Multisource optimization of a column for electron lithography

Mankos, M.; Coyle, S. T.; Fernandez, A.; Sagle, A.; Allen, Paul C.; Owens, William R.; Sullivan, Joseph; Chang, T. H. P.

doi:10.1116/1.1321752

Cited by 28 publications

(13 citation statements)

References 15 publications

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“…Although it is versatile and capable of extremely high patterning resolution, its usage is still limited in the semiconductor fabrication industry because of its low throughput, which primarily results from its "direct write" nature. Among the approaches to improve the performance of electron-beam lithography is the usage of shaped [201][202][203] and multiple [204][205][206][207][208][209][210][211] beams. For example, rather than using a focused beam with a nanoscale spot size to create an entire pattern point by point in a full-direct-right strategy, one may employ a wide beam shaped with various apertures to project large portions of the pattern with simple shapes such as rectangles and triangles.…”

Section: Applications Of Light-induced Thermionic Emission Frommentioning

confidence: 99%

Carbon Nanotube Electron Sources: From Electron Beams to Energy Conversion and Optophononics

Nojeh

2014

ISRN Nanomaterials

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Carbon nanotubes have a host of properties that make them excellent candidates for electron emitters. A significant amount of research has been conducted on nanotube-based field-emitters over the past two decades, and they have been investigated for devices ranging from flat-panel displays to vacuum tubes and electron microscopes. Other electron emission mechanisms from carbon nanotubes, such as photoemission, secondary emission, and thermionic emission, have also been studied, although to a lesser degree than field-emission. This paper presents an overview of the topic, with emphasis on these less-explored mechanisms, although field-emission is also discussed. We will see that not only is electron emission from nanotubes promising for electronsource applications, but also its study could reveal unusual phenomena and open the door to new devices that are not directly related to electron beams.

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Section: Applications Of Light-induced Thermionic Emission Frommentioning

confidence: 99%

Carbon Nanotube Electron Sources: From Electron Beams to Energy Conversion and Optophononics

Nojeh

2014

ISRN Nanomaterials

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“…Photocathodes have problems with poor current stability, short lifetime, and low brightness. [12][13][14][15][16][17] Cold field emitters, on the other hand, are promising candidates due to their high brightness, small virtual source size, and low energy spread. They can be produced easily and cost effectively in a microfabricated array.…”

Section: -11mentioning

confidence: 99%

Multibeam scanning electron microscope: Experimental results

Gheidari

Hagen

Kruit

2010

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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The authors present the first results obtained with their multibeam scanning electron microscope. For the first time, they were able to image 196 ͑array of 14ϫ 14͒ focused beams of a multielectron beam source on a specimen using single beam scanning electron microscope ͑SEM͒ optics. The system consists of an FEI Novanano 200 SEM optics column equipped with a multielectron beam source module. The source module consists of the multibeam source and an accelerator lens. In the multibeam source, the wide angle beam of a high brightness Schottky source is divided into 196 beamlets and focused by an aperture lens array. The accelerator lens is positioned on the image plane of the multibeam source to direct the beams toward the SEM column. The array of source images is further imaged by the SEM magnetic lenses, and the beam opening angle is defined at the variable aperture of the SEM. The system is designed to deliver 14ϫ 14 arrays of beamlets with a minimum probe size of 1 nm. In this article, the performance of the system is examined for a fixed magnification case.

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“…7 This in turn introduces aberrations in the beams and a distortion of the square array of beams. The most important negative effects of off axis illumination are (1) chromatic aberration in each beam, (2) spherical aberration in each beam, (3) distortion of the array positions, (4) defocus due to field curvature.…”

Section: Design Approach For a Multi-beam Electronmentioning

confidence: 99%

Addendum to Proceedings of SCANNING 2005 April 5-7, 2005 Monterey, Calif., USA

2006

Scanning

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Electron-beam lithography is used extensively in nanoscience and technology for making masks for the semiconductor industry and, on a limited scale, for maskless lithography, that is, writing the patterns directly on the chip. We expect the latter application to extend in the years to come. Control of the dimensions of the written structures is essential in the semiconductor industry. For the 45 nm generation, which is presently under development and should reach production at the end of the decade, the required control over the line width is between 1.5 and 5 nm depending on the application. One of the factors of influence on the line width control is the statistics in the number of electrons illuminating the resist. This effect gives line edge roughness or, in other words: a lack of control over the local position of a resist edge. This has long been recognized and often been discussed. Recently, we developed an analytic model for the line edge position variation. The model, supported by Monte Carlo simulations, demonstrates that the line width variation is inversely proportional to the dose used for the illumination of the resist. This makes it impossible to increase the lithography throughput by developing ultrasensitive resists. For features written at the 45 nm generation with a typical resolution of 30 nm, a 30 µC/cm 2 resist gives 3σ line width variation of 3.5 nm over line segments 45 nm long. An expansion of the model demonstrates the dependence on the resolution, or blur, of the lithography machine.The line width is usually measured in an adapted critical dimension scanning electron microscope (CD-SEM). This measurement needs to be more precise than the result of the lithography step, so the requirements are typically sub-nm. Apart from all the problems to avoid systematic errors, this measurement also suffers from statistical variations, resulting from the finite number of electrons used for the measurement. We have derived an estimate for that variation with a similar model as used for the shot noise effect in the lithography step. Shot noise can usually be reduced by increasing the measurement time, but this is often not an option because many features must be inspected in a limited time. One of the conclusions is that for the most precise measurements of the line width it is not advisable to tune the CD-SEM for the best resolution. It is better to allow a larger probe size of the electron beam because that can be accompanied by a much larger current and thus a decrease in the noise level. Design Approach for a Multi-Beam Electron Beam-Induced Deposition SystemB. VAN SOMEREN, M.J. VAN Electron beam-induced deposition (EBID) is a new application in scanning electron beam systems that has gained considerable interest in the past decade. If this application is used to make structures of 1 to 2 nm, 1-5 the time required for one operation increases with the resolution of the deposition. We are currently developing a multi-beam approach for EBID applications to decrease the time required to make a stru...

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Multisource optimization of a column for electron lithography

Cited by 28 publications

References 15 publications

Carbon Nanotube Electron Sources: From Electron Beams to Energy Conversion and Optophononics

Carbon Nanotube Electron Sources: From Electron Beams to Energy Conversion and Optophononics

Multibeam scanning electron microscope: Experimental results

Addendum to Proceedings of SCANNING 2005 April 5-7, 2005 Monterey, Calif., USA

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