JPH0364467A - Method and device for synthesizing carbon film - Google Patents

Abstract

PURPOSE:To form a carbon film on the surface of an org. photosensitive body layer by trapping the ions in plasma by a meshed electrode and irradiating a substrate with a gas contg. active species at the time of irradiating the substrate with the gaseous hydrocarbon converted to plasma. CONSTITUTION:The gaseous hydrocarbon flowing from a gas inlet 4a into a vacuum vessel 1 is converted to the plasma by using a plasma generating means 12. The meshed electrode 8 and the substrate 7 on the downstream side thereof are disposed in the flow route of this plasma and the circumference of the substrate 7 is coated with the electrode 8. The pressure on the upstream side of the above-mentioned substrate 7 is set higher by >=11 digit than the pressure on the downstream side. Potential is impressed to the electrode 8 by a voltage impressing means 6 simultaneously therewith and the ions in the plasma are removed. The substrate 7 is irradiated with the gas contg. the active species obtd. as a result thereof, by which the carbon film is obtd. thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to a hard carbon film (diamond-like thin layer 1-C) containing some diamond bonds and exhibiting properties similar to those of diamond.
arboa) and a synthesis apparatus.

Conventional Technology Recently, diamond has been synthesized using various gas phase synthesis methods even under relatively low temperature and low pressure conditions, and its mechanical direct thermal properties are expected to be used to develop applications.

Films currently synthesized include polycrystalline thin films, which are usually called diamond thin films, and amorphous hard carbon films, which are called diamond-like thin films.

A diamond thin film is an accumulation of diamond grains of 1-20 μm in diameter, and its properties are almost the same as those of diamond. Poor adhesion to the substrate (＼
For these reasons, it is rarely used industrially at present.Although hard carbon films are amorphous, they exhibit properties such as hardness and resistivity that are close to those of diamond.

This is thought to be due to the fact that although there is no regularity in the atomic bonds, microscopically they include diamond bonds (SF3). Furthermore, there are relatively few restrictions on process aspects such as substrate temperature and synthesis speed, and it is expected to be a highly practical film. Regarding the synthesis method of hard carbon membranes, a method in which carbon or hydrocarbon ions are bombarded with a substrate has been reported (for example, a method using time-opening N
o [No. 1O-2993fi).

FIG. 4 shows a typical example of a conventional hard carbon film synthesis apparatus. 1
Hydrocarbon gas is introduced into a vacuum chamber l evacuated to O-6 Torr or more, hydrocarbon ions are generated in a high-frequency plasma space induced by a reduced pressure of IO'' Torr, and then a DC current is applied between two parallel plate electrodes. A hard carbon film is synthesized by accelerating in the field and colliding with the base 3.

Problems to be Solved by the Invention However, in the conventional method of accelerating ions to collide with a substrate, there was a problem that the substrate was damaged by the ion collision. Particularly in the case of soft substrates such as organic thin films or substrates that are easily sputtered, this damage becomes a very serious problem.

As a specific example, a case will be described in which a hard carbon film is synthesized on the surface of a photoreceptor drum used in a copying machine or the like.

The mainstream of photosensitive materials used in photosensitive drums is changing from conventional inorganic materials such as Se to organic photosensitive materials from the viewpoints of cost, safety, etc.

However, organic photoreceptor materials are susceptible to wear, requiring frequent replacement of the photoreceptor drum. Therefore, efforts are being made to solve this problem by applying a hard carbon film to the protective film of the organic photoreceptor (Jkai No. 60-107327). ).However, since organic photoreceptor materials are soft, if a hard carbon film is synthesized using the conventional method of accelerating and colliding ions, the material may change and the properties as a photoreceptor may deteriorate, or depending on the conditions of collision, The present invention, which had the problem of the organic photoreceptor layer being destroyed, solves these problems and provides its properties even on materials that are easily damaged, such as insulating substrates and organic photoreceptors. An object of the present invention is to provide a synthesis method and a synthesis apparatus that can synthesize a hard carbon film without deteriorating it.

Means for Solving the Problems The present invention is based on carbon sources such as hydrocarbons, etc., by converting the gas containing gas into plasma and shining it onto the substrate through a mesh-shaped electrode at position 111, which is lower than the plasma, to generate carbon + IQ. This is a method of synthesizing.

The present invention includes a vacuum container, a plasma generating means for converting raw material gas into plasma in the container, a substrate holding member for holding the substrate in a plasma atmosphere, and a surrounding area of the substrate held by the holding member. This is a carbon membrane synthesis device equipped with a covering mesh-shaped electrode.

In addition, the present invention (particularly the present invention) has a structure including a first space having a gas inlet and a second space having a gas outlet, and the first and second spaces communicate with each other through a communication part. has a vacuum container, and converts the gas into plasma in the first space.
This is a carbon film synthesis apparatus equipped with a holding section that holds a substrate near the communication section that is a plasma flow path.

When a substrate is irradiated with a hydrocarbon gas that has been turned into a plasma, the ions in the plasma are trapped by a mesh-shaped electrode that has a lower potential than the plasma, and only neutral particles containing active species such as radicals reach the substrate.

Therefore, a film can be synthesized without ion collision, and a carbon film can be synthesized even on easily damaged substrates such as organic photoreceptor materials.

Furthermore, with the above device configuration, the base body is held near the communication portion between the first space and the second space, so that the first space into which gas flows and the second space into which gas flows out are separated. The pressure inside the first space is higher than the pressure inside the second space.

This pressure difference makes it possible to efficiently irradiate the active species onto the substrate.

Embodiment FIG. 1 shows a first embodiment of the present invention. The configuration of FIG. 1 will be explained below along with its operation.

The gas flowing from the inlet 4a provided in the first space 4 of the vacuum container I flows through the coil 9, the matching device 10. The plasma is turned into plasma in the first space 4 by the plasma generating means 12 constituted by a high frequency power source 11, and is then transferred to the second space through the communication section (3) between the first space 4 and the second space 5. Part 5
The gas flows out of the vacuum container 1 from the gas outlet 5a provided in the. In the flow path of this plasma, a mesh-shaped electrode 8 and a base 7 are arranged on the downstream side thereof. The base body 7 is held at its end by being inserted into the holding recess of the holding member 7a. The holding member 7a has an elongated hole 7b.
The distance to the communication portion 13 can be adjusted. 7C is a bolt that fixes the holding member 7a.

A negative potential is applied to the mesh-shaped electrode 8 by a DC power supply 6 which is a voltage application means. High frequency power is applied to the coil 9 wound around the outer periphery of the first space 4 from a high frequency power source 11 via a matching box 10 .

After evacuating the vacuum container 1 to 10-'Torr or more,
CHa gas is introduced into the first space 4.

Regarding the pressure in the spaces 4 and 5, it is easy to set the pressure in the space 4 higher than the pressure in the space 5 by adjusting the distance between the base 7 and the communication part 13 to increase the gas flow resistance. can be done. The pressure in the first space 4 is maintained at 10-3 Torr, which is higher than the pressure in the second space 5.

Thereafter, high frequency power is applied to the coil 9 to generate plasma. Due to the flow caused by the pressure difference between the two spaces, the plasma flows through the mesh-shaped electrode 8 to the substrate 7.
The ions in the plasma are removed by the mesh-shaped electrode 8 to which a negative potential is applied.
is irradiated.

When evaluating the hardness and film quality of the film synthesized on the glass substrate under the conditions shown in Table 1, the hardness was 2500 kg/mm in Vickers hardness.
2, and the results of Raman spectroscopy confirmed that it had the same Raman spectrum as the high-quality hard carbon film that has been previously reported.Furthermore, we attempted to synthesize the film onto the surface of an aluminum substrate with an organic photoreceptor layer. The film was synthesized with good adhesion up to a thickness of 3 μm, and no peeling or cracking was observed.The substrate was also adjusted so that the pressure difference between the space 4 and the second space 5 was two orders of magnitude or more. When installed, a uniform film (
5% of film thickness unevenness and 10% of hardness unevenness) were synthesized. As the pressure difference increases, the uniformity, especially the uniformity of the film thickness, improves. When there is almost no pressure difference, the film thickness unevenness is ±
It is about 30%.

Therefore, if little uniformity of film thickness is required, the above pressure difference is not necessary. Even in this case, defects such as adhesion, cracking, and peeling of the carbon film do not occur.

Table 1 Synthesis conditions In addition, if a certain degree of film thickness uniformity is required, 2
It is desirable to set the flow resistance so that there is a pressure difference of at least one order of magnitude between the two spaces.
It is desirable that this pressure difference be as large as possible, and 1.% Figure 2 shows a second embodiment of the present invention; as in the first embodiment, the vacuum vessel has two spaces 4.5. . A pair of opposing mesh-shaped electrodes 17a and 17b are installed in the first space, and are powered by a DC power source 16.
A DC electric field is applied with the polarity shown.

A photoreceptor drum 14 having an organic photoreceptor layer on the surface of an aluminum rough tube is installed as a base in the second space 5, and is rotated around the central axis of the drum by a rotational drive mechanism (not shown). It has a structure that can be rotated according to the

Mesh-shaped electrode 17ai1 is set in an arc shape with a radius slightly larger than that of the photoreceptor drum 14 in the area of the communication portion 13, and gas flow resistance is adjusted by adjusting the distance between the photoreceptor drum 14 and the communication port 13. By doing so, the pressure in the space 4 can be easily made higher than the pressure in the space 5, as in the case of FIG.

After the two spaces are evacuated to 10-' Torr or more, CeHe gas is introduced into the first space 12 to maintain the pressure at 10-3 Torr. Thereafter, a DC electric field is applied between the mesh-shaped electrodes 17a and 17b by the DC power supply 16 to turn the Ce Hs gas into plasma and start film synthesis.

At this time, ions in the plasma are transferred to the mesh-shaped electrode 17a.
removed by As a result, the mesh-shaped electrode 17a
A neutral gas containing active species is irradiated onto the photosensitive drum 14 on the downstream side (upper side) through the mesh-shaped electrode 17a to form a carbon film on the surface of the photosensitive layer.

When synthesized under the conditions shown in Table 2 on the surface of a photoreceptor drum equipped with an organic photoreceptor layer, it achieved a Vickers hardness of 2300 kg/m without causing damage or deterioration of properties to the organic photoreceptor layer.
Between the two vacuum vessels in which the hard carbon film of m2 was synthesized (as in the case of the first example), gas flow was carried out to create a pressure difference of at least one order of magnitude in order to make the film uniform. It is desirable to set a resistance.

1 2- Table 2 Synthesis Conditions According to this example, a life test was conducted on a photoreceptor drum whose surface was synthesized with a hard carbon film with a film thickness of 0.5 μm. te1
When using a hard carbon film as a protective film for an organic photoreceptor, the film thickness is 0.02-2.
μm, more preferably O, Oll p m. This is because when the film thickness is less than 0.02 μm, the protective effect is weakened, and when it is more than 2 μm, the amount of light irradiated to the organic photoreceptor layer is reduced due to absorption of light by the hard carbon film.

In this example, the upper photoreceptor layer is not limited to an organic photoreceptor layer, and may include Cd, Hg, Sb, Si, Bi,
Of course, it can also be applied to inorganic photoreceptor layers such as Ti, Se, etc. The photoreceptor was drum-shaped, but it could also be belt-shaped.1 In addition, as shown in Figure 2, a discharge between opposing mesh electrodes was used as a means of plasma generation. A third embodiment of the present invention is shown in FIG. 3, which may be the generating means shown in FIG. 1.

The basic configuration is the same as the conventional example, with a pair of parallel plate electrodes 22 and 23 arranged in the vacuum vessel 18, to which high frequency power is applied by the high frequency power source 21. At the same time, a DC electric field is applied between the two electrodes by the DC power supply 20. The electrode 23 (Y) also serves as a holding member for the base 24, and
A mesh-shaped electrode 19 having the same potential as the electrode 23 is installed around the electrode 23 where the electrode 4 is installed.

Let CH4 gas be introduced into the vacuum container 18 to 1O
After maintaining the pressure at -3 Torr level, this is turned into plasma by high frequency power applied to the electrodes 22 and 23. The 3-4 ions in the plasma move to the substrate 24 due to the potential difference between the electrodes 22 and 23.
The force accelerated in the direction ＼ is removed by the mesh-shaped electrode 19 before reaching the base 24. Therefore, the substrate 24 is irradiated only with neutral gas containing active species.

Pressure Crab in a Vacuum Container 3x 10-” Torr, High Frequency Power = 50W, DC Electric Field, 500V.
It is possible to synthesize hard carbon films with a diameter of /mm2 or more.
We have also succeeded in creating a synthetic skin on an AI base plate with an organic photoreceptor layer, and it is possible to use a film with almost the same hardness as the base without deteriorating the characteristics of the organic photoreceptor. In this case, CH4 and Co are used as raw material gases.
8. Using He The present invention is not limited to these gases, and any hydrocarbon gas may be used.

In addition, a mixed gas of hydrocarbon gas and an inert gas such as Ar may be used. In the present invention, there is no limitation on the means for turning gas into plasma, and it is possible to use a microwave or (Any method such as thermionic is acceptable). Furthermore, a magnetic field may be used in combination to increase the density of the plasma.

Regarding the mesh spacing of mesh-shaped electrodes (more
If it is larger than the Debye length in the plasma generation state, some of the ions will pass between the meshes without being trapped by the electrodes. Especially when forming a carbon film on a soft material or a material that is easily sputtered (the mesh spacing is It is effective to make it less than the Debye length.

Effects of the Invention As described above, according to the present invention, it is possible to synthetically coat a hard carbon film on an insulating substrate or a soft substrate that is easily sputtered without damaging the substrate, resulting in industrial effects. is very large.

In addition, the rate of membrane synthesis can be increased, and the pressure in the synthesis zone can be made uniform, resulting in uniform membrane quality.

In particular, it has become possible to apply a hard carbon film to the surface of the organic photoreceptor layer, which was difficult with conventional methods (
It is extremely important to dramatically improve the lifespan of organic photoreceptors and contribute to the development of electrophotographic equipment.

[Brief explanation of drawings]

The first is the second @ Figure 3 (respectively) The outline of the first, second and third embodiments of the present invention is as follows. Figure 4 is a schematic diagram of the conventional example. ...First Space Question 5...
...Second space 1"! 6. 16... Voltage application means, 7.24... Base tree 7a... Holding member, &
17a, 19...Mesh-shaped electrode 12...
・Plasma generation means, 13...Communication enemy 14...
photoreceptor

Claims (5)

[Claims] (1) A method for synthesizing a carbon film, in which a raw material gas containing at least a hydrocarbon gas is turned into plasma, some or all of the ions in the plasma are removed, and a film is synthesized on a substrate. (2) a plasma generation means for turning raw material gas containing hydrocarbon gas into plasma; a base body holding member for holding the base body in a plasma atmosphere; A carbon film synthesis apparatus comprising a covering mesh-shaped electrode and means for applying a voltage to the mesh-shaped electrode. (3) a vacuum container having a first space having a gas inlet and a second space having a gas outlet and communicating with the first space; a plasma generating means for generating gas plasma; and a mesh-shaped electrode held in a plasma flow path in the vacuum container; a substrate holding member that holds a substrate downstream of the mesh-shaped electrode in the plasma flow path; A carbon film synthesis device having a member. (4) A mesh-shaped electrode and a base body are disposed on the downstream side of the mesh-shaped electrode in the flow path of plasma in the vacuum vessel, and a part of the vacuum vessel on the upstream side of the base body is disposed as a boundary. The pressure is set to be at least one order of magnitude higher than the pressure in the vacuum vessel on the downstream side, and a potential is applied to the mesh-shaped electrode to remove some or most of the ions in the plasma at the mesh-shaped electrode, A method for synthesizing a carbon film, in which a carbon film is synthesized on a substrate by irradiating the resulting gas containing active species onto the substrate. (5) The mesh spacing of the mesh-shaped electrode is shorter than the Debye length in the plasma generation state, and the substrate is a photoreceptor;
The carbon film synthesis apparatus according to claim (4).