JPH1068068A - Formation of compound thin coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the scattering of droplets from a cathode of an arc type evaporating source and the form a thin coating film high in smoothness by using the nitrided of the group 4a, 5a or 6A metals or the nitrided of the alloys of these metals for the cathode. SOLUTION: In the formation of a compound thin coating film, as the material for the cathode 16 of an arc type evaporating source 14, the nitrides of the group 4A, 5A or 5A metals or the nitrides of the alloys among these metals are used. As the nitrides of the metals, e.g. TiN, ZrN, HfN, VN, NbN, TaN, CrN, MoN or WN is used, and, as the nitrides of the alloys, TiZrN is used. These nitrides of the high m.p. metals and the nitrides of the alloys are electrically conductive compounds and are usable as the material for the cathode 16. Furthermore, these nitrides have the m.p. higher than that of the original m.p. metals, and by using these nitrides for the cathode 16, the melted zone by arc is numerously and finely dispersed on the surface of the cathode 16. As a result, the generation of the coarse melted zone on the surface of the cathode 16 can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used, for example, for improving the wear resistance of tools, molds, decorative articles, etc., and is applied to the surface of a substrate by a so-called arc type ion plating method. And a method of forming a compound thin film in which a group 4A, 5A or 6A metal of the periodic table of elements or a reactive gas is combined with each other, and more specifically, a method in which droplets are scattered from a cathode of an arc evaporation source. The present invention relates to a method for suppressing and improving the smoothness of the surface of a compound thin film.

[0002]

2. Description of the Related Art In an arc ion plating method, a reactive gas is introduced into a vacuum vessel and a zero or negative bias voltage is applied to a substrate using an arc evaporation source that dissolves a cathode by arc discharge. This is a method for forming a compound thin film in which a cathode constituent material and a reactive gas are combined on the surface of a base material in a state where the thin film is formed, and is a thin film forming method excellent in terms of thin film adhesion, productivity, and the like.

In such an arc ion plating method, in order to form a thin film of a compound of a group 4A, 5A or 6A metal of the periodic table of elements or a combination thereof with a reactive gas on the surface of a substrate, For example, an apparatus as shown in FIG. 1 is used.

This device includes a vacuum container 2 evacuated by a vacuum exhaust device (not shown), a holder 10 provided in the vacuum container 2 for holding a substrate 8, and a holder 10 facing the substrate 8. And an arc evaporation source 14 attached to the wall surface of the vacuum vessel 2.

The arc-type evaporation source 14 causes the cathode 16 to be locally melted by an arc discharge between the cathode 16 and the vacuum vessel 2 serving as an anode (in some cases, an anode is provided), thereby evaporating the cathode material 18. Things. An arc discharge voltage of, for example, about several tens of volts to several hundred volts is applied between the cathode 16 and the vacuum vessel 2 from the direct current arc power supply 20 with the former being on the negative side. Thereby, for example, several tens of A
An arc current of about 300 A can be passed.
The cathode 16 is made of a metal of Group 4A of the periodic table (ie, Ti, Z).
r, Hf) made of a Group 5A metal (ie, V, Nb, Ta) or a Group 6A metal (ie, Cr, Mo, W) or an alloy thereof.

[0006] A reactive gas 6 which reacts with the cathode material 18 to form a compound is introduced into the vacuum vessel 2 from a gas inlet 4. The reactive gas 6 is, specifically, a gas containing one or more of nitrogen, oxygen and carbon,
More specifically, it is a nitrogen gas, an oxygen gas, a hydrocarbon-based gas, or a mixed gas thereof.

[0007] Holder 10 and base material 8 held thereon
From the DC bias power supply 22, for example, -200
A bias voltage of about 0 V or less, more specifically, about 0 V to about -1000 V is applied.

At the time of film formation, the inside of the vacuum vessel 2 is, for example, 1 × 10
After evacuating to ^-5 Torr or less, vacuum vessel 2
The above-described reactive gas 6 is introduced thereinto, and an arc discharge is performed in the arc-type evaporation source 14 with a bias voltage of, for example, about −several hundred V applied from the bias power supply 22 to the substrate 8. Thereby, the cathode material 18 is evaporated from the cathode 16. A portion of this cathodic material 18 is ionized, which is attracted to and impinges on the substrate 8 to which a zero or negative bias voltage has been applied, and reacts with the surrounding reactive gas 6, whereby the substrate 8
A compound thin film is formed on the surface of the substrate. Bias voltage is 0V
However, the reason why a compound thin film is formed in the same manner as when a negative bias voltage is applied to the base material 8 is as follows. That is, the cathode 16 is melted by the arc discharge heat, and metal atoms, metal particles, and the like fly out of the cathode 16, but the metal atoms collide with electrons to become metal ions, which form a cloud of a positive potential near the cathode. Therefore, even if the bias voltage applied to the base material 8 is 0 V, the cathode 16 and the base material 8
A potential gradient is created between the two, which causes the metal ions to be attracted and accelerated toward the substrate 8 and impinge on the substrate 8 while reacting with the surrounding reactive gas, whereby the substrate 8 A compound thin film is formed on the surface of the substrate. To apply a bias voltage of 0 V to the base material 8 means to set the output voltage of the bias power supply 22 to 0 V, in other words, to apply no bias voltage to the base material 8, Therefore, in this case, the substrate 8 may be simply grounded without providing the bias power supply 22.

[0009]

In the above-described film forming method using an arc evaporation source, since the cathode 16 is directly melted by the arc and the arc current can be easily increased, the productivity is high. , Arc evaporation source 14
The cathode material 18 which is evaporated from contains a large proportion of ionized particles, which can be accelerated toward the substrate 8 by zero or negative bias voltage and collide with the substrate 8. Therefore, it has an advantage that a thin film having high adhesion can be formed.
A large mass of cathode material (which is called a droplet) is also generated together with the fine cathode material 18 from the surface, and this fly over and adheres to the substrate surface, so that the thin film surface has poor smoothness (that is, the surface roughness of the thin film). Is bad). In addition, there is a problem that the adhesion of the droplet portion is weak, which adversely affects abrasion resistance and corrosion resistance.

Accordingly, an object of the present invention is to provide a method capable of forming a compound thin film having high smoothness by suppressing the scattering of droplets from a cathode of an arc evaporation source.

[0011]

According to a method of forming a compound thin film of the present invention, the cathode of the arc-type evaporation source is provided with a nitride of a metal belonging to Group 4A, 5A or 6A of the periodic table or an alloy of an alloy of these metals. It is characterized by using nitride.

Since the above-mentioned so-called high melting point metals or nitrides of alloys thereof are all conductive compounds, they can be used as a cathode of an arc evaporation source.

Moreover, since such high-melting-point metal nitride or nitride of such an alloy of metals has a higher melting point than the original high-melting-point metal or the like, when they are used for the cathode, an arc due to an arc is generated. The molten portion is finely and finely dispersed on the cathode surface. As a result, generation of a coarse molten portion on the cathode surface is suppressed, and generation and scattering of droplets are suppressed. Therefore, a compound thin film having high smoothness can be formed on the surface of the substrate.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method for forming a compound thin film according to the present invention, for example, the apparatus shown in FIG. 1 is used. However, the material of the cathode 16 of the arc evaporation source 14 is different from that of the above-described conventional example.

That is, in the method according to the present invention, the cathode 16 is provided with a Group 4A metal (ie, Ti, Zr,
Hf) Group 5A metal (ie, V, Nb, Ta) or 6
Group A metal (ie, Cr, Mo, W) nitrides (eg, Ti
N, ZrN, HfN, VN, NbN, TaN, CrN,
MoN, WN) or a nitride (for example, TiZrN) of an alloy of these metals (for example, TiZr) is used.

Materials other than the material of the cathode 16, for example, the type of the reactive gas 6 introduced into the vacuum vessel 2, the magnitude of the bias voltage applied to the substrate 8, and the like are the same as those in the above-described conventional example. .

Since the above-mentioned nitrides of so-called high-melting metals or alloys thereof are all conductive compounds, they can be used as the cathode 16 of the arc evaporation source 14. If it is not conductive, no current can flow through it, so it cannot be used as the cathode 16.

Moreover, such a high-melting-point metal nitride or an alloy of such metals has a higher melting point than the original high-melting-point metal (for example, the melting point of Ti is about 1
900 ° C., whereas that of TiN is about 2900
° C), when it is used for the cathode 16, a large number of molten parts by the arc are finely dispersed on the cathode surface. As a result, generation of a coarse molten portion on the cathode surface is suppressed, and generation and scattering of droplets are suppressed. Therefore, a compound thin film having a high smoothness, that is, a good surface roughness can be formed on the surface of the substrate 8.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Using a device as shown in FIG. 1, the film formation was carried out by changing the material of the cathode 16 of the arc evaporation source 14 and the reactive gas 6 introduced into the vacuum vessel 2 in various ways. The results are shown in Table 1.

In this case, the diameter of each of the cathodes 16 is 10
0 mm, a high-speed steel plate was used as the base material 8, and the inside of the vacuum vessel 2 was evacuated to 1 × 10 ⁻⁵ Torr or less, and then an arc current of 150 A, a bias voltage of −200 V,
Film formation was performed until the film thickness became 1 μm with the gas partial pressure in the vacuum vessel 2 shown in Table 1. However, the arc current and the gas pressure may be values within a range in which the arc discharge can be maintained. For example, the arc current may be about 30 A to 300 A, and the gas pressure may be about 1 × 10 ⁻⁵ Torr to 1 Torr.
The magnitude (absolute value) of the zero or negative bias voltage applied to the base material 8 may be, for example, about 2000 V or less.

[0021]

[Table 1] ○: good, ×: not good

As can be seen from this table, Example 1 using a nitride of such a metal or an alloy as compared with Comparative Examples 1 to 7 using a high melting point metal or an alloy thereof as the cathode material itself. In each of Nos. 1 to 7, the maximum surface roughness and average surface roughness of the film were small, and a compound thin film having good surface roughness, that is, high surface smoothness could be formed.

[0023]

As described above, according to the present invention, the nitride of a high melting point metal or the nitride of an alloy of such metals as described above has a higher melting point than the original high melting point metal or the like. Therefore, by using it for the cathode, the melted portion due to the arc is finely and finely dispersed on the cathode surface. As a result, generation of a coarse molten portion on the cathode surface is suppressed, and generation and scattering of droplets are suppressed. Therefore, a compound thin film having high smoothness can be formed on the surface of the substrate.

As a result, it becomes possible to coat parts that require high dimensional accuracy, to produce gloss on the surface and to expand the applicability to decorative articles, and to reduce unevenness on the thin film surface and reduce friction. Further effects such as improvement of the wear resistance of the coated product can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an apparatus for forming a compound thin film on a substrate surface by an arc ion plating method.

[Explanation of symbols]

 2 Vacuum container 6 Reactive gas 8 Base material 14 Arc evaporation source 16 Cathode 18 Cathode material 22 Bias power supply

Claims (1)

[Claims] 1. A method in which a reactive gas is introduced into a vacuum vessel and a zero or negative bias voltage is applied to a substrate using an arc-type evaporation source for melting a cathode by arc discharge. In a method of forming a compound thin film in which a reactive gas is combined with a metal of Group 4A, 5A or 6A of the Periodic Table of Elements or an alloy thereof, the cathode of the arc-type evaporation source is provided with 4A, 5A of the Periodic Table of Elements. Alternatively, a method of forming a compound thin film, comprising using a nitride of a Group 6A metal or a nitride of an alloy of these metals.