JPH06306612A - Hard carbon film production device and formation of hard carbon film using the device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the adhesion and quality of a carbon film to be formed by introducing a gaseous reactant contg. carbon into a reaction chamber, impressing a negative potential on an electrode to produce plasma around the electrode and decomposing the gaseous reactant. CONSTITUTION:CH4 is introduced into a reaction chamber 11, and the flow rate of the CH4 is controlled to keep the chamber at 0.2Torr. A negative potential of about 1000V is impressed on an electrode 19 carrying a sample 21 by a DC power source 13 to produce plasma around the electrode 19. The CH4 is decomposed by the plasma into the positive ion, electron and neutral exciton. A negative potential is independently impressed on the sample 21 from the controllable power source 13. The energy of the positive ion impinging on the sample 21 is controlled by the impressed voltage independently of the plasma. The positive ion is allowed to impinge on the sample 21 surface with an optional high energy, and the diamond bonds are increased in the hard carbon film.

Description

Detailed Description of the Invention

The present invention relates to a structure of a manufacturing apparatus for forming a hard carbon film and a method of forming a hard carbon film using the manufacturing apparatus.

[0002]

2. Description of the Related Art A hard carbon film is a super hard carbon film called an i-carbon film which has been studied in the United Kingdom since the late 1970s. This hard carbon film does not show long-period crystallinity in the bonding state of carbon atoms, and has a bonding state similar to that of amorphous silicon.

The physical properties of the hard carbon film have many similarities to those of diamond, and have excellent properties such as high hardness, wear resistance, lubricity, insulation and chemical resistance. , Coating of various machines and electronic parts,
Alternatively, it is expected to be applied to functional devices.

The manufacturing apparatus and forming method of this hard carbon film will be described with reference to the sectional view of FIG.

As shown in FIG. 2, an electrode 19 for disposing a sample 21 is provided in a reaction chamber 11 having a gas inlet 15. Then, the inside of the reaction chamber 11 is depressurized by the exhaust means 17, and the reaction gas containing carbon is introduced from the gas inlet 15.

Further, an electrode lead-in wire 25 is attached to the electrode 19.
The high frequency power supply 23 is connected via. The high frequency voltage applied to the electrode 19 generates high frequency plasma in the reaction chamber 11.

As a result, the reaction gas is decomposed by the high frequency plasma, and the generated carbon ions collide with the sample 21 to form a hard carbon film on the sample 21.

[0008]

However, the method of forming a hard carbon film described with reference to FIG. 2 has problems that the adhesion of the hard carbon film is poor and the quality of the hard carbon film is poor. The reason for this is described below.

In the method of forming a hard carbon film using high frequency plasma shown in FIG.
A high-frequency voltage applied to generate high-frequency plasma.

At this time, the reaction gas containing carbon is decomposed into positive ions, electrons and neutral excited species in the high frequency plasma.

Since the electrons in the high frequency plasma have a small mass, they can move by following the fluctuation of the electric field of the high frequency plasma. On the other hand, since positive ions have a heavier mass than electrons, it is difficult to move by following the voltage fluctuation of the high frequency plasma. Furthermore, since the neutral excitation species are electrically neutral, they do not move under the electric field of the high frequency plasma.

Therefore, in the high-frequency plasma, the electrons can follow the fluctuation of the high-frequency electric field violently, and the positive ions cannot follow, so that they can move only slowly.

For this reason, many electrons collide with the sample 21 on the electrode 19, but positive ions collide with the sample 21 in a very small number as compared with the electrons. Therefore electrode 1
Excess electrons are charged on the surface 9.

In this state, electrically, a negative offset bias is externally applied to the electrode 19, which is exactly the same. Excessive charges on the electrode 1
This is the same as the generation of a negative DC voltage on N. This generated negative DC voltage is called DC self-bias (Vdc).

The magnitude of the DC self-bias described above is determined by the amount of electrons striking the electrode 19, and the high frequency plasma cannot be controlled independently from the outside.

This DC self-bias (Vdc) is large when the electron density in the high frequency plasma is high and the number of colliding electrons is large. On the contrary, if the electron density in the high-frequency plasma is low and the number of colliding electrons is small, the value of the DC self-bias becomes small.

That is, the DC self-bias generated in the electrode 19 changes depending on the state of the high frequency plasma, and as described above, it cannot be controlled independently from the high frequency plasma.

The value of this negative DC self-bias potential is
The energy of the positive ions that collide with the sample 21 is determined, and is an important factor that determines the adhesion and film quality of the hard carbon film.

In forming the hard carbon film, when the negative DC self-bias potential is high, the positive ions of the gas containing carbon collide with the sample 21 with high energy, and the sample 2
The reactivity on one surface becomes high. Therefore, the diamond structure in the hard carbon film increases, and as a result, a hard carbon film having good adhesion and high quality can be obtained.

On the other hand, when the potential of the negative DC self-bias is low, the positive ions of the gas containing carbon collide with the sample 21 with low energy, and the reactivity of the surface of the sample 21 is low. In this case, the hard carbon film cannot have a diamond structure and can only have a weakly bonded state like a polymer. As a result, the adhesion becomes poor and the film quality becomes a low quality hard carbon film.

As described above, the sample 21 and the electrode 19 are
Although the value of the negative DC self-bias generated in the above is an important factor that determines the adhesion and the film quality of the hard carbon film, as described above, the conventional high frequency power source as shown in FIG. With the method used, the value of the negative DC self-bias cannot be controlled independently of the high frequency plasma.

That is, in the conventional method using the high frequency power supply, the value of the negative DC self-bias changes depending on the high frequency plasma state. Therefore, depending on the high-frequency plasma state, the value of the negative DC self-bias does not increase, and as described above, the hard carbon film has poor adhesion and only low quality film can be obtained.

An object of the present invention is to solve the above problems and provide a hard carbon film manufacturing apparatus and a method for forming a hard carbon film in which deterioration of the adhesion and film quality of the hard carbon film do not occur. Especially.

[0024]

A hard carbon film production apparatus of the present invention comprises a reaction chamber for connecting a wall surface to a ground potential, a DC power source for applying a negative potential to electrodes arranged in the reaction chamber,
A gas introducing port for introducing a reaction gas into the reaction chamber, and an evacuation unit for making the reaction chamber have a predetermined reduced pressure atmosphere are provided.

According to the method of forming a hard carbon film of the present invention, a reaction gas containing carbon is introduced into a reaction chamber through a gas introduction port, a negative potential is applied to an electrode by a DC power source, and plasma is generated around the electrode. The reaction gas is decomposed to cause carbon ions to collide with the sample placed on the electrode to form a film.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hard carbon film manufacturing apparatus and a hard carbon film forming method in embodiments of the present invention will be described below with reference to the drawings. First, the configuration of the hard carbon film manufacturing apparatus of the present invention will be described with reference to FIG.

As shown in FIG. 1, the wall surface of the reaction chamber 11 having the gas inlet 15 and the exhaust means 17 is connected to the ground potential.

Further, an electrode 19 for disposing a sample 21 is provided in the reaction chamber 11. Then, a negative voltage is applied to the electrode 19 by the DC power supply 13.

Next, a method of forming a hard carbon film using the apparatus shown in FIG. 1 will be described with reference to FIG.

[0030] The first exhaust means 17, the vacuum degree in the reaction chamber 11 3 × 10 ^- to 5Torr following reduced pressure atmosphere.
Next, CH ₄ is supplied from the gas inlet 15 as a gas containing carbon.
Is introduced into the reaction chamber 11, and the flow rate of CH ₄ is controlled so that the degree of vacuum is about 0.2 Torr.

A DC power supply 13 applies a negative potential of about 1000 V to the electrode 19 on which the sample 21 is placed. Due to the negative DC potential applied to the electrode 19, plasma is generated in the peripheral portion of the electrode 19. Then the electrode 19
CH ₄ is decomposed into positive ions, electrons, and neutral excited species by the plasma in the peripheral portion of.

The generation mechanism of this plasma is considered as follows. That is, the electrons in the space are accelerated by the electric field and pulled by the high negative potential of the electrode 19, and move toward the electrode 19 at high speed. Here, the pressure is 0.2 Torr
Since it is two orders of magnitude higher than that of ordinary direct current sputtering, etc., electrons easily collide with gas molecules of CH ₄ and plasma is generated.

Here, the sample 21 on the electrode 19 has a DC power source 13 whose DC potential to be applied can be controlled independently of plasma.
A negative potential is applied from. Therefore, the DC power supply 13
The energy of the positive ions colliding with the sample 21 can be controlled independently of the plasma by the applied voltage of.

Therefore, positive ions can be made to collide with the surface of the sample 21 at an arbitrarily high energy, and the number of diamond bonds in the hard carbon film can be increased.

Therefore, the adhesion of the hard carbon film is improved, and the film quality of the hard carbon film is also improved.

The negative DC self-bias (Vdc) generated by applying a high-frequency voltage to the conventional electrode causes the negative DC self-bias (Vdc) when the number of samples placed in the reaction chamber is increased. There is a problem that the value decreases.

This is because in the means for applying the high frequency voltage to the electrode, the upper limit of the negative DC self-bias generated depends on the area ratio of the electrode to the wall surface area of the reaction chamber.

Therefore, when the electrode area, that is, the number of samples is increased, the negative DC self-bias (Vdc) value is lowered, the film quality of the hard carbon film is deteriorated, and the adhesion is also deteriorated.

On the other hand, in the means for applying a high negative voltage to the electrodes by the DC power supply of the present invention, even if the electrode area, that is, the number of samples arranged in the reaction chamber is increased, the voltage is increased only by increasing the current. Is constant. Therefore, unlike the conventional case, the deterioration of the quality of the hard carbon film and the deterioration of the adhesion of the hard carbon film do not occur.

Further, in the conventional means for applying a high-frequency voltage to the electrodes, in order to increase the formation rate of the hard carbon film and shorten the processing time, a gas containing a large amount of carbon, such as C ₂ H, is used instead of CH _{4. 4} , using C ₆ H ₆ ,
The aforementioned negative DC self-bias (Vdc) is reduced.

Therefore, in order to improve the processing capacity, even if a gas containing a large amount of carbon is used, a negative DC self-bias (V
dc) is deteriorated, the quality of the hard carbon film is deteriorated, and the adhesion is also deteriorated.

On the other hand, in the means for applying a negative high voltage of the present invention to the electrode by the DC power source, the voltage applied to the electrode can be set regardless of the kind of the reaction gas,
It becomes possible to form a hard carbon film at a high speed.

Furthermore, in the conventional means for applying the high frequency voltage to the electrodes, as shown in FIG. 2, a strong discharge is generated from the high frequency power source 23 to the electrode lead-in wire 25 connected to the electrode 19. Even if the electrode lead-in wire 25 is insulated and sealed due to the high frequency, a discharge is generated. For this reason, the film quality, adhesion, formation speed, etc. of the hard carbon film formed on the sample 21 placed on the electrode 19 are adversely affected.

On the other hand, in the means for applying a negative high voltage of the present invention to the electrodes by the DC power supply, if the electrode lead wire connecting the DC power supply 13 and the electrode 19 is insulated and sealed,
No discharge occurs.

[0045]

As is clear from the above description, according to the hard carbon film manufacturing apparatus and the method for forming the same of the present invention, deterioration of the quality of the hard carbon film and deterioration of the adhesion of the hard carbon film occur. do not do.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a hard carbon film manufacturing apparatus and a method for forming the same according to the present invention.

FIG. 2 is a cross-sectional view for explaining a conventional hard carbon film manufacturing apparatus and a method for forming the same.

FIG. 3 is a graph for explaining problems with a conventional apparatus for manufacturing a hard carbon film and a method for forming the same.

[Explanation of symbols]

 11 Reaction Chamber 13 DC Power Supply 15 Gas Inlet 17 Exhaust Means 19 Electrode 21 Sample

Claims (2)

[Claims] 1. A reaction chamber in which a wall surface is connected to a ground potential, and a DC power source for applying a negative potential to electrodes arranged in the reaction chamber,
An apparatus for producing a hard carbon film, comprising: a gas inlet for introducing a reaction gas into the reaction chamber; and an exhaust means for making the reaction chamber have a predetermined reduced pressure atmosphere. 2. A reaction gas containing carbon is introduced into the reaction chamber through a gas introduction port, a negative potential is applied to the electrode by a direct current power source, plasma is generated around the electrode to decompose the reaction gas, and the electrode is decomposed. A method for forming a hard carbon film, characterized in that a film is formed by causing carbon ions to collide with a sample arranged above.