Electric lamp and discharge devices: systems – Discharge device load with fluent material supply to the... – Electron or ion source
Reexamination Certificate
2000-06-09
2001-09-18
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Discharge device load with fluent material supply to the...
Electron or ion source
C315S366000, C313S336000, C250S492230, C250S492300
Reexamination Certificate
active
06291940
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an electron source, and in particular to an electron source that uses a glow discharge and multiple individually extinguishable electron-emitting apertures to create multiple electron beamlets.
BACKGROUND
Electron lithographic or detection systems typically use a single electron beam to expose or image a substrate. A single beam approach, however, poses severe limitations to the maximum achievable pixel rate, whether used for pixel exposure or pixel detection. In order to satisfy the throughput requirements of present day manufacturing environments several techniques are being developed to increase this pixel rate. For example, one technique used to increase throughput is to increase the number of electron beams that are used for exposure or detection.
In order for such a multiple electron beam system to function properly numerous requirements must be met for each single beam, i.e., each beamlet, as well as the collection of beamlets, i.e., the array. Crucial parameters for each beamlet include, e.g., spot size, brightness, beam uniformity and energy spread, while parameters for the array include uniformity, reliability and manufacturability standards.
In a multi-beam system it is typically desirable to have the ability to individually extinguish each beamlet independently, i.e., blanking a beam. Conventionally, a beam is blanked by shifting the direction of the beam away from a transmission aperture thereby stopping the flow of electrons through the aperture. Electron beamlets, however, propagate in close proximity to each other and, thus, such an approach might be undesirable. The stray electrons created by this type of blanking action could very well disturb the propagation of the neighboring beamlets. It is therefore preferred to extinguish the beamlets at the source thereby preventing any unneeded electrons from entering the optical system.
SUMMARY
A multipixel electron emission device in accordance with the present invention separates a source of electrons from a plasma region. The electron source is contained in an electron source chamber and produces an electron beam that is passed through a wall separating the electron source chamber and the plasma region, e.g., through an entrance aperture. The plasma region, for example, may contain a heavy noble gas, such as Xenon, at low pressure and is surrounded by a high frequency helical coil to produce a plasma. The electron beam enters the plasma region and is diffused in the plasma, which advantageously provides a more uniform energy to the electrons in the electron beam. Moreover, the current of the electron emission device is advantageously controlled by the electron current produced by the electron source and is not limited by the characteristics of the plasma and wall interactions as found in conventional devices. An aperture grid coupled to the plasma region pulls electrons out of the plasma region over a large area thereby producing a broad area electron emission. A focusing chamber is positioned down stream of the plasma region and aperture grid and includes, for example, an multi-beam optical system with beam acceleration grids and deflection devices.
In accordance with an aspect of the present invention, an aperture grid is used as a blanking array. The aperture grid may be used in the above described electron source or may be used in other suitable electron sources. The aperture grid includes a base electrode, which is at a certain potential, and has at least one aperture. A dielectric layer fully or partially overlays the base electrode and surrounds the aperture. A blanker electrode overlays the dielectric layer and also surrounds the aperture. The dielectric layer isolates the blanker electrode from the base electrode. The blanker electrode and base electrode are switchably coupled.
In an “off” state, the blanker electrode is floating, i.e., not coupled to the base electrode, which permits the blanker electrode to become negatively charged from the electron stream that contacts the blanker electrode. Once the blanker electrode is negatively charged, the blanker electrode pinches off the electron stream through the aperture. In an “on” state, the blanker electrode is switchably coupled to the base electrode which drains the negative charge. Thus, the blanker electrode is at the same potential as the base electrode and the electron stream is permitted to pass through the aperture.
The aperture grid may be an integrated blanking and switching device which is manufactured using conventional thin film deposition and patterning techniques. A method of fabricating the integrated blanking and switching device includes providing a conductive substrate, such as a silicon substrate; forming, e.g., a pnp type transistor on the bottom side of the substrate, i.e., on the side that will not be exposed to the plasma region; etching at least one aperture through the substrate so that it extends through the collector of the transistor; depositing and patterning an insulating layer over the substrate so that it surrounds the aperture and covers the sidewalls of the aperture; and depositing and patterning a conductive layer to form a blanker electrode that surrounds the aperture and covers the sidewalls of the aperture. In addition, an inert conductor may be deposited on the top side of the substrate, i.e., the side that will be exposed to the plasma region. The inert conductor can serve as a base electrode or as merely a protective layer that protects the substrate from the glow discharge in the plasma region or electron bombardment from the electron sources. The blanker electrode is coupled to the collector of the pnp type transistor, the emitter is coupled to the conductive substrate and the base is coupled to an external lead and is used to turn on and off the transistor. If desired, additional embedded logic may be included on the aperture grid.
REFERENCES:
patent: 4684848 (1987-08-01), Kaufman et al.
patent: 4686554 (1987-08-01), Ohmi et al.
patent: 5003178 (1991-03-01), Livesay
patent: 5363021 (1994-11-01), MacDonald
patent: 5659329 (1997-08-01), Yamanobe et al.
patent: 5752142 (1998-05-01), Staples et al.
patent: 5876576 (1999-03-01), Fu
patent: 6166387 (2000-12-01), Muraki et al.
Baltakov, et al., “Use of a high-voltage glow discharge in an electron gun”, Sov. Phys. Tech. Phys., vol. 21, No. 10, pp. 1290-1291 (Oct. 1976).
Bauer, et al., “High current plasma based electron source”, Appl. Phys. Lett. 57, No. 5, pp. 434-436, (Jul. 30, 1990).
Bayless, “Plasma-cathode electron gun”, Rev. Sci. Instrm., vol. 46, No. 9, pp. 1158-1160 (Sep. 1975).
Belyuk, et al., “Emitter and beam parameters of a plasma electron source with a high brightness”, Sov. Phys. Tech. Phys., vol. 11, pp. 1427-1428 (Nov. 1979).
Belyuk, et al., “Operation of a plasma electron source over a broad range of working-gas pressure”, Sov. Phys. Tech. Phys. No. 25, pp. 124-125 (Jan. 1980).
Bevov, et al., “Pulsed electron sources with a plasma electron emitter”, Sov. Phys. Tech. Phys. 28 (4), pp. 412-413 (Apr. 1983).
Bowden, et al., “Comparison of electron property measurements in an inductively coupled plasma made by Langmuir probe and laser Thompson scattering techniques”, J. Vac. Sci. Technol. 17(2), pp. 493-499 (Mar./Apr. 1999).
Fedorov, “Electron Source in a plasma”, Sov. Phys. Tech. Phys. 25(7), pp. 808-809, (Jul. 1980).
Hori, et al., “Measurements of electron temperature, electron density and neutral density in a radio-frequency inductively coupled plasma”, 14(1), pp. 144-150 (Jan./Feb. 1996).
Ivanov, et al., “Electron temperature in heavy inert gas plasmas at low etching fields”, Sov. Phys. Tech. Phys. 31(10), pp. 1202-1204, (Oct. 1986).
Kaufman, “Broad-beam electron source”, J. Vac. Sci. Technol. A 3(4), pp. 1774-1778, (Jul./Aug. 1985).
Kim, et al., “Dually driven radio frequency plasma simulation with a three moment model”, J. Vac. Sci Technol. A 16(4), pp. 2162-2172 (Jul./Aug. 1998).
Kolokolov, et al., “Electron energy distribution function in a afterglow plasma with a radial electric field”, Sov.
Applied Materials Inc.
Philogene Haissa
LandOfFree
Blanker array for a multipixel electron source does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Blanker array for a multipixel electron source, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Blanker array for a multipixel electron source will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2454643