JPH0230762A - Composite body having film composed principally of carbon - Google Patents

Abstract

PURPOSE:To satisfy simultaneously mechanical stress resistance, troubles due to static electricity, and transparency by forming a film having a composition which is composed principally of carbon and in which nitrogen or nitrogen and hydrogen are added on the surface of a substrate by a CVD method. CONSTITUTION:A film having a composition which is composed principally of carbon and in which about 0.1-50 atomic % of nitrogen or nitrogen and hydrogen are actively added is formed on a substrate of glass, metal, ceramics, organic resin, etc., by using a plasma CVD method. It is desirable to use nitride as the nitrogen in consideration of the trouble of the corrosion of the inner wall of a reaction chamber. The characteristics of this film, such as electric conductivity, hardness, and transmissivity, can be easily changed by changing electric discharge parameters, such as applied electric power, reaction pressure, shape of electric discharge vessel, and flow rates of carbon starting raw material and nitrogen starting raw material. By this method, the service life and reliability of a composite body can be improved.

Description

Detailed Description of the Invention "Field of Application of the Invention" The present invention aims to simultaneously solve mechanical stress resistance and static electricity countermeasures on the surfaces of glass, metals, ceramics, organic resins, etc. The present invention relates to a composite body having a carbon-based coating, which is coated with a transparent carbon-based coating.

``Prior art'' Coating the surface of relatively soft materials such as glass, metals, plastics, and resins with a film that is harder than the soft materials is effective against mechanical stresses such as abrasion and scratches. It is valid.

Such films include AlzOi, TiN, BN, W
Inorganic films such as C, S i C, S i, N, SiO□, etc., and "Composite J with a carbon film (Patent Application No. 146930 of 1982) filed by the present inventor are known. However, the above-mentioned known protective films already have high electrical resistivity, tend to generate static electricity, and tend to attract dirt and dust in the atmosphere to their surfaces. When used in composite materials that actively apply an electric field and utilize static electricity, such as photoreceptors used in processes, charges accumulate in the protective film with high electrical resistance, and the expected There was a problem that the performance could not be achieved for a long time.

One possible way to solve such problems is to add a conductive substance to the known film.

In this case, the added conductive substance becomes a light absorption center,
Light absorption occurs in the known protective film, making it unsuitable for applications requiring transparency in the infrared and visible ranges.

Furthermore, depending on the conditions of the film-forming process, the known protective film may accumulate internal stress and have dents during which the film becomes beaded. Therefore, it is necessary to take measures such as reducing the thickness of the film or providing an intermediate layer between the protective film and the underlying material to improve the density. This means that the presence of an intermediate layer causes the problem of increased costs due to increased processes.

``Structure of the Invention'' The present invention solves the above-mentioned problems and provides a coating that satisfies mechanical stress resistance as a protective film, problems arising from static electricity, and transparency at the same time. Or it has a coating mainly composed of carbon, which is characterized by adding 0.1 to 50 atomic percent of hydrogen and nitrogen and coating the surface of the substrate with a coating mainly composed of carbon to which the nitrogen is added. The purpose is to provide a complex.

The coating mainly composed of nitrogen-doped carbon used in the composite according to the present invention uses Nokun (CH,) as the carbon raw material,
It can be formed by introducing hydrocarbons such as ethane (C, H&), ethylene (CZH4), acetylene (C2H2), etc. into plasma, decomposing and exciting the carbon raw material, and depositing it on a predetermined substrate. . At this time, a raw material gas such as Nl (, , NF, , N, etc.) is simultaneously introduced into the plasma as a nitrogen raw material to add nitrogen to the film whose main component is carbon. can be controlled by the flow rate.

Here, as the raw material gas containing carbon, in addition to the above hydrocarbons, fluorocarbons such as CF, CH, F, etc., carbon chlorides such as CCl4, and brominated hydrocarbons such as CH, Br may be used.

However, as nitrogen, nitrides are most easily used due to the problem of corrosion of the walls of the plasma reaction chamber. Furthermore, from the viewpoint of controlling the amount of nitrogen added, hydrocarbons that do not contain nitrogen are effective as carbon raw materials.

The film according to the present invention is produced by introducing the above-mentioned raw materials, that is, a carbon raw material and a nitrogen material into a plasma reaction chamber at the same time, and adjusting the amount of nitrogen added to the film by adjusting the meteorite of the nitrogen-containing raw material. can be controlled.

The amount of nitrogen added is observed as a difference in conductivity, transmittance, and hardness. The experimental results of changes in electrical conductivity when the flow rate of the nitrogen source material is changed are shown below.

NH was used as a nitrogen source material. Ethylene was used as the carbon raw material, and the ethylene flow rate was 1105 cC, the reaction pressure was 10 Pa, and the input power density was 0.08 W/cm.As shown in Figure 1, as the number of NH stars increases, the conductivity increases. In addition, as shown in Figure 2, as the NH flow rate increases, the permeability increases.Furthermore, as shown in Figure 3, as the NH flow rate increases, the hardness decreases. That is, it means that internal stress is reduced.

By using a film whose main component is nitrogen or carbon to which nitrogen and hydrogen are added, the conductivity, hardness, and transmittance of the film can be varied over a relatively wide range, as described above. That is, the optimum characteristics required for various applications can be easily obtained at relatively low cost.

Although it has been described above that the amount of nitrogen added is changed by changing the flow rate of the nitrogen raw material, the discharge conditions such as the input power during discharge, the reaction pressure, the shape of the discharge vessel, and the flow rate of the carbon raw material are constant. Furthermore, the amount of nitrogen added can be changed by changing one or more of these discharge conditions.

- As an example, FIG. 4 shows the change in conductivity when the input power is changed. That is, as the input power increases, the conductivity increases. In this case, of course, the discharge parameters other than the input power are the reaction pressure, the shape of the discharge vessel, NH, flow rate,
C2H, flow rate, etc. are constant.

As mentioned above, the film properties such as conductivity, hardness, and transmittance of a film whose main components are nitrogen or hydrogen and carbon containing nitrogen are determined by the input power, reaction pressure, the shape of the discharge vessel, the flow rate of the carbon raw material, etc. By changing discharge parameters such as the flow rate of the nitrogen raw material, it is possible to easily and inexpensively change the discharge parameters over a relatively wide range.

Furthermore, a coating mainly composed of carbon to which nitrogen is added is characterized by low internal stress. This is because the dangling bonds that normally exist in carbon are terminated with hydrogen and reduce the internal stress by relaxing the attractive force of the dangling bonds. Rather, some dangling bonds remain in the film, and this is thought to be one of the causes of internal stress.

It is thought that if nitrogen, which is more reactive than hydrogen, such as nitrogen, is present in the plasma, nitrogen and carbon will easily form a CN bond, and the number of dangling bonds in carbon will be reduced compared to when only hydrogen is present. In other words, internal stress is reduced. Another feature is that the reduction in internal stress prevents the occurrence of membrane beerling.

Furthermore, a coating mainly composed of carbon to which nitrogen is added has excellent heat resistance.

Further, one of the characteristics of the n-containing material, which is mainly composed of carbon to which nitrogen is added, is that it can be formed into a film at a deposition temperature of a substrate ranging from room temperature to 150° C. or less. Therefore, the substrate of the composite can be made of materials that cannot be heated to high temperatures, such as organic materials such as plastics and resins, and selenium semiconductors.

The production method will be described below according to the drawings.

FIG. 5 shows an outline of a plasma CVD apparatus used in the present invention for forming a film mainly composed of carbon doped with nitrogen.

In the drawing, in the doping system (1), hydrogen is used as a carrier gas (2), a hydrocarbon gas such as methane or ethylene is used as a reactive gas (3), and a gas containing nitrogen such as NH3 is added (4) as a reactive gas. It is introduced into the reaction system (8) through a nozzle (9) through a valve (6) and a flow meter (power).Before reaching this nozzle, microwave energy is applied to excite the reactive gas. In addition, it is effective to activate it in advance.

The reaction system (8) includes a first electrode (11) and a second electrode 02.
) was established. In this case, the condition (first electrode area/second electrode area) <1 was satisfied. A pair of electrodes (11
) and 021, electric energy is applied from a high frequency power source 0■, a matching transformer 04), and a DC bias power source 05), and plasma is generated. Exhaust system 0ω is pressure adjustment valve 07), turbo molecular pump side, rotary pump 0
9) to exhaust unnecessary gas. Energy of 0.1 to 5 KW is applied to the reactive gas by high frequency or direct current energy under a pressure of 0.001 to 10 Torr, typically 0.01 to ITorr, in the reaction space e (D).

In particular, when the excitation source has a frequency of IGH2 or higher, for example 2.45GH2, hydrogen is separated from the C-H bond, and the frequency source is 0.1 to 50MH2, for example 13°56MH2.
At the frequency of , the C-C bond and C-C bond are decomposed,
-C-C- bonds are formed, and the unpaired carbon bonds collide with each other to form covalent bonds, resulting in a structure locally having a stable diamond structure.

DC bias is -200 to 600V (substantially -4
00~+400V). This is because when the DC bias is zero, the self-bias has a voltage of 1200V (with the second electrode at the ground level).

As described above, nitrogen-containing carbon having an amorphous structure or a microcrystalline structure with a large number of C--C bonds formed on the formation surface was generated by plasma. Further, this electromagnetic energy was supplied at 50 W to 1 KW, and plasma energy of 0.03 to 3 W/ci per unit area was added. As shown in FIG. 6, the transmittance of this nitrogen-containing carbon was 95% or more in the wavelength range of 600 nm or more, and an almost transparent film with 50% or more transmission even at 400 nm was obtained. Also, the internal stress of the film is 107 dyn/
cm" or less. Even if the surface was immersed in chemicals such as acids, alkalis, organics, and solvents for one hour at room temperature, no change was observed as long as the surface was observed with an optical microscope at 400x magnification. In addition, a constant temperature bath heated to 500°C (
Although the film was left in air for 1 hour, no change was observed on the surface, and a chemically and thermally stable film could be obtained.

The above-described production method is just an example, and the well-known glow discharge plasma, arc discharge plasma, or plasma using ECR may be used.

Hereinafter, a composite to which the present invention is applied will be described in more detail according to Examples.

"Example 1" An example in which the composite according to the present invention is applied to a photoreceptor used in an electrophotographic process will be described below.

FIG. 7 shows the structure of a photoreceptor to which a coating mainly composed of carbon according to the present invention is applied. Approximately 200μm thick PE
A1 vapor deposition layer (2) with a thickness of 600 people on the T-sheet (1),
A charge generation layer (4) with a thickness of 0.6 to 1.271 m is provided between the intermediate layer (3), and light (7 ) is absorbed by the charge generation layer, and electron-hole pairs are generated. If the charge transfer layer or the protective layer is negatively charged in advance, the genuine tag generated in the charge generation layer moves through the charge transfer layer only in the area where light is incident, neutralizing the negative charges. At this time, electrons generated in the charge generation layer pass through the intermediate layer, reach the A1 deposited layer, and are discharged. The negative charge remaining in the area where no light was incident then adsorbs toner and is transferred to the transfer paper, forming an image on the transfer paper depending on whether or not light is incident.

The 3WN formed here uses the present invention, and its specific resistance can be varied from 10'' to 109 (Ωc) depending on the NH and flow rate.
m). Therefore, there is no lateral movement of the band'@heavy charge, which occurs because the specific resistance is too low, and the boundary of the area where the light is incident is clear without being blurred. Therefore, the transferred image was also clear.

In addition, if the specific resistance is too high, the charge will gradually accumulate on the protective film with repeated use, and the used toner will not be removed and the transfer paper will become black.However, the protective film according to the present invention has no charge. Since the resistivity was controlled to such an extent that no accumulation occurred, it was possible to obtain high-quality transferred images over a long period of time without such a phenomenon.

Further, the transmittance of the protective film used here was 80% or more in a wavelength range of 500 nm or more, and 60% or more in a wavelength range of 400 nm or more. Therefore, the photoreceptor of this practical example was sufficiently usable even in the visible light range.

Of course, it goes without saying that the durability against mechanical damage such as abrasion resistance and scratch resistance is improved.

Furthermore, the protective film used here had reduced internal stress and good adhesion. That is, even when the sheet-like photoreceptor was bent to a radius of curvature of 10 mm, no cranking was observed in the protective film, and no beering occurred.

In this embodiment, a sheet-like organic photoreceptor has been described as a photoreceptor, but the protective film according to the present invention can be similarly constructed for a drum-shaped organic photoreceptor, an amorphous silicon photoreceptor, and a selenium photoreceptor. The effect of this can be obtained.

"Example 2" A typical thermal print head structure is shown in FIG.

A glaze (2) is formed on an insulating substrate (1), a protruding glaze (3) is formed on the part corresponding to the heating element at the same time as the glaze (2), and then a heating element (4) is formed on the substrate 01). The electrical conductors (5) are sequentially laminated, and then the protruding glaze -F is formed using a known photolithography technique.
A heating element element portion (21) was formed thereon, and finally a film containing nitrogen-containing carbon according to the present invention as a main component was formed as a protective film (6).

The protective film usually used is an inorganic film such as a silicon nitride film.
Although the film thickness is as large as 5 μm, the protective film (6) used in this application example has the same characteristics as the protective film formed in application example 1, and by controlling the NH:l flow rate, A hard film with a hardness of 2000 kg/mm" or more can be formed. Therefore, a film thickness of about 1 μm is sufficient for practical use.

In addition, the protective film used in this example has an internal stress of 10" dy
It was found that the adhesion was as small as "n/cm" and had good adhesion, and that it was also good in a heat resistance test at 500°C for 1 hour (in air).

Further, a specific resistance of about 10I6ΩcIIl is convenient for countermeasures against static electricity, and it is possible to reduce dirt and dust that cause scratches, and also to reduce the influence of static electricity on electronic circuits.

In this application example, a known heating element (4) was used, but it is also possible to use the coating mainly composed of carbon containing nitrogen according to the present invention as the heating element. That is, the film is formed under film forming conditions that increase the concentration of nitrogen, and the resistivity of the film is reduced to 10.
If the resistance is 3 to 104 Ωcm, this film can be used as a heating element.

``Example 3'' In this example, the film containing carbon as the main component of the present invention was applied to a contact type image sensor to form a film containing carbon as the main component having the structure shown in FIG. 9.

As shown in FIG. 9, electrodes and amorphous silicon are deposited on a transparent glass substrate (33) using a known plasma CVD method, and the electrodes and amorphous silicon layer are processed using an excimer laser to form a photosensor element ( After forming 34), transparent polyimide (35)
is applied using a known spinner method to create a contact image sensor.
was created. Thereafter, a protective film (36) was formed to a thickness of 2.0 um on the transparent polyimide (35) of the image sensor by the method described in Example 1.

The Vickers hardness of the protective film was measured and was 2500.
Kg/mm'', and the specific resistance was 1 x 1030 cm.The formed carbon film had a hardness similar to diamond on the surface to be formed and the surface, and an appropriate electrical insulation property for static electricity countermeasures. , the above layer was not scratched by irregularities on the document surface or stapler metal fittings, and even if static electricity was generated due to friction between the document and the paper, it was possible to prevent the accumulation of static electricity. In addition, it was possible to suppress the electrical influence on the optical sensor element and to prevent the contamination of impurities in the translucent polyimide.

``Effects'' As described above, the present invention is a composite material having an IQ mainly composed of nitrogen or carbon to which hydrogen and nitrogen are added, and the coating can be easily and inexpensively coated by adding nitrogen. The hardness, translucency, and specific resistance of the IA can be changed, and in addition, the internal stress of the IA is small and the adhesion is good.

As described in the examples, in a composite to which the coating mainly composed of carbon to which nitrogen or hydrogen and nitrogen are added according to the present invention is applied, when the coating mainly composed of carbon according to the present invention is not applied. In comparison, the lifespan and reliability of the composite could be significantly improved.

[Brief explanation of the drawing]

Figure 1 shows N11. Shows the relationship between flow rate and conductivity. Figure 2 shows the relationship between NH, flow rate, and transmittance. Figure 3 shows the relationship between NH, flow rate and hardness. FIG. 4 shows the relationship between input power and conductivity. FIG. 5 shows an outline of a plasma CVD apparatus for forming carbon or a film containing carbon as a main component according to the present invention. FIG. 6 shows the transmittance of carbon containing nitrogen. FIG. 7 shows the structure of a photoreceptor to which a coating mainly composed of carbon according to the present invention is applied. FIG. 8 shows a typical thermal printer 1-head structure. FIG. 9 shows a contact type image sensor to which the film containing carbon as a main component of the present invention is applied.

Claims (1)

[Claims] A film created using plasma CVD (chemical vapor deposition) and consisting mainly of carbon to which nitrogen or hydrogen and nitrogen are actively added is created on a substrate such as glass, metal, ceramics, or organic resin. A composite material having a coating mainly composed of carbon.