Low-voltage high-resolution Scanning Electron Microscopy of semiconductors

1989 ◽  
Vol 47 ◽  
pp. 82-83
Author(s):  
S.J. Krause ◽  
G.N. Maracas ◽  
W.J. Varhue ◽  
D.C. Joy
Keyword(s):  
High Resolution ◽  
High Performance ◽  
Low Voltage ◽  
Image Recording ◽  
Surface Charging ◽  
New Information ◽  
Negative Surface ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

The advent of scanning electron microscopes (SEMs) with reliable, high performance field emission guns (FEG) has afforded many opportunities to obtain new information at low voltages not available at higher voltages in traditional SEMs equipped with tungsten hairpin or LaB6 filaments. The FEG SEMs are able to operate at low voltages with both high brightness and high resolution (HR) due to the small source size and low energy spread of the beam. Resolution of 4 nm down to 1.5 nm are routinely possible in the energy range from 1 to 5 keV along with standard image recording times of 1 to 2 minutes. The low voltage capabilities have allowed insulating materials, such as polymers, composites, and ceramics to be imaged at high resolutions at energies below the second crossover, usually around 1 to 2 keV, without experiencing image artifacts from negative surface charging normally found in uncoated insulators at higher operating voltages.

Current State of Biological High-Resolution Scanning Electron Microscopy

1988 ◽  
Vol 46 ◽  
pp. 180-181 ◽  
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Performance ◽  
Low Voltage ◽  
Backscattered Electrons ◽  
Lens Position ◽  
Low Voltage Operation ◽  
Signal Collection ◽  
Probe Size ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

A new generation of high performance field emission scanning electron microscopes (FSEM) is now commercially available (JEOL 890, Hitachi S 900, ISI OS 130-F) characterized by an "in lens" position of the specimen where probe diameters are reduced and signal collection improved. Additionally, low voltage operation is extended to 1 kV. Compared to the first generation of FSEM (JE0L JSM 30, Hitachi S 800), which utilized a specimen position below the final lens, specimen size had to be reduced but useful magnification could be impressively increased in both low (1-4 kV) and high (5-40 kV) voltage operation, i.e. from 50,000 to 200,000 and 250,000 to 1,000,000 x respectively.At high accelerating voltage and magnification, contrasts on biological specimens are well characterized1 and are produced by the entering probe electrons in the outmost surface layer within -vl nm depth. Backscattered electrons produce only a background signal. Under these conditions (FIG. 1) image quality is similar to conventional TEM (FIG. 2) and only limited at magnifications >1,000,000 x by probe size (0.5 nm) or non-localization effects (%0.5 nm).

Direct Defect Imaging in the High Resolution Sem

1990 ◽  
Vol 183 ◽  
Author(s):  
David C Joy
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
High Performance ◽  
Necessary Conditions ◽  
Electron Channeling ◽  
Electron Microscopes ◽  
Crystallographic Defects ◽  
Scanning Electron Microscopes ◽  
Defect Imaging ◽  
Scanning Electron

AbstractThe theory of imaging crystallographic defects in solid specimens through the use of electron channeling contrast is reviewed and the necessary conditions for observation are deduced. It is shown that current high performance field emission scanning electron microscopes can meet these requirements and produce dislocation images from suitable materials.

High resolution Scanning Electron Microscopy

1989 ◽  
Vol 47 ◽  
pp. 6-7
Author(s):  
David C. Joy
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
High Performance ◽  
Secondary Electron ◽  
Wide Energy Range ◽  
Wide Energy ◽  
Electron Microscopes ◽  
Electron Imaging ◽  
Scanning Electron

High resolution scanning electron microscopy is still a relatively new and unfamiliar concept because in the early days of the SEM it was expected, that secondary electron imaging would be limited to a resolution of between 5 and 10nm at best. Now, however, because of improvements in instrumentation and technique based on advances in the understanding of electron beam interactions with solids current SEMs can demonstrate spatial resolutions below 1nm, rivaling those obtained by transmission instruments.High performance scanning electron microscopes always incorporate two advanced items of instrumentation. Firstly they use field emission guns (FEGs). The high brightness, low energy spread, and small source size of the FEG makes it possible to produce an electron probe of sub-nanometer size which contains sufficient current for secondary electron imaging (i.e 10-12 amps or more) and which can maintain this performance over a wide energy range (3 to 30keV). Secondly, the new high performance instruments place the specimen within a high excitation, immersion, probe forming lens.

Applications of High Resolution Immersion Lens Scanning Electron Microscopes to Sem-Based Defect Review at 250nm Design Rules

1998 ◽  
Vol 523 ◽  
Author(s):  
B. Tracy
Keyword(s):  
High Performance ◽  
Low Voltage ◽  
Semiconductor Industry ◽  
Image Resolution ◽  
Objective Lens ◽  
Dramatic Improvement ◽  
Design Rules ◽  
Electron Microscopes ◽  
Routine Observation ◽  
Scanning Electron

IntroductionThe use of SEM-based defect review tools has increased dramatically over the past five years as the semiconductor industry moved from 0.7 micron to 0.25 micron design rules. During this period, a dramatic inflection occurred at the 0.5 micron node; optical microscopy lacked sufficient resolution to determine even if a simple etch step was properly performed. Accordingly, many “inspection SEMs” were introduced into the wafer fabrication facility. With ever increasing focus on yield improvement, defect review SEM's proliferated in the fab in an effort to drive down both baseline defects and process excursions. In order for such an effort to be successful, a clear improvement in the low voltage image resolution performance of the scanning electron microscope was required. Commercial vendors have responded with impressive tools achieving image resolutions of 2.5–4nm @1 kV. At this level of performance, routine observation of semiconductor wafers is possible at 100,000X magnification. This dramatic improvement in resolution is the result of many factors, by far the biggest of which is the use of “immersion lens” designs which employ a strongly excited objective lens operated at short working distances (∼2mm). This electron optic design was first introduced into the laboratory SEM market, with instruments capable of producing approximately 1.2nm resolution at 20kV. These high performance lenses in which the magnetic field extends below the bottom of the polepiece, were fitted onto 200mm platforms allowing whole wafer inspection/defect review. The features of such tools and their application to the IC industry is the subject of this paper. An example of the superb imaging performance of such a 200mm tool is illustrated in figure 1.

scholarly journals Depth Information Available from the Backscattered Electron Signal

1995 ◽  
Vol 3 (6) ◽  
pp. 8-9
Author(s):  
V.N.E. Robinson
Keyword(s):  
Surface Topography ◽  
Atomic Number ◽  
Secondary Electron ◽  
Low Voltage ◽  
Depth Information ◽  
New Techniques ◽  
Backscattered Electron ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

Although the secondary electron (SE) signal is still the most commonly used signal in scanning electron microscopes (SEMs), the backscattered electron (BSE) signal is now in wide use. Imaging both atomic number and surface topography have been the major applications of BSE detectors, with some applications in channelling, magnetic contrast and similar specialized applications. Over the last few years, low voltage BSE imaging has been used for imaging surface features to a depth of a few nm. But the BSE signal contains much more information and new techniques are being developed to take advantage of its versatility.

Ceramics in the environmental Scanning Electron Microscope

1993 ◽  
Vol 51 ◽  
pp. 910-911
Author(s):  
Stuart McKeman
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Low Voltage ◽  
Ceramic Materials ◽  
Environmental Scanning Electron Microscope ◽  
Environmental Scanning ◽  
Dynamic Experiments ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

Several recent advances have had a major potential impact on the microscopy of ceramic materials. The ability of modern scanning electron microscopes to image uncoated materials, at low voltage for example, whilst still maintaining high resolution should make possible a wide variety of experiments that were hitherto impossible to contemplate. This ability to look at the unmodified surface of a ceramic enables iterative or dynamic experiments to be done with a lot more confidence in the results than has been possible before. A second advance has been the introduction of microscopes capable of operating at higher pressures than was previously possible. This makes possible the ability to image specimens in a variety of different environments. The environmental scanning electron microscope (ESEM) exploits of both of these novel areas. The aim of this review is to highlight areas where the unique capabilities of the ESEM may be applied to advance our understanding of ceramics.

Caustic patterns combined with second and third order astigmatism in high resolution scanning electron microscopes

1990 ◽  
Vol 21 (1-2) ◽  
pp. 57-68 ◽  
Author(s):  
Koichi Kanaya ◽  
Eisaku Oho ◽  
Koichi Adachi ◽  
Yoshiaki Yamamoto ◽  
Hiroshi Doi
Keyword(s):  
High Resolution ◽  
Third Order ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron
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