Patent Grant
7029560
1. Field of the Invention
The present invention relates to a rod target for an arc evaporation source used for anti-wear coating treatment with respect to cutting tools, mechanical components and the like, a manufacturing method therefor, and an arc deposition device.
2. Description of the Related Art
As shown in
In actuality, however, when attempting to obtain a uniform film thickness by such conventional arts, if the height of the work 53 and that of the target 52 are relatively close to each other, the amount of evaporation of the target material from the opposite ends of the rod target 52 must be increased as shown in
In light of the above-described problems, the object of the present invention is to provide work with a uniform film thickness, and improve the availability of the rod target, thereby preventing the rod target from going to waste.
As technical means for solving the above-described technical problems, the present invention provides a rod target for an arc evaporation source, the rod target employing its outer peripheral surface as an evaporation surface, wherein the opposite ends thereof in the longitudinal direction thereof are each formed thicker than the central part thereof.
In the present invention, the length of the thicker portion at each of the opposite ends of the rod target in the longitudinal direction thereof is preferably set to be not less than 75 mm nor more than 200 mm. In the present invention, the length of the thicker portion affects the uniformity of film thickness and the availability of the rod target, irrespective of the entire length of the rod target.
In the present invention, the ratio of the effective consumed sectional area of the thicker portion at each of the opposite ends of the rod target in the longitudinal direction thereof with respect to the effective consumed sectional area of the narrower portion in the central part thereof is preferably set to be more than 1.0 and not more than 3.0.
In the present invention, the boundary portion between the thicker portion at each of the opposite ends of the rod target in the longitudinal direction thereof and the narrower portion in the central part thereof may be changed in the thickness in a step-by-step manner so that the thickness thereof gradually decreases from the thicker portion at each of the opposite ends thereof in the longitudinal direction thereof toward the narrower portion in the central part thereof.
In the present invention, a taper portion may be provided in the boundary portion between the thicker portion at each of the opposite ends of the rod target in the longitudinal direction thereof and the narrower portion in the central part thereof so that the diameter thereof gradually decreases from each of the thicker portions toward the narrower portion.
Further, the present invention provides a method for manufacturing the rod target for an arc evaporation source as mentioned above, comprising integrally assembling the thicker portion at each of the opposite ends thereof in the longitudinal direction thereof and the narrower portion in the central part thereof, after, at least, separately producing the thicker portion at each of the opposite ends thereof in the longitudinal direction thereof and the narrower portion in the central part thereof.
Still further, the present invention provides an arc deposition device in which a rod target for an arc evaporation source and work are provided in a vacuum vessel, in which a target material is evaporated from the outer peripheral surface of the rod target for an arc evaporation source, and in which the evaporated target material is caused to be adhered to the work. In this arc deposition device, the rod target for an arc evaporation source as mentioned above is used as the rod target for an arc evaporation source provided in the vacuum vessel.
According to the present invention, the work is provided with a uniform film thickness, and the availability of the rod target is improved, whereby waste of the target material is eliminated, resulting in an economic advantage.
Hereinafter, the present invention will be described with illustrated embodiments.
In
The rod target 2 is disposed in the central part of the vacuum vessel 1 along the up-and-down direction. A rotational table 5 is provided in a lower portion of the vacuum vessel 1. The rotational table 5 is supported so as to be rotatable about its vertical axis substantially coaxial with the rod target 2. The work 3 is placed on the rotational table 5 through the intermediary of a holding member 6. The work 3 is configured to revolute about the rod target 2 with the rotation of the rotational table 5 and simultaneously to rotate together with the holding member 6 about the vertical axis thereof.
A magnet 8 is provided in the rod target 2 so as to be movable up and down. The cathode of an arc power supply 10 is connected to the top end of the rod target 2. The anode of the arc power supply 10 is connected to the vacuum vessel 1.
In order to form a coating on the work 3 by the vacuum deposition device, the vacuum vessel 1 is first evacuated by a vacuum pump (not shown) to keep the inside of the vacuum vessel in a vacuum state with a predetermined pressure. When a vacuum arc discharge is generated from the rod target 2 by an ignition unit (not shown), an arc spot in which an arc current is concentrated appears on the surface (outer peripheral surface) of the rod target 2. Herein, a target material is evaporated from the outer peripheral surface of the rod target 2 while controlling the position of the arc spot by ascending/descending of the magnet 8.
The vapor of the evaporated target material moves toward the work 3 disposed in the vacuum vessel 1, and forms a coating on the work 3. A negative voltage (bias voltage) is applied to the work 3 by a power supply (not shown) as required, and coating formation is performed while accelerating ions in the vapor. Also, as required, a reactive gas such as nitrogen may be introduced into the vacuum vessel 1 to form a coating comprising a compound of the target material and nitrogen.
As shown in
The length x of the thicker portion 13 at each of the opposite ends of the target rod 2 in the longitudinal direction thereof is set to be not less than 75 mm nor more than 200 mm, and is preferably set to 100 to 150 mm.
The ratio of the effective consumed sectional area of the thicker portion at each of the opposite ends of the target rod 2 in the longitudinal direction thereof with respect to the effective consumed sectional area of the narrower portion in the central part thereof is set to be more than 1.0 and not more than 3.0, and is preferably set to 1.5 to 2.5.
Here, as shown in
Sy=(y/2)2·π−(d/2)2·π
Sz=(z/2)2·π−(d/2)2·π
Therefore, the Sy/Sz ratio is set to be in the followingrange.
1.0<Sy/Sz≦3.0
Meanwhile, in
According to the above-described embodiment, the following effects are produced.
Specifically, the length of each of the opposite ends of the rod target 2, which needs to be increased in the evaporation amount in order to meet a general requirement that variations in the thickness of a film formed on the work 3 should be within ±5%, is restricted, and is not subjected to an influence of the entire length of the target. That is, by limiting the length of the thicker portion at each of the ends of the rod target to a necessary and sufficient length, the utilization efficiency of the rod target 2 is improved. If each of the larger diameter portions 13 is longer than necessary, the excessive part thereof is left over. Conversely, each of the larger diameter portions 13 is shorter than necessary, each of the end sides of the rod target unfavorably early arrives at its consumption limit. In either case, the utilization efficiency decreases.
Specifically, as in the case described in (2), the evaporation amount to be increased at each of the ends of the rod target 2 in order to fulfill the requirement that variations in the film thickness should be within 5%, is restricted. If a necessary and sufficient consumed amount (by target diameter) is secured, it is possible to improve the utilization efficiency, and simultaneously increase the overall amount of evaporation source (i.e., usable volume). With the target diameter larger than necessary, each of the larger diameter portions 13 becomes surplus when the smaller diameter portion 14 arrives at its consumption limit, thereby reducing the utilization efficiency. Conversely, with the target diameter smaller than necessary, each of the ends (larger diameter portions 13) unfavorably early arrives at its consumption limit, thereby reducing the overall amount of evaporation source.
In the embodiment shown in
In the embodiment shown in
According to the embodiments shown in
(4) With regard to the surface perpendicular to an ordinary discharge surface, it differs in its positional relationship with the anode (positive pole) from that of the ordinary discharge surface; the anode is unfavorably difficult to see therefrom; and the magnetic field configuration thereof with respect to its discharge surface differs to a large degree from that of the ordinary discharge surface. As a result, if the surface perpendicular to the ordinary discharge surface is caused to discharge over a long period of time, an accident fire is apt to occur therefrom. Therefore, changing the target diameter in a step-by-step manner makes it possible to prevent the occurrence of an accident fire when an arc spot transfers to regions in which the target diameter varies.
As shown in
Unlike the case where a surface discharge is performed from the entire surface of a target as in a sputtering method, in the arc evaporation source, an arc spot irregularly moves on the surface of the target. As a result, in the arc evaporation source, specific problems such as the occurrence of an accident fire and the concentration of thermal stress at spots in which the diameter varies, tend to occur. However, according to the embodiments shown in
Specifically, as shown in
Accordingly, by reducing the tilt angle α to thereby get the relative angle between each line of magnetic force and the discharge surface of each of the taper portions 17 closer to that in the portion other than the taper portions 17, it is possible to avoid an undesirable arc behavior. From this viewpoint, the smaller the tilt angle α, the more desirable the arc behavior is. However, in order to optimize the length and diameter of the larger diameter portion 13, the tilt angle α is naturally subjected to constraints.
According to the embodiment shown in
The manufacturing method for the rod target 2 shown in
Next, descriptions will be made of the results of the tests performed with respect to the rod target 2 according to the present invention.
Table 1 shows the target consumption amount (volume), and the consumption efficiency (up to the limit consumption), i.e., (the volume consumed or evaporated until the lifetime expires)÷(the initial volume), when the length x of the larger diameter portion 13 of the rod target is varied, using a rod target having the entire length L of 700 mm, the outer diameter z of its smaller diameter portion 14 of 100 mm, and the outer diameter y of its larger diameter portion 13 of 125 mm. Variations in the film thickness distribution was maintained within ±5%, and the target consumption limit was set to Φ70 mm. As a result, the consumption efficiency was higher when the length x of the larger diameter portion 13 was 100 to 150 mm, and was the highest when the length x of the larger diameter portion 13 was 125 mm. The length x of the larger diameter portion 13 that allows the consumption efficiency to be the maximum, somewhat depends upon the distance between the rod target 2 and the work 3, or the like. However, irrespective of the difference in the distance between the rod target 2 and the work 3, substantially the same consumption efficiency tendency was observed, and the consumption efficiency was optimum when the length x of the larger diameter portion 13 is in the neighborhood of 150 mm.
Table 2 shows the consumption efficiency of the rod target 2 when the outer diameter y of the large diameter portion 13 thereof is varied, with the length of the large diameter portion 13 set to 125 mm.
As can be seen from Table 2, the smaller the outer diameter y of the large diameter portion 13, the higher the consumption efficiency was. However, when the outer diameter y of the larger diameter portion 13 becomes below 120 mm, the consumption efficiency peaks out, and the consumable amount steeply decreases as a matter of course. After all, by setting the ratio of the effective consumed sectional area of each of the larger diameter portion 13 with respect to that of the smaller diameter portion 14 is set to 1.5 to 2.5, it was possible to maximize a consumption amount while achieving a high consumption coefficient.
When the film thickness distribution shown in
Meanwhile, in the above-described embodiment, as the rod target 2, a hollow cylindrical one was used. However, the shape of the rod target 2 is not limited to a hollow cylindrical one. A solid cylindrical shape may be used, or alternatively a hollow elliptic cylindrical shape or a solid elliptic cylindrical shape may also be adopted.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002-273880 | Sep 2002 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3400070 | Naff | Sep 1968 | A |
| 4505947 | Vukanovic et al. | Mar 1985 | A |
| Number | Date | Country |
|---|---|---|
| 0 658 634 | Jun 1995 | EP |
| 1 081 247 | Aug 2000 | EP |
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| 2000-80466 | Mar 2000 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20040055884 A1 | Mar 2004 | US |
