JPH01319228A - Ecr type ion source - Google Patents

Abstract

PURPOSE:To reduce the spattering abrasion on the surface of each electrode of an extracting electrode system by coating a material with high-temperature stability and high ion spattering abrasion resistance on the surface of each electrode of the extracting electrode system provided on one face of a plasma generation chamber generating plasma with microwaves. CONSTITUTION:A material made of TiC, TaC or TaN with high-temperature stability and high ion spattering abrasion resistance is coated on the surface of each electrode of an extracting electrode system provided on one face of a plasma generation chamber forming plasma with microwaves. The spattering abrasion of the electrode can be reduced, the life of the extracting electrode system constituted of these electrodes can be extended. The mixing of the material spattered from the electrode into plasma can be reduced, thereby an ion beam with little impurities can be formed and the pollution of the plasma generation chamber can be reduced, the life of an ECR type ion source is improved, a stable ion beam is obtained by the ECR type ion source.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applied to materials on the surfaces of components exposed to plasma or ions in an ECR type ion source.

[Prior Art] FIG. 2 is a cross-sectional view showing the configuration of a conventional general ECR type ion source. In the figure, l is a microwave waveguide for propagating microwaves from a microwave source, 2 is a plasma generation chamber in a vacuum state, and 3 is a microwave introduction window for introducing microwaves into the plasma generation chamber 2. . Further, 4 is a magnet for forming a magnetic circuit for causing electron cyclotron resonance, and 5 is a gas introduction [J] for introducing plasma gas into the plasma generation chamber 2.

6 is provided on one side of the plasma generation chamber 2, and electrodes 6A, 6
B, an extraction electrode system consisting of 6C, 7 is the plasma generation chamber 2
8 is an ion beam extracted from the plasma 7, and 11 is an insulator provided between the electrodes 6A to 6C.

Next, the operation of the above-mentioned conventional ECR type ion source will be explained. Microwaves are propagated from a microwave source (not shown) through a microwave waveguide l.Plasma generation chamber 2
is formed in a shape that satisfies the conditions for a cavity resonator, which is one of the conditions for causing electron cyclotron resonance. The plasma gas introduced into the plasma generation chamber 2 through the gas introduction port 5 is converted into plasma by the microwave introduced into the plasma generation chamber 2 through the microwave introduction window 3, and plasma 7 is formed. In addition, the plasma 7 causes electron cyclotron resonance by matching the wavelength and power of the microwave, the magnetic field strength of the magnet 4, and the shape of the plasma generation chamber 2 so as to cause electron cyclotron resonance. The electrons, which have gained high energy, actively excite and ionize the gas, resulting in high density. The ion beam 8 is extracted from the plasma 7 by applying a suitable positive potential with respect to ground potential to the electrode 6A directly facing the plasma 7 in the extraction electrode system 6. Here, the electrode 6C that is farthest from the plasma 7 is at ground potential, that is, the inner electrodes 6A and 6C
The potential difference between them becomes the energy of the ion beam 8. Normally, the extraction electrode system 6 is often composed of three electrodes 6A, 6B, and 6C with an insulator 11 interposed between them. The beam shape is controlled using an electric lens effect. A negative potential with respect to the ground potential is applied to the middle electrode 6B, and is used to prevent people from flowing back into the ion source. Note that the ion beam 8 formed
The number of electrodes in the lead-out electrode system 6 changes depending on the characteristics of the lead-out electrode system 6.

FIG. 3 is a sectional view showing the configuration of one electrode of the extraction electrode system in the ECR type ion source of FIG. 2. FIG. In the figure, 6A is one electrode of the extraction electrode system 6 shown in FIG. 2, and 9 is a plurality of ion extraction holes provided in the electrode 6A, from which ions are extracted. The individual shapes of the holes 9 may be round or hexagonal. Note that the electrodes 6B and 6C shown in FIG. 2 are also similar to the electrode 6A, and these electrodes may have only one hole 9.

In addition, since the electrodes 6A to 6C of the extraction electrode system 6 usually face or are close to the high-temperature plasma 7 (see FIG. 2), their constituent materials may be, for example, those described by Junzo Ishikawa. “Ion Source Engineering” published by Ionics Co., Ltd.
As described in PP, 323-324, materials such as Mo and Ta are used, which are conductors that are relatively easy to process into a desired shape, have high temperature stability, and have a low coefficient of thermal expansion. On the other hand, when applying the above ion source to processing steps where metal contamination is avoided, such as processing of semiconductor substrates,
For example, as disclosed in Japanese Unexamined Patent Publication No. 55-141729, the material of the electrodes 6A to 6C of the extraction electrode system 6 is a semiconductor or a conductor made of at least one of the components of the semiconductor substrate, such as Si or C. ing.

[Problems to be Solved by the Invention] Since the conventional ECR type ion source is configured as described above, the surfaces of the electrodes 6A to 6C of the extraction electrode system 6 are subject to spatter wear due to ion collision and removal. Become.

As a result, the shapes of the individual electrodes 6A to 6C of the extraction electrode system 6 change and they no longer have their original functions. That is,
The shape of the ion beam 8 extracted from the extraction electrode system 6 or the It (ion current j1) of the ion beam 8 changes, which impairs the stability of the ECR type ion source and, in Nagato's view, shortens the life of the ECR type ion source. There were problems such as inviting

This invention was made to solve the above-mentioned problems, and by reducing the sputter wear on the surface of each electrode of the extraction electrode system, the formed ion beam is stabilized for a long time and has a long life. , the purpose is to obtain an ECR type ion source.

[Means for Solving the Problems] The ECR type ion source according to the present invention has high-temperature stable, TiC, TaC, and Ti, which also have high ion sputter wear resistance.
It is coated with a material such as N or TaN.

[Function] The ECR type ion source according to the present invention has TiC, TaC, TiN, which has high ion sputter wear resistance, on the surface of each electrode of the extraction electrode system provided on one side of the plasma generation chamber where plasma is generated by microwaves. Or TaN
This coating reduces sputter wear caused by ions on each electrode in the extraction electrode system, and also reduces the incorporation of impurities into the plasma and contamination of the plasma generation chamber, thereby increasing the lifespan and stability of the ECR type ion source. can improve performance, including

[Example] FIG. 1 is a sectional view showing the configuration of one electrode of an extraction electrode system in an ECR type ion source which is an example of the present invention. In the figure, 6A is one electrode of the extraction electrode system 6 (see Figure 2), 9 is a plurality of ion extraction holes provided in the electrode 6A, and IO is a TiC coating that uniformly covers the surface of the electrode 6A. It is a membrane. Further, Mo is used as the material for the electrode 6A, and the electrodes 6B and 6C (see FIG. 2) are also coated in the same manner as the electrode 6A, and the extraction electrode system 6 is constructed by these.

The extraction electrode system 6 is a conventional EC shown in FIG.
It is arranged at the same position as the R-type ion source, and the other components of the ECR-type ion source according to the present invention are the same as those of the above-mentioned conventional example, and their arrangement is also the same.

Now, as a coating method for uniformly coating the surface of the electrode 6A with the TiC coating film 1O, there are two methods: a vapor phase chemical vapor deposition method such as a CVD method, and a physical film formation method such as an ion sputter coating method. There is electrode 6
It may be used appropriately depending on the specifications of the coating film 10 for A, such as thickness, crystal structure, coating area, etc. Here, since the inner wall of the hole 9 of the electrode 6A is also coated and a coating thickness of several hundred μm is required, TIC is coated on the surface of the electrode 6A by the former CVD method.

By the way, when ions collide with a certain material, that material undergoes sputter wear. This phenomenon is influenced by the mass and energy of the colliding ions, the crystallinity of the substance irradiated by the ions, the mass of atoms constituting the substance, the bond energy, etc., and has not yet been fully elucidated. Therefore, the sputter wear amount of materials caused by ions is often determined experimentally, and this invention is also based on experiments conducted by us.

Next, an example of the experiment will be described. Xenon (Xe) ions with an energy of 1 keV are
Each material of iC and TiN was irradiated and the wear rate of each was determined. The wear rates of each material due to ions for the same ion irradiation dose (unit ion current density) were as follows.

Mozloo (,μm/m1n-A/cm2)Ti
Nz36 (μm/m1n-A/cm2) TiNz3
6 (μm/m1n·A/am2) From these results, the wear rate of TiC, TiN, and Al2O3 due to ions was about 1/3 that of Mo. These values are based on the type of ion, which is a factor in the sputtering phenomenon caused by ions,
energy.

It is thought that it changes depending on the mass, etc., but it can be said from experience that the trends are the same. From the above, the sputter wear of the electrode 6A can be reduced by using the electrode structure of the present invention as shown in FIG. 1, in which the surface is coated with TIC, rather than using Mo alone. .

Although MO is used as the base material of the electrode material in the above embodiment, the same can be said of other single metal materials such as Ta.

Further, in the above embodiment, TiC is used for the coating film 10, but other materials such as charcoal or nitride having a cubic crystal structure may also be used.

Further, in the above embodiment, each electrode 6A to 6 of the extraction electrode system 6
Although the case of coating C with the low spatter coating film 10 has been described, it is also effective when coating a portion exposed to the plasma 7, such as the inner wall of the plasma generation chamber 2.

Further, although the ECR type ion source was described in the above embodiment, the present invention may be applied to other ion sources.

[Effects of the Invention] As described above, according to the ECR type ion source of the present invention,
On the surface of each electrode of the extraction electrode system installed on one side of the nolasma generation chamber where plasma is formed by microwaves,
Ti with high temperature stability and high ion sputter wear resistance
Since the electrodes are coated with a material such as c, TaC, or TaN, sputter wear of the electrodes can be reduced, and the life of the lead-out electrode system constituted by these electrodes can be extended. Furthermore, by reducing the mixing of substances (impurities) sputtered from the electrodes into the plasma, it is possible to form an ion beam with less impurities and reduce contamination of the plasma generation chamber, and also to improve the lifespan of the ECR type ion source. The ECR type ion source provides excellent effects such as being able to obtain a stable ion beam.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of one electrode of an extraction electrode system in an ECR type ion source which is an embodiment of the present invention;
FIG. 2 is a cross-sectional view showing the configuration of a conventional general ECR type ion source, and FIG. 3 is a cross-sectional view showing the configuration of one electrode of the extraction electrode system in the ECR type ion source of FIG. In the figure, l...Microwave waveguide, 2...Plasma generation chamber, 3...Microwave introduction window, 4...Magnet, 5...Gas inlet, 6...Extraction electrode system ,
6A to 6C... Electrode, 7... Plasma, 8... Ion beam, 9... Hole, 10... Coating film,
11... It is an insulator. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A microwave introduction window for introducing microwaves into a vacuum and a plasma generation chamber for forming plasma using the microwaves are provided. It has a configuration that satisfies the conditions as a cavity resonator for causing resonance, and is equipped with a magnet for forming a magnetic circuit around the plasma generation chamber, and further for extracting ions from the plasma and forming an ion beam. , TiC with high ion sputter wear resistance is applied to the surface of the extraction electrode provided on one side of the plasma generation chamber.
An ECR type ion source characterized by being coated with a material such as , TaC, TiN or TaN.