JP5656995B2 - Sputtering target and manufacturing method thereof - Google Patents

Description

  The present invention relates to a sputtering target that is economical and suitable for recycling, and a method for manufacturing the sputtering target.

  In general, a sputtering target has a limited region (erosion region) that is consumed by the sputtering effect of ions. For this reason, the use efficiency of a sputtering target is as low as about 30%, for example. Thus, various techniques for economically manufacturing a target by using a used sputtering target have been proposed. For example, in Patent Document 1 below, there is a method in which a solid block formed of a used sputtering target is filled so as to be covered with a powder having substantially the same composition as the solid block, and is sintered by a hot isostatic press. Have been described.

  On the other hand, Patent Document 2 described below describes a method of manufacturing a large sputtering target by arranging a plurality of plate-like target constituent members in the same plane and mutually friction stir welding.

JP 2001-342562 A JP 2005-15915 A

  In general, since a sputtering target generally stably forms a high-quality thin film, high uniformity in material structure is required on the target surface sputtered by ions. However, in the sputtering target manufacturing methods described in Patent Document 1 and Patent Document 2, the presence of a solid block or a joint portion of a target constituent member is inevitable on the target surface. For this reason, there is a concern that the joint portion may cause generation of particles or abnormal discharge during sputtering, and there is a possibility that a high-quality thin film cannot be stably formed.

  In view of the circumstances as described above, an object of the present invention is to provide a sputtering target which is excellent in economic efficiency and can stably form a high-quality thin film and a method for producing the same.

In order to achieve the above object, a sputtering target according to one embodiment of the present invention includes a first target portion and a second target portion.
The first target portion forms an erosion region.
The second target portion has a first region covered with the first target portion and a second region forming a non-erosion region. The second target portion is integrated with the first target portion by friction stir welding.

The manufacturing method of the sputtering target which concerns on one form of this invention includes the process of forming an opening part in the erosion area | region of the target surface.
The opening is filled with a target material to be sputtered.
The target material and the non-erosion region of the target are integrated by friction stir welding.

It is a schematic perspective view of the sputtering target which concerns on one Embodiment of this invention. It is a schematic sectional drawing of each process explaining the manufacturing method of the sputtering target which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the used sputtering target explaining the reproduction | regeneration method of a sputtering target.

The sputtering target which concerns on one Embodiment of this invention comprises a 1st target part and a 2nd target part.
The first target portion forms an erosion region.
The second target portion has a first region covered with the first target portion and a second region forming a non-erosion region. The second target portion is integrated with the first target portion by friction stir welding.

  In the above sputtering target, since the boundary region between the first target portion and the second target portion does not exist in the erosion region, it is possible to suppress the generation of particles and abnormal discharge and to perform stable sputter deposition. In addition, since the first target portion and the second target portion are integrated by friction stir welding, it is possible to realize material organization integration between both target portions, and the appearance of the target surface is impaired. It will never be. Furthermore, since only the erosion region can be selectively regenerated, the utilization efficiency of the target material can be improved, and the recycling effect of the sputtering target is enhanced by continuing to use the second target portion in common. be able to.

  Here, the “erosion region” includes both a region that is still flat and eroded during use, and a concavo-convex region that is actually eroded by use, before and after using the sputtering target.

The first target portion and the second target portion may be formed of the same target material or different target materials.
When both target parts are formed of the same kind of target material, a good bonded state of both target parts can be easily obtained. On the other hand, when both target parts are formed of different target materials, the second target part that does not contribute to film formation is manufactured at a lower cost in terms of material or process than the first target part. Can do.

When both target parts are formed of the same kind of material, the first target part may be formed of a material having a higher purity than the second target part.
As a result, the second target portion can be manufactured at a relatively low cost while ensuring the required high-quality thin film formation.

  The first target portion may be crystal tempered. Thereby, quality improvement of the thin film formed can be achieved. The tempering of the first target portion can be realized at the same time in the friction stir welding process with the second target portion, and by optimizing the stirring conditions, the fine and uniform crystal structure required for the erosion region The first target portion can be tempered.

The manufacturing method of the sputtering target which concerns on one Embodiment of this invention includes the process of forming an opening part in the erosion area | region of the target surface.
The opening is filled with a target material to be sputtered.
The target material and the non-erosion region of the target are integrated by friction stir welding.

  In the manufacturing method, after filling the erosion region of the target with the target material, the target material and the non-erosion region of the target are integrated by friction stir welding to manufacture the sputtering target. Therefore, since only the erosion region can be selectively regenerated, the utilization efficiency of the target material can be improved, and the recycling effect of the sputtering target is enhanced by continuing to use the second target portion in common. be able to. In addition, since there is no boundary region between the first target portion and the second target portion in the erosion region, it is possible to suppress the generation of particles and abnormal discharge and perform stable sputter deposition.

The step of forming the opening may include a step of removing an erosion region on the target surface.
Thereby, the collected used sputtering target can be easily regenerated. Further, the recycling of the sputtering target can be promoted.

In the step of friction stir welding the target material and the non-erosion region, the entire filling region of the target material including the boundary between the target material and the non-erosion region may be friction stir.
Thereby, the material structure of the target material in the erosion region can be made uniform, stable discharge during sputtering can be realized, and a high-quality thin film can be formed. Further, by optimizing the stirring conditions, the crystal structure of the target material can be tempered simultaneously during bonding.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an external perspective view schematically showing a sputtering target according to an embodiment of the present invention. The sputtering target 10 of the present embodiment is formed in a square or rectangular plate shape, but is not limited to the illustrated rectangular shape, and may be formed in other shapes such as a circle, an oval, an ellipse, and the like.

  The sputtering target 10 has a front surface 11 a that forms a surface to be sputtered and a back surface 11 b that is bonded to the backing plate 20. The surface 11a to be sputtered is sputtered by ions in plasma of a process gas formed in a vacuum chamber (not shown). The backing plate 20 is formed of a metal plate having an appropriate shape for connecting the sputtering target 10 to a sputtering cathode (not shown) and holding the sputtering target 10 in a vacuum chamber. A cooling water circulation path is formed inside the backing plate 20 to suppress heat generation of the sputtering target 10 due to the sputtering action. The sputtering target 10 and the backing plate 20 may be integrally handled as a target assembly.

  The surface 11 a of the sputtering target 10 has an erosion region 12 and a non-erosion region 13. The erosion region 12 means a region where the target surface is eroded by the sputtering effect of ions, and the non-erosion region 13 means a region that is less likely to be eroded than the erosion region 12. In some cases, there is no clear boundary between the erosion region 12 and the non-erosion region 13, but here, the main erosion region is referred to as an erosion region. In this embodiment, the “erosion region” includes both a region that is still flat and is eroded during use, and a concavo-convex region that is actually eroded by use, before and after using the sputtering target. It is.

  The erosion region 12 has a different shape depending on the specifications of the sputtering apparatus. In the present embodiment, the erosion region 12 is formed in an annular shape on the target surface 11a. The erosion region 12 having such a shape is often found in a sputtering target for a magnetron type sputtering apparatus. In this case, the size, shape, and the like of the erosion region 12 are often determined by the arrangement form of the magnet unit (not shown) arranged on the back side of the backing plate 20. In the example shown in the figure, magnets are arranged at the central part and the peripheral part of the sputtering target 10, respectively, and high-density plasma is formed in an annular shape by a magnetic field formed between these magnets, so that the erosion of the form shown in the figure. Region 12 is formed. In the illustrated example, the outer peripheral side and inner peripheral side corner portions of the erosion region 12 are drawn at substantially right angles. However, the present invention is not limited to this, and each corner portion may have a rounded curved shape. Good.

  The sputtering target 10 according to the present embodiment is formed of a joined body of a first target portion that forms the erosion region 12 and a second target portion that forms the non-erosion region 13. 2A to 2C are schematic cross-sectional views of main steps for explaining a method for manufacturing the sputtering target 10.

  First, as shown in FIG. 2A, a second target portion 130 having an annular opening 131 formed on the surface is manufactured. The opening 131 is formed in an erosion region on the surface of the second target unit 130, and forms a region (first region) covered with the second target unit 120 as described later. The second target portion 130 may be formed simultaneously with the opening 131 by molding, or the opening 131 may be formed in a separate process after the plate material is formed.

  The opening 131 is formed with a depth smaller than the thickness of the second target portion 130. In the example shown in the figure, the opening 131 is formed to have a rectangular cross section. However, the present invention is not limited to this. For example, the opening 131 may have a curved surface with a curved bottom. The surface region (second region) of the target unit 130 where the opening 131 is not formed forms the non-erosion region 13.

  Next, as illustrated in FIG. 2B, the first target portion 120 is filled into the opening 131. The first target portion 120 is configured by an annular block body that is formed in advance corresponding to the shape of the opening 131, and is fitted into the opening 131. The first target portion 120 has a thickness equal to or greater than the depth of the opening 131, and the surface thereof is flattened so as to align with the surface of the second target portion 130 as necessary.

  Subsequently, as shown in FIG. 2C, the first target unit 120 and the second target unit 130 are joined and integrated. In the present embodiment, a friction stir welding (FSW) method is employed as a joining method. Friction stir welding refers to the materials to be joined while softening and stirring the materials to be joined by frictional heat and processing heat generated between the rotary tool 100 and the materials to be joined (first and second target portions 120 and 130). Is a technology for solid phase bonding. The rotary tool 100 has a rotor 101 that enters each of the target portions 120 and 130 at the tip portion, and moves the target portions 120 and 130 to each other by moving in the direction of the arrow while rotating the rotor 101. To join.

  The rotor 101 of the rotary tool 100 has a length dimension that is greater than the depth of the opening 131 (the thickness of the first target portion 120), and the tip of the rotor 101 is located at the bottom of the opening 131. Can penetrate even deeper. The rotary tool 100 is moved so as to scan the non-erosion region near the boundary between the first target unit 120 and the second target unit 130 and the entire erosion region including the boundary. As a result, as shown in FIG. 2D, the sputtering target 10 having the joint J formed by the rotary tool 100 is manufactured. After the bonding step, a planarization process of the surface 11a of the sputtering target 10 may be performed as necessary.

  In the sputtering target 10 manufactured as described above, as shown in FIG. 2D, the surface region on the joint J is an erosion region 12, and the vicinity of the boundary region of the joint J and the non-bonding of the joint J are formed. The formation region is a non-erosion region 13. That is, the main region of the joint portion J is constituted by the first target portion 120, and the vicinity of the boundary region of the joint portion J is a mixed region of both target portions 120 and 130.

  In the sputtering target 10 of the present embodiment, since the boundary region between the first target unit 120 and the second target unit 130 does not exist in the erosion region 12, the generation of particles and abnormal discharge during use is suppressed and stabilized. Sputter deposition is possible.

  In addition, since the first target unit 120 and the second target unit 130 are integrated by friction stir welding, the material organization integration between the target units 120 and 130 can be realized. The appearance of the surface is not impaired.

  Furthermore, since only the erosion region 12 can be selectively reproduced, the utilization efficiency of the target material can be improved. Moreover, the recycling effect of the sputtering target 10 can be improved by using the second target unit 130 in common.

  The first target portion 120 and the second target portion 130 may be formed of the same target material or different target materials. As the target material, various metal materials such as Al, Cu, Ag, Au, Cr, Ta, Mo, Ti, and Nb, and alloys or compounds thereof can be used. In particular, metals having a relatively low softening temperature, such as Al, Cu, Ag, Au, etc., have the advantage that friction stir welding is easy.

  When the first and second target portions 120 and 130 are each formed of the same type of target material, it is possible to easily obtain a good bonding state between the target portions 120 and 130.

  In this case, the first target unit 120 may be formed of a material having a higher purity than the second target unit 130. For example, a material with a purity of 5N or more (99.999% or more) is used for the target material of the first target unit 120, and a material with a purity of 4N or less is used for the target material of the second target unit 130. . As a result, the second target portion can be manufactured at a relatively low cost while ensuring the required high-quality thin film formation.

  On the other hand, when the first and second target portions 120 and 130 are formed of different target materials, the second target portion 130 that does not contribute to film formation is compared with the first target portion 120 as a material. Alternatively, it can be manufactured at a low cost in terms of process.

  Furthermore, simultaneously with the bonding process of the first target unit 120 and the second target unit 130, the first target unit 120 can be crystal-refined by the friction stir action. Thereby, quality improvement of the thin film formed can be achieved. In particular, in the present embodiment, the entire filling region of the first target portion 120 is frictionally agitated, so that the material structure of the target material in the erosion region 12 is made uniform, and stable discharge at the time of sputtering is realized. A high-quality thin film can be formed. Further, by optimizing the stirring conditions, the crystal structure of the target material can be tempered simultaneously during bonding.

  The tempering of the first target portion 120 can be realized at the same time in the friction stir welding process with the second target portion. By optimizing the stirring conditions, fine and uniform crystals required for the erosion region are obtained. The organization can temper the first target portion. For example, by setting the shaft diameter of the rotor 101 to 20 mm, the rotation speed to 1500 rpm, and the movement speed to 0.008 m / s, the first target portion 120 made of Al material can be conditioned to an average crystal grain size of 60 μm. it can.

  And according to this embodiment, a sputtering target can be manufactured using the material crystal-controlled with high precision only to the area | region which contributes to film-forming substantially. Thereby, compared with the conventional sputtering target manufactured so that the whole target may become an equivalent crystal state, material cost can be reduced significantly.

  Moreover, according to the said sputtering target manufacturing method, there exists an advantage that a used sputtering target can be reproduced | regenerated easily. For example, FIG. 3 shows an example of a used sputtering target 1. In the illustrated sputtering target 1, the erosion region 12 is eroded in a convex shape. In the present embodiment, such a used sputtering target 1 can be regenerated through the steps described above.

  That is, by removing the erosion region of the sputtering target 1 shown in FIG. 3, an opening 131 (FIG. 2A) is formed on the target surface. For forming the opening 131, machining using a drilling machine, fusing using laser light, chemical etching using a chemical solution, or the like can be used. Prior to the formation of the opening 131, a grinding process may be performed for the purpose of flattening the target surface.

  After the opening 131 is formed, the target material filling step and the friction stir welding step described with reference to FIGS. 2B and 2C are performed, as shown in FIGS. 1 and 2D. The sputtering target 10 having the configuration can be manufactured.

  As described above, according to this embodiment, since the sputtering target can be easily reused, the economy can be improved. In addition, since a target material whose crystal is controlled with high precision is used only in the erosion region, it is possible to achieve a significant reduction in material cost while ensuring high-quality thin film formation.

  The embodiment of the present invention has been described above, but the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.

  For example, in the above embodiment, the example in which the sputtering target 10 and the backing plate 20 are configured as separate members has been described. However, the present invention is not limited to this, and the present invention can also be applied to a sputtering target integrated with the backing plate. .

  Moreover, the 1st target part 120 and the 2nd target part 130 are not restricted to the example formed with a casting, and may be formed with the sintered compact of sputtering material powder.

DESCRIPTION OF SYMBOLS 1 ... Used sputtering target 10 ... Sputtering target 12 ... Erosion area | region 13 ... Non-erosion area | region 20 ... Backing plate 100 ... Rotating tool 101 ... Rotor 120 ... 1st target part 130 ... 2nd target part 131 ... Opening part

Claims (7)

A first target portion forming an erosion region;
A second target having a first region covered with the first target portion and a second region forming a non-erosion region and integrated with the first target portion by friction stir welding ; and a part,
A sputtering target in which the entire region of the first target portion including the boundary portion between the first target portion and the second target portion is frictionally stirred by the friction stir welding . The sputtering target according to claim 1,
The first target portion is crystal tempered by the friction stir welding sputtering target. The sputtering target according to claim 2,
The erosion region is annular;
The friction stir welding is scanned radially with respect to the annular erosion region
Sputtering target. Forming an opening in the erosion region of the target surface,
Filling the opening with a target material to be sputtered;
The target material and the non -erosion region of the target are integrated by friction stir welding that frictionally stirs the entire filling region of the target material including the boundary between the target material and the non-erosion region . Production method. It is a manufacturing method of the sputtering target of Claim 4, Comprising:
Crystal tempering the target material by the friction stir welding
A method for producing a sputtering target. It is a manufacturing method of the sputtering target according to claim 4 or 5,
The step of forming the opening includes a step of removing an erosion region on the surface of the target. It is a manufacturing method of the sputtering target as described in any one of Claims 4-6 ,
The erosion region is annular;
The method of manufacturing a sputtering target in which the friction stir welding is scanned in a radial direction with respect to the annular erosion region .

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