JP2002100297A - Method and device for producing ions - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for taking out clean ions. SOLUTION: An ion outlet portion 20 of this device has, across an ion passage 21 in the order from the side of an ion generation chamber 10, a first electrode 22 which has the same polarity as the polarity of the ions generated in the chamber, a second electrode 23 which has the opposite polarity to the polarity of the ions, and a third electrode 24 which has a medium electric potential between the potential of the electrode 22 and the potential of the electrode 23. The first to the third electrode have coaxial openings that form the ion passage 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ion generating method and an ion generating apparatus, and more particularly to an ion generating method and an ion generating apparatus capable of deriving a clean ion beam.

[0002]

2. Description of the Related Art An ion generator that ionizes a gas serving as an ion source in a high vacuum to generate an ion cloud, ie, plasma, and guides ions from the plasma as an ion beam to a processing chamber includes sputtering, ion beam cleaning, and the like. It is used when performing a process such as an oxide or nitride film formation assist. FIG. 7 shows an example of a conventional ion generator. This ion generating apparatus 100 is generally an ion generating chamber 110.
And an ion deriving unit 120.
Reference numeral 20 is connected to a processing chamber 130 for performing processes such as sputtering and ion beam cleaning using ions.

A discharge cathode 111 also serving as a heating device and a discharge anode 112 serving as a counter electrode are arranged on the outer periphery of the ion generation chamber 110 to constitute an ion generator 118. A magnet 113 for concentrating the generated ions at the center of the chamber is mounted on the peripheral wall of the ion generation chamber 110, and a gas supply pipe 114 for supplying a gas G of an ion source to the ion generation unit 118 and a gas exhaust pipe for indoor exhaust are provided. An exhaust pipe 115 is provided.

The ion deriving section 120 includes an ion generating chamber 1
An ion extraction electrode 121 is provided on the side of the processing chamber 130.
An ion acceleration electrode 122 is provided on the side. Each of the ion extraction electrode 121 and the ion acceleration electrode 122 is formed of a mesh plate or a perforated plate having a small diameter.

[0005] The ion generator 100 includes an exhaust pipe 11.
5, the inside of the ion generation chamber 110 is evacuated to a high vacuum, a high potential difference is applied between the discharge anode 112 and the discharge cathode 111, and the discharge cathode 111 is heated. When the gas G is introduced, the gas molecules are ionized by the discharge between the electrodes to generate plasma, and this plasma is concentrated at the center of the chamber by the magnet 113. Ion generation chamber 110 concentrated in the center of the chamber
The plasma inside is extracted as an ion stream by the ion extraction electrode 121 of the ion extraction section 120, accelerated by the ion acceleration electrode 122, and extracted into the processing chamber 130 as an ion beam.

[0006]

Recently, there has been a strong demand for high purity during the formation of electronic equipment members.
The purity of the ion beam led out to the processing chamber 130 has become a problem. That is, non-ionized gas molecules that are not turned into plasma and residual atmosphere gas molecules (such as nitrogen molecules) that cannot be exhausted exist as impurities in the ion generation chamber 110, and the generated ions are sputtered on the vessel walls and electrodes. There are also impurities such as other species ions and fine particles generated by the process. Therefore, ions extracted and beam-formed by the conventional ion deriving unit 120 accompany these impurities. Further, also in the ion deriving unit 120, the beam-formed ions are sputtered on the mesh of the electrodes and generate impurities, so that the purity of the ions extracted to the processing chamber 130 is not so high as required.

[0007] Japanese Patent Application Laid-Open No. 5-152182 discloses an ion deriving unit that does not use a mesh plate. However, this technique aims at narrowing down the ion beam, and it is not possible to extract clean ions by this technique.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide an ion generation method and an ion generation apparatus capable of extracting clean ions.

[0009]

According to the present invention, there is provided a first electric field having the same polarity as that of ions, the ions being sequentially formed from a source side along an ion path.
A second electric field having a polarity opposite to that of the ions, and a third electric field having a potential intermediate between the first electric field and the second electric field.
And a method for generating ions derived by passing through an electric field.

According to this ion generation method, the ions generated by the ion source are first attracted to the second electric field having the opposite polarity to the ions, and the first electric field having the same polarity as the ions is generated. pass. At this time, the ions have the same polarity as the electrode forming the first electric field and repel the electrode, and pass through the center of the electric field away from the electrode.
No secondary impurities are generated. Ions that have passed through the first electric field are accelerated when passing through a second electric field having a polarity opposite to that of the ions, are converted into an ion beam, and are led to the processing chamber side with required energy. At this time, the ion beam is diffused because it is attracted to the electrode forming the second electric field at the same time as being accelerated. This diffusion lowers the ion density with respect to the target in the processing chamber, and sputters peripheral members to become a source of impurities in the processing chamber. The third electric field having an intermediate potential between the first electric field and the second electric field suppresses the diffusion of the ion beam, and directs the ion beam having an appropriate diffusion angle corresponding to the shape of the target to the processing chamber. Derived.

In the above, a fourth electric field is formed after the second electric field, and the potential of the fourth electric field is adjusted in the cross-sectional direction of the ion passage, so that the irradiation pattern of the ion beam derived from the ion passage is changed. Is preferably controlled. 4th
By adjusting the electric field potential in the cross-sectional direction of the ion path, the bending angle of the ion beam can be locally changed. By locally adjusting the bending angle of the ion beam, the irradiation pattern of the ion beam applied to the target in the processing chamber can be changed. The fourth electric field is preferably formed in a third electric field.

The present invention is also an ion generating apparatus having an ion generating chamber and an ion deriving section, wherein the ion deriving section crosses an ion passage through which the ions pass, in order from the ion generating chamber side. A first electrode having the same polarity as the ions generated in the chamber, a second electrode having a polarity opposite to the ions, and a third electrode having an intermediate potential between the first electrode and the second electrode. And an ion generator in which the first, second, and third electrodes each have a coaxial opening serving as an ion passage.

This ion generating apparatus includes first, second, and third electrodes having coaxial openings formed across the ion passage, wherein the first electrode has the same polarity as the ions, and the second electrode has the same polarity. Are charged to the opposite polarity to the ions, and the third electrode is charged and adjusted to an intermediate potential between them, so that the ions generated in the ion generation chamber close the opening of the first electrode by the attraction of the second electrode. When passing through, it repels the electrode and concentrates at the center of the opening, so that ions do not sputter the first electrode to generate impurities. When the ions pass through the opening of the second electrode, the ions are given acceleration energy toward the processing chamber and become an ion beam. This ion beam is diffused by the attraction force of the second electrode having a different polarity, but when passing through the opening of the third electrode, the excessively diffused diffusion angle is adjusted to adapt to the shape of the target. The third electrode may be at a ground potential.

In the above, it is preferable that the edge of the opening of the first electrode on the side of the ion generation chamber is formed at an acute angle. In this case, in the first electrode, the edge of the opening on the side of the ion generation chamber is a knife edge, and electric field concentration occurs in this portion, and ions concentrate at the center of the opening near the entrance of the ion passage. Therefore, ions flowing into the opening do not collide with the electrode, and no impurity is generated by sputtering. In addition, since the diameter of the opening is increased toward the second electrode, the possibility that ions are attracted to the second electrode and bend outwardly to collide with the inner wall of the opening and sputter is reduced.

In the above, the third electrode is divided into two along the ion path, and a fourth electrode capable of adjusting the potential across the ion path is inserted into the divided gap. It is preferable that an opening coaxial with the openings of the first, second, and third electrodes is formed. The fourth electrode adjusts the load potential to form the second electrode.
The diffusion angle of the ion beam accelerated by passing through the third electrode and having its diffusion angle adjusted by the third electrode can be controlled to adapt to the shape of each target in the processing chamber.

Preferably, the fourth electrode is radially divided into a plurality of pieces around the ion path, and each piece is charged to an independent potential. When the divided pieces are charged to an independent potential, the density of the electric field crossing the ion path changes in the cross-sectional direction, so that the ion beam is deflected in accordance with the space potential at the site. This makes it possible to control the irradiation direction and the density distribution of all the ion beams led into the processing chamber and irradiate a desired region of the target with the ion beam with a desired density distribution.

The openings of the second and subsequent electrodes are preferably formed so as to gradually increase in diameter along the ion path from the ion generation chamber side. In this case, the diameter of the ion passage is generally increased toward the processing chamber. Although the beam of ions entering the ion outlet from the ion generation chamber side is suppressed by the third electrode as described above, it tends to diffuse as a whole due to the diffusing force of the second electrode. Therefore, the probability that ions are sputtered on each electrode to generate impurities is reduced by expanding the diameter of the ion passage as a whole toward the processing chamber.

Preferably, a plurality of the openings are formed in each of the electrodes. Although one aperture generally forms a radial beam bundle as described above, a single beam bundle may not have sufficient extraction current value for sputtering a target. In some cases, the entire target is not irradiated with ions at a uniform density. In this case, a plurality of openings are formed, and by adjusting the irradiation area of the beam bundle passing through each of the openings, it is possible to irradiate a target with a large area or various shapes with ions at a uniform density or in a specific density pattern. .

It is preferable that an exhaust passage leading to the ion passage is provided in the ion deriving section. Since the ion beam formed in the ion deriving unit tends to diffuse in the direction of the beam as a whole due to the Coulomb force repelling each other, in the unlikely event that some of the ions may collide with any of the electrodes. It needs to be considered.
In particular, the second electrode is strongly sucked. In this case, if an exhaust path leading to the ion path is provided, even if impurities are generated by sputtering to the electrodes, these impurities are removed through the exhaust path and can be prevented from entering the processing chamber. Of course, this exhaust passage is also effective for removing impurities and non-ionized gas that have entered the ion outlet from the ion generation chamber through the opening of the first electrode.

It is preferable that at least a wall surface of the ion generation chamber adjacent to the first electrode is covered by an auxiliary electrode charged to the same polarity as ions generated in the ion generation chamber. This prevents ions from being sputtered on the chamber wall at least in the vicinity of the first electrode of the ion generation chamber, and enables the ion beam to be highly purified.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings, but the following embodiments do not limit the present invention at all. FIG. 1 shows an ion generator of the present embodiment. The ion generating apparatus 1 generally includes an ion generating chamber 10 and an ion deriving unit 20, and the ion deriving unit 20 is used for sputtering, ion beam cleaning, and oxide and nitride film formation assisting by using ions. It is connected to a processing chamber 30 that performs processing.

The ion generating chamber 10 is provided with an ion generating section 18 for generating microwaves comprising a microwave antenna 11 and an electrode 12. A magnet 13 for concentrating the generated ions at the center of the chamber is provided on the peripheral wall of the ion generation chamber 10.
Is installed. Also, on the peripheral wall of the ion generation chamber 10,
Gas supply holes 14 for introducing an ion species generation gas G serving as a plasma source and exhaust holes 15 for exhausting the ion generation chamber are formed. An annular auxiliary electrode 16 is provided on a wall surface of the ion generation chamber 10 adjacent to the ion deriving section 20.
Is provided. The ion species generation gas G used in the present embodiment is an argon gas.

FIG. 2 is a plan view of the ion deriving unit 20 as viewed from the processing chamber 30 side. FIG. 3 is a cross-sectional view passing through the axis X of the ion deriving unit 20. FIG. 4 shows the ion deriving unit 20.
It is sectional drawing which traverses the 4th electrode in FIG. The ion deriving unit 20 has a disk shape as a whole, and one surface of the disk faces the ion generation chamber 10 and the other surface is the processing chamber 30.
For the time being. In the ion deriving unit 20, four ion passages 21A, 21B, 21C, and 21D having an axis O parallel to the axis X are formed at regular intervals from the axis X. Since all of these ion passages have the same structure, any one of the ion passages is referred to as an ion passage 21 unless otherwise specified.

The ion deriving section 20 includes a first electrode (hereinafter, referred to as a "first electrode 22") and a second electrode (hereinafter, referred to as a "second electrode 23") in order from the ion generation chamber 10 side across the ion passage 21. ) And a third electrode (hereinafter “third electrode 24”)
) And a fourth electrode (hereinafter referred to as “fourth electrode 25”)
And Among them, the third electrode 24 is connected to the third electrode 24A and the third electrode 24B along the axis O of the ion passage 21.
The fourth electrode 25 crossing the ion passage is inserted into the divided gap. Further, the fourth electrode 25
Are four pieces 2 radially around the ion passage 21.
It is divided into 5A, 25B, 25C, and 25D, and different electric potentials can be applied to each part.

The opening 26 of the first electrode 22 is
The opening 26 has an acute angle at the edge on the ion generation chamber 10 side. Also,
The openings of the electrodes after the second electrode 23 are located in the ion generating chamber 1.
The diameter is gradually increased along the ion passage 21 from the 0 side toward the processing chamber 30. Exhaust holes 27 are provided annularly in the gap between the first electrode 22 and the second electrode 23, and these exhaust holes are connected to a vacuum pump.

Next, the operation method and operation of this embodiment will be described. First, the ion generating chamber 10, the ion deriving unit 20, and the processing chamber 30 of the ion generating apparatus 1 of the present embodiment are evacuated to a high vacuum of, for example, 1 × 10 ⁻⁴ Torr or less. The processing chamber 30 may be further evacuated to a high vacuum, for example, 1 × 10 ⁻⁵ Torr or less. The first electrode 22 is loaded with a potential of +2 KV, for example. For example, a potential of -2 KV is applied to the second electrode 23.
For example, a ground potential (0 V) is applied to each of the third electrodes 24A and 24B. In addition, a potential that is finely adjusted, for example, using +4 KV as an average value, is applied to each piece of the fourth electrode 25 so that the ion beam forms a suitable irradiation pattern.

The ion generator 18 comprising the microwave antenna 11 and the electrode 12 is operated, and argon gas is introduced as the ion species generation gas G from the gas supply holes 14. As a result, the argon gas is ionized and cations (hereinafter referred to as “A
r ⁺ ) is generated. As schematically shown in FIG. 5, the generated plasma P is concentrated in the central portion by the magnet 13 in the ion generation chamber 10 and is introduced into the ion passage 21 from the opening 26 of the first electrode 22.
The introduced Ar ⁺ is attracted and accelerated by the second electrode 23 having a (−) potential, and is ion beam bundle (hereinafter, “beam bundle”).
), The second electrode 23, the third electrode 24A, the fourth
The electrode 25 and the third electrode 24B are led out to the processing chamber 30 through the respective openings. At this time, the beam bundle expands in the traveling direction due to the repulsive force between the ion beams and the second electrode 23 having a (-) potential, and the diffusion angle is averaged to each of the pieces 25A, 25B, 25C, and 25D. + 4KV
Is appropriately converged by the loaded fourth electrode 25. Further, each piece 25A of the fourth electrode 25,
25B, 25C, and 25D are loaded with appropriately finely adjusted potentials, so that the divergence angle of the beam bundle is 25A, 25A.
25B, 25C, and 25D locally change in accordance with the potentials respectively applied thereto. Thereby, as shown in FIG. 6, the irradiation pattern of the ion beam irradiating the target 40 in the processing chamber 30 is 41A, 41B, 41, respectively.
Deform like C, 41D. Each ion passage 21A, 2
The fourth electrode 25 for each of 1B, 21C, and 21D
Can independently change the potential, whereby the pattern of the ion beam irradiated on the target 40 can be appropriately controlled.

In FIG. 5, in the ion generating chamber 10, Ar ⁺ existing around the first electrode 22 and its surroundings is repelled by the first electrode 22 and the auxiliary electrode 16 because the first electrode 22 and the auxiliary electrode 16 are charged to (+). Therefore, no impurities are generated by sputtering. As a result, generation of impurities near the opening 26 is prevented.

Ar ⁺ near the opening 26 of the first electrode 22 is:
Large potential difference between first electrode 22 and second electrode 23 (4 KV)
, And is strongly absorbed by the first electrode, and flows into the ion deriving section 20 as a strong ion flow from the opening 26 of the first electrode. At this time, since the edge of the opening 26 on the side of the ion generating chamber 10 is a knife edge, strong electric field concentration occurs in this portion, and Ar ⁺ is concentrated in the center of the opening 26, so that the opening 2
Ar ⁺ flowing into 6 never cause sputtering collides with the first electrode 22.

The non-ionized gas (indicated by “Ar” in FIG. 5) and impurities (indicated by “▲” in FIG. 5) existing in the ion generating chamber 10 concentrate on the electric field at the edge of the opening 26 and the portion thereof. The opening 26 is blocked by the incoming ion current.
Hardly flows into the interior. The slightly ionized non-ionized gas and impurities are exhausted from the exhaust holes 27 provided in the gap between the first electrode 22 and the second electrode 23 and are not led out to the processing chamber 30 side. The Ar ^{+ that} is strongly attracted to and collided with the second electrode 23 after passing through the opening 26 causes sputtering to generate impurities, which are also immediately discharged to the exhaust holes 27.
And is not discharged to the processing chamber 30 side.

When the beam of Ar ⁺ formed through the opening 26 passes through the opening of the second electrode 23,
The light is strongly diffused in the traveling direction by the (-) charge of No. 3. However, the spread of the diffused beam is reduced by the third electrodes 24A and 24B having an intermediate potential between the first electrode and the second electrode, and the fourth electrode 25 having an average (+) potential. As described above, the diffusion angle of the beam bundle finally derived from the ion deriving unit 20 depends on the first electrode, the second electrode,
It changes depending on the load potential of each of the third electrode and the fourth electrode. At this time, the diffusely radiated Ar ⁺ is supplied to the second electrode 23.
Since the openings of the subsequent electrodes gradually increase in diameter toward the processing chamber 30 at a predetermined diffusion angle, they do not collide with any of the electrodes and cause sputtering.

As described in detail above, Ar ⁺ generated in the ion generation chamber 10 is derived from the ion generator of the present embodiment as an extremely clean ion beam accompanied by non-ionized gas and impurities. The irradiation pattern of the derived ion beam on the target 40 in the processing chamber 30 can be appropriately controlled by adjusting the potential of each part of the fourth electrode.

In the ion generator of the present invention, the configuration of the ion generation chamber is not particularly limited. For example, the type of the ion generating unit, the arrangement of the magnets, the arrangement of the ion source and the gas supply pipe, the arrangement and number of the exhaust pipes, and the like can be arbitrarily changed within the scope of the present invention. Also in the ion deriving unit 20, the number and arrangement of the ion passages, the number and arrangement of the pieces of the fourth electrode, and the arrangement and number of the exhaust holes are not limited to those in the above-described embodiment.

[0034]

According to the ion generation method of the present invention, the ions are sequentially formed into a first electric field having the same polarity as the ions, a second electric field having the opposite polarity to the ions, and the first electric field.
And the third electric field having an intermediate potential between the second electric field and the third electric field is passed therethrough, so that clean ions that do not accompany non-ionic gas or impurities can be introduced into the processing chamber as an ion beam. If a fourth electric field is formed after the second electric field and the potential of the fourth electric field is changed in the cross-sectional direction of the ion path, the path of ions is controlled to control the irradiation pattern of ions on the target. be able to.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view of the ion deriving unit of the embodiment as viewed from a processing chamber side.

FIG. 3 is a cross-sectional view passing through an axis X of the ion deriving unit.

FIG. 4 is a cross-sectional view crossing a fourth electrode in the ion lead-out section.

FIG. 5 is a schematic view showing the operation of the embodiment.

FIG. 6 is a plan view showing an example of an ion density pattern in a target.

FIG. 7 is a cross-sectional view showing an example of a conventional ion generation device.

[Explanation of symbols]

1: Ion generator 10: Ion generation chamber 14: Gas supply hole 15: Exhaust hole 16: Auxiliary electrode 18: Ion generation unit 20: Ion derivation unit 21, 21, A, 21B, 21C, 21D: Ion passage 22: First electrode 23: second electrode 24, 24A, 24B: third electrode 25: fourth electrode 25A, 25B, 25C, 25D;
One part 26: Opening 27: Exhaust hole

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroshi Saeki 2--24 Shiosaki, Oshio-cho, Himeji-shi, Hyogo Towa Himeji-Oshio High Town Room 412 (72) Inventor Ken Takahashi 2--20-2 Hitokita, Taishiro-ku, Sendai City, Miyagi Prefecture ( 72) Inventor Yoshinori Takahashi 2--17-15 Tsukushima Machine, Chuo-ku, Tokyo Inside Tsukishima Machinery Co., Ltd. (72) Inventor Hidenori Goto 2-17-15 Tsukuda, Chuo-ku, Tokyo Tsukishima Machinery Co., Ltd. (72) Inventor Jun Ohno 2-17-15 Tsukuda, Chuo-ku, Tokyo Tsukishima Kikai Co., Ltd. F-term (reference) 5C030 DD02 DE04 DG09 5F004 AA14 BA11 BB12 BB14 DA23 EA38

Claims (10)

[Claims] 1. A first electric field having the same polarity as the ions in the order from the source side along the ion path,
A second electric field having a polarity opposite to that of the ions, and a third electric field having a potential intermediate between the first electric field and the second electric field.
An ion generation method characterized in that the ion is generated by passing through an electric field. 2. An irradiation pattern of an ion beam derived from the ion path by forming a fourth electric field after the second electric field and adjusting the potential of the fourth electric field in a cross-sectional direction of the ion path. The method according to claim 1, wherein the ion generation is controlled. 3. An ion generating apparatus having an ion generating chamber and an ion deriving section, wherein the ion deriving section generates ions in the ion generating chamber in order from an ion generating chamber side across an ion passage through which ions pass. A first electrode having the same polarity as the ion, a second electrode having a polarity opposite to that of the ion, a third electrode having an intermediate potential between the first electrode and the second electrode, Wherein the first, second, and third electrodes each have a coaxial opening serving as an ion passage. 4. The ion generator according to claim 3, wherein an edge of the opening of the first electrode on the side of the ion generation chamber is formed at an acute angle. 5. The method according to claim 1, wherein the third electrode is provided along the ion path.
A fourth electrode capable of adjusting the potential across the ion path is inserted into the divided gap, and the fourth electrode is coaxial with the openings of the first, second, and third electrodes. The ion generating device according to claim 3 or 4, wherein a typical opening is formed. 6. The device according to claim 5, wherein the fourth electrode is radially divided into a plurality of pieces around the ion path, and each piece is charged to an independent potential. 3. The ion generator according to claim 1. 7. The opening of the second and subsequent electrodes is formed so as to gradually increase in diameter along the ion passage from the side of the ion generation chamber.
The ion generator according to any one of the above. 8. The ion generator according to claim 3, wherein a plurality of the openings are formed in each of the electrodes. 9. The ion generating apparatus according to claim 3, wherein an exhaust passage communicating with the ion passage is provided in the ion deriving unit. 10. The ion generation chamber may include at least a first
The ion generator according to any one of claims 3 to 9, wherein a wall surface adjacent to the electrode is covered with an auxiliary electrode charged to the same polarity as ions generated in the ion generation chamber. .