JPH06340976A - Production of carbon - Google Patents

Abstract

PURPOSE:To form a carbon coating film having strong C-C covalent bonds and energy band width equal or close to that of diamond by applying electromagnetic energy to gaseous hydrocarbon and hydrogen and carrying out dehydrogenation. CONSTITUTION:Gaseous hydrocarbon and hydrogen are converted into plasma by applying DC high-frequency or microwave electromagnetic energy under reduced pressure. By this electromagnetic energy, the gaseous hydrocarbon is activated and decomposed to form the objective carbon coating film on a substrate. This coating film is made of AS or SAG insulating carbon or is based on the carbon and contains >=30mol% (atomic %) hydrogen and silicon in the carbon and has >=2.0eV energy band width close to that of diamond.

Description

Detailed Description of the Invention

The present invention forms a carbon coating with carbon or a material containing carbon as a main component, which has a maximum thermal conductivity in a solid and has an energy band width of 2.0 eV or more similar to diamond having the highest wear resistance. Is intended.

The present invention relates to a plasma vapor phase method such as a carbon coating which is amorphous (amorphous, hereinafter referred to as AS) or semi-amorphous (semi-amorphous, hereinafter referred to as SAS) having a crystallinity of 5 to 20 Å. It is formed at a low temperature of 100 to 450 ° C, preferably 200 to 350 ° C. The purpose is to provide the carbon coating on silicon.

As a result, a carbon-based or carbon-based coating film is formed on a surface having poor adhesion to carbon or a carbon-based coating film having an energy band width of 2.0 eV or more similar to diamond. It becomes possible to apply.

According to the present invention, such a coating is formed by a plasma vapor phase method, that is, under a reduced pressure of 0.01-10 torr and a direct current high frequency of 500 KHz-50 MH.
z) or microwave (for example, a frequency of 2.45 GHz) electromagnetic energy or generate an arc discharge to generate plasma, and the reactive gas vaporized by the electromagnetic energy such as hydrocarbon gas such as ethylene and propane By activating and decomposing, the main component is insulating carbon of AS or SAS or carbon or carbon having an energy band width of 2.0 eV or more similar to diamond containing 30 mol% or less of hydrogen and silicon in carbon. It is intended to form a film.

The energy band width of carbon formed by the plasma vapor phase method is 2.0 eV or more, typically 2.5 to
It is an insulator with 3eV and its thermal conductivity is 2.5 or more, typically 5.0 (W / cm deg) and diamond's 6.60 (W / cm).
It has a very high value close to deg).

Further, the Vickers hardness of 4500 kg / mm ² or more, typically having a hardness of 6500 kg / mm ^{2 which} is similar to a diamond, has been found to have extremely excellent characteristics. It has a high-speed, heat-sensitive response.

Further, the present invention provides such an AS or SAS 450
Electrical conductivity of 10 ^-2 -10 ^-6 (Ωcm) ^{-1 when} trivalent or pentavalent impurities such as boron or phosphorus are added at a concentration of 0.1 to 3 mol% in a carbon film formed at a temperature of ℃ or below. Can be Therefore, in this case, there is another feature that it can be used as a heat generating element and can have characteristics such as not necessarily forming a wear resistant layer due to its mechanical characteristics.

Further, according to the present invention, since the abrasion resistant layer is formed by using the plasma vapor phase method under reduced pressure, the side portion of the heat generating layer can be protected with the same thickness as the upper surface. Therefore, when the sputtering method, atmospheric pressure vapor phase method, etc. have been used up to now, as a result, the wear-resistant layer is 2 μm or more in the thickness of the upper surface (the thickness of the side surface is 0.2 μm or more) to cover this side surface
Needed. However, in the present invention, since the upper surface and the side surface can be formed to have almost the same thickness, the thickness of the upper surface is 0.1 to 0.3.
Since μm is sufficient, and the thickness is reduced to about 1/10, the heat-sensitive response speed can be further improved.

In the present invention, the reactive gas is a hydrocarbon such as acetylene (C ₂ H ₂ ) or methane hydrocarbon (C _n H _{2n + 2} ).
Gas such as tetramethylsilane ((CH ₂ ) ₄ Si) or tetraethylsilane ((C ₂ H ₅ ) ₄ Si
) Or the like may be used. In the former case, carbon has 30 hydrogen.
Although it was present in a low range of 0.01 to 5 mol% when mol% or less, especially SAS, it had a strong covalent bond between carbon atoms and had physical properties similar to diamond. In the latter case, hydrogen is 0.01-
An insulating material containing 20 mol% and further containing 1/3 to 1/4 of carbon as carbon, which is a so-called carbon-rich silicon carbide, and whose main component is carbon (optical energy band width Eg> 2.0 eV Was 2.5-3.0 eV). Examples will be described below with reference to the drawings.

[0010]

EXAMPLE In this example, a case where the present invention is applied to a thermal head is shown as an application example.

[First Embodiment] FIG. 1 is a vertical sectional view of a thermal head printer used in the present invention. FIG. 1 (B) is a sectional view taken along the line AA ′ in FIG. 1 (A).
(C) shows a cross-sectional view of BB ′.

In the drawing, a glass layer (2), a heating element layer (3) and an electrode (4) which are glaze on a substrate, especially a ceramic substrate.
A wear-resistant layer (5) is laminated. Also the first
As shown in Figure (C), the area where the thermal paper is rubbed is the heating layer.
(3) A wear resistant layer (5) is provided in contact with the top.

In the present invention, the wear resistant layer (5) is made of carbon or a material containing carbon as a main component, and this material is formed by the plasma vapor phase method. Therefore, as shown in FIGS. 1 (B) and 1 (C). The feature is that the thickness of the side portion of the heating element layer can approximately match the thickness on the heating element layer.

This is because the pressure is reduced (0.01 to 10 torr), the mean free path of the reactive gas is long, and the sneak to the side is large even when performing the gas phase method. In addition, the plasma is turned into plasma, and a large amount of kinetic energy is given to the reactive gases to cause them to collide with each other and promote flight in all directions.

The wear resistant layer was prepared as follows. That is, a substrate having a surface to be formed is sealed in a reaction vessel, the reaction vessel is evacuated to 10 ^-3 torr, and the substrate is heated to 100 to 450 ° C, preferably 200 to 350 ° C, for example 300 ° C. Heated. After that, hydrogen and helium were introduced into this atmosphere to adjust the pressure to 10 ^-2 to 10 torr, and then electromagnetic energy was applied by induction method or capacitive coupling method. For example, the frequency of the applied electrical energy is 13.56MH
z, the output is 50 to 500 W, and the actual electrode gap is 15
It was about 150 cm long. This is because carbon, which is a reactive gas when it is turned into plasma, is an extremely stable material, and thus gives high energy to each element or an associated molecule in which carbon is associated with each other so that the carbon atoms are covalently bonded to each other. When the output of 50-150 W is applied to the formed film, the AS
SAS was observed when 250-500 W was added, and in the middle, a mixed structure thereof was observed by electron diffraction.

Further, for this plasmaized atmosphere,
A carbide gas such as methane or propane was introduced. Then, this reactive gas was dehydrogenated, and carbon bonds were covalently bonded to each other to form a carbon film on the surface to be formed. When the substrate temperature was 100 to 200 ° C, the hardness was slightly low and the adhesion to the substrate was not always desirable, but at 200 ° C or higher, especially 250 to 350 ° C, a very stable and strong surface to be formed. It had adhesion to.

When the heat treatment is carried out at 450 ° C. or higher, there is a problem that stress is inherent due to the difference in the coefficient of thermal expansion from the substrate, and the film formed at 250 to 450 ° C. was an ideal wear resistant material. .

Starting materials were TMS ((CH ₂ ) ₄ Si), TES ((C ₂ H ₆ ) ₄ S
When i) was used, the formed film was a film containing carbon as the main component and containing 15 to 30 atomic% of silicon. Even this had the same hardness as carbon alone. Only carbon has a thermal conductivity of 5 W / cm deg, but it is as small as 2-3 W / cm deg.

The carbon film formed as described above has a density of 0.
05 to 0.2 even thickness or thinness of the conventional 1/5 to 1/10 of μm had a wear resistance to withstand the use of 10 ⁵ hours.

[Embodiment 2] In this embodiment, a thermal head having the same hardness as that of Embodiment 1 is used to form a heating element layer by using the same plasma vapor phase method as that of Embodiment 1.

The production was carried out by the plasma vapor phase method under the same conditions as in Example 1. However, since the formed film needs to be conductive (resistive) or semiconductive, the formed film is doped with trivalent or pentavalent impurities such as boron or phosphorus, for example, impurity gas / silicide gas = A silicon film of AS or SAS added to 0.01% or less or a film containing such impurities to an impurity gas / carbide gas = 0.01 to 3% to form a resistive or semiconductive carbon-based film was formed.

That is, for the former silicon coating, silane (SinH _{2n + 2} n ≧ 1) silicon tetrafluoride is used as a starting material,
The film was formed at the same temperature of 100 to 450 ° C, for example, 200 to 350 ° C.
The high-frequency energy was 13.56 MHz at 10 to 50 W, AS, or 50 to 200 W to form SAS. The trivalent impurity was used, for example, with boron B ₂ H _6, and the pentavalent impurity was used with, for example, phosphorus using PH ₃ with a slight doping or non-doping as described above. Hydrogen in the formed film
Although the content was 20 mol% or less, they were released to the outside by heat generation.

For carbon, the same acetylene as used in Example 1 was used. Where B ₂ H ₆ / C ₂ H ₂ = 0.01-3%, PH
₃ / C ₂ H ₂ = 0.01-3% was formed. As a result, the electric conductivity of the formed film was 10 ^-8 to 10 ^-4 (Ωcm) ^-1 .

As is clear from the above description, since the present invention uses the plasma vapor phase method as its basic idea, the conventional method of forming a film at a substrate temperature of 100 to 450 ° C., typically 250 to 400 ° C., especially 300 ° C. If we think about it, it is possible at a low temperature. Especially when the temperature is 500 ° C. or less, when glass is used as the substrate material, the strain due to the thermal expansion is extremely reduced, and major defects such as warpage of the substrate due to the conventional high temperature treatment can be prevented. For this reason, only 6 heat generating parts per mm of conventional thermal printers could be made.
It has become possible to increase this to 24.

As will be apparent from the above description, the present invention uses an insulating and translucent carbon having an energy band width of 2.0 eV or more, typically 2.5 to 3 eV as an abrasion resistant material. It is characterized in that a resistor or a semiconductor containing carbon as a main component is used as a heating element layer. For that purpose, the present invention can form one or both of them by the plasma vapor phase method and can be produced at a temperature of 500 ° C or lower which is 300 to 500 ° C lower than the temperature formed by the conventional vapor phase method. It had a great degree of freedom and was extremely excellent in reducing costs.

When the method of the present invention is applied to a thermal head, the thickness of the heating element layer of the thermal head can be formed to be approximately the same as the thickness of the upper surface and the side surface of the thermal head. On the contrary, if the thickness is made more than the required amount, the thickly formed portion does not become ten times thicker.

Further, when the upper surface and the side surface are covered, there is an effect that the adhesion between the substrate and the heating element layer is enhanced.

The present invention has been described primarily with respect to the plasma vapor phase method. However, as long as such abrasion resistance is obtained, ion plating or other electromagnetic energy such as plasma or laser, or light energy may be used.

The structure of FIG. 1 in the embodiment of the present invention shows an example thereof, and the heating element layer may be a single crystal and may be a transistor structure, or may be used for a silicon mesa structure, a planar structure or the like. You can

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a thermal printer of the present invention.

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[Procedure amendment]

[Submission date] September 19, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction content]

The present invention provides a carbon coating with diamond, which has the highest thermal conductivity in the solid state and has the highest wear resistance, or similar carbon, which has an energy band width of 2.0 eV or more, or carbon-based material. The purpose is to form.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

According to the present invention, such a coating is formed by a plasma vapor phase method, that is, under a reduced pressure of 0.01 to 10 torr, a direct current high frequency of 500 KHz to 50
MHz) or microwave (for example, a frequency of 2.45 GHz) electromagnetic energy or generate an arc discharge to generate plasma, and the reactive gas vaporized by the electromagnetic energy such as hydrocarbon gas such as ethylene and propane By activating and decomposing, an energy band width similar to that of insulating carbon of AS or SAS or diamond containing 30 mol% (atomic%) or less of hydrogen in carbon is 2.
It is intended to form carbon or a coating film containing carbon as a main component having 0 eV or more.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

The wear resistant layer was manufactured as follows. That is, a substrate having a surface to be formed is sealed in a reaction vessel, the reaction vessel is evacuated to 10 ^-3 torr, and the substrate is heated to 100 to 450 ° C, preferably 200 to 350 ° C, for example 300 ° C. Heated. After that, hydrogen and helium were introduced into this atmosphere to adjust the pressure to 10 ^-2 to 10 torr, and then electromagnetic energy was applied by induction method or capacitive coupling method. For example, the frequency of the applied electrical energy is 13.56M
Hz, the output is 50 to 500 W, and the effective electrode gap is 15
It was about 150 cm long. This is because carbon, which is a reactive gas when it is turned into plasma, is an extremely stable material, so that high energy is given to each element or an associated molecule in which carbon is associated with each other so that the carbon atoms are covalently bonded to each other. When the output of 50-150 W is applied to the formed film, the AS
A SAS crystal structure was observed when 250 to 500 W was added, and a mixed structure thereof was observed in the middle by electron diffraction.

Claims (2)

[Claims] 1. A method for producing carbon, characterized in that electromagnetic energy is applied to a hydrocarbon compound gas and hydrogen to dehydrogenate the carbon to form a covalent bond between the carbons to produce carbon having crystallinity. 2. A carbon which is characterized in that it is dehydrogenated by applying electromagnetic energy to a hydrocarbon gas and hydrogen to form a covalent bond between carbons to produce carbon containing 30 mol% or less of hydrogen. Of manufacturing.