JPH0762528A - Sputtering target - Google Patents

Abstract

PURPOSE:To prevent abnormal electric discharge between target chips at the time of sputtering and to prevent the generation of particles by combining materials of the same kind and/or materials of different kinds with each other and integrating the target chips by diffusion bonding so that a gap is not left. CONSTITUTION:A block is formed by alternately combining materials of the same kind and/or materials of different kinds with each other so that a section is allowed to coincide with that of a desired sputtering target. At this time, the diffusion bonding faces of the materials are cleaned, fixed under pressure and diffusion-bonded by heating. The resulting block is cut to a prescribed thickness to obtain the objective mosaic sputtering target.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to sputtering targets.

[0002]

2. Description of the Related Art Recently, for example, amorphous silicon (α-S
i) Attention has been focused on an active matrix type liquid crystal display device configured by using a thin film transistor (TFT) using a film as a switching element.

This is a large-area, high-definition, high-quality, and inexpensive panel display (flat type) by forming a TFT array using an α-Si film that can be formed at a low temperature on an amorphous glass substrate. This is because there is a possibility that television will be realized.

In order to make the display pixel of this active matrix type liquid crystal display device as small as possible and have a large area, it is necessary to make the signal line to the TFT, that is, the gate electrode wiring, thin and long.

For example, when a reverse stagger type TFT structure in which a gate electrode wiring is provided on the glass substrate side and an insulating film or an α-Si film is stacked on the glass substrate to form a TFT, the gate electrode wiring is thin and sufficient. It is required that the material has low resistance and can withstand subsequent chemical treatment.

Further, when the stagger type TFT structure in which the drain and source electrode wirings are provided on the substrate side is adopted, the drain and source electrode wirings also have lower resistance and good workability, and can withstand the subsequent chemical treatment. It is required to be a material.

Conventionally, tantalum (Ta) and molybdenum (M) have been used as materials for gate electrode wirings that satisfy such requirements.
Various metal films such as o), titanium (Ti), and aluminum (Al), or alloy films thereof are used.

In particular, there is a Mo-Ta alloy film as a material satisfying the above required characteristics, and as a film forming technique for forming the thin film, sputtering is used because it is excellent in mass productivity and film forming stability. There is.

As a sputtering target used for forming various alloy films such as the Mo-Ta alloy film used as the material for the above-mentioned gate electrode wiring, the composition of the film obtained can be easily controlled and a large screen can be obtained. Since it is required that the size of the film-forming target be large enough, a mosaic-type sputtering target that combines blocks (target pieces) of each material forming the alloy film is used. ing. When film formation is performed using such a sputtering target, the composition ratio of the formed film can be freely changed by changing the type and combination of target pieces, and the width and length of the target piece can be changed. There is an advantage that the target can be made larger by increasing the value.

In addition to the sputtering target for forming the alloy film, it is necessary to increase the size of the sputtering target of the same material as the size of the object to be formed in recent years. On this occasion,
To obtain a sputtering target as a single unit, there are many restrictions on production, such as increasing the size of the manufacturing equipment such as presses. Therefore, this is used as a block (target piece) of each material of the same type, and a mosaic combining these blocks is used. The use of mould-type sputtering targets is under consideration.

As the sputtering target as described above, a rectangular plate-shaped sputtering target is formed by alternately arranging strip-shaped target pieces, or a plurality of wedge-shaped target pieces are alternately combined into a disk-shaped target. Known sputtering targets are known.

[0012]

When a film is formed using the mosaic type sputtering target, a material different from the material forming the sputtering target, such as a brazing material, is used between the target pieces forming the target. Since they cannot be joined by using them, the joined portions are merely brought into contact with each other and have a gap.

Therefore, if the sputtering is performed with a gap, a high voltage is applied to the sputtering target in the sputtering even if the gap is very small, so that an abnormal discharge occurs in the gap between the target pieces. The corners of each target piece or the film deposited on the corners is missing and particles (fine particles) are generated.

When the particles are mixed in the formed film, for example, in a wiring such as a gate electrode wiring of an active matrix type liquid crystal display device, a defect such as a short circuit or an opening of the wiring occurs after the circuit is formed,
That portion appears as a point defect on the screen of the display device, and there is a problem that the product yield decreases. Further, the above-mentioned problems are also important problems in narrowing the line width of the wiring and making the pitch finer as the circuit becomes higher in density.

The above-mentioned problems are problems in all applications in which a film is formed using a sputtering target, and the state of particle generation tends to become more remarkable as the sputtering target becomes larger. Therefore, a target that produces a small amount of particles is desired. Therefore, the present invention has been made in view of the above points, and it is an object of the present invention to provide a sputtering target in which the generation of particles is much less than in the past.

[0016]

The sputtering target of the present invention is characterized in that the same kind and / or different kinds of materials are combined by diffusion bonding. A feature of the present invention is that the target-pieces, which are generation sources of particles, are integrated by diffusion bonding to eliminate a gap, thereby preventing abnormal discharge between the target pieces during sputtering and preventing generation of particles. That is, the sputtering target of

An example of the diffusion bonding method of the present invention will be described below. First, in the case of a rectangular plate-shaped sputtering target, plate materials of each constituent material are alternately laminated so that the cross-section has an intended strip-shaped structure of the sputtering target, and after fixing it under pressure, heating and diffusion are performed. By joining, a large integrated block whose cross-section is similar to the intended plate-shaped sputtering target is formed. A sputtering target is obtained by cutting the block to a predetermined sputtering target thickness by a cutting means such as a wire cut electric discharge machine.

Alternatively, in the case of a disk-shaped sputtering target, each of the constituent materials having a wedge-shaped cross-section so that the cross-section has the intended structure of the sputtering target is alternately combined to form a cylindrical block, which is fixed under pressure from the peripheral portion. After that, by heating and diffusion bonding, a large columnar integrated block having a cross section similar to the intended disk-shaped sputtering target is formed. A sputtering target is obtained by cutting the block to a predetermined sputtering target thickness by a cutting means such as a wire cut electric discharge machine.

Here, it is necessary to join clean surfaces from which contaminant adsorbing substances such as oxide films or oils and fats have been removed to the diffusion-bonded surfaces of the respective constituent materials. Therefore, the bonded surfaces are alkali-cleaned before diffusion-bonding. Alternatively, it is preferable to perform a surface cleaning treatment such as pickling.

Further, it is preferable that the surface roughness of the joint portion between the respective materials when the respective constituent materials are combined is smaller, because diffusion is better performed. The heating temperature (diffusion temperature) at the time of diffusion bonding is an important factor for forming a diffusion layer between the constituent materials and bonding the materials together. If the temperature is too low, diffusion will be insufficient and diffusion bonding will not occur,
On the other hand, if the temperature is too high, the material is thermally deformed and it is difficult to obtain a predetermined shape, and the crystal grains of the material become coarse, which adversely affects the uniformity of the film resistance. The preferred diffusion temperature is the melting temperature of the lower material of each melting temperature of the material used,
The temperature range is 1/2 to 2/3.

The heating atmosphere at the time of diffusion bonding should be performed in vacuum or in a non-oxidizing atmosphere such as argon (Ar) so that a coating film such as an oxide which hinders diffusion is not formed on the bonding surface. preferable.

The heating time (diffusion time) at the time of diffusion bonding is a factor that influences the size of the diffusion layer and influences the bonding strength. If the time is too short, diffusion will be insufficient and peeling will tend to occur, and conversely, if the time is too long, progress of the diffusion layer cannot be expected and workability will be deteriorated. The preferred diffusion time is in the time range of 2 to 6 hours.

Further, the pressing force at the time of fixing under pressure is a factor that promotes diffusion and improves bondability. If the applied pressure is too small, the effect cannot be obtained. On the contrary, if the applied pressure is large, the material is thermally deformed during heating, and it becomes difficult to obtain a predetermined shape. The preferred pressure is 10 to 150 kg / cm
^{Is 2} .

In the present invention, it is preferable that the material used for diffusion bonding has less deformation (flatness) at the bonded portion of the material in order to improve the bondability. When this material is severely deformed, diffusion bonding is insufficient, and there are some places where diffusion bonding is not performed. In particular, this tendency becomes more remarkable as the material becomes larger, so the smaller the warp amount of the joint surface of the material, the better. However, the warp amount is at least 1 mm or less, preferably 0.5 mm or less, and more preferably 0.3 mm. It is the following. Here, the warp amount of the joint surface in the present invention is the maximum distance between the horizontal surface and the joint surface when the joint surface side of the material is placed on the horizontal surface. Therefore, it is different from the warpage in the plate material. When the material has a concave portion or a convex portion, the amount of warpage refers to the distance between the mating material to be joined and the mating material.

In the present invention, it is preferable that each constituent material is directly diffusion-bonded in order to avoid mixing of impurities, but when the constituent materials are further combined, each constituent material easily diffuses between the constituent materials. Intervening metal foil or powder, or plating, ion plating, thermal spraying on the joint surface,
After performing various surface coating treatments such as CVD, PVD, and PCVD, diffusion bonding may be performed.

As the metal foil, powder or surface coating material interposed between the respective constituent materials, in the case of metal foil, at least one material foil of each constituent material or an alloy foil made of each material, and in the case of powder, each A powder of at least one of the constituent materials, an alloy powder of each material or a mixed powder of each material, and a coating layer of a material to be joined in the case of surface coating treatment is preferable.

In the present invention, the apparatus used for the above diffusion bonding is preferably a hot press or a hot isostatic press capable of producing a large integrated block at once.

The present invention is not limited to the above-mentioned manufacturing method, but the surface treatment, diffusion temperature, heating time,
The pressing force and the like are set appropriately.

In the example of the above-mentioned manufacturing method, the case where a predetermined sputtering target is manufactured by manufacturing a large block and cutting it has been described, but the present invention is not limited to this, and a predetermined sputtering target may be manufactured individually. good.

In addition to the above manufacturing method, various diffusion bonding methods may be adopted. The sputtering target intended by the present invention is a combination of materials of the same kind or materials of different kinds by diffusion bonding, but may be composed of these combinations. Also,
The material of the present invention can be applied to all materials formed by sputtering, such as single metals, alloys thereof, and ceramics.

[0031]

【Example】

Example 1, Comparative Example 1 Mo plate having a purity of 99.9% (width 256 mm x length 130 mm x
Thickness 12.5 mm) and Ta plate with a purity of 99.9% (width 25
6mm x length 130mm x thickness 23.5mm) are stacked alternately in the thickness direction, width 256mm x length 130mm x height 324mm
And Then, this is placed in a vacuum hot press machine 14
After heating to 00 ° C., a pressure of 80 kg / cm ² was applied for 3 hours to carry out diffusion bonding to obtain a large integrated block.
After cutting the obtained block into a plate shape having a width of 256 mm, a length of 324 mm and a thickness of 10 mm by a wire cut electric discharge machine, this is joined to a Cu backing plate for cooling,
The Mo-Ta sputtering target of Example 1 was obtained.

For comparison, Mo with a purity of 99.9% is used.
Block (width 256mm x length 12.5mm x thickness 10mm)
And Ta blocks with a purity of 99.9% (width 256 mm x length 23.5 mm x thickness 10 mm) are arranged alternately in the length direction and width 2
After forming into a plate shape of 56 mm × length 324 mm × thickness 10 mm, this was bonded to a Cu backing plate for cooling to obtain a Mo—Ta sputtering target of Comparative Example 1.

These Mo-Ta sputtering targets were attached to a sputtering apparatus, and a glass substrate (width 200
mm × length 260 mm), a 0.3 μm thick Mo—Ta film was formed. This sputtering operation was performed 30 times, and the numbers of particles of 5 μm or more and 1 μm or more mixed in the film were measured. The results are shown in Table 1.

Example 2 and Comparative Example 2 Mo plate having a purity of 99.9% (width 256 mm x length 130 mm x
(Thickness 27 mm) is laminated in the thickness direction, width 256 mm x length 1
The size is 30 mm × height 324 mm. Then, this was heated to 1700 ° C. in a vacuum hot press machine, and a pressure of 80 kg / cm ² was applied for 3 hours to carry out diffusion bonding to obtain a large integrated block. The obtained block is processed by a wire cut electric discharge machine to a width of 256 mm, a length of 324 mm and a thickness of 1.
After cutting into a 0 mm plate shape, this was bonded to a Cu backing plate for cooling to obtain a Mo sputtering target of Example 2.

As a comparison, Mo with a purity of 99.9% is used.
Blocks (width 256 mm x length 27 mm x thickness 10 mm) are arranged alternately in the width direction width 256 mm x length 324 mm x thickness 10
After having a plate shape of mm, this was joined to a Cu backing plate for cooling to obtain a Mo sputtering target of Comparative Example 2.

These Mo sputtering targets were attached to a sputtering apparatus, and M of 0.3 μm thickness was formed on a glass substrate (width 200 mm × length 260 mm) in the same manner as in Example 1.
o film was formed. This sputtering operation was performed 30 times, and the numbers of particles of 5 μm or more and 1 μm or more mixed in the film were measured. The results are also shown in Table 1.

Example 3, Comparative Example 3 Mo plate having a purity of 99.9% (width 256 mm x length 130 mm x
Ti plate with a thickness of 10.5 mm and a purity of 99.9% (width 25
6mm x length 130mm x thickness 25.5mm) are laminated alternately in the thickness direction, width 256mm x length 130mm x height 324mm
And Then, this is placed in a vacuum hot press machine for 10
After heating to 00 ° C., a pressure of 60 kg / cm ² was applied for 3 hours to carry out diffusion bonding to obtain a large integrated block.
After cutting the obtained block into a plate shape having a width of 256 mm, a length of 324 mm and a thickness of 10 mm by a wire cut electric discharge machine, this is joined to a Cu backing plate for cooling,
The Mo-Ti sputtering target of Example 3 was obtained.

As Comparative Example 1, a Mo block having a purity of 99.9% (width 256 mm × length 10.5 mm × thickness 10)
mm) and a Ti block with a purity of 99.9% (width 256 mm x
(25.5 mm in length x 10 mm in thickness) are alternately arranged in the length direction to form a plate having a width of 256 mm x a length of 324 mm x a thickness of 10 mm, and this is joined to a Cu backing plate for cooling,
A Mo-Ti sputtering target of Comparative Example 3 was obtained.

These Mo-Ti sputtering targets were attached to a sputtering apparatus, and a thickness of 0.3 μm was formed on a glass substrate (width 200 mm × length 260 mm) as in Example 1.
m Mo-Ti film was formed. 30 times this spattering operation
5 μm or more mixed on the glass substrate, and 1
The number of particles of μm or more was measured. The results are also shown in Table 1.

Example 4, Comparative Example 4 Ta material with a wedge-shaped cross section having a purity of 99.9% (vertical angle 10 ° × radius 125 mm × thickness 50 mm) and Ti plate with a wedge-shaped cross section having a purity of 99.9% (vertical angle 20 ° × 125 mm radius × 50 mm thickness) are alternately arranged in the circumferential direction to have a diameter of 250 mm × thickness of 50 mm. Then, this is put in a metallic capsule, the inside is evacuated and sealed, and then 1000 ° C. and an inert gas pressure of 500.
Hot isostatic pressing was performed at kgf / cm ² . Then, the metallic capsule was removed by machining to obtain a large integrated block. The obtained block was cut into a disk shape having a diameter of 250 mm and a thickness of 10 mm by a wire cut electric discharge machine, and this was joined to a Cu backing plate for cooling to obtain a Ta-Ti sputtering target of Example 4. .

For comparison, a Ta material having a purity of 99.9% and a wedge-shaped cross section (vertical angle 10 ° × radius 125 mm × thickness 10 m)
m) and a Ti plate having a wedge-shaped cross section with a purity of 99.9% (vertical angle 20
(° × radius 125 mm × thickness 10 mm) are alternately arranged in the circumferential direction to form a disc having a diameter of 250 mm × thickness of 50 mm, which is joined to a Cu backing plate for cooling, and Ta-Ti of Comparative Example 4 is used. A sputtering target was obtained.

These Ta-Ti sputtering targets were attached to a sputtering apparatus, and a thickness of 0.3 μm was formed on a glass substrate (width 150 mm × length 150 mm) as in Example 1.
m Ta-Ti film was formed. 30 times this spattering operation
5 μm or more mixed on the glass substrate, and 1
The number of particles of μm or more was measured. The results are also shown in Table 1.

Example 5, Comparative Example 5 Mo plate having a purity of 99.9% (width 256 mm x length 130 mm x
Ti plate (width: 25 mm, thickness: 15.5 mm) and purity: 99.9%
6mm × length 130mm × thickness 38.5mm) and purity 9
While holding a 9.9% Ti foil, the Ti foil was alternately laminated in the thickness direction to give a width of 256 mm × a length of 130 mm × a height of 324 mm.
Then, after heating this to 1100 ° C. in a vacuum hot press machine, a pressure of 50 kg / cm ² was applied for 3 hours to carry out diffusion bonding to obtain a large integrated block. Width of the obtained block is 256mm by wire cut electric discharge machine
After being cut into a plate shape having a length of 324 mm and a thickness of 10 mm, this was joined to a Cu backing plate for cooling, and Example 5 was used.
The Mo-Ti sputtering target of was obtained.

As a comparison, Mo with a purity of 99.9% is used.
Block (width 256mm x length 15.5mm x thickness 10mm)
And Ti blocks with a purity of 99.9% (width 256 mm x length 38.5 mm x thickness 10 mm) are arranged alternately in the length direction and width 2
After forming a plate having a size of 56 mm × length 324 mm × thickness 10 mm, this was bonded to a Cu backing plate for cooling to obtain a Mo—Ti sputtering target of Comparative Example 5.

These Mo-Ti sputtering targets were attached to a sputtering apparatus, and a thickness of 0.3 μm was formed on a glass substrate (width 200 mm × length 260 mm) as in Example 1.
m Mo-Ti film was formed. 30 times this spattering operation
5 μm or more mixed on the glass substrate, and 1
The number of particles of μm or more was measured. The results are also shown in Table 1.

Example 6, Comparative Example 6 A Ta plate (width 256 mm × length 130 mm × thickness 12 mm) having a purity of 99.9% and having a Ti coating layer having a thickness of 2 μm provided on both sides by ion plating, and a purity of 99. 1.9% Ti plates (width 256 mm x length 130 mm x thickness 24 mm) are laminated alternately in the thickness direction, width 256 mm x length 130 mm x height 32
It was 4 mm. Then, after heating this to 1000 ° C. in a vacuum hot press machine, a pressure of 50 kg / cm ² was applied for 3 hours to carry out diffusion bonding to obtain a large integrated block. The obtained block was cut into a plate shape having a width of 256 mm, a length of 324 mm, and a thickness of 10 mm by a wire cut electric discharge machine, and the cut block was joined to a Cu backing plate for cooling to prepare a Ta-Ti sputtering target of Example 6. Got

As a comparison, Ta having a purity of 99.9% is used.
A block (width 256mm x length 12mm x thickness 10mm),
99.9% pure Ti block (width 256mm x length 24
mm x thickness 10 mm) are arranged alternately in the length direction and width 256 mm x
After forming a plate shape having a length of 324 mm and a thickness of 10 mm, this was joined to a Cu backing plate for cooling, and Ta of Comparative Example 6 was used.
-Ti sputtering target was obtained.

These Ta-Ti sputtering targets were attached to a sputtering apparatus, and a thickness of 0.3 μm was formed on a glass substrate (width 200 mm × length 260 mm) as in Example 1.
m Ta-Ti film was formed. 30 times this spattering operation
5 μm or more mixed on the glass substrate, and 1
The number of particles of μm or more was measured. The results are also shown in Table 1.

[0049]

[Table 1]

As is clear from Table 1 above, the sputtering target integrated by diffusion bonding according to the present invention is 5 μm thicker than the conventional sputtering target.
The amount of particles above is small, and the amount of particles of 1 μm or more is small. Therefore, the line width of the electrode wiring can be made narrower and the pitch can be made finer, and it is suitable for a large sputtering target for a large display.

[0051]

According to the present invention, it is possible to obtain a sputtering target in which the generation of particles is much less than in the conventional case.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Komatsu 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Incorporated company Toshiba Yokohama Office

Claims (1)

[Claims] 1. A sputtering target comprising the same kind and / or different kinds of materials combined by diffusion bonding.