JPS60150547A - Plasma x-ray generator - Google Patents

Abstract

PURPOSE:To obtain a device in which an X-ray permeation window is not damaged and X-rays with high intensity can be efficiently obtained by providing a conical plasma orifice and a charged particle deflection means arranged near the centerl axis of the solid angle of the plasma orifice. CONSTITUTION:The center of the solid angle of a plasma orifice 6 is made to nearly coincide with an X-ray radiation point. The accelerated plasma is focused via the pinch effect, a hot spot 11 with high temperature and high density is formed on the axis near the tip of an anode 1, and soft X-rays are radiated from this hot spot 11 together with ions, electrons, and neutral particles. Although ions, electrons, and neutral particles are discharged together with soft X-rays from portions other than the hot spot 11, these particles discharged from portions other than the hot spot 11 are shielded by the plasma orifice 6 and are prevented from hitting an X-ray permeation window 8. Out of particles radiated from the hot spot 11, charged particles of ions and electrons are bent in orbit by a charged particle deflection means 7 and are prevented from hitting the X-ray permeation window 8.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a plasma X-ray generator that generates soft X-rays.

(Prior art) X-ray generators, especially X-ray generators that generate soft X-rays,
Today, studies have begun to consider its use as an X-ray source in X-ray exposure devices, X-ray microscopes, short wavelength lasers, etc. that take soft images of minute i4 turns in semiconductor integrated circuits. Synchrotrons and rotating anode cathode X-ray tubes are also known as X-ray sources that emit soft X-rays; It has the disadvantage of being low. By the way, plasma X-ray generators are beginning to be expected to be superior to the above-mentioned conventional X-ray sources, as they have high brightness, are compact, efficient, inexpensive, and practical. This plasma X-ray generator generates a large-current Noculus discharge between a rod-shaped anode and a cylindrical cathode that are coaxially arranged in a rare gas atmosphere, and shifts the generated plasma by a pinch effect. (hereinafter referred to as plasma focus), a high-temperature, high-density hot spot is formed on the axis of the electrode, and a soft X-ray is emitted from this hot spot.
It is designed to emit a line. However, this plasma X-ray generator had the following problems.

Not only plasma spots, that is, X-ray emitting points, but also
Charged particles such as ions and electrons, as well as neutral particles, are emitted from sources other than the radiation point, and windows made of perillam, which can withstand atmospheric pressure and are conventionally used as X-ray transparent window members, do not emit the charged particles, neutral particles, etc. There was a problem in that the window could be damaged by collision with particles. In particular, the hot spots formed by one plasma focus are aligned on the axis of the electrode, and these become X-ray emission points. If a conventional X-ray transparent window as described above is provided perpendicular to this axis,
Charged particles accelerated in the axial direction of the electrode collide, easily damaging the X-ray transmission window. However, if the window member is simply made stronger to prevent damage to the X-ray transmitting window, the X-ray brightness will drop significantly.

(Object of the Invention) An object of the present invention is to generate X-rays that can efficiently obtain high-intensity X-rays without damaging the X-ray transmission window due to the impact pressure caused by the collision of charged particles, etc. The goal is to provide equipment.

(Structure of the Invention) The plasma X-ray generator of the present invention includes a cylindrical anode in a rare gas atmosphere, and a cylindrical cathode disposed coaxially with the cylindrical anode at a predetermined interval. A cone-shaped plasma that spreads at a predetermined solid angle approximately at the center of the X-ray radiation point generated by applying a pulsed high voltage to this electrode pair, and has an opening at the cone end. A charged particle deflection means is arranged near the diaphragm and the central axis of the solid angle of the plasma diaphragm, and XIw! X to release to the outside
It is characterized in that the line-transmitting window is located on the central axis of the above. That is, in the present invention, since the plasma aperture and the charged particle deflection means are arranged as described above, charged particles and neutral particles generated from sources other than the X-ray emission point are blocked by the plasma aperture, and the plasma aperture is opened. Among the particles that have passed through the hole, the charged particles are deflected by the charged particle deflection means, so it is possible to remove the impact pressure that is applied to the conventional X-ray transmitting window. It became possible to use thin members with high brightness, and to obtain high-intensity X-rays.

The charged particle deflection means used in the present invention not only has the effect of preventing damage to the X-ray transmission window, but also has the effect of preventing damage to the X-ray transmission window. When used for turning, another advantage is that it can prevent impurity implantation and crystal defects from occurring due to energetic ions colliding with semiconductor substrates due to passing through the X-ray transmission window. can be obtained. Either an electric field type or a magnetic field type deflector can be used as this charged particle deflection means, but if the central axis of the solid angle of the plasma constrictor and the axis of the electrode are aligned, the electrode Since ions having particularly high energy are incident in the axial direction, the electric field required for deflection with an electric field type deflector is too high, and a magnetic field type deflector must be used in many cases. It goes without saying that either a permanent magnet or an electromagnet can be used as this magnetic field type deflector, but in the present invention, it is more preferable to use a permanent magnet because of its simpler structure. In addition, when using a magnetic field type deflector, the plasma constrictor is made of a highly permeable material to prevent the magnetic field for charged particle deflection from leaking outside the plasma constrictor and adversely affect the formation of hot spots. It is desirable to prevent giving. Note that any material that can withstand atmospheric pressure and transmit soft X-rays with high transmittance can be used as the window member forming the X-ray transmission window. For example, beryllium, aluminum, polymer, etc. It is preferable to use

(Example) An example of the present invention will be described below with reference to FIG. 7th
The figure is a longitudinal sectional view showing an example of the plasma X-ray generator of the present invention. Inside the discharge tube, a cylindrical anode 1 and a cylindrical cathode 2 surrounding it are arranged coaxially, and the base of the anode is electrically insulated from the cathode 1 with an insulator 3 such as glass. ing.

These are sealed by a case 4 and a flange 5, and rare gases such as neon, argon, krypton, etc.
Enclosed at a pressure of ~/Tqrr. The end of a conical plasma diaphragm is adhered to the inside of the flange 5. The center of the solid angle of this plasma diaphragm #) 6 almost coincides with the X-ray emission point, and the soft X-rays emitted from the The plasma is made to enter the plasma aperture 6. In this embodiment, the axes of the electrodes 1 and 2 are made to coincide with the open center axis of the solid angle of the plasma diaphragm, so that the R degree is the highest. Inside the plasma aperture 6, a charged particle deflecting means 7 for deflecting charged particles is arranged near the - central axis of the solid angle of the plasma aperture. The flange 5 is provided with an X-ray transmitting window 8 for emitting soft X-rays to the outside. It is arranged. A capacitor 9 is connected between the anode 1 and the cathode 2.
are connected via switch 10. With the plasma X-ray generator having such a button configuration, the switch 10
is closed and the energy charged in the capacitor 9 is instantaneously applied between the electrodes, and when a high voltage is applied across the positive and negative electrodes 1.2, the exposed voltage between the anode 1 and the cathode 2 is A discharge occurs along the creeping surface of the insulator 3, and active plasma is generated there.

The ions and electrons of this generated plasma are attracted by the electric field and move, but due to the loop-shaped magnetic field that exists between the electrodes, the ions and electrons are parallel to the axes of the electrodes 1 and 2, and
is accelerated along the axis of the electrode 1.2. After passing over the edges of the electrodes 1 and 2, the accelerated plasma is focused by the pinch effect to form a high-temperature, high-density hot spot 11 on the glaze near the tip of the anode 1, and this hot spot 11 emits soft X-rays. are ions, electrons,
Emitted along with neutral particles. Ions, electrons, neutral particles, etc. are emitted along with soft X-rays from places other than the hot spot 11, but the particles emitted from places other than the hot spot are blocked by the plasma diaphragm 96 and collide with the X-ray transmission window 8. is prevented. Charged particles such as ions and electrons among the particles emitted from the hot spot 11 are deflected by the charged particle deflection means 7 to prevent them from colliding with the X-ray transmission window 8 . Some of the ions emitted from the hot spot 11 have an energy close to /Me■, so in order to deflect these charged particles from the X-ray transmission window 8, a magnetic field type deflector is used as the charged particle deflection means 7. is preferable. In this case, a magnetic flux of about 70' is used.

This level of magnetic flux can be achieved using permanent magnets such as rare earth-cobalt magnets. Furthermore, in this example, the plasma diaphragm #
) 6 is made of pure iron, and the magnetic field of the charged particle deflection means 7 arranged inside the plasma diaphragm leaks to the outside.
This prevents any negative effects on plasma hot spot formation. Further, the flange 5 that fixes the plasma diaphragm is made of an insulating material such as polyoxymethylene, and the Zolaz i diaphragm is electrically insulated, reducing the electric field between it and the anode 1. However, new acceleration of the loaded particles is prevented. It is effective to further reduce the electric field strength by using an insulating material such as ceramics for the end portions forming the openings 6a of the glazed diaphragm.

Incidentally, scattered objects such as neutral particles, infrared rays, and visible light that have not been removed by the plasma aperture p1 charged particle deflection means 7 are removed by the X-ray transmission window 8.

In the case where beryllium with a thickness of 50 μm is used as the X-ray transmission window in a plasma X-ray generator configured the same as this example without providing a plasma aperture or a charged particle deflection means, the
It was confirmed that whereas the kilojoule is damaged by one discharge, the present invention does not break and can be used continuously.

FIG. 2 is a longitudinal sectional view showing another embodiment of the f2 Zuma X-ray generator of the present invention.

In this example, the opening and opening axis of the solid angle of the Zolaz i-diaphragm does not coincide with the axis of the electrode, and the loaded particles accelerated in the axial direction of the electrode do not reach the X-ray transmission window 8. It becomes possible to use an electric field type deflector as the charged particle deflection means 7.

FIG. 3 is a longitudinal cross-sectional view showing yet another embodiment of the plasma X-ray generating device of the present invention, in which a plurality of X-ray transmission windows 8 are provided.

(Effects of the Invention) According to the present invention, charged particles and neutral particles emitted from sources other than the X-ray emission point are completely blocked by the plasma aperture, and the
Charged particles emitted from the radiation point and entering the plasma constrictor through the aperture are also prevented from reaching the X-ray transmission window by the charged particle deflection means, thereby preventing damage to the X-ray transmission window. , high-intensity soft X-rays can be obtained by increasing the transmittance of the X-ray transmission window. In addition, high-energy charged particles,
Since no particles are released to the outside, it is possible to effectively use equal pressure for semiconductor pattern transfer.

[Brief explanation of drawings]

FIG. 7, FIG. 2, and FIG. 3 are longitudinal cross-sectional views of embodiments of the X-ray plasma generator of the present invention. 1...Anode, 2...Cathode, 3...Insulator, 6......
・Plasma aperture, 7...Charged particle deflection means, 8...X-ray transmission window

Claims (1)

[Claims] l) An electrode pair consisting of a cylindrical anode and a cylindrical cathode disposed coaxially with the columnar anode at a predetermined distance in a rare gas atmosphere; A conical plasma diaphragm that spreads at a predetermined solid angle approximately at the radiation point of the X-rays generated by applying a pulsed high voltage to the pair, and has an opening at the conical end; A charged particle deflector is arranged near the central axis of the solid angle of the glazma aperture.
IP that the line-transmitting window is located on the -1 central axis.
j9 plasma X-ray generator. 2) Claim 1, characterized in that the central axis of the solid angle coincides with the axes of the anode and cathode.
The plasma X-ray generator described in Section 1. 3) The plasma X-ray generator according to claim 7 or 2, wherein the charged particle deflecting means is a magnetic field deflection type deflector. 4. The plasma X-ray generator according to claim 3, wherein the magnetic field deflection type deflector is a permanent magnet. 3) The plasma X-ray generation device according to claim 3 or 7, wherein the plasma diaphragm is made of a highly permeable material.