X-ray or gamma ray systems or devices – Source
Reexamination Certificate
1998-11-18
2001-05-01
Bruce, David V. (Department: 2876)
X-ray or gamma ray systems or devices
Source
C378S121000
Reexamination Certificate
active
06226354
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to short-wavelength electromagnetic-radiation generators that generate electromagnetic radiation having short wavelengths by causing photons and electrons to collide.
2. Description of the Related Art
In lithography applied to the production of semiconductor devices, a base is formed and patterned by performing predetermined exposure of a resist, developing the exposed resist, and etching the developed resist.
Recently, with refinement of design rules, it is necessary to use photolithography using a short-wavelength electromagnetic-radiation source. A KrF excimer laser (whose wavelength is 248 nm), an ArF excimer laser (whose wavelength is 193 nm), etc., are used as the short-wavelength electromagnetic-radiation source.
For obtaining short-wavelength electromagnetic radiation, electron-beam lithography, and X-ray-beam lithography to which synchrotron radiation is applied, are under consideration.
The electron-beam lithography is suitable for limited production of a wide variety of goods, but is not suitable for mass production due to its low throughput. The X-ray-beam lithography to which synchrotron radiation is applied requires a large, complicated apparatus as an X-ray source, which disadvantageously increases cost in production of semiconductor devices.
Accordingly, a method is being researched utilizing the inverse Compton effect as a technique which will allow a small apparatus to be used to yield short-wavelength exposure electromagnetic radiation. An electromagnetic radiation source which utilizes the inverse Compton effect uses electromagnetic-radiation scattering caused by electrons moving at a relativistic velocity, to supply photons with the energy of the electrons, whereby shortening the wavelength of the scattered electromagnetic radiation.
In the inverse Compton effect, a problem occurs in that the yield of obtained photons in X-ray regions is small because a scattering cross section based on the electrons and the photons is an extremely small value of 10
−27
cm
2
. Therefore, in lithography, sufficient X-ray energy cannot be produced, which is a likely problem in practice.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a short-wavelength electromagnetic-radiation generator capable of generating sufficient X-ray energy for lithography.
To this end, according to an aspect of the present invention, the foregoing object has been achieved through provision of a short-wavelength electromagnetic-radiation generator including: reflector means composed of at least a pair of concave reflectors; emitting means for emitting electromagnetic radiation so as to be incident on the reflector means; and electron-beam generating means for emitting an electron beam so as to be incident on the electromagnetic radiation, which is repeatedly reflected and converged.
According to another aspect of the present invention, the foregoing object has been achieved through provision of a short-wavelength electromagnetic-radiation generator including: reflector means composed of at least a pair of concave reflectors; electron-beam generating means for emitting an electron beam having a diameter adjusted to the diameter of electromagnetic radiation converged by at least a pair of concave reflectors in the reflector means so that the electron beam is incident on a region where the electromagnetic radiation is converged by the pair of concave reflectors; and emitting means for emitting a pulse beam having a pulse width corresponding to the diameter of the electron beam so as to be incident on the reflector means.
Preferably, the reflector means comprises concave reflector groups disposed to be opposed, each concave reflector group being composed of a plurality of aligned concave reflectors
The emitting means may comprise a Q-switched laser source, a mode-locked laser source, a Q-switched laser source, or a mode locked laser source.
According to the present invention, in a small short-wavelength electromagnetic-radiation generator, an electron beam is emitted to be incident on electromagnetic radiation being repeatedly reflected and converged by reflectors, whereby the electron beam and the electromagnetic radiation can collide successively. Thus, high scattering frequency can greatly increase the yield of scattered electromagnetic radiation. This makes it possible to apply the present invention to lithography in the production of semiconductor devices.
REFERENCES:
patent: 4456812 (1984-06-01), Neiheisel et al.
patent: 4598415 (1986-07-01), Luccio et al.
patent: 5247562 (1993-09-01), Steinbach
patent: 5539764 (1996-07-01), Shields et al.
Bruce David V.
Hobden Pamela R.
Kananen Ronald P.
Rader Fishman & Grauer
Sony Corporation
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