JPS627262B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for forming a diamond-like carbon film by performing vacuum deposition or sputter deposition using carbon as a base material and simultaneously irradiating an ion stream with hydrogen gas or hydrocarbon gas as the ion species. It is related to the creation method.

Conventionally, carbon films have been created by electrical heating of graphite electrodes or by coating carbon powder.
This method had poor controllability, and the resulting film was black, opaque, soft, and had poor adhesion to the substrate. Furthermore, as a simpler and more controllable method, there is a method of using graphite or diamond as the base material, irradiating it with an ion beam, laser beam, or electron beam, and creating a carbon film by sputtering or vapor deposition. A method has been proposed for forming a hard, transparent film with high electrical resistance by simultaneously irradiating the substrate with charged particles using this method (Japanese Patent Application No. 55-180504).
issue). The films obtained by these methods are carbon films containing a mixture of diamond parts and graphite parts. In general, it is believed that the more diamond parts a carbon film has, the harder and more transparent the film is, and the higher its electrical resistance. However, it is very difficult to construct a film consisting only of diamond parts, and since a considerable proportion of graphite parts are present, the film quality deteriorates and transparency and electrical resistance are reduced.

The present invention aims to provide a method for selectively removing graphite portions in a carbon film to create a carbon film with a high proportion of diamond portions.
Here, an ion stream obtained from hydrogen gas or a hydrocarbon gas such as methane is used as the charged particles, and the ion flow is irradiated onto the substrate to promote diamondization of the formed thin film. Hydrogen atoms are known to have strong reactivity with graphite, but weak reactivity with diamond. Under a hydrogen atmosphere of 1000℃ and 50 atm,
99.9% of graphite is removed, while only 0.02% of diamond is removed.
When these hydrogen atoms are ionized to increase their reactivity and irradiated onto the substrate, only the graphite portions in the carbon film are selectively removed, forming a film that is overwhelmingly composed of diamond portions.

Hereinafter, the invention will be explained in detail with reference to the drawings.
Figure 1 shows an outline of the apparatus used in the present invention, in which 1 is a vacuum container, 2 is an ion source for sputtering a carbon base material, 3 is an ion beam, and 4 is a carbon base material (for example, graph 5 is a vapor deposition substrate, 6 is an ion gun for simultaneously irradiating ions onto the vapor deposition substrate, 7 is an ion flow (for example, a hydrogen ion flow), and 8 is a carbon film formed on the vapor deposition substrate. To operate this, first evacuate the inside of the vacuum container 1 to a high vacuum, then introduce an inert gas such as argon gas into the ion source 2, generate ions by electric discharge, and accelerate them to about 5 to 10 KV. The ion beam 3 is extracted and irradiated onto the carbon base material 4.
The carbon atoms of the base material that have been bombarded by the ions are sputtered and deposited on the substrate 5 to form a film. Figure 2 shows d obtained from the electron diffraction pattern of the prepared film.
- diagram showing spacing; The position of the line indicates the d-spacing obtained from the diameter of the diffraction ring, and the thickness of the line indicates the intensity of the diffraction ring. In addition, a is for a film created only by ion beam sputter deposition, and b is for a film created by simultaneous irradiation with hydrogen ions in addition to ion beam sputter deposition. When the crystallinity of the film obtained by this method is evaluated by electron diffraction, the diffraction pattern is shown in Figure 2a.
The results shown are obtained. (In this figure, the position of the line indicates the d-spacing determined from the diffraction ring, and the thickness of the line indicates the intensity of the diffraction ring.) Here, d-
Spacings of 2.07 and 1.17 Å are typical of amorphous carbon films with a mixture of graphite and diamond bonds. Next, at the same time as the ion beam sputtering described above, hydrogen gas is introduced into the ion gun 6 and ionized, and the ion stream 7 accelerated to several tens to several hundreds of volts is irradiated onto the deposition substrate 5. The activated hydrogen ions react with the graphite portion in the carbon film that is being deposited on the substrate, and are desorbed as hydrocarbon gas. However, since the diamond portion hardly reacts with hydrogen, it remains in the film.
Therefore, the resulting film formed on the substrate has an overwhelmingly large proportion of diamond parts, and the film hardness, transparency, and electrical resistance all increase, and in terms of crystallinity, as shown in Figure 2b. As shown in Figure 2, electron diffraction patterns with d-spacings of 2.08, 1.28, and 1.07 Å, which can be identified as diamond polycrystals, are observed. In addition, when hydrocarbon gas is used instead of hydrogen gas as the gas introduced into the ion gun 6, it has been confirmed by mass spectrometry that the ions obtained from gases such as methane, ethane, and propane contain a large amount of hydrogen ions. Even by irradiating a substrate with these ions, a film with many diamond parts is still formed. Furthermore, the same effect can be obtained even when a mixed gas of hydrogen and hydrocarbon is introduced into the ion gun 6 and ionized.

Although the ion beam sputtering method has been described here as a method for evaporating the carbon base material, it goes without saying that laser heating or electron beam heating may also be used.

As explained above, the present invention makes it possible to create a diamond-like carbon film, which was impossible with conventional techniques, and its application value is extremely high. Further, according to the method of the present invention, a transparent, hard, high electrical resistance, and dense carbon film can be produced with good controllability, so there is an advantage that it can be expected to have a wide range of applications as an electronic device material.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the apparatus used in the present invention, and Figure 2 is the d obtained from the electron diffraction pattern of the prepared film.
- diagram showing spacing; 1... Vacuum vessel, 2... Ion source, 3... Ion beam, 4... Base material, 5... Vapor deposition substrate, 6...
Ion gun for simultaneously irradiating the substrate with hydrogen ions, 7... Ion flow, 8... Carbon film.

Claims (1)

[Claims] 1. A carbon film is deposited on a substrate by an ion beam sputtering method, a laser heating method, or an electron beam heating method, and at the same time, the carbon film is irradiated with a hydrogen ion flow accelerated to several tens to hundreds of volts. A method for creating a diamond-like carbon film.