Applied Physics Technologies Inc.

McMinnville, OR, United States

Applied Physics Technologies Inc.

McMinnville, OR, United States

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MacKie W.A.,Applied Physics Technologies Inc. | Magera G.G.,Applied Physics Technologies Inc.
Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics | Year: 2011

The authors report on electron emission defining and stability techniques use for specialized thermionic cathodes. Primarily lanthanum hexaboride and cerium hexaboride have been used for cathode materials but we also use hafnium carbide for cases where background atmospheres preclude the use of hexaborides. A common form of emission suppression is to embed an oriented single crystal in graphite to suppress side emission and to help shape the electric field. Single planar discs 50 μm in diameter have been tested for use as high brightness, stable, and long life thermal sources. Line sources have also been developed with linewidth/lengths to 10/500 μm. Emission tests performed have shown that long-term drift and short-term instabilities can originate from boride and carbon interactions respectively. Improved mounting techniques are shown to yield emission with short-term beam current stability <0.05%. © 2011 American Vacuum Society.


Mackie W.A.,Applied Physics Technologies Inc. | Lovell J.M.,Applied Physics Technologies Inc. | Curtis T.W.,Applied Physics Technologies Inc. | Magera G.G.,Applied Physics Technologies Inc.
Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics | Year: 2014

The authors report on electron emission from HfC(310) operating in extended Schottky emission mode. Data are gathered from test stands as well as through operation in a commercial scanning electron microscope. Emitter end-form geometry consisted of rounded, via electrochemical etching, and truncated, via ion milling. The authors demonstrate high angular intensity operation of >60mA/sr especially for the rounded end-form emitters. Advantages include robustness of the material, which is not reliant on material supply as is the case with standard ZrO/W(100) sources. Hence, operation is available over a much larger range of temperatures, fields, and potentially pressures. Operation in a commercial scanning electron microscope gave ten times higher beam currents for identical operational parameters over a standard Schottky source. © 2014 American Vacuum Society.


Mackie W.A.,Applied Physics Technologies Inc. | Magera G.G.,Applied Physics Technologies Inc. | Lovell J.M.,Applied Physics Technologies Inc.
2016 IEEE International Vacuum Electronics Conference, IVEC 2016 | Year: 2016

We report on high-brightness, thermal-field emission cathodes using (210) and (110) oriented hafnium carbide. HfC(210) cathodes are shown to deliver very high angular intensities to >50 mA/sr and remain stable. Modeling and experimental data are shown which highlights the utility of these sources for SEM and other high-brightness uses. © 2016 IEEE.


Magera G.G.,Applied Physics Technologies Inc. | Katsap V.,Applied Physics Technologies Inc.
2010 IEEE International Vacuum Electronics Conference, IVEC 2010 | Year: 2010

LaB6 cathode is still the emitter of choice in a variable-shape beam (VSB) electron beam lithography tool. In commercial LaB6 cathodes, the (100) crystalline plane is used as the emissive surface. Typical size of emitter is ∼70 μm DIA. Though generally stable, this crystalline plane is sensitive to residual atmosphere, and it may have microscopic defects (inclusions, dislocations, etc.) which appear and evolve over the time. Routine initial microscopic inspection of LaB6 cathodes gives us an initial optical/SEM image of surface, which may change during cathode life. With a simple technique, we have obtained LaB6 cathode emission images, which showed features unavailable to optical and electron microscopy. This technique can be used for LaB6 quality evaluation during standard cathode test runs. © 2010 IEEE.


Mackie W.A.,Applied Physics Technologies Inc. | Magera G.G.,Applied Physics Technologies Inc. | Fast C.L.,Applied Physics Technologies Inc.
2010 IEEE International Vacuum Electronics Conference, IVEC 2010 | Year: 2010

We have produced thermionic cathodes using (100) oriented lanthanum and cerium hexaboride as the emission sources. These cathodes use the Vogel mount system for mechanical alignment and heating. While this mount is superior for mechanical stability we show methods to improve emission stability which are mount related. © 2010 IEEE.


Mackie W.A.,Applied Physics Technologies Inc. | Magera G.G.,Applied Physics Technologies Inc.
23rd International Vacuum Nanoelectronics Conference, IVNC 2010 | Year: 2010

HfC was evaluated as a cold field emission source. Single crystal HfC was produced and fabricated into cold field emitters, then angular intensity and reduced brightness were determined from experimental I(V) data. Energy distribution data were in agreement with a theoretical model. The reduced brightness, energy distribution, and emission stability are compared to commercially available sources which show that HfC produced a higher brightness and a lower energy spread than a W cold field source or a ZrO/W Schottky emitter. HfC maintains its emission level for one hour in moderate UHV condition; a dramatic improvement over the stability of W. This combined with a durability that allows for frequent flash cleaning without degradation of the emitter end form make HfC a highly promising source. We compared stability and noise to emission from a tungsten tip at the same angular intensity. By increasing the emitter temperature slightly, stability is improved while maintaining a low energy spread. © 2010 IEEE.


Patent
Applied Physics Technologies Inc. | Date: 2013-11-11

A thermionic emission assembly includes a Wehnelt cap that has a cap beam aperture and a cavity within which a cathode is supported. Electrical energy applied to the cathode causes it to reach a sufficiently high temperature to emit a beam of electrons that propagate through the cap beam aperture. An anode having an anode beam aperture is positioned in spatial alignment with the cap beam aperture to receive the electrons. The anode accelerates the electrons and directs them through the anode beam aperture for incidence on a target specimen. A ceramic base forms a combined interface that electrically and thermally separates the Wehnelt cap and the anode. The thermal isolation of the Wehnelt cap from the anode allows the Wehnelt cap to increase in heat to rapidly reach a stable temperature as the cathode emits the beam of electrons.

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