JP2001140064A - Target joined body for sputtering and producing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the warpage of a joined body of a target material for sputtering and a backing plate material at the time of joining both materials, moreover to reduce the residual strain of the joined body generated by the application of mechanical stress to the joined body and to obtain the same joined body. SOLUTION: A joined body in which a brazing filler metal is interposed between a target material and a plate material is heated, thereafter, at the time of its cooling, the amount of warpage generated along with the cooling is discontinuously measured, and each time, reverse warpage offsetting the generated warpage is applied thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a target assembly for sputtering in which a brazing material is interposed between a target material for forming a thin film on a substrate by sputtering and a backing plate material, and a method of manufacturing the same. is there.

[0002]

2. Description of the Related Art A target material for sputtering (hereinafter, referred to as "target material").
When joining a backing plate material (hereinafter, referred to as a plate material) that plays a role of mechanically reinforcing the target material with a backing plate material, the conventional technology for suppressing the warpage of the joined body of the two materials can be roughly classified. There are two types as follows. That is, a method of reducing the occurrence of warpage occurring in a joined body of a target material and a plate material (hereinafter, referred to as a joined body) and omitting the warpage correction itself, and a method of reducing the warpage occurring in the joined body by efficient straightening It is.

The former method is disclosed in, for example,
As disclosed in Japanese Patent No. 62462, there is a structure in which a graphite sub-backing plate is interposed between a target material and a plate material, and the sub-backing plate is clamped to prevent warpage of the joined body. Further, Japanese Patent Application Laid-Open No. 1-262088 discloses a method for preventing warping of a joined body by heating a target material and a plate material in accordance with a shrinkage ratio. Further, Japanese Unexamined Patent Application Publication No.
No. 11759 discloses a method for preventing warpage of a joined body by using a jig for restraining a plate material when heating and cooling the target material and the plate material. In addition, in JP-A-5-25620,
Pre-treatment of plating or vapor deposition is performed on the bonding surface of the target material, and a buffer material is inserted between the target material and the plate material to prevent warpage of the bonded body. In any of these methods, the warpage caused by the difference in the coefficient of thermal expansion when the target material and the plate material are joined and cooled is prevented by taking measures to offset the coefficient of thermal expansion with respect to the ordinary joining method. is there.

[0004] On the other hand, as the latter method, for example, as disclosed in Japanese Patent Application Laid-Open No. 5-214518, a method in which a joined body is heated to just below the melting point of a high melting point brazing material and cooled to enable correction. It has been disclosed. Further, Japanese Patent No. 2573653 discloses a method for efficiently correcting a warp by giving a reverse warp in a direction opposite to a direction of a warp generated in a joined body from a difference in a coefficient of thermal expansion in a cooling process in accordance with a warp amount. ing. These methods are methods for reducing the warpage caused by the difference in the coefficient of thermal expansion between the target material and the plate material by performing an efficient correction.

[0005]

The above prior art has the following problems. That is, JP-A-64-6
As described in Japanese Patent Application Laid-Open No. 2462 and JP-A-5-25620, the method of using a cushioning material between a target material and a plate material increases the thickness of the joined body due to the use of the cushioning material, and restricts the dimensional design of the joined body. In addition, the joining operation is complicated because the joining is performed twice. Also, in the case of Japanese Patent Application Laid-Open No. 1-262088, it is stated that heating is performed in accordance with the contraction rate of the target material and the plate material. It is also necessary to consider the shrinkage of the brazing material, which has an important effect on the application, and it is often difficult to apply. further,
In the case of JP-A-2-11759, a jig for restraining a plate material to which a target material is joined is used. Usually, a screw hole for fixing the plate material to a sputtering device to restrain the plate material and the jig is used. It is necessary to prepare a jig suitable for the plate material for use each time, so that there is a disadvantage that the manufacturing cost is significantly increased.

In addition, JP-A-5-214518 can be applied to a high melting point brazing material, but is difficult to apply to a low melting point brazing material generally used when joining a target material and a plate material. There is. Patent 257
With respect to No. 3653, the amount of warpage generated in the joined body must be predicted with a required accuracy from the difference in the coefficient of thermal expansion during the cooling process, and a predetermined warp correction cannot be performed. In addition, the amount of warpage when cooling after heating for joining is extremely large at 3 mm, so that the mechanical stress of the reverse warp for correcting the warp needs to be large, and therefore, the residual strain generated in the joined body is reduced. There are major drawbacks.

Therefore, in the present invention, when the sputtering target material and the backing plate material are joined, the warpage of the joined body of the two members is suppressed, and further, a mechanical stress is applied to the joined body, so that the joined body is formed. It is an object to reduce generated residual strain and to obtain such a joined body.

[0008]

SUMMARY OF THE INVENTION In the joined body of a target material and a plate material according to the present invention, after the joined body having a brazing material interposed between the target material and the plate material is heated, the cooling occurs when cooling. The amount of warpage is measured intermittently, and in each case, the warpage is suppressed by applying a reverse warp that cancels out the generated warpage, and furthermore, the residual generated in the bonded body by applying a mechanical stress of the reverse warp to the bonded body A target material and a plate material with reduced distortion are formed.

Immediately after the brazing material is joined between the target material and the plate material, the temperature difference from the melting point of the brazing material is small, and the warpage generated in the joined body is small. That is, the warpage of the joined body is such that the target material and the plate material are physically joined,
This is because the amount of warpage is caused by the difference in the amount of thermal expansion between the two. Therefore, it is not necessary to apply a reverse warp to the joined body at this time, but it is better to hold the joined body with mechanical stress so that the joined body is horizontal so as to suppress the warp occurring in the joined body thereafter. . At this time, applying a reverse warp
It should not be performed because it is not effective because no warpage has occurred and to give unnecessary strain to the joined body in order to apply mechanical stress to the joined body.

After temporarily holding the joined body so as to be horizontal, the joined body is warped. At that time, measure the amount of warpage that occurred by releasing the mechanical stress that held the joined body so that it was horizontal, and apply mechanical stress so that reverse warpage that offsets the amount of warpage was applied . In this case, it is conceivable to apply a reverse warpage larger or smaller than the generated warpage amount.

When a larger amount of warpage is applied than the amount of warpage generated, the amount of warpage generated thereafter can be reduced. However, since a mechanical stress more than necessary is applied to the joined body, a strain corresponding to the stress is reduced. If the target material is subjected to a strain larger than the allowable strain of the target material, the target material may be broken. In particular, in the case of a ceramic target material, the allowable distortion is small and attention is required.

Also, when a reverse warpage amount smaller than the generated warpage amount is applied, the mechanical strain applied to the target material and the plate material becomes smaller than when a counteracting reverse warpage amount is applied, and the tolerance is particularly large. Although the possibility that the target material having a small distortion exceeds the limit and causes the breakage is reduced, there is a possibility that the correction amount of the warpage becomes small and the desired warpage amount cannot be finally obtained.

Further, after a lapse of time, a larger warp occurs in the joined body. Also in this case, after releasing the mechanical stress applied to the joined body, measure the amount of warpage of the joined body,
A mechanical stress is applied so that a reverse warp that offsets the warpage is applied. Also in this case, when a large or small amount of reverse warpage is applied to the canceling reverse warpage, the same result as when the same reverse warpage is applied immediately after joining is produced. However, in this case, since a relatively large warpage occurs immediately after joining, when a reverse warp larger than the amount of warpage offsetting the generated warpage is applied, a larger distortion is generated in the target material, and When a reverse warpage smaller than the warpage offsetting the generated warpage is applied, there is a possibility that the final warpage of the joined body increases. Thereafter, the same operation is intermittently repeated as necessary, and finally, the joined body is cooled until it reaches room temperature.

As described above, in the joined body of the target material and the plate material according to the present invention, after the joined body with the brazing material interposed between the target material and the plate material is heated, the warpage generated upon cooling is accompanied by cooling. The amount is measured intermittently, and in each case, the warpage is suppressed by applying a reverse warp that cancels out the generated warpage, and the residual strain generated in the bonded body by applying a mechanical stress of the reverse warp to the bonded body Thus, a sputtering target joined body having a reduced value is formed.

[0015]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the state of the joined body immediately after joining. As described above, the bonded body hardly warps. FIG. 2 shows the state of the joined body after the joined body has been temporarily cooled. The temperature at which the target material and plate material are joined,
That is, since the temperature difference from the melting point of the brazing material is not large, the warpage of the joined body is not large. FIG. 3 shows the state of the joined body after cooling the joined body for a considerable time. Since the difference between the joining temperature of the target material and the joining temperature of the plate material is large, the amount of warpage of the joined body increases. Therefore, the amount of reverse warpage that offsets the amount of warpage also increases. FIG. 4 shows a situation where a reverse warp is applied to offset the warp amount. FIG. 5 shows the situation of the finally obtained joined body. By repeating the manufacturing operation according to the present invention, a joined body having a small amount of warpage and a small residual strain can be obtained.

In the present invention, the target material can be nickel, cobalt or another metal, or alumina, silica, carbon, silicon or other ceramics, and the plate material can be oxygen-free copper, stainless steel or other metals. As the brazing material, metals such as tin, indium, and tin-lead solder, and alloys of the metals, or resins such as a thermosetting resin and a conductive resin can be used.

[0017]

[Example] 125 mm x 425 mm as target material
X5 mmt alumina, oxygen-free copper having the same shape as the target material as the plate material, and tin-lead solder as the brazing material were used. The target material and the plate material are previously heated by a heater. A eutectic alloy is usually used for the tin-lead solder, and its melting point is 183 ° C. Therefore, the tin-lead solder can be melted on the target material or the plate material by heating the target material and the plate material to the melting point or higher. After a suitable amount of tin-lead solder is melted on the target material, the plate material is placed and heating is stopped, and after a certain period of time, the brazing material reaches the melting point or below and solidifies, and the target material and the plate material adhere to each other. Become. A fulcrum is placed horizontally at both ends of the lower surface of the joined body to hold the joined body. When not much time has passed since the tin-lead solder has solidified, the joined body is substantially horizontal. In this state, the entire joined body is held by holding the press on the upper surface of the target material from above.

When 10 minutes have passed in this state, the amount of warpage has reached 0.2 mm. Therefore, after measuring the amount of warpage, a reverse warp of 0.2 mm was applied by a press on the upper surface of the target material. Furthermore, when the amount of warpage was measured after elapse of 5 minutes, the warpage reached 0.3 mm. Therefore, a reverse warp of 0.3 mm was applied by using a press. Further, when the amount of warpage was measured after elapse of 5 minutes, the warpage reached 0.4 mm. Therefore, a reverse warp of 0.4 mm was applied by using a press. Ten minutes later, when the warpage was measured, the amount of warpage was 0.2 mm. Thus, the step of applying the reverse warp is completed. As described above, in the present invention, the amount of warpage generated in the process of cooling the joined body is extremely smaller than the amount of warpage disclosed in Japanese Patent No. 2573653. Therefore, since the amount of reverse warpage necessary for correcting the warp is small, the distortion remaining in the joined body is extremely small.

Next, the joined body was mounted on a mounting portion of a magnetron sputtering apparatus and sputtered. Output 6K
W was sputtered at a sputter rate of 30 ° / sec and 300 KWH, but no abnormality was observed in the alumina target material.

[0020]

[Comparative example] A target, a backing plate, and a brazing filler metal were used with the same material and dimensions as those of the embodiment, and a joined body was manufactured by the same manufacturing method as that of the embodiment. The amount was 3 mm, which was an extremely large amount of warpage. After applying a reverse warp of 3 mm to the joined body once using the same press as in the example, the warpage was measured, and the amount of warp was 0.5 mm. Next, the joined body was sputtered under the same sputtering apparatus and under the same sputtering conditions as those of the example. As a result, several cracks were observed in the alumina target due to thermal distortion caused by sputtering. This result is considered to be due to the fact that this joint has a larger strain remaining in the joint than the joint according to the present invention.

[0021]

Since the present invention has been described above, it has the following effects. In the joined body of the present invention, the amount of warpage finally generated can be reduced. In addition, since the mechanical stress required to correct the warp is small and the residual strain applied to the joined body is small, the target material is not broken at the time of manufacturing the joined body. Furthermore, since the stress applied to the joined body is small, the strain remaining in the joined body is also small, and the possibility that the target material will be broken even if thermal strain added to the surface of the target material due to heating during sputtering is reduced. Become.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state of a joined body immediately after joining.

FIG. 2 is a view showing a state of the joined body after the joined body has been temporarily cooled.

FIG. 3 is a view showing a state of the joined body after the joined body has been cooled for a considerable time.

FIG. 4 is a diagram illustrating a situation in which a reverse warpage is applied to cancel the warpage amount generated in FIG. 3;

FIG. 5 is a view showing a situation of a finally obtained joined body.

[Explanation of symbols]

 1. 1. Target material Plate material 3. Brazing material

Claims (2)

[Claims] 1. After heating a joined body between a target material of a sputtering target and a backing plate material with a brazing material interposed therebetween, when cooling, intermittently measuring the warpage generated with cooling, the warpage generated each time is measured. A sputtering method characterized by suppressing the warpage of the joined body of both materials by adding a reverse warp that cancels out and reducing the residual strain of the joined body caused by applying the mechanical stress of the reverse warp to the joined body. Target zygote. 2. After heating a joined body between a target material of a sputtering target and a backing plate material with a brazing material interposed therebetween, when cooling, the warpage generated with cooling is intermittently measured, and the warpage generated each time is measured. For the sputtering, characterized in that the warpage of the joined body of both materials is suppressed by adding a reverse warp that cancels, and the residual strain of the joined body generated by applying the mechanical stress of the reverse warp to the joined body is reduced. A method for manufacturing a target joined body.