Impact of secondary electron emission noise in SEM

Microscopy ◽  
2019 ◽  
Vol 68 (4) ◽  
pp. 279-288 ◽  
Author(s):  
Makoto Sakakibara ◽  
Makoto Suzuki ◽  
Kenji Tanimoto ◽  
Yasunari Sohda ◽  
Daisuke Bizen ◽  
...  
Keyword(s):  
Semiconductor Device ◽  
Secondary Electron Emission ◽  
Image Noise ◽  
Sem Images ◽  
Sem Image ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Primary Electrons ◽  
Imaging Conditions ◽  
Si Wafer

Abstract In semiconductor-device inspection using scanning electron microscopes (SEMs), the irradiation dose of the electron beam becomes lower because of increasing needs for higher throughput and lower damage to the samples. Therefore, it is necessary to form images using fewer primary electrons, making noise reduction of SEM images one of the main challenges. We have modeled the imaging process of SEMs, which consists of the generation of primary, secondary and tertiary electrons (PEs, SEs and TEs, respectively), and detection. Furthermore, a method to accurately evaluate the fluctuation in the number of SEs and TEs are proposed. We found that SEM-image noise can be minimized by directly detecting SEs generated in the sample, in which case the fluctuation in the number of SEs determines the image quality. The variance number of SEs emitted from a 500-eV PE irradiation onto a Si wafer is 1.9 times as large as the value derived assuming a Poisson process. A Monte-Carlo simulation result was used to explain the experimental results and predict that PE energy less than 1 keV suppresses the fluctuation in the number of SEs, and consequently, the SEM-image noise level. These findings provide a method for determining imaging conditions that improve the throughput of SEMs.

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.

Field of View and Image Distortion : A Review of Low Magnification Imaging In the Environmental and Conventional Scanning Electron Microscopes (SEM)

1997 ◽  
Vol 3 (S2) ◽  
pp. 1193-1194
Author(s):  
Brendan J. Griffin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Field Of View ◽  
Depth Of Field ◽  
Aperture Size ◽  
Sem Image ◽  
Electron Microscopes ◽  
Working Distance ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

Most scanning electron microscopy is performed at low magnification; applications utilising the large depth of field nature of the SEM image rather than the high resolution aspect. Some environmental SEMs have a particular limitation in that the field of view is restricted by a pressure limiting aperture (PLA) at the beam entry point of the specimen chamber. With the original ElectroScan design, the E-3 model ESEM utilised a 500 urn aperture which gave a very limited field of view (∼550um diameter at a 10mm working distance [WD]). An increase of aperture size to ∼lmm provided an improved but still unsatisfactory field of view. The simplest option to increase the field of view in an ESEM was noted to be a movement of the pressure and field, limiting aperture back towards the scan coils1. This approach increased the field of view to ∼2mm, at a 10mm WD. A commercial low magnification device extended this concept and indicated the attainment of conventional fields of view.

Stereological Analysis Of Sem Images

1977 ◽  
Vol 35 ◽  
pp. 212-213
Author(s):  
H. S Schmiβer ◽  
R. A. Swensson
Keyword(s):  
Image Analysis ◽  
Three Dimensional ◽  
Quantitative Information ◽  
Quantitative Image Analysis ◽  
Sem Images ◽  
Detection Systems ◽  
The Past ◽  
Quantitative Image ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes

Development of new signal detection systems for STEREOSCAN scanning electron microscopes has greatly increased the applicability of quantitative image analysis to pictures obtained with an s.e.m. While quantitative image analysis has proven to be a powerful technique to draw quantitative information from pictures obtained from light microscopes as well as various other sources of images, the field of scanninq electron microscopy has largely been uncovered in the past.This was mainly due to the particular appearance of “normal” s.e.m. pictures. Exactly those features which make s.e.m. pictures easy to interpret intuitively an aesthetically attractive i.e. the pseudo three dimensional appearance made it virtually impossible to treat these images with the well known methods of electronic image analysis.

Imaging the Probe Skirt in the Environmental SEM

2000 ◽  
Vol 6 (S2) ◽  
pp. 794-795
Author(s):  
B.L. Thiel ◽  
I.C. Bache ◽  
P. Smith
Keyword(s):  
Mean Free Path ◽  
High Energy ◽  
Large Area ◽  
Resolution Imaging ◽  
The Mean ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Primary Electrons ◽  
Environmental Sem ◽  
Better Than

In low vacuum scanning electron microscopes, the primary beam is partially scattered by the gas present in the specimen chamber. The development of these microscopes, in particular the so-called ‘Environmental’ SEM, was initiated when it was realized that this scattering does not necessarily compromise the imaging capabilities of the instrument. Indeed, some modern commercial instruments are capable of better than 2 nanometer resolution at gas pressures of several torr. The accepted explanation for this is as follows: The mean-free-path of the high energy primary electrons is several millimeters in one torr of water vapour (for example). Because the actual pathlength of electrons travelling through the gas is only a few millimeters, most of them do not scatter at all. Those that do scatter are supposedly distributed over a relatively large area. Thus, the probe features a high-intensity central region surrounded by a slowly decaying low-intensity skirt. High resolution imaging is possible because the signal-to-(skirt)background ratio is high.

scholarly journals Ultra Low Voltage BSE Imaging

2003 ◽  
Vol 11 (6) ◽  
pp. 26-29 ◽  
Author(s):  
Michael D.G. Steigerwald
Keyword(s):  
Field Emission ◽  
Low Voltage ◽  
Incident Beam ◽  
Primary Energy ◽  
Pole Piece ◽  
Magnetic Lens ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Primary Electrons ◽  
Scanning Electron

LEO's field emission scanning electron microscopes are all based an the “GEMINI” principle as shown in figure 1. In order to reduce aberrations and sensitivity to interfering stray-fields the electron optical column possesses a positively biased booster that shifts the energy of the primary electrons. The incident beam is focussed by a combination of a magnetic lens with an axial gap that avoids field leakage to the specimen and an electrostatic retarding lens formed by the beam booster together with the grounded pole piece cap. Shortly before the electrons hit the specimen they are decelerated down to the desired primary energy.

Application of Peltier Cooling Device in a Variable-Pressure SEM

2015 ◽  
Vol 231 ◽  
pp. 139-144
Author(s):  
Anna Wassilkowska ◽  
Teresa Woźniakiewicz
Keyword(s):  
Observation Time ◽  
Variable Pressure ◽  
Water Protection ◽  
Cooling Device ◽  
Peltier Cooling ◽  
Optimal Observation ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Imaging Conditions ◽  
Scanning Electron

In environmental monitoring and water protection one has to deal with various hydrated specimens, and therefore, there is a need for scanning electron microscopes which are suited for hydrated specimens. Wet specimens can be observed in a hydrated state using a commercial Peltier cooling holder for conventional microscopes. However, the optimization of the time of observation for the sample needs to be determined by carrying out experiments in advance for specifically determining the optimal observation time. The temperature-pressure conditions also require optimization to obtain good quality images of amoeba and fungi. Further studies are required to establish whether the same imaging conditions would be possible to replicate closely the observation on other biological specimens.

scholarly journals Alteration in surface roughness of reciprocating endodontic instruments

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 875
Author(s):  
Khoa Van Pham
Keyword(s):  
Surface Roughness ◽  
Roughness Parameters ◽  
Root Canal Preparation ◽  
Sem Images ◽  
Significance Level ◽  
Glide Path ◽  
Before And After ◽  
Electron Microscopes ◽  
Imagej Software ◽  
Scanning Electron Microscopes

Background: Surface roughness is one of the most important characteristics of endodontic instruments, correlating to instrument fracture. The purpose of this study was to measure the surface roughness values of these instruments before and after resin root canal preparation without previous glide path preparation, with the new method. Data was obtained from field emission scanning electron microscopes (FE-SEM) combined with independent ImageJ software (NIH, Bethesda, MD, USA). Methods: A total of 20 simulated J-shape resin blocks with a radius of 4.5 mm, length of 16 mm, and angle of inflection of 600 were chosen and distributed into two equal groups. Each group was prepared by the WaveOne Gold Primary (Dentsply Sirona, Maillefer, Ballaigues, Switzerland) or the Reciproc Blue R25 (VDW, Munich, Germany) instruments, without glide path preparation. Special molds were used to confirm the same areas on the cutting blade at 3 mm and the instruments’ tips were scanned by FE-SEM, at different observed times. The parameters of Ra, Rq, and Rz in each sample were collected using the ImageJ software for analyses. The data was processed using the paired t-test with a significance level of 0.05. Results: Right after the first resin canal instrumentation, the surface roughness parameters of the two reciprocating investigated instruments were decreased. Conclusions: The FE-SEM images processed using the ImageJ software offered a trustworthy and suitable method for assessment of the NiTi endodontic file surface roughness.

scholarly journals SEM Image Sharpness Analysis

1996 ◽  
Vol 4 (8) ◽  
pp. 18-19
Author(s):  
M.T. Postek ◽  
A.E. Vladar
Keyword(s):  
Image Sharpness ◽  
Critical Dimensions ◽  
Sem Image ◽  
Electron Microscopes ◽  
Automated Scanning ◽  
Automated Instrument ◽  
Scanning Electron Microscopes ◽  
Day By Day ◽  
Scanning Electron ◽  
Semiconductor Production

Fully automated or semi-automated scanning electron microscopes (SEM) are now commonly used in semiconductor production and other forms of manufacturing. The industry requires that an automated instrument must be routinely capable of 5 nm resolution (or better) at 1.0 kV accelerating voltage for the measurement of nominal 0.25-0.35 micrometer semiconductor critical dimensions. Testing and proving that the instrument is performing at this level on a day-by-day basis is an industry need and concern which has been the object of a study at IMIST. The fundamentals and results are discussed in this paper.

Trends in Electron Energy Loss Spectroscopy

1977 ◽  
Vol 35 ◽  
pp. 228-229
Author(s):  
C. Colliex ◽  
P. Trebbia
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Materials Science ◽  
Analytical Technique ◽  
Recent Developments ◽  
Quantitative Results ◽  
Electron Microscopes ◽  
Electron Energy Loss ◽  
Primary Electrons

The physical foundations for the use of electron energy loss spectroscopy towards analytical purposes, seem now rather well established and have been extensively discussed through recent publications. In this brief review we intend only to mention most recent developments in this field, which became available to our knowledge. We derive also some lines of discussion to define more clearly the limits of this analytical technique in materials science problems.The spectral information carried in both low ( 0<ΔE<100eV ) and high ( >100eV ) energy regions of the loss spectrum, is capable to provide quantitative results. Spectrometers have therefore been designed to work with all kinds of electron microscopes and to cover large energy ranges for the detection of inelastically scattered electrons (for instance the L-edge of molybdenum at 2500eV has been measured by van Zuylen with primary electrons of 80 kV). It is rather easy to fix a post-specimen magnetic optics on a STEM, but Crewe has recently underlined that great care should be devoted to optimize the collecting power and the energy resolution of the whole system.

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