JPH02109236A - Ion source equipment - Google Patents

Abstract

PURPOSE:To lengthen the service life of an electron emission source, by generat ing electrons necessary to generate plasma in a subsidiary plasma chamber, and then supplying the generated electrons to the main plasma chamber. CONSTITUTION:A main plasma chamber 29 is formed by a main casing body 28 made of the metal of a non-magnetic body, while a subsidiary plasma cham ber 31 is formed by a subsidiary casing body 30 made of the metal of another non-magnetic body, mounted via an insulator 18 onto the left-side opening of the main casing body 28, and then an electron emission hole 32 is formed be tween the main and subsidiary plasma chambers 29, 31. Subsidiary plasma 37 is generated by high-frequency discharge in the subsidiary plasma chamber 31 serving as an electron emission source so that electrons (e) necessary to generate plasma in the main plasma chamber 29 that generates ion beams by DC discharge are generated, and then supplied to the main plasma chamber 29. The electron emission source thus becomes considerably long-lived without wasting the material thereof, whereby it is permitted to operate continuously for a long time of not less than hundreds of hours.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ion source device that generates an ion beam by direct current discharge.

[Conventional technology]

Conventionally, typical ion source devices used for ion beam sputtering, ion beam mixing, ion assist, etc. include a Kauffman type ion source device and a packet type ion source device.

(Conventional Example 1) A conventional Kauffman type ion source device has a configuration shown in FIG. 6, in which (1) is a casing made of non-magnetic metal such as stainless steel, and (2) is a plasma generation chamber formed by the housing (1), and (3) is a filament installed in the generation chamber (2), which is made of tungsten (W), lanthanum boride (LaBa), or the like. (4) is a filament power supply for heating the filament (3), and (5) is a cylindrical anode provided in the generation chamber (2).

(6) is a gas introduction port to the generation chamber (2), and (7) is an ion beam extraction electrode group, including a first electrode (8) and a second electrode (9).

It is composed of a third electrode 00. 0υ is a cylindrical permanent magnet or electromagnet for generating a magnetic field provided outside the housing (1).

@ is an arc power source, and the anode is the anode (5).

A cathode is connected to the housing (1) via a resistor, and an anode voltage is applied to the anode (5). (14) is an accelerating power source whose anode is connected to the cathode of the arc power source 04, and applies positive accelerated electrons lower than the anode voltage to the first electrode (8) having the same potential as the case (1). θυ is a deceleration power supply that applies a negative voltage to the second electrode (field).

The filament (3) is a thermionic emission source as a cathode, and is kept at a high temperature by the resistance heating of the filament power source (4) and emits thermionic electrons e'. So 1300
It is heated to about ℃.

On the other hand, an ionized gas such as a rare gas such as argon (Ar) or a reactive gas such as oxygen gas is introduced into the plasma generation chamber (2) from the gas introduction port (6).

A plasma of the introduced ionized gas is generated by the discharge between the filament (3) and the anode (5), and due to the beam extraction action of the electrode group (7), the ion gas in the plasma becomes an ion beam and is sputtered. It is led out to the room etc.

At this time, the magnetic field of the magnet 0υ improves the production efficiency of the plasma OQ or the confinement of the plasma θQ.

(Conventional Example 2) A conventional packet type ion source device has a configuration shown in FIG. 7, and the differences from the configuration shown in FIG. 6 are as follows.

There is no anode (5) in Figure 6, the anode of the arc power supply 02 is directly connected to the housing (1), the housing (1) becomes the anode, and the anode of the acceleration power supply Q41 is connected to the housing (1) as an insulator. A permanent magnet 0υ is connected to the first electrode (8) of the electrode group (7) via a force, either directly or through a resistance, and is composed of a plurality of annular bodies, creating a cusp magnetic field inside the housing (1). The points are arranged so as to form a

The operation is almost the same as that shown in FIG.

(Conventional Example 3) A conventional hollow cathode ion source device has a configuration shown in FIG. 8, and the differences from FIG. 7 are as follows.

There is no filament (3), and a cathode casing (19) made of non-magnetic metal is attached to the left opening of the casing (1) via an insulator Q8). A non-magnetic metal lid plate Qυ is attached via the body (A) to form a cathode chamber (1).

A hollow cathode (c) is installed in the cathode chamber @.

A heater coil (C) is wound around the outer periphery of a cylindrical body (C) that is integrally formed with the lid plate Q1), and a thermionic emission material (A) is provided on the inner surface of the cylindrical body. A cathode is constructed, a heater coil (c) is heated by a power source (4), and a thermionic emission material (e) is heated via a cylindrical body (material).

The cover plate Q1) is provided with a gas inlet to the inside of the cylindrical body (C).

The cathode of the arc power supply 0 is connected to the cover plate @1), that is, the cylindrical body (material), and is also connected to the cathode housing O1 and the first pole (8) via a resistor 03.

Then, the ionized gas is completely introduced into the generation chamber (2) from the introduction port (6), and the introduction port (
A rare gas for hollow discharge such as argon is introduced from the cylindrical body (goods), and when power is applied, a discharge occurs between the housing (1) forming the anode and the hollow cathode), and the inside of the cylindrical body (goods) A hollow discharge of rare gas occurs in space, and thermionic e' is emitted from the thermoelectron and electron emitting material @ due to thermionic emission, and the emitted thermionic e' is generated due to the anode voltage. It is introduced into the chamber (2).

Therefore, K plasma aQ is generated in the generation chamber (2) due to the discharge between the housing (1) and the hollow cathode (to).
The discharge is sustained by thermionic electrons e' supplied from the cathode (to the cathode), and as in the case of Fig. 7, the ionized gas from the gas inlet (6) is ionized, and an ion beam is led out through the electrode group (7). be done.

[Problem to be solved by the invention]

The conventional ion source device shown in FIGS. 6 and 7 is.

The filament (3) is maintained at high temperature as an electron emission source.

In order to emit thermionic electrons e' necessary for generating plasma 00 using thermionic emission phenomenon, the filament (3) is
Materials evaporate due to high-temperature heating and are exposed to harsh conditions such as sputtering due to ion bombardment, resulting in fiwomen I.
- (3) is severely consumed and when the ionized gas is argon, 50 hours for tungsten and 100 hours for lanthanum boride.
There is a problem that it can only be used for a limited time, and the ionized gas is a reactive gas.

For example, in the case of oxygen, there is a problem that the filament (3) is rapidly oxidized and consumed in a short period of time.

Next, in the ion source device shown in Fig. 8, a hollow discharge of thermionic emission is performed using a rare gas in a cathode chamber (a) that is separate from a plasma generation chamber (2) to which an ionized gas is supplied. , it can be used for a long time compared to the devices shown in Figures 6 and 7, but even when the ionized gas is a rare gas such as argon, the thermionic emitting material (a) is not affected by ion bombardment at high temperatures. There is a problem that it can be used for only 100 to 200 hours due to sputtering.

Moreover, since the ionized gas introduced into the generation chamber (2) flows into the cathode chamber, when the ionized gas is oxygen, etc., the thermionic emitting material (c) is produced in a shorter time than when the ionized gas is a rare gas.
There is a problem that it wears out.

In addition, there is a rare gas for hollow discharge inside the cylindrical body.

Because it mixes with the ionized gas in the plasma generation chamber (2), the generated plasma oo becomes a mixed plasma of ionized gas and rare gas for hollow discharge, making it impossible to generate plasma using only ionized gas. .

There is a problem that a desired ion beam cannot be obtained.

The present invention takes the above points into consideration, generates the electrons necessary for plasma generation of ionized gas without using the thermionic emission phenomenon of consumable materials, completely eliminates material consumption of the electron emission source, and enables long-term use. It is an object of the present invention to provide an ion source device that can be used, generates plasma of only ionized gas, and forms a high-quality ion beam.

[Failure to solve the problem]

In order to solve the above problems, 1. The ion source device of the present invention.
It is equipped with a main plasma chamber that generates an ion beam by direct current discharge, and a sub-plasma chamber that serves as an electron emission source that generates a plasma by high-frequency discharge and supplies electrons necessary for the direct current discharge to the main plasma chamber. be.

[For production]

In the ion source device of the present invention configured as described above, plasma is generated by high-frequency discharge in the sub-plasma chamber, and plasma is generated in the main plasma chamber.

In other words, the electrons necessary for plasma generation of ionized gas are generated and supplied to the main plasma chamber.

Unlike conventional methods, there is no need to use filaments and thermionic emitters that are maintained at high temperatures and consume significant material consumption, resulting in an extremely long life of the electron emitting source.

Furthermore, in the gas used for plasma generation in the second sub-plasma chamber,
When the same gas as the ionized gas in the main plasma chamber is used, the plasma in the main plasma chamber is generated with only the desired gas, and a high-quality ion beam can be formed.

〔Example〕

An embodiment will be described with reference to FIGS. 1 to 5.

In those drawings, the same symbols as in FIGS. 6 to 8 indicate the same things.

(Example 1) Example 1 will be described with reference to FIG. 1, which shows a packet type ion source device.

The figure shows a system that uses microwave discharge as a high-frequency discharge. is formed, and a sub-plasma chamber 0) is formed by a sub-casing (a) made of non-magnetic metal attached to the left opening of the main casing (c) via an insulator barrel. .

An electron emission hole 4 is formed between the sub-plasma chamber wall and 0υ.

The left side opening of the sub-casing (to) is closed with an insulator 33).

A waveguide connected to the insulator (331) supplies microwaves in the form of high frequency to the sub-disaster chamber 0υ via the insulator (33).

An electromagnetic coil for generating a magnetic field is installed on the outer periphery of the sub-casing (to), and a magnetic field exceeding electron cyclotron resonance (ECR) conditions is generated in the sub-plasma chamber 6]), and the magnetic field is generated in the sub-casing (to). A gas inlet (7) is formed.

The cathode of the arc power supply O
i(8).

The sub-plasma chamber 6υ is dimensioned under the conditions of a microwave cavity encirclement to facilitate the generation of microwave discharge.

The shape is set 1. For example, in the TEm mode of the microwave of 2.45 GH2, 2 the inner diameter lOα and the length 8°7C.
It is set to PH.

When microwaves are introduced into the sub plasma chamber 0υ by the second waveguide (2 waveguides), microwave discharge occurs in the sub plasma chamber 01), and the rare energy that has been introduced into the sub plasma chamber 131) from the introduction port (7) is generated. The gas for deuteron release such as gas is ionized,
A secondary y'' lasma Gη is generated, and the electrons e generated by ionization with the generation of the secondary plasma G7)
The plasma is drawn out from the discharge hole 0''A to the main plasma chamber by an anode voltage of about

At this time, I! When the magnetic cocoil C51 is applied to a magnetic field that exceeds the ECR conditions, the secondary defsuma C3η that is generated is a high-density filter.

The electrons e are supplied to the main plasma chamber very efficiently.

Next, in the main plasma chamber wall, the supplied electrons e are used for direct current discharge, and ionized gas such as a rare gas introduced from the inlet (6) is ionized to generate a main plasma chamber.
The discharge is sustained by the supply of electrons e.

And due to the beam extraction action of the electrode group (7).

Ions from the generated main plasma μs become an ion beam and are led out to a sputtering chamber or the like.

On the other hand, the main plasma chamber is efficiently confined by the cusp magnetic field of the magnet αη, and a uniform and stable main plasma S8i is generated over a large area near the electrode group (7).

Furthermore, the gas introduced into the sub-plasma chamber 0υ is.

There is no effect even if a gas other than rare gas is used, and the same gas as the ionized gas in the main plasma chamber is used in the sub plasma chamber at 0υ.
can be introduced into

Further, a permanent magnet may be used instead of the electromagnetic coil '351.

(Example 2) Example 2 will be explained with reference to FIG.

In this figure, microwaves are introduced into the sub-plasma chamber 0η in Fig. 1 using a coaxial cable (39) and an antenna package 0), and the microwave is introduced into the sub-plasma chamber 0η in Fig. A cover plate (41) made of a magnetic material or a non-magnetic material is attached to the left opening, and the right cover plate (41) is attached to the main casing (to) via an insulator (08). Lid plate I
Thirteen electron-emitting holes are formed in 11.

The antenna HB provided in the sub-plasma chamber 0υ is connected to the left cover plate [2 through which the coaxial cable 9] is connected.

A gas inlet (to) is formed in the sub-plasma chamber (OT), and a permanent magnet 0υ is provided on the outer periphery of the sub-casing (7) to generate a magnetic field in the sub-plasma chamber 0υ that is better than the ECR conditions.

Note that the tip of the antenna frame is provided close to the wall surface of the sub-plasma chamber 0υ so as to easily cause microwave discharge.

When microwaves are completely introduced into the sub-plasma chamber 0]) through the cable relay 9) and the antenna frame, even if the sub-plasma chamber 01) is not formed under microwave cavity resonator conditions, the tip of the antenna frame Microwave discharge is easily generated due to the high electric field between the plasma chamber and the wall of the sub-plasma chamber 0υ.

Then, before the microwave discharge is generated, the gas introduced from the inlet (7) into the sub-glazma chamber 0υ is ionized to generate sub-plasma aη, and from the discharge hole G to the main plasma chamber (2). Electrons e are supplied to .

In this case, since the coaxial cape /l/a9) and antenna cage ω are used, the secondary plasma chamber 0]) is not restricted by the microwave cavity resonator conditions as shown in Figure 1, so the secondary plasma chamber 0υ can be made smaller. can be formed into

Furthermore, by increasing the number of antenna elements.

It is possible to increase the amount of electron emission.

Further, the magnet αυ may be an electromagnet, and the cover plate Hn
, @"If 2h is made of magnetic material, magnet 0])
can be made smaller.

(Example 3) Generating means (A,,) of sub-plasma t37) in Fig. 2 Q
Embodiment 3, which is applied to a Kauffman type ion source device, is shown in FIG.

In the ion source device shown in Fig. 3, 22°45GI (z
.

As a result of an experiment using a 20W microwave, the beam current was 100mA when the microwave number +
The argon ion beam was stably extracted.

(Embodiment 4) FIG. 4 shows Embodiment 4 in which two of the sub-plasma 37) generating means (A) in FIG. 2 are applied to a packet type ion source device.

In this case, since electrons e are supplied to the main plasma chamber from the two generation means (A), that is, the two sub-plasma chambers 0υ, the amount of supplied electrons increases, which is effective for large ion source devices. .

Note that three or more generation means (A,) may be used.

And, the generation means (B) of the sub-plasma S7) in FIG.
Of course, one or more of these can be applied to the Kauffman type ion source device.

In addition, when using a plurality of generation means (A) and (B), the microwave power is individually controlled, and each generation means (A)
.

The amount of electrons emitted from ()3) can be adjusted.

(Example 5) Example 5 shown in FIG. 5 shows an example in which high-frequency discharge is generated using high-frequency power lower than that of microwaves.

The figure shows the case of a packet-type ion source device.

The sub-casing (1)' is made of heat-resistant glass;
The electron emission hole 3z is connected to the main plasma chamber wall, and a high-frequency power source (431) that outputs a high-frequency voltage on the order of MHz (431 is connected to a pair of high-frequency type WA←, Keihin is connected, and one of the plate-shaped electric fMI4 is provided in the sub-plasma chamber 0υ, and the other cylindrical electrode (451) is provided on the outer periphery of the sub-casing (1)'.

Then, the picture electrodes (441, 1451
A high-frequency discharge is generated by the high-frequency voltage between the two, and as in the case of microwaves, secondary plasma light is generated in the secondary plasma chamber 0]), and electrons are emitted from the secondary plasma chamber 01) to the main plasma chamber (A). Supplied.

In this case, a high frequency power source (4
3), the cost of the two devices is low.

Further, by providing a permanent magnet or an electromagnetic coil for generating a magnetic field outside the sub-plasma chamber 6υ, it is possible to increase the density of the sub-plasma chamber.

Furthermore, it goes without saying that this embodiment can also be applied to a Kauffman type ion source device.

〔Effect of the invention〕

Since the present invention is constructed as described in one or more of the above descriptions, it achieves the advantages described below.

A secondary plasma 31 is generated by high-frequency discharge in the secondary plasma chamber 0υ as an electron emission source, and electrons e necessary for plasma generation in the main plasma chamber are generated and supplied to the main plasma chamber. , filamen l-,
heating and maintaining a consumable material such as a thermionic emitting phase at a high temperature;
Compared to the case where thermionic emission phenomenon is utilized, there is no material consumption, and the 6-electron emission source has an extremely long life, and can be operated continuously for a long period of several hundred hours or more.

Furthermore, gases other than rare gases can be used as the gas used to generate the sub-plasma 6η in the sub-plasma chamber 0υ, and there are no restrictions on the type of gas. Therefore, when the same gas as the ionized gas in the main plasma chamber 6υ is used as the gas in the sub-plasma chamber 6υ, the main plasma c (81) in the main plasma chamber 6υ becomes a plasma containing only the desired ionized gas, producing a high-quality ion beam. can be formed.

Even in the case of reactive gases such as 22-oxygen, there is no oxidation and consumption, and plasma can be generated and maintained stably for a long period of time.

[Brief explanation of drawings]

FIGS. 1 to 5 are block diagrams of respective embodiments of the ion source device of the present invention, and FIGS. 6 to 8 are block diagrams of conventional ion source devices, respectively. Kan...Main plasma chamber, e1)...Secondary plasma chamber, c(
η...Secondary plasma, (9)...Main plasma, e...
A child.

Claims (1)

[Claims] (1) A main plasma chamber that generates an ion beam by DC discharge, and a sub-plasma chamber that serves as an electron emission source that generates plasma by high-frequency discharge and supplies electrons necessary for the DC discharge to the main plasma chamber. An ion source device characterized by: