JPH036220B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a sputtering cathode for forming a thin film on the outer peripheral surface of a thin wire such as a fiber by a sputtering method.

(b) Prior art () and its problems Generally, in the sputtering method, a thin film is formed on a substrate in the following manner. That is, in FIG. 2, a flat target 31 is placed on the surface of a target holder 32 in a vacuum atmosphere in a vacuum chamber (not shown) controlled at a gas pressure of 10 ^-1 to ^{10 -2} Torr. attached to the target holder 32
A permanent magnet or electromagnetic coil 33 is provided inside. A shield plate 34 is provided on the side surface of the target holder 32, that is, the surface on which the target 31 is not mounted, to prevent discharge. A substrate 35 on which a thin film is to be formed is placed in the vacuum atmosphere at a predetermined distance from the target 31.

In order to form a thin film on the substrate 35, the vacuum chamber is kept in a grounded state, and a negative DC voltage or a high frequency high voltage is applied to the target 31. Then, electrons are generated from the target 31 and a glow discharge is generated. These electrons generate spiral motion due to the magnetic field of the electromagnetic coil 33, collide with gas (for example, argon gas) in the vacuum atmosphere, and generate plasma. The positive ions generated at this time are attracted to the target 31 and collide with it, causing atoms constituting the target 31 to fly out. The atoms react with the gas and deposit on the substrate 35 to form a thin film.

In general, the desired material can be selected as the target material, and the shape can be manufactured freely.
The sputtering method is an effective method that can form a thin film of uniform thickness even on a substrate with a complicated surface shape.

However, when forming a thin film on a thin wire with a circular cross-sectional shape, such as a fiber, and a diameter of 5 mm or less, the two-pole sputtering device shown in Figure 2 has drawbacks. It was hot.

(a) Since there is only one target 31, in order to form a uniform film on the entire outer peripheral surface of the substrate 35 made of a thin wire, the substrate 35 must be rotated, and a rotation mechanism is required. Therefore, the equipment becomes complicated and expensive. Furthermore, since the substrate 35 is a thin wire, it is difficult to rotate it. As a result, it is difficult to form a uniform film using the apparatus shown in FIG.

(b) Since the surface area of the substrate 35 is too small relative to the area of the target 31, most of the atoms that become the raw material for the thin film that fly out from the target 31 are wasted, resulting in poor effectiveness.

Prior Art () and Problems Therein FIG. 3 shows a schematic diagram of the main parts of a facing target type sputtering apparatus, in which flat targets 41, 41 are arranged facing each other at a constant interval.
In FIG. 3, 42a target holder, 43
1 is an electromagnetic coil, 44 is a shield plate, and 45 is a substrate made of the thin wire, which are placed in a vacuum atmosphere in a vacuum chamber (not shown). The substrate 45 is placed between the targets 41, 41, so that films are formed from both sides. The sputtering method is the same as in the embodiment shown in FIG. 2, and utilizes electrical discharge between the targets 41, 41 and the vacuum chamber. In this case, due to wraparound, which is a characteristic of sputtering, a film is also formed on the surface of the substrate 45 that does not face the targets 41, 41.
A rotation mechanism becomes unnecessary. Furthermore, since the film is formed from both sides, the film formation rate becomes faster.

However, even in the facing target type sputtering apparatus shown in FIG. 3, the following problems cannot be solved. That is, (a) the film thickness distribution of the substrate 45 is as follows in its cross section:
It becomes an ellipse with a ratio of short axis to long axis of 4:6, and the film becomes thicker in the direction facing the targets 41, 41, making the film non-uniform.

(b) Since the surface area of the substrate 45 is too small compared to the area of the target 41, the efficiency of film formation is poor;
Therefore, the target material yield is poor.

Prior art () and its problems FIG. 4 shows a schematic diagram of the main parts of a hollow cathode type sputtering device, in which a cylindrical vacuum chamber 52
A target 51 is adhered to the entire inner wall of the target. Therefore, the entire vacuum chamber functions as a target holder. The substrate 55 is placed at the center of the vacuum chamber 52. This apparatus is an advantageous structure for forming films on substrates with circular external surfaces. Reference numeral 53 indicates an electromagnetic coil, and the sputtering method is performed by applying a voltage between the substrate 55 and the target 51 to excite discharge. The substrate 55 used in this device is a thick wire with a diameter of 50 mm or more, and the device is also large-sized.

The use of the hollow cathode type sputtering apparatus shown in FIG. 4 for forming a film on a thin wire of 5 mm or less has the following drawbacks.

(a) Since the device is large, the distance from the surface of the target 51 to the substrate surface is large, and atoms ejected from the target surface may combine with undesirable gases, resulting in a low purity film formed on the substrate surface. Become. Furthermore, the adhesion of the film to the substrate deteriorates.

(b) Since the surface area of the substrate is small relative to the effective area of the target, the efficiency of film formation is poor, and the yield of target material is therefore poor.

(c) Since this method applies voltage using the substrate as one electrode, film formation cannot be performed if the substrate is made of an insulating material.

(c) Purpose of the Invention The purpose of the present invention is to provide a sputtering cathode that can uniformly and efficiently form a thin film on a thin wire having a diameter of 5 mm or less.

Another object of the present invention is to provide a sputtering cathode that can be easily attached to a ready-made sputtering device and can perform sputtering using the ready-made sputtering device.

(d) Means for Solving the Problems The sputtering cathode of the present invention applies a voltage to a cylindrical target in a vacuum atmosphere to excite a discharge inside the cylinder. Thin wire material (including hollow tube material) of 5 mm or less to which no voltage is applied for sputtering
Form a thin film on the surface. For this reason, the sputtering cathode is constructed in a small size suitable for forming a thin film of the wire.

Further, the sputtering cathode includes a target holder in which the target is provided on an inner circumferential wall surface and a flow path for a fluid for cooling the target is provided therein; a shield box having a chamber communicating with the atmosphere; a sealing means for blocking the atmospheric condition in the chamber from the vacuum atmosphere; and a cylindrical electromagnetic coil or permanent magnet disposed in the chamber with the target passing through it. including.

According to a preferred embodiment of the present invention, a ready-made sputtering cathode is placed in the shield box in a vacuum atmosphere within a vacuum chamber of the sputtering apparatus.

(E) Embodiment FIG. 1 shows a longitudinal sectional view of a sputtering cathode of the present invention. In Figure 1, reference numeral 1
1 is a flange on the wall of a vacuum chamber of a ready-made sputtering device, and a shield box 2 is attached to this flange 1 by bolts 3, 3. A storage space is formed in the shield box 2 so that cathode parts such as a target holder 4 and an electromagnetic coil 5 can be stored therein, and the axial direction of a circular hole 2a that communicates this storage space with the outside is aligned with the flange 1.
The axial direction of the cylinder 2b is provided perpendicularly to the flange 1, and the other portions are separated from the storage space by the wall surface of the shield box. A ring-shaped electromagnetic coil 5, 5 or a permanent magnet having a center magnetic flux density of 100 G (Gauss) or more is housed in the storage space. Next, target holder 4
is stored in the storage space. Target holder 4
The target mounting portion 4a is formed into a cylindrical shape with a diameter slightly smaller than that of the circular hole 2a, and the target support portion 4b is formed integrally with the target mounting portion 4a and has a cross-sectional diameter smaller than that of the cylinder 2b. . At both ends of the outer circumferential surface of the target attachment part 4a, there are O.
Rings 6, 6 are attached, and a target 7 is attached to the inner peripheral wall surface of the target attachment portion 4a. Furthermore, a cylindrical channel 8 is provided in the target mounting section 4a surrounding the inner peripheral wall surface of the mounting section, and this channel 8 is provided in communication with the inside of the target support column 4b. The target support portion 4b is the flange 1
It extends to the outside of the vacuum chamber through a circular hole 1a provided in the vacuum chamber. A liquid or gas such as water or liquid nitrogen flows into the flow path 8 to prevent heat generation in the target 7.

A cylindrical seal member 9 made of an insulating material is provided in the gap between the shield box 2 and the target holder 4.
9 pass through the circular holes 2a, 2a, respectively, and are fitted to both ends of the mounting portion 4a of the target holder 4. Here, an O-ring 10,
10 is installed. Further, the shield members 9, 9 are pressed by presser caps 11, 11 and fixed to the shield box 2 with bolts 12. The presser caps 11, 11 have a circular hole 11a, which is slightly smaller in diameter than the target 7, in the center.
11a, which has the role of grounding excess electrons generated in the target 7 by discharge through this circular hole. An O-ring 13 is attached to the upper surface of the shield box 2, and a lid 14 is further fixed with bolts 15, 15 and nuts. An insulating ring 16 is provided between the outer peripheral wall surface of the target support column 4b and the inner wall of the base of the shield box 2.
is interposed therebetween, and the lead wires of the electromagnetic coils 5, 5 extend through this insulating ring 16. A chamber 17 surrounded by the shield box 2, the target holder 4, and the shield members 9, 9, in other words, a part of the storage space serves as a storage section for the electromagnetic coils 5, It communicates with the atmosphere outside the vacuum chamber through.

The sputtering cathode configured as described above is installed in a vacuum atmosphere in a vacuum chamber of a ready-made sputtering device. Thus, the space surrounding the sputtering cathode and the space in contact with the target 7 are placed in a vacuum atmosphere. This vacuum atmosphere space and the atmospheric pressure space in the chamber 17 are airtightly separated by the sealing means of the O-rings 6, 6, 10, 10 and seal members 9, 9. A substrate 18 made of a thin wire with a diameter of 5 mm or less is placed on the central axis of the target 7. A feeding and winding device (not shown) for continuous operation is attached to this substrate 18.

To perform sputtering, the vacuum chamber is grounded and a negative direct current or high frequency voltage is applied to the target 7. At this time, no sputtering voltage is applied to the substrate 18. On the other hand, the electromagnetic coil 5,
5 and flows into the flow path 8 to cool the target 7. A discharge is excited inside the cylinder of the target 7, and the electrons generated thereby perform a spiral motion due to the action of the electromagnetic coils 5, 5.
It moves toward the circular hole 11a of the cap 11 on one side and is grounded. The protons generated by this discharge collide with the target 7 and generate atoms,
The atoms are deposited on substrate 18 to form a thin film.
The distance that these generated atoms move toward the substrate 18 is short, and the cylindrical target 7 allows them to move toward the substrate 18.
Since the atoms are uniformly deposited over the entire surface of the substrate 8, the apparent sputtering speed becomes faster and a highly pure thin film is formed.

In addition, if it is configured so that it can be freely attached to a ready-made sputtering device as in this example,
It is inexpensive because the equipment such as the vacuum layer and electrical system of an off-the-shelf sputtering device can be used as is, and this sputtering cathode can be attached when forming a thin film on a thin wire, and for other purposes, it can be used as is. equipment is available.

(F) Effect The sputtering cathode of this invention has a diameter of 5
When forming a thin film on a thin wire of mm or less, it can be formed efficiently and uniformly with high purity, and the apparent sputtering speed at which the thin film is formed becomes faster. Moreover, since the discharge is excited in a state where no voltage is applied to the wire, thin film formation can be performed without any problem even when the wire is made of an insulating material. Also,
Since the chamber in which the electromagnetic coil is placed is maintained at atmospheric pressure, the heat generated by energizing the electromagnetic coil and the gas generated from the coil can be released, and this chamber is hermetically sealed from the vacuum atmosphere space. In addition, since the entire sputtering cathode is constructed in a small size to fit a thin wire, it is convenient to transport.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIGS. 2, 3, and 4 are schematic views of the main parts of a conventional sputtering apparatus. 1...flange, 2...shield box, 4
...Target holder, 5...Electromagnetic coil, 6,
10, 13...O-ring, 7...Target, 8
... Channel, 9 ... Seal member, 11 ... Presser cap, 14 ... Lid body, 16 ... Insulation ring, 17
...Chamber, 18...Substrate.

Claims (1)

[Claims] 1. Applying a voltage to a cylindrical target in a vacuum atmosphere to excite a discharge inside the cylinder, and forming a thin film on a wire rod for sputtering placed within the target to which no voltage is applied. A sputtering cathode comprising: a target holder in which the target is provided on an inner circumferential wall surface and a flow passage for a fluid for cooling the target is provided therein; and a chamber surrounding the target holder and enclosed together with the target holder. A shield box that communicates with the atmosphere,
A thin film of the wire rod having a diameter of 5 mm or less, comprising a sealing means for blocking the atmospheric condition in the room from the vacuum atmosphere, and a cylindrical electromagnetic coil or permanent magnet disposed in the chamber with the target passing through. A sputtering cathode configured to a size suitable for forming. 2. The shield box according to claim 1, wherein the shield box is provided with a mounting means to be attached to a ready-made sputtering device, and is placed in a vacuum atmosphere in a vacuum chamber of the sputtering device. Sputtering cathode.