JPH0987853A - Formation of protective film and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a protective film having uniform strength by increasing the strength of the magnetic field from a supporting body toward the microwave entering port of a plasma reaction tube and, in the middle of increasing the magnetic field, forming the crest of magnetic field strength smaller than the magnetic field strength in which electron cyclotron resonance occurs. SOLUTION: A protective film is formed on a supporting body opposite to a plasma reaction tube by an ECR plasma CVD method. A reaction gas is introduced into the plasma reaction tube, and plasma is excited by microwaves. The strength of the magnetic field is increased as advancing from the supporting body toward the microwave entering port of the plasma reaction tube. In the middle of the increase, the magnetic field having a magnetic field distribution having the crest of magnetic field strength smaller than the magnetic field strength in which electron cyclotron resonance occurs is generated. Again, the magnetic field having a magnetic field distribution in which the strength of the magnetic field increases to the magnetic field strength in which electron cyclotron resonance occurs is generated. Since the energy and flow rate of plasma to the supporting body are controlled, the protective film is made uniform.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ECR plasma C
The present invention relates to a technique for forming a protective film by the VD method.

[0002]

In a magnetic recording medium such as a magnetic tape, a magnetic layer provided on a support is not a coating type using a binder resin, but a binder. A metal thin film type using no resin has been proposed. That is, there has been proposed a magnetic recording medium having a magnetic layer formed by a wet plating means such as electroless plating or a dry plating means such as vacuum deposition, sputtering or ion plating. This type of magnetic recording medium has a high filling density of a magnetic material and is suitable for high-density recording.

In order to protect the metal magnetic film in this type of magnetic recording medium, it has been proposed to provide various protective films on the surface. There are various means for providing the protective film on the surface. For example, hot filament CVD apparatus, photo CVD apparatus, RF plasma CVD apparatus, microwave plasma CVD apparatus, ECR microwave plasma CV
CVD (Chemical Vapor Deposition) such as D equipment
Device, etc.

In particular, the ECR microwave plasma CVD apparatus draws high-density plasma generated by electron cyclotron resonance (ECR) and uses it for reaction, and has an advantage that the support is less damaged, and is widely used. It's being used. However, the conventional ECR microwave plasma CVD method cannot control the energy and flux of plasma with respect to the support. Therefore, there is a drawback that a protective film having a uniform strength cannot be obtained.

Therefore, an object of the present invention is to provide an ECR microwave plasma CVD technique capable of forming a protective film having uniform strength.

[0006]

The object of the present invention is to provide a method for forming a protective film on a support at a position facing a plasma reaction tube by an ECR plasma CVD method.
The step of introducing a reaction gas into the plasma reaction tube, the step of introducing microwaves into the plasma reaction tube to excite the plasma, and the strength of the magnetic field from the support toward the microwave entrance of the plasma reaction tube. The magnetic field has a magnetic field distribution in which the magnetic field intensity increases and the magnetic field intensity has a peak smaller than the magnetic field intensity at which electron cyclotron resonance occurs, and the magnetic field intensity increases again until the magnetic field intensity at which the electron cyclotron resonance occurs. And a step of generating the protective film.

Another object of the present invention is an apparatus for forming a protective film by the ECR plasma CVD method, which is a plasma reaction at a position facing a vacuum chamber and a support disposed in the vacuum chamber. Tube, a reaction gas supply means for supplying a reaction gas into the plasma reaction tube, and the strength of the magnetic field increases from the support toward the microwave entrance of the plasma reaction tube, and electron cyclotron resonance occurs during the increase. And a magnetic field generating means for generating a magnetic field having a magnetic field distribution in which the magnetic field strength increases again up to the magnetic field strength at which the electron cyclotron resonance occurs again. It is achieved by the protective film forming apparatus.

The above-mentioned peak of magnetic field strength means that the magnetic field strength has a peak which is smaller than the magnetic field strength at which electron cyclotron resonance occurs, and the magnetic field is once weakened from the peak. In the present invention, in particular, it is preferable to generate a magnetic field so that the above-mentioned mountain is generated at a position closer to the support side than the center position between the support and the microwave entrance, and more preferably the support. It is to generate so that there are mountains in the vicinity.

The present invention can be applied to any field in which a protective film is provided. For example, a magnetic film of a magnetic recording medium,
Particularly, it is used for forming a protective film for protecting a metal thin film type magnetic film.

[0010]

1 is a schematic view of the entire protective film forming apparatus (ECR microwave plasma CVD apparatus) of the present invention. In FIG. 1, 1 is a roll of a magnetic recording medium provided with a metal magnetic film on the surface of a support, 2 is a vacuum tank, 3a is a roll on the roll of feed 1, 3b is a roll on the roll of roll 1, Reference numeral 4 is a cooling can roll, and the original fabric 1 is configured to travel from the supply-side roll 3a through the cooling can roll 4 to the winding-side roll 3b and be wound up.

Reference numeral 5 is a plasma reaction tube provided so as to face the cooling can roll 4, and reference numeral 6 is a reaction gas (for example, methane,
A pipe for supplying hydrocarbon gas such as ethylene and benzene), and 7 is a microwave waveguide. The mouth of the reaction gas supply pipe 6 is inside the plasma reaction tube 5,
It is located near the cooling can roll 4. Reference numeral 8 is an ECR coil. The ECR coil 8 generates a magnetic field in the same direction as the traveling direction of microwaves to cause cyclotron resonance. Then, as shown in FIG. 2, when the distance is increased in the crystal window 9 direction with the cooling can roll 4 as the origin, the magnetic field distribution increases as the distance increases.
The magnetic field strength increases at a constant rate, and the magnetic field strength at which electron cyclotron resonance occurs again at a constant rate is given a peak of magnetic field strength smaller than the magnetic field strength (ECR point) at which electron cyclotron resonance occurs during the increase. A magnetic field having a magnetic field distribution such that the strength of the magnetic field increases up to the (ECR point) is generated. In particular, the ECR coil 8 is arranged such that the above-mentioned peaks are formed on the cooling can roll 4 side, that is, when the distance from the cooling can roll 4 to the crystal window 9 is L, the peaks are located at positions smaller than L / 2. Generate a magnetic field so that The position of this peak can be changed by appropriately adjusting the ECR coil 8.

Then, a protective film is formed on the metal magnetic film by performing ECR plasma CVD using the above apparatus.

[0013]

[Embodiment 1] In this embodiment, in the above-mentioned apparatus, the distance L from the cooling can roll 4 to the crystal window 9 is 40 cm.
And the ECR point was set to 875 G (ECR power 600 w). Further, as shown in FIG. 3, a peak of about 450 G was set so that a distance from the cooling can roll 4 was about 12 cm.

Then, using methane as a reaction gas, the gas is supplied from the pipe 6 into the plasma reaction tube 5, and a microwave of 2.45 GHz is introduced into the plasma reaction tube 5 by the waveguide 7 to excite plasma. A magnetic field is generated by the ECR coil 8 in the same direction as the microwave traveling direction to cause cyclotron resonance, and a thickness of 0.2 is provided on the support.
A protective film (diamond-like carbon film) was formed on the Co metal magnetic film having a thickness of μm. The tape winding speed is 1
m / min.

[0015]

COMPARATIVE EXAMPLE 1 In Example 1, instead of the magnetic field distribution shown in FIG. 3, the magnetic field distribution shown in FIG. 4 (at a position where the distance from the cooling can roll 4 is about 12 cm, the magnetic field strength (about 400 G) is flat (mountain (peak)). The procedure was carried out in accordance with Example 1 except that a magnetic field distribution) that "(valley) none" was used.

[0016]

COMPARATIVE EXAMPLE 2 In Example 1, instead of the magnetic field distribution of FIG. 3, the magnetic field distribution of FIG. 5 (from the cooling can roll 4 to the crystal window 9) is used.
Example 1 was performed according to Example 1 except that a magnetic field distribution in which the strength of the magnetic field uniformly increases) was used.

[0017]

[Characteristics] In order to examine the strength of the protective film (diamond-like carbon film) of the magnetic recording medium obtained as described above, the strength was measured by a scratch test. For the scratch test method, tape was attached to a slide glass, and a Shimadzu scanning scratch tester for thin film evaluation (Shimadzu S
Using ST-101), the output fluctuation under a constant load (200 mN) was measured to measure the strength distribution of the protective film.
The results are shown in FIGS.

As can be seen from FIGS. 6 to 8, it can be seen that the present embodiment (FIG. 6) has a certain characteristic. On the other hand, it can be seen that the comparative examples (FIGS. 7 and 8) have variations. Next, a still durability test was conducted to examine the durability. In the still durability test, the obtained magnetic recording medium (8 mm VTR magnetic tape) was heated at 20 ° C. and 50% RH.
Still reproduction was performed under the conditions of, and the time until the output dropped to 3 dB was measured. The results are shown in Table-1.

Table 1 Example 1 Comparative Example 1 Comparative Example 2 Still Durability 4.5 hr 2.2 hr 2.0 hr From this, it can be seen that the protective film of this Example has an excellent function.

[0020]

According to the present invention, a protective film which is homogeneous and has excellent strength can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view of the entire protective film forming apparatus of the present invention.

FIG. 2 is a magnetic field distribution diagram of the protective film forming apparatus of the present invention.

FIG. 3 is a magnetic field distribution diagram of Example 1.

FIG. 4 is a magnetic field distribution chart of Comparative Example 1.

FIG. 5 is a magnetic field distribution chart of Comparative Example 2.

FIG. 6 is a diagram showing a result of strength measurement by a scratch test on the protective film of Example 1.

FIG. 7 is a diagram showing the result of strength measurement by a scratch test on the protective film of Comparative Example 1.

FIG. 8 is a view showing a result of strength measurement by a scratch test on a protective film of Comparative Example 2.

[Explanation of symbols]

 1 Fabrication of magnetic recording medium 2 Vacuum tank 4 Cooling can roll 5 Plasma reaction tube 6 Pipe for supplying reaction gas 7 Microwave waveguide 8 ECR coil 9 Crystal window

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Sasaki 2606, Akabane, Kai, Haga-gun, Tochigi Prefecture Kao Co., Ltd.Institute of Information Science Research Institute (72) Junko Ishikawa 2606, Akabane, Kai-cho, Haga-gun, Tochigi Kao Shikisha Institute of Information Science

Claims (4)

[Claims] 1. A method of forming a protective film by ECR plasma CVD on a support located at a position facing a plasma reaction tube, the step of introducing a reaction gas into the plasma reaction tube, and the plasma reaction tube. A step of exciting a plasma by introducing microwaves into the plasma reaction tube, the strength of the magnetic field increases from the support toward the microwave entrance of the plasma reaction tube, and the magnetic field strength at which electron cyclotron resonance occurs during the increase And a magnetic field having a magnetic field distribution in which the magnetic field strength increases again until the electron cyclotron resonance occurs again. 2. The protective film formation according to claim 1, wherein the magnetic field is generated so that the peak is generated at a position closer to the support side than a center position between the support and the microwave entrance. Method. 3. The method for forming a protective film according to claim 1 or 2, wherein a protective film is formed on the magnetic film on the support. 4. An apparatus for forming a protective film by an ECR plasma CVD method, comprising: a vacuum chamber, a plasma reaction tube facing a support disposed in the vacuum chamber, and a plasma reaction tube in the plasma reaction tube. And a reaction gas supply means for supplying a reaction gas to the substrate, and the magnetic field strength increases from the support toward the microwave entrance of the plasma reaction tube, and the magnetic field strength is smaller than the magnetic field strength at which electron cyclotron resonance occurs in the course of the increase. An apparatus for forming a protective film, comprising: a magnetic field generating means having a magnetic field strength peak and generating a magnetic field having a magnetic field distribution in which the magnetic field strength increases again until the electron cyclotron resonance occurs.