JP2001226763A - Sputtering target and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve joining strength at brazing between a target material and a backing plate by devising the structure of a metallic layer to be formed on the joining surface of a nonmetallic target material. SOLUTION: In joining a nonmetallic target material to a Cu or Cu-alloy backing plate by brazing by the use of an In or In-alloy brazing filler metal, a Cr film 2 as an undercoat metallic layer, a Cu film 3 as an upper metallic layer laminated on the undercoat metallic layer, and an Ag film 4 as an oxidation inhibiting film covering the Cu film are successively formed on the joining surface of an Si sheet 1 as the above target material. Then the above brazing filler metal 20 is allowed to adhere to the above Ag film 4 and the to above backing plate 10, and the target material is put upon the backing plate in a heated state to undergo joining.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target in which a nonmetallic target material such as Si is bonded to a Cu or Cu alloy backing plate, and more particularly to a bonding strength between the nonmetallic target material and the backing plate. And a method for manufacturing the same.

[0002]

2. Description of the Related Art In general, a sputtering target is constituted by joining a target material and a backing plate made of a Cu material or the like for cooling and energizing. When the target material is a non-metal such as Si, it is difficult to directly braze (or solder) to the non-metal, and it has been proposed to form a metal film on the non-metal joint surface.
For example, Japanese Patent Application Laid-Open No. 7-48667 proposes forming a thin film of any of Cu, Ni, and a Cu-Ni alloy on a bonding surface of a target material.

[0003]

The metal film formed on the joining surface of the non-metallic target material is selected according to the brazing material to be used. If Cu of the same material as that of the plate is formed as a metal film, the brazing material of In or In alloy is eroded by the brazing material during brazing (Cu is taken into In to form an alloy), and the brazing material is directly targeted. There is a problem that the bonding strength is greatly reduced due to the state of contact with the material.

[0004] Further, since the Cu film is easily oxidized, it is difficult to braze the backing plate without using a flux. However, the use of the flux becomes a problem when the flux temporarily remains on the target.

[0005] As described above, how to make the surface of a non-metallic target material in a state in which brazing with high bonding strength can be performed is an important issue in manufacturing a target.

[0006] A first object of the present invention is to solve the above problems,
An object of the present invention is to provide a sputtering target in which the structure of a metal layer formed on a bonding surface of a non-metallic target material is improved to improve the bonding strength of brazing between the target material and the backing plate, and a method of manufacturing the same.

A second object of the present invention is to provide a sputtering target and a method of manufacturing the same, which enable brazing without using flux and eliminate the disadvantages associated with the use of flux.

[0008] Other objects and novel features of the present invention will be clarified in embodiments described later.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, a non-metallic target material is used.
In a sputtering target formed by bonding to a backing plate made of Cu or Cu alloy with a brazing material of n or In alloy, a Cr film as a base metal layer on a bonding surface of the target material, an upper metal layer laminated on the base metal layer A Cu film is formed as a layer, and the brazing material is interposed and joined between the Cu film and the backing plate.

[0010] The invention of claim 2 of the present application is characterized in that, in claim 1, Ag is contained in the joint between the Cu film and the brazing material.

[0011] The invention of claim 3 of the present application provides a method in which a nonmetallic target material is made of Cu or Cu by using an In or In alloy brazing material.
In a method of manufacturing a sputtering target to be joined by brazing to an alloy backing plate, a Cr film as a base metal layer on the bonding surface of the target material, a Cu film as an upper metal layer laminated on the base metal layer, and C
After sequentially forming an Ag film as an antioxidant film covering the u film,
The present invention is characterized in that the brazing material is adhered on the Ag film and the backing plate, and the target material and the backing plate are overlapped and joined in a heated state.

According to a fourth aspect of the present invention, in the third aspect, the Cr film, the Cu film, and the Ag film are sequentially formed by a vacuum or gas phase thin film technique such as vapor deposition, sputtering, ion plating, and plasma CVD. It is characterized by being filmed.

According to a fifth aspect of the present invention, in the third or fourth aspect, the Cu film has a thickness of 1 to 5 μm,
The r film and the Ag film have a thickness smaller than the Cu film.

According to a sixth aspect of the present invention, in the third, fourth or fifth aspect, the step of adhering the brazing material on the Ag film and the backing plate is performed by ultrasonic vibration using a soldering iron with a built-in ultrasonic vibrator. Is carried out without using flux while adding to the brazing material.

The invention of claim 7 of the present application is directed to claims 3, 4, 5
Or the step of 6, wherein the step of superimposing and joining the target material and the backing plate is performed on a heated hot plate, and after joining, a pre-heated weight is placed on the hot plate and gradually cooled while applying pressure. And

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a sputtering target and a method of manufacturing the same according to the present invention will be described below with reference to the drawings.

1 (A) to 1 (D), an embodiment of the present invention will be described by taking as an example the case of manufacturing a sputtering Si target.

First, as shown in FIG. 1A, a Cr film 2 serving as a base metal layer is formed on a bonding surface of a Si plate 1 as a target material to a backing plate (Cu or Cu alloy plate for cooling and energizing). Then, a Cu film 3 as an upper metal layer laminated on the base metal layer and an Ag film 4 as an antioxidant film covering the Cu film are sequentially formed by sputtering.

Here, since the backing plate 10 shown in FIGS. 1B and 1C is Cu or an alloy thereof,
The main film forming material on the bonding surface of the Si plate 1 is Cu.

If the thickness of the Cu film 3 is less than 1 μm, I
Most of the deposited Cu material is I
It is eaten by n (it becomes an alloy of In and Cu). 5μ
If it exceeds m, it takes a long time to form a film, which is disadvantageous in cost. Therefore, the thickness of the Cu film 3 is set to 1 to 5 μm.

Further, assuming that the Cu film 3 as the main film forming material is eroded, the Cr film 2 is formed under the Cu film. It is difficult for Cr to form an alloy with In as a brazing material (although it does not mean that it is not formed at all).
There is no direct contact with n. If the In brazing material comes into direct contact with the Si plate 1, the bonding strength of brazing is greatly reduced. The thickness of the Cr film 2 is Cu
The thickness may be equal to or less than the thickness of the film 3, and is about 0.3 μm to 2 μm. If the film thickness is less than 0.3 μm, there is a risk that a portion where the film thickness becomes partially zero may occur due to variation during film formation,
If it exceeds 2 μm, it takes a long time to form a film, which is disadvantageous in cost.

Further, when the main film forming material is Cu, Cu
Is easily oxidized and produces copper oxide. Copper oxide is said to be a difficult material to handle. Not suitable for brazing because of brittleness. Furthermore, since gas is generated, the wall surface of the vacuum chamber for film formation and the surface of the substrate on which film formation is performed may be stained when used as a target. Therefore, in order to prevent oxidation of the Cu film 3, the Ag film 4 is formed immediately after the Cu film is formed. The Ag film 4 may be thin if it is uniform. Ag film 4
May be equal to or less than the thickness of the Cu film 3, and may be 0.1 μm to 2 μm.
It is about μm. If the film thickness is less than 0.1 μm, there is a risk that a portion where the film thickness becomes zero may partially occur due to variation during film formation.
It is disadvantageous in terms of cost. Ag easily forms an alloy with In, which is said to be suitable as a brazing filler metal.

The Cr film 2, the Cu film 3 thereon, and the Ag film 4 thereon are sequentially formed by sputtering in the same film forming chamber in order to prevent generation of useless oxides. preferable.

As shown in FIG. 1A, when a multilayer metal layer 5 of a Cr film, a Cu film, and an Ag film is formed on the bonding surface of a Si plate 1 as a target material, as shown in FIG. A Si plate 1 is placed on a hot plate (electric heating type) 30 with its bonding surface facing up, and a Cu or Cu alloy plate backing plate 1
0 is also placed with the bonding surface up, and the hot plate 30 is
The temperature is raised to 80 to 250 ° C., and the Si plate 1 and the backing plate 10 are heated and heated. In this state, the wetting operation for bonding using In as the brazing material 20, that is, the operation of attaching the brazing material 20 to the bonding surface of the Si plate 1 and the bonding surface of the backing plate 10 is performed by a soldering iron with a built-in ultrasonic vibrator. At 35, the ultrasonic vibration is applied to the brazing material 20 without using any flux.

After the wetting work of the brazing material 20 shown in FIG. 1 (B) is completed, the heating surface is continuously heated and heated on the hot plate 30 while the joining surface (In wetting surface) of the backing plate 10 is formed as shown in FIG. 1 (C). ) And the bonding surface (In wetting surface) of the Si plate 1 are opposed to each other and brought into close contact with each other.
i-plate 1 is superimposed on the structure, and 400-2
Place a weight 40 of 000 g. At this time, the weight 40 used in advance is heated to 100 to 200 ° C. Weight 40
Is placed, the power of the hot plate 30 is turned off, and the hot plate 30 is gradually cooled (slowly cooled by natural cooling). Thus, as shown in FIG. 1D, the Si plate 1 as the target material and the backing plate 10
Thus, a sputtering target joined and integrated with the brazing material 20 is completed. After the bonding, since the Ag film 4 is a thin film, the Ag film 4 dissolves in the In brazing material 20 and does not remain as a film. It can be confirmed that the Ag film 4 was present before the bonding.

FIG. 2 shows the linear expansion coefficients of Si, Cr, Cu, Ag and In. The coefficient of linear expansion is Si <Cr <Cu <A
The relationship becomes gradually larger from Si to In as g <In, and the difference in linear expansion coefficient between Si of the target material and In of the brazing material is reduced by the interposition of the metal layers of Cr, Cu, and Ag. Can be relaxed. This also allows Cr, Cu, Ag
It can be understood that the three-layered film formation structure is suitable as an intermediate material between Si and In.

The following Table 1 shows the results of a bonding experiment of three-layer film formation and Cu-Ag two-layer film formation.

[0028]

[Table 1] Here, an ultrasonic flaw detector was used for the measurement. Experiment No.
1 and 2 are cases where the Cr film 2 of the base metal layer is omitted,
The results of ultrasonic flaw detection were 90% and 87%, indicating that there was a part where bonding was insufficient. Note that the experiment No. 2 indicates the average value with the number of samples n = 2. Experiment No. Each of 3 to 7 is the case of the three-layer film formation according to the embodiment, and the result of the ultrasonic flaw detection is 100%, which indicates a state without any flaw. Note that the experiment No. 7 shows the average value with the number of samples n = 6. As in this embodiment, three metal layers (C
It can be seen that by providing (r, Cu, Ag), very good joining by brazing can be obtained.

According to this embodiment, the following effects can be obtained.

(1) Since the backing plate 10 is made of Cu or a Cu alloy material, the main film forming material on the bonding surface of the Si plate 1 as the target material was Cu. By making Cu to Cu, bonding is easy and strong bonding strength is obtained.

(2) Assuming the erosion of Cu, the Cu film 3
The Cr film 2 is formed on the underlayer. It is difficult for Cr to form an alloy with In as the brazing material 20, and even in a thin Cr film,
Is no longer in direct contact with In, and Si is directly in contact with In, which can prevent a significant decrease in bonding strength.

(3) Cu is easily oxidized and copper oxide is formed. However, by forming an Ag film 4 on the Cu film 3, the Cu film 3
Can be prevented, and joining by brazing can be facilitated. Since Ag easily forms an alloy with In, the presence of the Ag film 4 makes the brazing by In easier,
And can be assured.

(4) As shown in FIG. 2, the linear expansion coefficient is
Si <Cr <Cu <Ag <In, the relationship gradually increases from Si to In as shown in FIG.
The interposition of r, Cu, and Ag can reduce the difference in linear expansion coefficient between Si and In. This also allows Cr, Cu,
It can be seen that the three-layer Ag film structure is suitable as an intermediate material between Si and In.

(5) When wetting work for bonding using In as the brazing material 20, that is, the work of attaching the brazing material 20 to the bonding surface of the Si plate 1 and the bonding surface of the backing plate 10, ultrasonic vibration By using the soldering iron 35 with built-in solder while applying ultrasonic vibration to the brazing material 20, it is possible to avoid using flux. As a result, it is possible to avoid problems associated with the use of the flux, for example, that the flux remains and evaporates during use as a target.

(6) Backing plate 1 during brazing
Weight 4 for pressurizing a structure in which 0 and Si plate 1 are overlapped
By using a temperature that has been previously raised to 100 to 200 ° C. as 0, the cooling rate of the target material and the backing plate 10 is moderated, and the reliability of joining by brazing can be further improved. At normal temperature, the weight 40 is rapidly cooled, and there is a danger that the brazing material will be damaged during joining.

In the above-described embodiment, Si is exemplified as the nonmetallic target material. However, the present invention can be applied to ceramic materials other than Si. The brazing material is In.
However, an In alloy mainly containing In may be used. Furthermore, although a Cr film, a Cu film, and an Ag film are provided by sputtering, they can be formed by a thin film technique in vacuum or gas phase such as vapor deposition, ion plating, and plasma CVD other than sputtering.

Although the embodiments of the present invention have been described above, it is obvious to those skilled in the art that the present invention is not limited to the embodiments and that various modifications and changes can be made within the scope of the claims. There will be.

[0038]

As described above, according to the present invention,
By devising the structure of the metal layer formed on the bonding surface of the non-metal target material, it is possible to improve the bonding strength of brazing between the target material and the backing plate.

In the manufacturing process, the step of attaching the brazing material to the target material and the backing plate is
If the ultrasonic vibration is applied to the brazing material using a soldering iron with a built-in ultrasonic vibrator, the brazing process can be performed without using the flux, and the inconvenience associated with the use of the flux can be eliminated.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a sputtering target and a method of manufacturing the same according to the present invention in the order of steps.

FIG. 2 is an explanatory diagram showing a linear expansion coefficient of a target material, a brazing material, and a metal layer interposed therebetween.

[Explanation of symbols]

 Reference Signs List 1 Si plate 2 Cr film 3 Cu film 4 Ag film 10 Backing plate 20 Brazing material 30 Hot plate 35 Solder iron with built-in ultrasonic vibrator 40 Weight

Claims (7)

[Claims] 1. A sputtering target in which a nonmetallic target material is joined to a backing plate made of Cu or Cu alloy with a brazing material of In or an In alloy, and a Cr film as a base metal layer on a joining surface of the target material. ,
A sputtering target, wherein a Cu film is formed as an upper metal layer laminated on the base metal layer, and the brazing material is interposed and bonded between the Cu film and the backing plate. 2. A joint is formed between the Cu film and the brazing material.
The sputtering target according to claim 1, wherein g is contained. 3. A method of manufacturing a sputtering target in which a nonmetallic target material is joined to a Cu or Cu alloy backing plate by brazing using a brazing material of In or an In alloy. Cr film as a base metal layer,
After sequentially forming a Cu film as an upper metal layer laminated on the base metal layer and further an Ag film as an antioxidant film covering the Cu film, the brazing material is adhered on the Ag film and the backing plate. Wherein the target material and the backing plate are overlapped and joined in a heated state. 4. The method according to claim 1, wherein the Cr film, the Cu film and the Ag film are deposited.
Sputtering, ion plating, plasma CV
4. The method for manufacturing a sputtering target according to claim 3, wherein the film is sequentially formed by a thin film technique in a vacuum or gas phase such as D. 5. The Cu film has a thickness of 1 to 5 μm,
5. The method for manufacturing a sputtering target according to claim 3, wherein the Cr film and the Ag film have a thickness less than the Cu film. 6. The step of adhering the brazing material on the Ag film and the backing plate is performed without using flux while applying ultrasonic vibration to the brazing material using a soldering iron with a built-in ultrasonic vibrator. 6. The method for producing a sputtering target according to 3, 4, or 5. 7. The step of superimposing and joining the target material and the backing plate on a heated hot plate, and after joining, gradually cooling while placing a pre-heated weight and applying pressure. 7. The method for producing a sputtering target according to 3, 4, 5 or 6.