JPH04365863A - Method for coating inside wall of metallic capillary - Google Patents

Abstract

PURPOSE:To form a film at a high speed on the inside wall of a metallic capillary by providing cylindrical targets constituting a hollow cathode equidistantly from the central axis and at equal intervals in the capillary. CONSTITUTION:A device or coating the inside surface of the metallic capillary 3 by a plasma magnetron sputtering method is arranged with plural cylindrical targets 2 equidistantly from the central axis in the capillary 3 and axially at the equal spacings from each other. Multihollow cathode type coaxial magnetron discharge is executed by impressing a DC voltage to these targets in the state where a magnetic field is generated in the perpendicular direction to the discharging electric field. High-density plasma is formed in the capillary in this way, by which the film is formed at a high speed on the inside wall of the capillary.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention provides corrosion resistance,
This invention relates to a method of coating the inner wall of a pipe with a protective film with good adhesion for the purpose of improving wear resistance.

0002

2. Description of the Related Art As a conventional method for coating the inner wall of a pipe, there is a method as shown in FIG. 2, for example. (Unexamined Japanese Patent Publication No. 62-180
(Refer to Publication No. 069) In FIG. 2, 21 is a tube whose inner wall is coated, 22 is a rod-shaped target, 23 is a coil for generating a magnetic field, and 24 is for applying an electric field between the tube 21 and the rod-shaped target 22. It is the power source.

[0003] In this method, the pressure condition for obtaining a good film is set to 10-2 Torr, and a magnetic field is applied in a direction perpendicular to the discharge electric field. This is a method (coaxial magnetron sputtering) in which glow discharge is generated in a space (coaxial magnetron sputtering) and the inner wall of the tube is coated by sputtering.

0004

[Problems to be Solved by the Invention] When this method is used to coat the inner wall of a thin tube (with an inner diameter of 20 mm or less, for example), the discharge space becomes extremely narrow, depending on the diameter of the rod-shaped target. In order to maintain stable glow discharge in this narrow discharge space, it is necessary to
A degree of vacuum of about 10 −1 Torr is required. However, at this degree of vacuum, ions and sputtered particles collide with gas molecules and lose energy, making it impossible to form a good sputtered film.

[0005] Furthermore, when the pressure condition is set to a high vacuum region of 10-2 Torr for good sputtering film formation, the initial electrons for discharge are lost to the inner wall of the tube, making it difficult to sustain glow discharge stably. I can't let you.

[0006] Therefore, in the conventional method, there was a problem in that the inner wall of the narrow tube in the discharge space could not be coated by sputtering.

[0007] The present invention was made by focusing on such conventional problems, and maintains a stable glow discharge in a very narrow discharge space inside a thin tube in a high vacuum region of 10-2 Torr. The purpose is to enable coating of the inner wall of a capillary by sputtering.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for coating the inner wall of a metal capillary, in which a magnetic field is applied in a direction perpendicular to the discharge electric field, and the inner wall of the metal capillary is coated at an equal distance from the central axis inside the capillary. Furthermore, a so-called hollow cathode discharge is realized by applying direct current (DC) to several cylindrical targets arranged on axes at equal intervals.

[0009]

[Operation] In the method of coating the inner wall of a metal capillary tube of the present invention configured as described above, the magnetic field is

[Example 1] The effect of increasing the number of collisions with neutral gas molecules and promoting the ionization of neutral gas molecules can be obtained. (Magnetron effect)

[0010] Furthermore, by arranging several cylindrical targets (cathode) on axes equidistant from the central axis of the tube and equally spaced from each other, electrons are reflected by the sheath electric field formed on the surface of the cathode. , electrons can be confined near the cathode. As a result, the effect of increasing the number of collisions between electrons and neutral gas and the discharge current can be obtained. (Hollow cathode discharge effect)

Therefore, in the present invention, which achieves both of these effects at the same time, under high vacuum (10-2 Torr level),
High-density plasma can be maintained with stable glow discharge inside a narrow tube with a very narrow discharge space.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the drawings. FIG. 1 is a diagram showing an embodiment of the present invention. 1 is a vacuum container, 2 is a plurality of cylindrical targets, 3 is a tubular substrate for coating the inner surface, 4 is a power source for applying an electric field between the tube 3 and the plurality of cylindrical targets 2, and 5 is a A magnetic field generating coil, 6 a power source for the magnetic field, 7 a gas inlet, 8 a vacuum gauge, 9 an exhaust port, and 10 a vacuum pump.

In this embodiment, four titanium cylinders each having a diameter of 4 mm were arranged as cylindrical targets 2 on axes equidistant from the central axis of the tubular substrate 3 and equally spaced from each other. As the tubular substrate 3, a metal tube with a diameter of 20 mm and a length of 200 mm was used. Note that the shortest distance between each cylindrical target 2 and the inner wall of the tubular substrate 3 at this time was 4 mm. With such an electrode configuration, titanium nitride (TiN) is coated on the inner wall of the tubular substrate 3.
) was deposited.

First, the vacuum container 1 was sufficiently evacuated by driving the vacuum pump 10 through the exhaust port 9. Next, a mixed gas of argon and nitrogen is introduced from a gas cylinder (not shown) through the gas inlet 7, and the degree of vacuum in the vacuum container 1 is increased to 5×10.
-2 Torr. Note that the degree of vacuum at that time was measured using a vacuum gauge 8. Power was supplied from the magnetic field power source 6 to the magnetic field generating coil 5 to generate a magnetic field in a direction perpendicular to the discharge electric field. The strength of the magnetic field at that time was about 300 Gauss.

In this state, when a DC voltage is applied between several cylindrical targets 2 and the tubular substrate 3 from the power source 4, a very high density plasma is generated in the discharge space between the tubular substrate 3. I was able to do that. When the discharge current was measured at this time, it remained stable at a high value until the discharge was terminated.

As a result, the inner wall of the thin tube could be coated with a titanium nitride film that had a golden color. Furthermore, due to the synergistic effect of the magnetron effect and the hollow cathode discharge effect, the film forming pressure was set in a high vacuum range, resulting in a film with good adhesion. In addition, since the discharge current during film formation also shows a high value,
It was possible to form a film at a very high speed of 100 angstroms/second.

That is, in this method, a stable and large-current glow discharge is generated on the inner wall of a narrow tube in a discharge space under high vacuum, thereby making it possible to form a film by sputtering.

[0018]

[Effect of the invention] As explained above, according to this invention,
The inner walls of metal tubes, which are used as structural materials for transporting gases and liquids in a wide range of fields, can be coated quickly and firmly with a protective film that has corrosion and abrasion resistance functions.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an embodiment of an apparatus for carrying out the method of the present invention.

FIG. 2 is an explanatory diagram schematically showing an apparatus using a conventional method.

[Explanation of symbols]

2 Cylindrical target 3 Tubular substrate (metal thin tube)

[Outside 2]

Claims (1)

[Claims] Claim 1: A method for coating the inner wall of a metal capillary tube by sputtering using glow discharge plasma, comprising:
Inside the thin tube set up in a high vacuum, several cylindrical targets forming a hollow cathode are placed on axes equidistant from the central axis and equally spaced from each other, and are placed in a direction perpendicular to the discharge electric field. A method for coating the inner wall of a metal capillary tube, the method comprising applying a magnetic field.