JPH04341591A - Spattering cleaning device - Google Patents

Abstract

PURPOSE:To provide a spattering cleaning device for which spattering cleaning to the surface of the inside wall of a metal thin tube having low electric conductivity and a small diameter can sufficiently be chieued. CONSTITUTION:Pure gaseous argon as ionizable gas is supplied from a gas supplying part 3 through an inlet 1c into a vacuum vessel 1 at the pressure set from a range of 0.1-10Pa, and on the other hand, electric potential difference between the metal thin tube 20 and the vacuum vessel 1 is imparted at >=1kV by a high DC voltage supplied from an power source 5. By this method, ionizable gas is ionized, beam-shaped plasma is generate in the metal thin tube 20 to remove an oxide film.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering cleaning apparatus for removing an oxide film from the inner surface of a metal tube using ion bombardment.

0002

2. Description of the Related Art Generally, in a nuclear fusion plasma device aimed at removing impurities with high adsorption energy remaining on the surface of the inner wall of a vacuum chamber, a Taylor discharge [L. Orenand R. Taylor: Nucl.
Fusion17 (1977) 1143. ], glow discharge [J. Winteret al. :J. Nucl
．． Mater. 93 and 94 (1980) 81
2. ], ECR discharge [Y. Sakamoto et.
al. :J. Nucl. Mater. 93 and
94 (1980) 933. ] Discharge cleaning is carried out using methods such as

On the other hand, in an accelerator, Ar gas or Ar+O2
Glow discharge cleaning using gas [A. G. Mathew
son: Vacuum 24 (1974) 505,
H. Kitamura: Nucl. Inst. Meth
．． 177 (1980) 107, H. C. Hseuh
,T. S. Chou and C. A. Christi
anson: J. Vac. Sci. Technol. A
3 (1985) 518, etc. ] is being carried out. Furthermore, glow discharge cleaning [R. P. Gouier
and G. W. McCracken: J. Vac. S
ci. Technol. 7 (1970) 552. ] is being carried out.

0004

[Problem to be solved by the invention] These discharge cleaning methods are
Although it can be applied to desorb heavy inhaled gases such as oxygen and carbon monoxide, it is not applicable because the amount of energy of the ions colliding with the wall is small, and it takes too long to clean the oxide film on the wall surface. There is a drawback that. Therefore,
In order to effectively remove the oxide film from the wall surface, it is necessary to increase the amount of energy of the ions.

By the way, the ion energy is high (several kV) and the ion current is relatively high (several mA/cm2).
) As a sputtering cleaning method that can be used, there is a plasma source nitrogen method using Ar gas [M. Nunogaki, H.
Suezawa et al. :Appl. Surf.
Sci. 33 and 34 (1988) 1135-1
141. ] There is. By using the plasma source nitrogen method, the oxide film on the wall surface can be removed in a short time.

However, even when this plasma source nitrogen method is used, when treating the inner surface of a metal tube, the plasma cannot penetrate the entire inside of the tube, so the inner surface of the tube is sputtered. The disadvantage is that you cannot get it. As described above, in order to remove the oxide film on the inner surface of the tube, it is necessary to introduce or generate plasma into the tube and bombard the inner surface with high energy ions from the plasma.

The present invention has been made to solve these problems, and its purpose is to provide a sputtering cleaning device that can efficiently perform sputtering cleaning on the inner wall surface of a metal tube in a short time. be.

[0008]

[Means for Solving the Problems] According to the present invention, a vacuum container is provided with an ionizing gas inlet and an exhaust port, as well as a mounting port, a sample mounting medium attached to the mounting port, and an inlet. 0.1-10 Pa of ionizing gas into the vacuum container through
A power source that provides a potential difference of 1 kV or more between the gas supply unit that supplies a pressure set within the range of , the metal capillary tube housed in the vacuum container via the sample mounting medium, and the vacuum container and the metal capillary tube. A sputtering cleaning device having a part is obtained.

[0009] The sputtering cleaning apparatus of the present invention will be described in detail below with reference to Examples. FIG. 1 shows the basic configuration of a sputtering cleaning apparatus that is an embodiment of the present invention.

The sputtering cleaning device shown in FIG. 1 includes an inlet 1c, an exhaust port 1b, and a mounting port 1a, and the degree of vacuum is increased to 3×10 − by an exhaust device (not shown).
It includes a vacuum container 1 maintained at 4 Pa, and a current introduction terminal 7 as a sample mounting medium attached to a mounting port 1a. A thin metal tube 20 is housed in the vacuum container 1 via a current introduction terminal 7, and one end of a pipe with an expansion valve 3a and a mass flow sensor 3b interposed therein is disposed at the introduction port 1c. Further, the other end of this pipe is connected to a gas cylinder 3c. Furthermore, the metal thin tube 20 is connected in series to the DC high voltage power supply unit 5 via a stabilizing resistor 6 via an electric wire. The vacuum container 1 and the power supply section 5 are each grounded.

The expansion valve 3a, mass flow sensor 3b, and gas cylinder 3c are collectively referred to as a gas supply section 3. This gas supply section 3 supplies pure argon gas as an ionizing gas to the vacuum container 1 at a pressure of 0.1 to 10 P through an inlet port 1c.
This is to set and supply within the range of a. on the other hand,
As the power source section 5, one that can provide a predetermined potential difference of 1 kV or more between the metal capillary tube 20 and the vacuum container 1 is used. In the illustrated example, the predetermined pressure is 0.6 Pa and the potential difference is 4 kV. Further, it is assumed that the metal thin tube 20 is made of an aluminum alloy material and has dimensions of 35 mm in diameter, 300 mm in length, and 3 mm in thickness.

[0012] The sputtering cleaning apparatus having such a configuration has the potential difference between the metal capillary tube 20 and the vacuum vessel 1;
The gas is sucked in from the inlet port 1c by the gas supply unit 3, and the gas is sucked into the exhaust port 1
When the pressure in the vacuum container 1 of the ionizing gas discharged from b is adjusted to the above potential difference and pressure, the metal capillary tube 20
It was discovered that a strong electric field was generated inside the chamber, ionizing the argon gas and generating a beam-shaped plasma. As a result,
Since the argon cations are extracted by a strong electric field and impact the inner wall surface of the metal capillary tube 20 with high energy, the oxide film attached to the inner wall surface of the metal capillary tube 20 can be removed in a short time.

FIG. 2 is for explaining the steady state of plasma generated within the metal capillary tube 20 at this time. Inside the vacuum vessel 1, equipotential lines appear symmetrically with respect to the central axis of the metal thin tube 20. The potential near the central axis of the metal tube 20 is approximately equal to the potential of the vacuum vessel 1, and a potential distribution is formed such that plasma is formed in this region and a negative electric field is applied from this region to the inner wall. .

Next, the plasma generation process will be explained. When secondary electrons e are emitted due to ion bombardment on the inner wall of the vacuum container 1, the secondary electrons e are caused by the positive electric field in the region from the inner wall of the metal tube 20 to the point where plasma is generated. Although it is accelerated in the radial direction, once it enters the region where plasma is generated, it moves at a constant speed because it is at equal potential. Then, when the plasma continues to exit the plasma generation region, it is decelerated up to the opposing inner wall by a reverse electric field (negative electric field). That is, the secondary electrons e released by ion bombardment move back and forth in the radial direction within the tube. This increases the probability of ionization collision between the gas molecules in the tube and the secondary electrons e, and generates plasma with high ion density.

When the ions d in the plasma leave the plasma boundary due to thermal motion, they are accelerated in the radial direction by riding on the negative electric field directed toward the inner wall, so that they impact the inner wall. As a result, the ability to remove the oxide film from the inner wall surface of the metal thin tube 20 is enhanced, so sputtering cleaning can be performed efficiently.

Next, referring to FIG. 3, a sputtering cleaning apparatus according to another embodiment of the present invention will be described. This sputtering cleaning apparatus further includes a plasma generating section 8 that converts argon gas into a plasma state and supplies it into the vacuum container 1;
A power supply section 9 is provided for supplying power to start up the plasma generation section 8. Here, argon gas in a plasma state is diffused into a vacuum container 1, and a metal capillary tube 2
A plasma interface is generated around 0.

FIG. 4 is for explaining the steady state of plasma diffused into the vacuum vessel 1 at this time. Plasma of argon gas is formed between a plasma interface m1 surrounding the metal capillary tube 20 and a plasma interface m2 along the vicinity of the inner wall of the vacuum vessel 1 by supplying a DC high voltage to the metal capillary tube 20. . This plasma interface m1 is formed at a distance x from the metal capillary tube 20 according to Langmuir-Child's 3/2 law.

Next, the steady state of plasma inside the metal capillary tube 20 under the above-mentioned conditions will be explained. As is clear from the comparison with FIG. 2, the requirements in FIG. 4 are the same as in the case where the vacuum vessel 1 shown in FIG. 2 is replaced with the plasma interface m1. As a result, the metal capillary tube 2 shown in FIG.
As far as the plasma generation phenomenon inside the metal tube 20 is concerned, it is the same as the plasma generation phenomenon inside the metal capillary tube 20 shown in FIG. Therefore, the differences from the case of FIG. 2 will be explained below.

The plasma inside the metal capillary tube 20 in FIG. 2 only comes into contact with the vacuum vessel 1 outside the tube, but in the case of FIG. It is in contact with the interface m1. For this reason, the plasma c in the metal capillary tube 20 shown in FIG. 4 is supplied with electrons and ions d from the plasma interface m1 of another plasma, and the plasma density (electron density, ion density) in the metal capillary tube 20 is increased. This effect is added. As a result, the metal thin tube 20
Since the current density of ion bombardment on the inner surface increases, the cleaning efficiency of the sputtering cleaning device is improved. That is, FIG.
The sputtering cleaning apparatus shown in FIG. 2 has the advantage of being able to perform sputtering cleaning at a higher speed than that shown in FIG.

FIG. 5 shows a metal capillary tube 20 (A
5052, diameter 35mm x length 300mm x thickness 3mm
) shows the analysis results of the inner wall surface condition (residual oxygen O) analyzed by EPMA (electron probe X-ray microanalyzer). Here, waveform g1 indicates the amount of residual oxygen when cleaning is performed using the sputtering cleaning device shown in FIG. 1, and waveform g2 represents the amount of residual oxygen when cleaning is performed using the sputtering cleaning device shown in FIG. . Note that the waveform g3 indicates the amount of oxygen on the inner wall surface before the cleaning treatment. Each waveform has a wavelength in the range of 22 to 25 angstroms, and has a frequency of 25 cps (color phase alternation).
Waveforms g1 and g2 show the residual oxygen adhesion amount analyzed by spectra for each indicator, and the waveforms g1 and g2 are obtained by cleaning the metal capillary for 2 hours and maintaining the potential difference between the metal capillary and the vacuum vessel at 4 kV. Is going.

As is clear from the comparison of the peak values of the oxygen adhesion amount O of each waveform, the peak value of waveform g3 is large, whereas the peak value of waveform g1 is considerably lower than that of waveform g3. , almost no peak value can be seen in waveform g2. This means that when the sputtering cleaning apparatus of the present invention is used, the oxide film on the inner wall surface of the metal capillary tube 20 can be almost completely removed.

The diameter of the thin metal tube 20 to be cleaned by the sputtering cleaning apparatus of the present invention may be even smaller.

[0023]

As described above, according to the present invention, even if the metal tube has low conductivity and a small diameter, the inner wall surface of the tube can be efficiently and sufficiently cleaned by sputtering. A device is obtained. This makes it possible to perform periodic maintenance inside the metal capillary, which has not been possible in the past, and provides great convenience for all industrial products that include metal capillaries. Moreover, in the present invention,
Although the sputtering cleaning apparatus was constructed using pure argon gas (inert gas) as the ionizing gas, for example, the ionizing gas could be replaced with reactive gas such as nitrogen (N2) or methane (CH).
4), the present invention can also be applied to an apparatus for nitriding or carbonizing the inner wall surface of a metal capillary.

[Brief explanation of the drawing]

FIG. 1 shows the basic configuration of a sputtering cleaning apparatus that is an embodiment of the present invention.

FIG. 2 is shown to explain the steady state of plasma within the metal capillary.

FIG. 3 shows the basic configuration of a sputtering cleaning apparatus according to another embodiment of the present invention.

FIG. 4 is shown to explain the steady state of plasma within the metal capillary.

FIG. 5 shows the results of analyzing the amount of oxygen adhering to the inner wall surface of a metal capillary tube after sputtering cleaning using the sputtering cleaning apparatus of the present invention.

[Explanation of symbols]

1 Vacuum container 1a Mounting port 1b Exhaust port 1c Inlet 2 Steel pipe 3 Gas supply section 5 Power supply section 6 Resistance 7 Current introduction terminal (sample mounting medium) 8 Plasma generation part 9 Power supply section 20 Metal thin tube

Claims (2)

[Claims] Claims: 1. A vacuum container comprising an ionizing gas inlet and an exhaust port as well as an attachment port; a sample mounting medium attached to the attachment port; a gas supply unit that supplies the vacuum container with a pressure set in a range of 0.1 to 10 Pa; a metal capillary tube housed in the vacuum container via the sample mounting medium; A sputtering cleaning device comprising: a power supply section that provides a potential difference of 1 kV or more between thin metal tubes. 2. The sputtering cleaning device according to claim 1, further comprising:
A sputtering cleaning apparatus comprising: a plasma generation section that converts the ionizing gas into a plasma state and supplies it into the vacuum container; and a power supply section that supplies power for starting the plasma generation section. .