cs of a 400kV high resolution TEM is 1.0 mm and its resolution is 0.167 nm. The Cs of 400kV analytical TEM is 1.8 mm and the pre-field spherical aberration coefficient (Csp) is 1.8 mm. Fig. 2 (A), (B) show beam broading in specimens against the thickness when a 200kV and a 400kV electron beam transmit the specimen (C-Au), respectively. The broading of 400kV electron beam is about half of 200kV one. Then it is expected that spacial resolution of x-ray analysis improve. The above-captioned 400kV ultrahigh resolution analytical TEM is designed by applying a new technology which is adopted for a 200kV ultrahigh resolution analytical electron microscope, JEM-2010.Its fundamental construction is the same as the 400kV analytical electron microscope JEM-4000FX, except the 0L. The goniometer is a modified JEM-2010 goniometer, because it is too small for 400kV EM. Although it was expected that the focus ampere turn increases because of its short gap length, the objective lens coil used by JEM-4000EX/FX is adopted, because it has enough capacity. The shapes of the upper yoke and objective polepiece were calculated by the finite element method (55×110 Meshes) under the following condition: (1) maximum tilting-angle 10° (2) x-ray take-off angle 17.5° and solid angle 0.068 strad (3) minimized Cs.

scholarly journals Is Low Accelerating Voltage Always the Best for Semiconductor Inspection and Metrology?

2004 ◽  
Vol 12 (1) ◽  
pp. 46-47
Author(s):  
M. T. Postek ◽  
A. E. Vladár
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Beam ◽  
Electron Microscope ◽  
Operating Conditions ◽  
Dynamic Charging ◽  
Induced Signal ◽  
And Control ◽  
Scanning Electron ◽  
Semiconductor Production

Low accelerating voltage operation is an excellent mode of scanning electron microscopy and it is extensively used for measurements in semiconductor production. The beam penetration is small, and if properly applied, the specimen charging is kept at acceptable levels. But, is this always enough? Today, the scanning electron microscope (SEM) is being used in photomask metrology and imaging where charging is excessive. Charging is difficult to quantify and control as it varies greatly with instruments, operating conditions and sample. Therefore, it is also very difficult to model accurately. For accurate metrology charging must be overcome because the dynamic charging of the sample deflects the electron beam from its intended position and the intensity of the induced signal may vary uncontrollably. Deflection of the electron beam of even a few nanometers potentially results in a measurement error that is significant to modern semiconductor production.

High Resolution Side-Entry Goniometer

1980 ◽  
Vol 38 ◽  
pp. 56-57
Author(s):  
T. Honda ◽  
H. Watanabe ◽  
K. Ohi ◽  
E. Watanabe ◽  
Y. Kokubo
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Resolution Limit ◽  
Tilting Angle ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
High Resolution Images

An analytical electron microscope equipped with a side-entry goniometer (SEG) has recently become more widespread than a conventional electron microscope by the following reasons: (1) a variety of specimen holders, (2) large tilting angle with eucentricity. However, the resolution of SEG-system is about 0.4 nm, whereas the resolution of 0.25 nm or less can be obtained by an electron microscope equipped with a top-entry goniometer (TEG)1). Factors determining the resolution of an electron microscope are (1) the aberration coefficients of the objective lens, (2) stability of exciting currents, (3) illumination angle of the electron beam on the specimen, (4) energy spread of the electron beam, and ( 5) vibration and specimen drift. It has been usually difficult to observe high resolution images during use of the SEG system, because of the aberration coefficients of the objective lens, vibration and specimen drift. In order to obtain a resolution of less than 0.3 nm with SEG system at 200 kV, both of spherical and chromatic aberration coefficients should be reduced less than 2 mm. Moreover, relative amplitude of vibration between the specimen and pole pieces should be less than a half value of resolution limit. The image drift should be less than 0.02 nm/sec, because the exposure time usually required for photographing a high resolution image is about 5 second.

A Liquid Nitrogen Cooled Stage for STEM

1974 ◽  
Vol 32 ◽  
pp. 444-445
Author(s):  
Louis T. Germinario
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Liquid Nitrogen ◽  
Room Temperature ◽  
Objective Lens ◽  
Thermal Drift ◽  
Specimen Holder ◽  
Resolution Capability ◽  
Focal Position

A liquid nitrogen stage has been developed for the JEOL JEM-100B electron microscope equipped with a scanning attachment. The design is a modification of the standard JEM-100B SEM specimen holder with specimen cooling to any temperatures In the range ~ 55°K to room temperature. Since the specimen plane is maintained at the ‘high resolution’ focal position of the objective lens and ‘bumping’ and thermal drift la minimized by supercooling the liquid nitrogen, the high resolution capability of the microscope is maintained (Fig.4).

Observability of Very Thick Specimen by Using Transmission Scanning Electron Microscope

1971 ◽  
Vol 29 ◽  
pp. 26-27
Author(s):  
K. Shibatomi ◽  
T. Yamanoto ◽  
H. Koike
Keyword(s):  
Electron Microscope ◽  
Image Quality ◽  
Scanning Electron Microscope ◽  
Chromatic Aberration ◽  
Image Contrast ◽  
Objective Lens ◽  
Thick Specimen ◽  
Transmission Electron ◽  
Scanning Electron

In the observation of a thick specimen by means of a transmission electron microscope, the intensity of electrons passing through the objective lens aperture is greatly reduced. So that the image is almost invisible. In addition to this fact, it have been reported that a chromatic aberration causes the deterioration of the image contrast rather than that of the resolution. The scanning electron microscope is, however, capable of electrically amplifying the signal of the decreasing intensity, and also free from a chromatic aberration so that the deterioration of the image contrast due to the aberration can be prevented. The electrical improvement of the image quality can be carried out by using the fascionating features of the SEM, that is, the amplification of a weak in-put signal forming the image and the descriminating action of the heigh level signal of the background. This paper reports some of the experimental results about the thickness dependence of the observability and quality of the image in the case of the transmission SEM.

Resolving Crystallites in Zirconium Oxide Films

1969 ◽  
Vol 27 ◽  
pp. 140-141
Author(s):  
R.A. Ploc
Keyword(s):  
Electron Microscope ◽  
Inelastic Scattering ◽  
Zirconium Oxide ◽  
Oxide Films ◽  
Optic Axis ◽  
Objective Lens ◽  
Microscope Objective ◽  
Linear Optic ◽  
A Current ◽  
Microscope Objective Lens

The optic axis of an electron microscope objective lens is usually assumed to be straight and co-linear with the mechanical center. No reason exists to assume such perfection and, indeed, simple reasoning suggests that it is a complicated curve. A current centered objective lens with a non-linear optic axis when used in conjunction with other lenses, leads to serious image errors if the nature of the specimen is such as to produce intense inelastic scattering.

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