JP3082979B2 - Method for forming a-DLC-Si film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of forming an a-DLC (diamond-like carbon) -Si film having a low coefficient of friction and excellent adhesion.

[0002]

2. Description of the Related Art In a gas phase synthesis method of diamond, a mixed gas of hydrocarbon and hydrogen is used as a reaction gas, and the reaction gas is heated, heated, microwaved, or heated in a reaction tank maintained at several tens of Torr. It is excited and guided on a substrate heated to 600 to 1000 ° C., and the carbon having a diamond structure is deposited on the substrate by the thermal decomposition of hydrocarbons and the action of activated hydrogen.

In this diamond vapor phase synthesis method, a CVD method (vapor phase chemical reaction deposition method) is mainly used.
Examples of the VD method include a hot filament method, a microwave plasma method, an electron impact CVD method, and a direct current plasma method. For example, in the microwave plasma method, a plasma in which a methane-hydrogen mixed gas is excited is generated around a substrate using a microwave as an excitation source, and the substrate is heated by absorption of the microwave and impact by the plasma, and a pressure of several Torr to 300 T
Diamond is synthesized at orr and a substrate temperature of 700 to 1000 ° C.

However, in these CVD methods, 20 to
Since the reaction is performed at a relatively high pressure of 200 Torr, the reaction region or the precipitation range is limited, and it is difficult to deposit diamond uniformly over a wide region. This problem is solved by reducing the reaction pressure. This is because, by lowering the reaction pressure, the mean free path of electrons is lengthened, and the plasma density can be easily increased over a wide area using a magnetic field.

However, recently, using a magnetic field and microwave energy, electron cyclotron resonance (Electron) has been proposed.
Cyclotron Resonance, hereafter ECR
Plasma generation method using a phenomenon called
Because of its features such as low gas pressure, high activity, and high ionization rate, it has attracted attention as a plasma processing technology.
D has also been put to practical use.

The basic structure of the ECR plasma CVD apparatus will be described with reference to FIG.
Is introduced into the plasma chamber 17 using As the microwave, 2.45 GHz, which is an industrial frequency, is usually used. The excitation coil 4 is arranged around the plasma chamber 17 and has a divergent magnetic field structure in which the magnetic field intensity gradually decreases in the direction from the microwave introduction part toward the reaction chamber 14, and satisfies the ECR condition in an appropriate region in the plasma chamber. Generate a magnetic field. The reaction gas introduced into the plasma chamber 17 by the reaction gas introduction pipe 6 is excited in the plasma chamber 17 and supplied to the substrate 11 in the form of a plasma flow 18 along a magnetic field.

Using this ECR plasma CVD apparatus,
A report of forming a diamond film has been made by Suzuki et al. (Japanese Journal of A
Applied Physics Vol. 28, No.
2, 1989, p. L281-L283), according to this report, 1 × 10
A high-density plasma of ¹¹ cm ^-3 was obtained, and a diamond film was obtained using CO / H ₂ gas at a low pressure of 0.1 Toor at a temperature of 600 ° C. Further, when this diamond film was analyzed by Raman light, it was found that the diamond film was composed of a crystalline portion of diamond and an amorphous carbon layer deposited at the grain boundaries (generally referred to as diamond-like carbon). Has been confirmed.

On the other hand, in these ECR plasma CVD methods, a mixed film (a-DLC) of DLC and Si is mixed by mixing a chloride gas or hydride gas of Si into a reaction gas.
-Si) is obtained. This a-DLC-Si film has a very low coefficient of friction, and FIG.
The relationship between the C concentration measured in s and the coefficient of friction is shown below.
And very small.

[0009]

However, this a
-The DLC-Si film is an amorphous film formed at a low temperature by a plasma CVD method, and has poor adhesion to a substrate. For example, the result of measuring the adhesion of an a-DLC-Si film formed by a conventional method and having a C concentration of 80 atomic% by a scratch method is only 3 × 10 ⁸ dyn / cm ² .

The present invention has been made to solve the above-mentioned problem that the a-DLC-Si film formed at low pressure and low temperature by the ECR plasma CVD method has poor adhesion. An object of the present invention is to provide a method for forming an a-DLC-Si film having a low coefficient of friction and excellent adhesion to a film.

[0011]

The ECR plasma PVD method has a lower pressure than the other plasma CVD methods and has a pressure of 10 ^-4 to 1 ^-4.
The reaction is performed at a gas pressure of about 0 ^-6 Torr. Therefore,
The inventor of the present invention conceived of combining this ECR plasma PVD method and vacuum deposition with excellent adhesion, and as a result of intensive studies, when combined with laser PVD, an a-DLC-Si film with excellent adhesion was obtained. The inventor has newly found out that it can be obtained and completed the present invention.

According to the method of forming an a-DLC-Si film of the present invention, a substrate is placed obliquely in a reaction chamber so as to face an ECR plasma chamber having a microwave rectangular waveguide and a magnetic coil. A Si target is placed in the reaction chamber facing the substrate, a reaction gas is introduced into the ECR plasma chamber, a DLC (diamond-like carbon) film is formed on the substrate by ECR plasma CVD, and a DLC (diamond-like carbon) film is provided in the reaction chamber. Laser light through the incident window
The target is irradiated to the substrate by laser PVD.
The gist is to deposit i and form an a-DLC-Si film on the substrate.

The ECR plasma CVD is performed under the conditions of a microwave wavelength of 2.45 GHz, a magnetic field of 875 gauss, a microwave power of 800 to 1200 W, and a gas pressure of 0.01.
Plasma can be stably generated between 0.1 and 0.1 Torr.

The CH ₄ concentration of the reaction gas diluted with H ₂ is:
It is preferable to set it to 0.1 to 6%. CH ₄ concentration is 0.
This is because if it is less than 1%, the deposition rate of diamond is extremely slow and almost no precipitation occurs, and if it exceeds 6%, C precipitates as soot and DLC is not formed.

The condition range of the laser PVD is as follows: laser power: 1 to 150 W, pulse energy: 50 to 400 m
J, energy density: 0.5 to 200 KJ / m ² , laser wavelength: 248 nm. The laser wavelength can be other than this, and for example, the wavelengths 193, 308, 35
A 1 nm excimer laser or a 1.06 μm wavelength YAG laser may be used.

An energy density of 0.5 to 200 KJ / m
^The reason for setting 2 is that the energy density calculated from the laser power, pulse energy, and spot diameter is 0.5 KJ / m.
^{If the} value is smaller than ² , the sputtering phenomenon does not occur, and the upper limit is the highest value of the current excimer laser, and a value larger than this may be used.

Substrates capable of forming diamond include simple substances such as molybdenum, tungsten, gold, copper, zirconium, and silicon, compounds such as cemented carbide, silica glass, and sapphire, as well as silicon carbide, titanium carbide, and boron nitride. And ceramics such as silicon nitride.

[0018]

The microwave 16 is introduced into the plasma chamber 17 using the rectangular waveguide 7. An excitation coil 4 is arranged around the plasma chamber 17 and the reaction chamber 1
A divergent magnetic field configuration in which the magnetic field strength gradually decreases in four directions, and generates a magnetic field satisfying the ECR condition in an appropriate region in the plasma chamber.

In the ECR plasma, due to the resonance phenomenon, electrons efficiently absorb microwave energy and convert it into kinetic energy. The electrons that have absorbed the microwave energy further collide with gas molecules, and have a high density and low gas pressure.
Generates highly active plasma. The reaction gas introduced into the plasma chamber 17 by the reaction gas introduction pipe 6 is excited in the plasma chamber 17 and supplied to the substrate 11 in the form of a plasma flow 18 by a divergent magnetic field.
A film forms.

On the other hand, at the same time, the laser light 1
Then, the light is condensed and irradiated to the Si target 10 installed in the reaction chamber 14 through the incident window 3. Laser light 1 is Si
When the target 10 is illuminated, the surface of the target 10 undergoes absorption, and the Si-evaporated particles emitted from the target 10 are placed on a substrate placed opposite to the DLC.
Deposits with the film. Since the evaporated particles have very high energy, a
-A DLC-Si film is formed.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in comparison with a conventional example.
The effect of the present invention will be clarified. FIG. 1 is a schematic sectional view of an apparatus used for carrying out the method of the present invention. The reaction chamber 14 is the substrate 1
A vacuum chamber in which 1 and the target 10 are installed,
An exhaust pipe 15 is provided on the bottom surface and is evacuated. The upper surface of the reaction chamber 14 communicates with the plasma chamber 17, and the entrance window 3 is provided on the side surface.

A water jacket is provided on the outer periphery of the plasma chamber 17 and is cooled by cooling water 5, and the exciting coil 4 is arranged around the water jacket. The rectangular waveguide 7 is attached to the upper surface of the plasma chamber 17, and the microwave 16 is introduced into the plasma chamber 17.
Further, a reaction gas introduction pipe 6 is attached to the plasma chamber 17, and methane gas diluted with hydrogen is supplied as a reaction gas.

On the other hand, at a position facing the plasma chamber 8 in the reaction chamber 14, the substrate 11 fixed to the substrate holder 12 is provided.
Further, at a position facing the substrate 11 and facing the entrance window 3 on the side surface, the Si target 10 supported by the target holder 9 is attached to the laser beam 1.
It is installed at an angle of °.

The operation of this device will be described.
The microwave 16 of 45 GHz is introduced into the plasma chamber 17 using the rectangular waveguide 7. The exciting coil 4 arranged around the plasma chamber 17 has a divergent magnetic field configuration in which the magnetic field strength gradually decreases from the microwave introduction part toward the reaction chamber 14, and generates the plasma 8 under the ECR condition of 875 G. Let it.

In the ECR plasma, due to the resonance phenomenon, electrons efficiently absorb microwave energy and convert it into kinetic energy. The electrons that have absorbed the microwave energy further collide with gas molecules, and have a high density and low gas pressure.
Generates highly active plasma. Therefore, the reaction gas introduced into the plasma chamber 17 by the reaction gas introduction pipe 6 is:
Since it is excited in the plasma chamber 17 and supplied to the substrate 11 in the form of a plasma flow 18 by a divergent magnetic field, a DLC film is formed on the substrate 11.

On the other hand, at the same time, the laser light 1
Then, the light is condensed and irradiated to the Si target 10 installed in the reaction chamber 14 through the incident window 3. Laser light 1 is Si
When the target 10 is illuminated, the surface of the target 10 undergoes absorption, and the Si-evaporated particles emitted from the target 10 are placed on a substrate placed opposite to the DLC.
Since it is deposited together with the film, an a-DLC-Si film having excellent adhesion is formed on the substrate 11.

Example 1 Using this apparatus, an a-DLC-Si film having a C concentration of 80 atomic% was obtained by the method of the present invention under the following conditions. Laser pulse energy 200 mJ Laser power 20 W Laser repetition frequency 100 pps Spot diameter on target 2 mm × 7 mm elliptical shape Energy density 14 KJ / m ² Reaction gas CH ₄ : 1%, H ₂ : 99% Vacuum degree 0.02 Torr Microwave Power 1000W Substrate temperature 800 ℃

For comparison, a conventional DC plasma CVD
When an a-DLC-Si film was formed by the method under the following conditions, an a-DLC-Si film having a C concentration of 80 atom% was obtained. Reaction gas CH ₄ : 4%, SiCl ₄ : 0.3% H ₂ : 58%, Ar: 37.7% Vacuum degree 4 Torr DC voltage 400 V Substrate temperature 550 ° C.

The obtained inventive example and conventional a-DLC-
The adhesion of the Si film was evaluated. The adhesive force is measured by a scratching method, in which a hard needle is pressed perpendicularly to a thin film, moved under a load, and the thin film is peeled off from the substrate by scratching.
The obtained results are shown in FIG.

As is clear from FIG. 2, the a-DLC-Si film formed in the conventional example has an adhesion of only 3 × 10 ^8.
dyn / cm ² , but the film formed by the method of the present invention showed a high adhesion of 50 × 10 ⁸ dyn / cm ² ,
The effect of the present invention was confirmed. Note that an excimer laser is used here, and the evaporated particles that fly out by excimer laser sputtering have extremely high energy, so that the adhesion of the film can be increased in this manner.

(Example 2) An a-DLC-Si film was formed under the conditions shown in Table 1 by the method of the present invention using the apparatus shown in FIG. 1 and a film having a C concentration of% shown in Table 1 was obtained. . The ECR condition was 1000 W and the laser condition was 200 m.
J, the spot diameter on the target: an ellipse of 2 mm × 7 mm, each of which was constant. The obtained film was subjected to a ball-on-disk friction and wear tester (partner material: diameter 6.
The friction coefficient was measured using a 35 mm (1/4 inch) SUJ2 ball), and the obtained results are shown in FIG.

[0032]

[Table 1] In the table, pps is the number of oscillations per second.

As shown in Table 1, according to the method of the present invention, the ratio between DLC and Si in the a-DLC-Si film can be freely changed by changing the laser repetition frequency, microwave power, and the like. it can. Further, as is apparent from FIG. 3, the friction coefficient of the formed film showed a very small value of 0.05 at a C concentration of 65 to 95%.

[0034]

As described in detail above, the method of forming an a-DLC-Si film according to the present invention is as follows.
Installed diagonally facing the CR plasma chamber, introducing a reaction gas into the ECR plasma chamber and forming a DLC (diamond-like carbon) film on the substrate by ECR plasma CVD, and also facing the substrate into the reaction chamber. A laser is applied to the placed Si target to deposit Si on the substrate by laser PVD to form an a-DLC-Si film on the substrate, and the reaction gas introduced into the plasma chamber is When excited and supplied to the substrate in the form of a plasma stream by a divergent magnetic field, a DLC film is formed on the substrate, and high-energy Si vaporized particles are deposited by laser PVD.
A DLC-Si film is formed.

[Brief description of the drawings]

FIG. 1 is a schematic side sectional view of an apparatus for carrying out the present invention.

FIG. 2 is a diagram showing the adhesive force between a film formed by the method of the present invention and a film formed by a conventional method.

FIG. 3 shows a-DLC-Si formed by the method of the present invention.
FIG. 3 is a diagram showing a relationship between a coefficient of friction of a film and a C concentration.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 laser light 3 entrance window 4 excitation coil 6 reaction gas introduction pipe 7 rectangular waveguide 8 plasma 10 target 11 substrate 13 evaporated particles 14 reaction chamber 16 microwave 17 plasma chamber 18 plasma flow

Continuation of the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 16/00-16/56 C01B 31/02 101 C23C 14/00-14/58 C23C 26/00 INSPEC (DIALOG)

Claims (1)

(57) [Claims] 1. A substrate is placed obliquely in a reaction chamber facing an ECR plasma chamber equipped with a microwave rectangular waveguide and a magnetic coil, and a Si target is placed in the reaction chamber facing the substrate. A reaction gas is introduced into the ECR plasma chamber, a DLC (diamond-like carbon) film is formed on the substrate by ECR plasma CVD, and a laser beam is directed to a Si target through an incident window provided in the reaction chamber. Irradiate to deposit Si on the substrate by laser PVD, a-DLC-Si on the substrate
A method for forming an a-DLC-Si film, comprising forming a film.