JPH1031963A - Ion generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heavy-current ion beam without deteriorating the filament of an ion source by colliding the X-ray generated by the collision between a thermion and an internal arc chamber against the neutral gas molecule and atom within a external arc chamber. SOLUTION: The thermion 2 generated form a filament 1 is partially accelerated by the dc voltage between an internal ac chamber 3 and the filament 1, and collided with the neutral gas molecule and atom 4 within the internal arc chamber 3. The neutral gas molecule and atom 4 is ionized to plus polarity by this collision. The resulting ionized gas molecule and atom 5 are extracted as an ion beam 7 by an extracting electrode 6. On the other hand, the thermion 2 not collided with the neutral gas molecule and atom 4 is collided with the internal arc chamber 3 to generate X-rays 9. Of the X-rays 9, those transmitted by the chamber 3 ionize the molecule and atom 4. The ionized molecule and atom 5 is extracted as the ion beam 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion generator for generating ions used, for example, when doping a semiconductor with impurities.

[0002]

2. Description of the Related Art FIG. 2 shows an ion source of a conventional ion generator.
This will be described with reference to the sectional view of FIG.

[0003] As shown in the figure, an ion source is filled with an electrically neutral neutral gas molecule / atom 4 and includes an arc chamber 3 as an anode electrode and a cathode electrode provided in the arc chamber 3. It has a certain filament 1 and an extraction electrode 6 for extracting ionized molecules and atoms 5 generated in the arc chamber 3 from the arc chamber 3.

[0004] The filament 1 is heated, so that thermions 2 emanating from the filament 1 are generated by the arc chamber 3.
50 to 100 depending on the DC voltage between
It is accelerated to eV and collides with a neutral gas molecule / atom 4. Due to this collision, the neutral gas molecules / atoms 4 are ionized to a positive polarity and are converted into ionized gas molecules / atoms 5. The ionized gas molecules and atoms 5 are extracted as an ion beam 7 from an ion beam port 3 k of the arc chamber 3 by an extraction electrode 6 having a negative potential with respect to the arc chamber 3.

[0005]

However, in the conventionally used ion source, the probability of thermionic electrons from the filament colliding with the neutral gas molecules / atoms in the arc chamber is all that is generated from the filament. Thermionic 10-2
It is said to be less than 0%. The non-colliding thermoelectrons reach the arc chamber and are not extracted as an ion beam. For this reason, it was difficult to obtain a large current ion beam.

Therefore, in order to obtain a high-current ion beam, the number of thermionic electrons generated is ten and several times the minimum number of thermionic electrons required to secure a certain amount of ionized gas molecules and atoms. Have to do. Therefore, it is necessary to apply a high voltage to the filament. For this reason, the life of the filament is shortened, and the filament needs to be replaced frequently, and productivity and economic efficiency deteriorate.

It is an object of the present invention to provide an ion generator capable of obtaining a high-current ion beam without deteriorating a filament of an ion source.

[0008]

The ion generating apparatus according to the present invention is of an electron impact type in which accelerated electrons collide with a gas inside a box filled with gas to generate ions. And an outer box filled with gas inside.

Further, the ion generator of the present invention is characterized in that the box is provided with a plurality of holes.

[0010] The ion generator of the present invention is characterized in that the outer case is provided in two or more layers.

As described above, the X-rays generated by the collision between the thermoelectrons and the box and passing through the box are caused to collide with the neutral gas molecules and atoms in the outer box to generate ions. A high-current ion beam can be obtained without deteriorating the filament.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An ion source of an ion generator according to an embodiment of the present invention will be described with reference to the sectional view of FIG.

As shown in the figure, the ion source is filled with an electrically neutral neutral gas molecule / atom 4 and has an internal arc chamber 3 as an anode electrode and an electrically neutral neutral gas inside. An outer chamber 8 filled with gas molecules and atoms 4 and surrounding the arc chamber 3; a filament 1 serving as a cathode electrode provided in the inner arc chamber 3; and ion molecules generated in the inner inner arc chamber 3 and the outer chamber 8 An extraction electrode 6 for extracting atoms 5 from the arc chamber 3; Several vents 10 are provided between the outer chamber 8 and the arc chamber 3, so that gas can enter and exit the arc chambers 3, 8 through the vents 10.

Some of the thermoelectrons 2 emitted from the filament 1 are accelerated to 50 to 100 eV by the DC voltage between the inner arc chamber 3 and the filament 1, and are converted into neutral gas molecules / atoms 4 in the inner arc chamber 3. collide. Due to this collision, the neutral gas molecule / atom 4 is ionized to a positive polarity, and is converted into an ionized gas molecule / atom 5. The ionized gas molecules and atoms 5 are extracted as an ion beam 7 from an ion beam port 3k by an extraction electrode 6 having a negative potential with respect to the internal arc chamber 3.

On the other hand, the thermoelectrons 2 which have not collided with the neutral gas molecules / atoms 4 in the arc chamber 3 reach the internal arc chamber 3 and collide. This collision generates continuous X-rays and special X-rays 9 (hereinafter collectively referred to as X-rays).

The characteristic X-ray has a wavelength specific to the anode material hit by the electrons, that is, the material of the inner arc chamber 3. On the other hand, continuous X-rays are emitted by high-speed electrons passing near the nuclei of material atoms constituting the internal arc chamber 3 under the influence of clones due to the positive charge of the nuclei, and have a continuous spectrum. Have.

The X-rays 9 transmitted through the inner arc chamber 3 are converted into neutral gas molecules in the outer chamber 8.
It collides with the atom 4 and ionizes the neutral gas molecule / atom 4 to a positive polarity. The ionized gas molecules / atoms 5 ionized in the outer arc chamber 8 pass through a vent 10 of the inner arc chamber 3 and are drawn by an extraction electrode 6 having a negative potential with respect to the inner arc chamber 3 to an ion beam port 3k. Is extracted as an ion beam 7.

As described above, the X-rays generated by the collision between the thermoelectrons and the internal arc chamber and transmitted through the internal arc chamber are made to collide with the neutral gas molecules and atoms in the external arc chamber, thereby forming the internal arc chamber. Thermionic electrons that do not collide with the neutral gas molecules / atoms in the inner arc chamber can be used for ion generation.

The external arc chamber may be further provided in two or more layers.

As a result, the life of the filament of the ion source can be extended, the frequency of regular replacement of the filament can be reduced, and productivity and economy can be improved.

[0021]

According to the present invention, it is possible to provide an ion generator capable of obtaining a high-current ion beam without deteriorating the filament of the ion source.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an ion source of an ion generator according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an ion source of an ion generator according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Filament 2 Thermoelectron 3 Arc chamber 4 Neutral gas molecule / atom 5 Ionized gas molecule / atom 6 Extraction electrode 7 Ion beam 8 External arc chamber 9 X-ray 10 Vent

Claims (3)

[Claims] 1. An electron bombardment type ion generator for generating ions by colliding accelerated electrons with said gas inside a gas-filled box, wherein said box is surrounded by said gas-filled outside. An ion generator comprising a box. 2. The ion generator according to claim 1, wherein the box is provided with a plurality of holes. 3. The ion generator according to claim 1, wherein the outer case is provided in two or more layers.