JPH07122137B2 - Hard carbon film formation method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a hard carbon film used as a protective film for magnetic disks, magnetic heads, optical parts, etc.
The present invention relates to a technique for forming a hard carbon film by an R (Electron Cyclotron Resonance) plasma CVD method.

[0002]

2. Description of the Related Art Generally, DLC (Diamond Like Carbon)
Films have recently attracted attention because they have excellent properties similar to diamond in terms of hardness, insulation, thermal conductivity, light transmission, and chemical stability. This DL
Ion beam method, sputtering method,
Various methods such as an ion plating method and a plasma CVD method are used.

On the other hand, recently, as a kind of plasma CVD method, ECR plasma CV capable of forming a high quality film at a low temperature.
Method D has been developed and is already in practical use. This EC
In the R plasma CVD method, high-density plasma is generated under a low gas pressure by exciting electron cyclotron resonance. This plasma flow is drawn out by a divergent magnetic field from an ECR ion source and irradiated on a sample such as a substrate to form a film.

[0004]

When a DLC film is formed on a substrate by using the above-described manufacturing method, a high compressive stress of about 10 ¹⁰ dyne / cm ² remains in the DLC film. Therefore, the adhesion between the DLC film and the substrate, particularly the metal substrate, is poor, and there is a problem that peeling, cracking, or the like occurs during the formation of the DLC film.

An object of the present invention is to provide a method for forming a hard carbon film having a high adhesion with a substrate.

[0006]

According to the method for forming a hard carbon film of the present invention, a microwave is introduced into a plasma chamber to generate plasma by electron cyclotron resonance, and a predetermined amount is formed on a substrate arranged in the reaction chamber. A method of applying a high-frequency voltage and irradiating the substrate with ions in the plasma to form a hard carbon film on the substrate, including the following steps. ◎ Argon gas is introduced into the reaction chamber to generate plasma, and the substrate is sputtered to roughen the surface and reduce the surface area.
The process of increasing . ◎ A step of forming a hard carbon film on a sputtered substrate.

[0007]

In the method for forming a hard carbon film according to the present invention, first, argon gas is introduced into the reaction chamber and the substrate is sputtered by plasma. As a result, the surface of the substrate is cleaned and the surface of the substrate is roughened to increase the adhesion area. Next, a hard carbon film is formed on the sputtered substrate. At this time, since the substrate has already been cleaned and the adhesion area has increased, the adhesion between the hard carbon film and the substrate is good. For this reason, a hard carbon film is formed without the risk of peeling or cracking.

[0008]

EXAMPLE First, an ECR plasma CVD apparatus to which an example of the present invention is applied will be described. FIG. 1 is a sectional configuration diagram of an ECR plasma CVD apparatus.

In the figure, the plasma chamber 1 is constructed so as to be a cavity resonator for the introduced microwave (frequency 2.45 GHz), for example, diameter 20c.
It is a cylindrical chamber having a height of m and a height of 20 cm. Plasma chamber 1
A waveguide 3 having a rectangular cross section for introducing microwaves through a microwave introduction window 2 made of quartz or the like is connected to the. An argon gas inlet 10 is formed in the upper part of the plasma chamber 1. Further, electromagnetic coils 4a and 4b as a magnetic circuit for generating plasma are arranged around the plasma chamber 1. The intensity of the magnetic field generated by the electromagnetic coils 4a and 4b is determined so that the conditions of electron cyclotron resonance by microwaves are satisfied inside the plasma chamber 1. A divergent magnetic field diverging downward is formed by the electromagnetic coils 4a and 4b.

A reaction chamber 5 is provided below the plasma chamber 1. A substrate 7 on which a plasma flow M drawn from the plasma chamber 1 is irradiated is held by a substrate holder 8 below the reaction chamber 5. The substrate holder 8 is attached to the support shaft 9. A high frequency power source (for example, a frequency of 13.56 MHz) 11 is attached to the substrate holder 8 via a support shaft 9.
Are connected, so that a predetermined high frequency voltage is applied to the substrate 7. Further, the high frequency power supply 11 can change the applied power supply voltage.

A shutter 12 which can be opened and closed is provided above the substrate holder 8 . The irradiation of the plasma flow M onto the substrate 7 can be adjusted by the opening degree of the shutter 12. A hydrocarbon gas inlet 5a is formed on the upper side surface of the reaction chamber 5. An exhaust port 5b is formed in the lower part of the reaction chamber 5, and the exhaust port 5b is formed.
Is connected to an exhaust system (not shown).

Next, a method for forming a hard carbon film will be described while explaining the operation of this apparatus. First, the substrate 7 to be deposited is held by the substrate holder 8. Next, the plasma chamber 1 and the reaction chamber 5 are evacuated by an exhaust system (not shown) so that the internal gas pressure is 5 × 10 ⁻⁶ Torr or less. Then, argon gas is introduced into the plasma chamber 1 through the argon gas inlet 10. Then, the electromagnetic coils 4a and 4b provided around the plasma chamber 1 are energized so that the magnetic flux density in the plasma chamber 1 becomes 875 Gauss. At this time, no high frequency voltage is applied to the substrate 7. From this state, a microwave having a frequency of 2.45 GHz is introduced into the plasma chamber 1 via the waveguide 3 to generate plasma in the plasma chamber 1.

Next, a high frequency (13.56 MHz) is applied to the substrate 7 from the high frequency power supply 11. Then, the shutter 12 is opened, the substrate 7 is irradiated with the plasma flow, and the substrate 7 is sputtered. Substrate 7 at this time
Has a bias voltage of -200 to -500V. The surface of the substrate 7 sputtered by the argon gas ions is cleaned and the surface of the substrate is roughened to increase the adhesion area.

In this way, argon gas is used as the reaction gas used for cleaning the substrate 7 and for increasing the adhesion area, but with other reaction gases, such as hydrogen gas, hydrogen is used in the substrate. Goes in,
The diamond-like carbon film may peel off.

After the sputtering of the substrate 7 is completed, argon gas is exhausted from the exhaust port 5b by the exhaust system, and the plasma chamber 1 and the reaction chamber 5 are again brought to a high vacuum state (5 × 10 ⁻⁶ To).
rr or less). Then, a hydrocarbon-based gas such as CH ₄ gas is introduced into the reaction chamber 5 through the hydrocarbon gas introduction port 5a.

Next, the electromagnetic coils 4a and 4b provided around the plasma chamber 1 are energized so that the magnetic flux density in the plasma chamber 1 becomes 875 gauss. Also, at this time,
No high frequency voltage is applied to the substrate 7. From this state, a microwave having a frequency of 2.45 GHz is introduced into the plasma chamber 1 through the waveguide 3 to generate plasma in the plasma chamber.

Under these conditions, in the plasma chamber 1, the frequency of the electrons rotated by the magnetic field of 875 gauss and the frequency of the microwave of 2.45 GHz match,
Causes electron cyclotron resonance. As a result, the electron efficiently absorbs energy from the microwave and is accelerated. The accelerated electrons collide with gas molecules and ionize the gas molecules, so that high-density plasma is generated in the low-pressure gas. The plasma generated in the plasma chamber 1 is
It is extracted along the lines of magnetic force of the divergent magnetic field formed by the electromagnetic coils 4a and 4b.

Next, a high frequency (13.56 MHz) is applied to the substrate 7 from the high frequency power source 11. Then, the shutter 12 is opened. Then, the plasma flow extracted from the plasma chamber 1 is irradiated onto the substrate 7, and a hard carbon film is formed on the substrate 7. The bias voltage of the substrate 7 at this time is -200V to -500V. At this time, the surface of the substrate 7 is already cleaned, and the adhesion area with the hard carbon film is increased in the roughened state, so that the adhesion of the hard carbon film to the substrate 7 is improved.

As described above, in one embodiment of the present invention, the adhesion of the hard carbon film to the substrate 7 can be improved by using the conventional ECR plasma CVD apparatus as it is.

Experimental Example 1 Argon (Ar) gas was used, and bias voltage was -500V.
Then, the Si wafer substrate was cleaned. The cleaning time was 1 minute. Then after evacuation, introducing a hydrocarbon gas (e.g., CH _4), was deposited diamond-like carbon film at a bias voltage -200 V. In this case, the diamond-like carbon film was not peeled off.

Experimental Example 2 A hydrogen (H ₂ ) gas was used to clean a Si wafer substrate at a bias voltage of −500V. The cleaning time was 4 minutes. This is because the etching rate with H ₂ gas is ¼ of the etching rate with Ar gas.
(Etched to the same depth.) Next, after evacuation, a hydrocarbon gas (for example, CH ₄ ) is introduced and a bias voltage of −20
A diamond-like carbon film was formed at 0V. In this case, the diamond-like carbon film was peeled off several times.

[0022]

In the method for forming a hard carbon film according to the present invention, since the hard carbon film is formed on the substrate which is previously sputtered by the plasma of argon gas, the adhesion to the substrate is good and peeling or cracking does not occur. A hard carbon film that does not occur can be formed.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional configuration diagram of an ECR plasma CVD apparatus to which an embodiment of the present invention is applied.

[Explanation of symbols]

 1 Plasma chamber 5 Reaction chamber 7 Substrate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/205

Claims (1)

[Claims] 1. A microwave is introduced into a plasma chamber to generate plasma by electron cyclotron resonance, and a predetermined high-frequency voltage is applied to a substrate arranged in a reaction chamber so that ions in the plasma are transmitted to the substrate. A method of forming a hard carbon film by irradiating a hard carbon film on a substrate, wherein argon gas is introduced into the reaction chamber to generate plasma, and the substrate is sputtered to roughen the surface.
A method of forming a hard carbon film, which comprises the steps of increasing the product and forming a hard carbon film on the sputtered substrate.