JPH086171B2 - Method for forming carbon-based film - Google Patents

Description

The present invention relates to a method for forming a carbon-based film such as an amorphous carbon film or a diamond film on the surface of a substrate.

[Conventional technology]

Conventionally, the formation of a carbon-based film as described above is performed by, for example, plasma CVD using a carbon-hydrogen-based or organic compound-based reaction gas.
Method, a CVD method (chemical vapor deposition method) such as a thermal CVD method, or an ion plating method in which evaporated carbon is ionized and accelerated by an electric field to deposit on the surface of the substrate.

[Problems to be solved by the invention]

However, in the above CVD method or ion plating method, the energy of particles reaching the substrate is extremely small (for example, the former is about 100 eV at most and the latter is at most 150 eV). There was a problem that the adhesion of the various carbon-based films was poor.

In particular, with respect to a stainless steel substrate, it is difficult to form the above-described carbon-based film stably and with good adhesion, because the carbon-based film does not have good compatibility with stainless steel. there were.

Therefore, an object of the present invention is to provide a method capable of forming a carbon-based film such as an amorphous carbon film or a diamond film stably and with good adhesion on the surface of various types of substrates including stainless steel. To do.

[Means for solving problems]

The method of forming a carbon-based film according to the present invention comprises, when forming a carbon-based film on the surface of a substrate, injecting at least one of carbon ions and ions of a substance containing carbon into the substrate in a vacuum. A carbonized layer of the substrate material is formed in advance on the surface layer of the substrate, and then the carbon-based film is formed thereon.

[Action]

By forming a carbonized layer of the base material in advance on the surface layer of the substrate by ion implantation, both the surface layer of the substrate and the carbon-based film to be formed later become carbon-based substances and their mutual compatibility is improved. As a result, a carbon-based film such as an amorphous carbon film or a diamond film can be formed stably and with good adhesion on the surface of various types of substrates including stainless steel.

〔Example〕

FIG. 1 is a schematic diagram showing an example of an apparatus for performing a method according to the present invention.

In a vacuum container (not shown), for example, a holder 10 is mounted to accommodate the substrate 2, and an ion source 12 and an evaporation source 18 in this example are disposed toward the substrate 2.

In this example, the ion source 12 is a bucket type ion source that uses a multipole magnetic field for plasma confinement, and ionizes the supplied gas G to direct uniform and large-area ions (ion beam) 14 to the surface of the substrate 2. Because it can be accelerated, it is possible to process a large area at a time.

However, instead of such a bucket type ion source, another type of ion source such as a Kauffman type may be used, or a spot-shaped ion beam extracted from the ion source and subjected to mass analysis is scanned over a required area. You may make it irradiate.

Since the evaporation source 18 is used only in the second step described later,
This will be described later.

At the time of processing, the inside of the vacuum vessel is, for example, 10 ^-5 to 10 ^-7 Torr.
After exhausting to a certain degree, as a first step, the ion source 12 is supplied with gas G such as carbon monoxide gas, carbon dioxide gas, hydrocarbon gas (eg methane gas, ethane gas), organic compound gas (eg acetone). By supplying at least one kind of gas containing carbon in terms of composition, etc., at least one of carbon ions and ions of a substance containing carbon (such as CH ions), that is, these, as the ions 14 from the ion source 12 Single ions or mixed ions are extracted and injected into the substrate 2. The implantation amount of the ions 14 into the substrate 2 at this time can be measured by, for example, the beam monitor 16.

As a result, for example, as shown in FIG. 2, a carbonized layer 4 of the base material is formed on the surface layer portion of the base 2.

In that case, the energy of the implanted ions 14 is not particularly limited because it is related by the type of the substrate 2 and the range of the ions 14 in the substrate 2, but the lower limit is the ion source 2.
From the limit that can extract ions 14 from, it will be about 10 eV or more in reality. The upper limit is usually 50 KeV or less in order to reduce damage in the film or the substrate, but 50 KeV
The carbonized layer can also be formed by the above, and in this case, an annealing treatment may be performed if necessary.

Also, the amount of ions 14 implanted into the substrate 2 is not particularly limited because the formation state of the carbonized layer 4 varies depending on the type of the substrate 2, but in order to prevent damage to the substrate 2 due to ion implantation, for example, 1 × preferably set to 10 ¹⁸ or less ² about ion / cm.

Further, during the implantation of the ions 14, depending on the type of the substrate 2, it may be cooled from the viewpoint of preventing thermal damage to the substrate 2, or the substrate 2 may be changed from the viewpoint of facilitating diffusion of the carbonized layer. You may heat at a transformation temperature or less. After the implantation, the substrate 2 may be annealed in the same gas as the implanted ions to recover damage.

Then, after the carbonized layer 4 is formed in advance on the surface layer portion of the substrate 2 as described above, then in a second step, a carbon-based film 6 such as an amorphous carbon film or a diamond film is formed thereon (see FIG. 2). ) Is formed.

The formation of the carbon-based film 6 may be performed by using an existing technique such as the above-described CVD method or ion plating method, or by using a method that uses both vacuum deposition and ion irradiation as described below. You can go.

Whichever method is used, the surface layer portion of the base body 2 and the carbon-based film 6 to be formed later are both carbon-based substances, so that the compatibility with each other is improved. As a result, the adhesion of the carbon-based film 6 to the substrate 2 is improved, and it is difficult to form the carbon-based film 6 such as an amorphous carbon film or a diamond film in the past on various types of substrates 2. It is possible to form these films stably and with good adhesiveness even on the conventional base body 2 such as stainless steel.

Next, an example of a method of forming the carbon-based film 6 described above by using both vacuum deposition and ion irradiation will be described. In this case, the evaporation source 18 is used together with the ion source 12.

The evaporation source 18 is, for example, an electron beam evaporation source, and carbon 20
Can be evaporated to deposit it on the surface of the substrate 2, although other types of evaporation sources may be used. Reference numeral 22 is a film thickness monitor for measuring the film thickness of the film deposited on the substrate 2.

In this case, the gas G supplied to the ion source 12 is at least one of the above-mentioned hydrocarbon-based gas, organic compound-based gas and inert gas (for example, helium gas, argon gas, etc.), that is, these gases. A single gas or a mixed gas is used. This is because when a hydrocarbon-based gas or an organic compound-based gas is used, the vapor-deposited carbon is irradiated with ions 14 of the same type as that of the vapor-deposited carbon, that is, a carbon-based ion, which makes it easier to excite the vapor-deposited carbon. This is because if the active gas is used, the inert element irradiated as the ions 14 has poor reactivity, and thus a good quality carbon-based film 6 free of impurities can be obtained. Further, in order to promote diamond formation, at least one of silicon-based gas and hydrogen gas may be mixed with the above gas.

In forming the carbon-based film 6, in this example, following the first step, the carbon 20 from the evaporation source 18 is deposited on the substrate 2 (specifically, on the carbonized layer 14 of the surface layer portion thereof) in the same vacuum container. (B) Simultaneously with or alternately with the vapor deposition, the ions 14 from the ion source 12 are continuously or intermittently irradiated to the substrate 2.

As a result, for example, as shown in FIG. 2, a carbon-based film 6 such as an amorphous carbon film or a diamond film is formed on the surface of the substrate 2, that is, on the carbonized layer 14 in the surface layer portion thereof. This is because the carbon deposited on the substrate 2 is made amorphous by the irradiation of the ions 14, or nucleation energy is supplied to the carbon of the graphite structure deposited on the substrate 2 to cause it to grow into diamond crystals. Because you can.

In that case, the film quality of the carbon-based film 6, for example, the ratio of diamond crystals and amorphous carbon in the film, is determined by the base 2
It can be controlled by conditions such as the ratio of ions / carbon incident on the ion source, the mixing ratio of various gases as described above supplied to the ion source 12, the energy of the ions 14, and the like.

Further, the energy of the ions 14 in this case is low energy of about 10 KeV or less, more preferably about several hundred eV from the viewpoint of minimizing damage (defects) inside the carbon-based film 6 due to the irradiation. The following is good. The lower limit is not particularly limited,
As in the case described above, it is about 10 eV or more in reality.

Also in this case, when the film is formed, if necessary, the substrate 2
May be heated or cooled. If heated, the reaction of diamond formation can be promoted by thermal excitation, and the defect portion generated in the carbon-based film 6 can be removed during the film formation, and the cooling can be performed. By doing so, it is possible to prevent the substrate 2 from being thermally damaged by the irradiation of the ions 14.

The features of forming the carbon-based film 6 by the above method are listed below.

Unlike the CVD method, it is not mainly subjected to thermal excitation, so that low-temperature treatment is possible, and as a result, the range of materials that can be used as the substrate 2 is greatly expanded.

It can be expected that a mixed layer of the base 2 and the carbon-based film 6 is formed in the vicinity of the interface between the base 2 and the carbon-based film 6 by the action of the ions 14 being knocked on, which further improves the adhesion of the carbon-based film 6 to the base 2. .

Since vapor deposition of carbon 20 is also used, a large film thickness can be obtained in a short time as compared with the CDV method, and the formation efficiency of the carbon-based film 6 is good.

Since the carbon-based film 6 can be formed continuously with the formation of the carbonized layer 4 in the same vacuum container, there is no fear of being polluted by the atmosphere and the processing efficiency is good.

〔The invention's effect〕

As described above, according to the present invention, the carbonized layer of the base material is preliminarily formed on the surface layer portion of the base by ion implantation, so that the amorphous carbon film is formed on the surface of various types of bases including stainless steel. It becomes possible to form a carbon-based film such as a diamond film or the like stably and with good adhesion.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for performing a method according to the present invention. FIG. 2 is a schematic cross-sectional view partially showing the vicinity of the surface of the substrate on which the carbon-based film or the like is formed. 2 ... Substrate, 4 ... Carbonized layer, 6 ... Carbon film, 12 ... Ion source, 14 ... Ion.

Claims (1)

[Claims] 1. When forming a carbon-based film on the surface of a substrate, by injecting at least one of carbon ions and ions of a substance containing carbon into the substrate in a vacuum, the surface layer of the substrate is injected. A method for forming a carbon-based film, which comprises forming a carbonized layer of the base material in advance and then forming the carbon-based film thereon.