JP4151859B2 - Method for joining sputtering target plates - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of joining a sputtering target plate made of a material substantially selected from carbon, silicon, and ceramic and its backing metal plate.
Here, “substantial” means that in addition to pure carbon or the like, inevitable impurities, a residual component of a manufacturing aid, or an intentionally added component may be included in a small amount.
[0002]
[Prior art]
The target member used for sputtering usually has a structure in which a backing metal plate made of copper or aluminum based metal having good thermal conductivity is joined to a target plate which is a material source of a thin film formed by sputtering.
The target plate and the backing metal plate are usually brazed with a soft In or Sn brazing material having a low melting point, but carbon, silicon, and ceramic are not wetted by these brazing materials, so that these are the main components. For brazing, Ni or Cu is usually coated on the joint surface prior to brazing so that the solder can be easily wetted.
Conventionally, this Ni or Cu film is formed by the following method.
That is, first, a film of Mo, W, Ti, Cr or the like having strong adhesion to carbon, silicon, and ceramic is sputtered on the joint surface of the target plate, and Ni or several μm to several tens of μm thick Ni or Cu is coated by plating or sputtering.
On the Ni or Cu film, a low melting point brazing material is hot dip plated.
A low melting point brazing material is also hot-plated on the surface of the backing metal plate, and the brazing material surfaces of both the target plate and the backing metal plate are overlapped with each other and heated and melted to join them.
The conventional method has the following drawbacks.
(1) At least three processes are required for hot dipping of the target plate, and the process is complicated and expensive.
(2) Expensive due to the use of sputtering. In particular, the carbon material is coated with Ni, Cu after sputtering of Mo, W, Ti, Cr, etc. In wet plating, since the plating solution penetrates into the carbon material, the wet plating method cannot be used, and Ni, Cu films can also be sputtered. It must be formed and is extremely expensive.
(3) The Ni, Cu film coated on the joint surface and the molten plating layer are alloyed, and as a result, the molten plating layer becomes harder and the melting point increases. The thermal stress at the joint interface increases, causing deformation and cracking.
[0003]
[Problems to be solved by the invention]
The present invention has been made in view of such problems, and the object of the present invention is substantially related to a sputtering target plate made of a material selected from {carbon, silicon, ceramic}.
(1) A hot dip plating film with high adhesion strength can be formed directly on the target plate in one step without using sputtering or wet plating.
(2) A new bonding method for the target plate and the backing metal plate that can reduce the thermal stress at the interface of the target member and (3) can be constructed at an extremely low cost.
[0004]
[Means for Solving the Problems]
The above problem can be solved by the following method. That is,
(1) An element selected from {In, Sn, Pb} and an active metal element are bonded to the joint surface of a sputtering target plate substantially made of a material selected from {carbon, silicon, ceramic}. An alloy powder or foil having the active metal element added in the range of 0.5 to 10 wt% as a main component is applied or pasted, and a temperature of 650 to 1200 ° C. in a vacuum, hydrogen, or an inert atmosphere. To heat the film, the process 1 for fusing the coating to the bonding surface, the process 2 for coating the bonding surface of the backing metal plate to be bonded to the target plate, and the target plate, backing A sputtering target plate joining method, comprising: a step of superimposing a metal plate coating; and heating and fusing the superposed coating at a temperature of 300 ° C. or lower .
(2) The joining method according to 1 above, wherein the active metal is Ti.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the active metal means a Ti group element such as Ti, Zr, or Hf, a V group element such as V, Nb, or Ta, a rare earth element such as La or Ce, or a part of an alkaline earth metal such as Ca or Mg. In addition, other elements such as Cr, Y, Al and the like, which easily form compounds with various elements, mean Ti, Zr, and V among these.
The addition amount of these active metals is in the range of 0.5 to 10 wt%, most preferably in the range of 1 to 5 wt%. If the active metal exceeds the upper limit, it becomes hard and the thermal stress at the joint interface increases, causing cracking and deformation, which is not preferable. On the other hand, if it is less than the lower limit, the adhesion strength is weak and may peel off.
[0006]
The sum of the elements selected from (In, Sn, Pb) and the active metal is preferably 85 wt% or more, and may be replaced with other elements in the range of less than 15 wt%.
If it is less than 15 wt%, examples of elements that can be substituted without adverse effects include Au, Ag, Cu, and Zn. In particular, Ag and Cu are effective in raising the heat-resistant use limit temperature.
[0007]
The melting point of an alloy in which an active metal element is added to (In, Sn, Pb) in the range of 0.5 to 10 wt% is approximately 100 to 200 ° C., and it is a metal with high ductility even after solidification, just like In, Sn, and Pb. It is. Moreover, these alloys have the property of being wetted and fused to carbon, silicon, and ceramic at 450 ° C. or higher.
Fusion is not made by fusing so-called alloys, but by active metal diffusing into ceramic, carbon, and silicon, and the fusion metal layer becomes brittle or hard due to diffusion. There is nothing.
The fusing metal layer does not change its original soft and ductile property even if fusing temperature and fusing time are changed. Further, even if the fusion layer is re-dissolved in the air, the fusion property is not deteriorated and the ductility is not hindered. In the conventional method, although the hot-dip plated layer becomes hard due to alloying with Ni and Cu used for the intermediate layer and the thermal stress increases, in the present invention, ductility is not hindered by remelting.
When these alloy powders or foils are applied or pasted to the joint surface and heated in a vacuum, hydrogen, or inert atmosphere, the melted melting point becomes wet and spreads above 450 ° C.
For fusing, heating at least 450 ° C. is essential, and heating at 650 to 1200 ° C. is most preferable. The higher the temperature, the better the fusion, but saturation occurs at about 1200 ° C, so heating above 1200 ° C becomes uneconomical.
Although there is no special restriction | limiting in the thickness of the film to fuse | melt, about 10-500 micrometers is good in general. If it is too thick, the amount of the metal protruding outside during joining to the backing metal increases, which is uneconomical. If it is too thin, the concave portion of the joint surface cannot be sufficiently filled and a void may remain.
[0008]
The backing metal plate is made of copper, copper alloy, aluminum, aluminum alloy, or other metal material with excellent thermal conductivity, which has excellent thermal conductivity. Prior to bonding with the target plate, In, Sn, Pb, Zn-based brazing material having a low melting point is hot-plated or electroplated. At this time, in order to improve the adhesion to the brazing material, a coating of Ni, Cu, Ag, Au or the like may be plated on the surface of the backing metal plate as necessary.
The thickness of the hot dipped or electroplated layer is also preferably about 10 to 500 μm.
[0009]
For joining the target plate and the backing metal plate, the fused metal layer of the target plate and the hot-plated or electroplated layer of the backing metal plate are overlapped and heated to a temperature equal to or higher than the melting point of at least one of the coating metals. Join by fusing. At this time, even if the fusion metal layer of the target plate is heated to a temperature equal to or higher than the melting point and remelted, the fusion effect of the fusion metal layer does not disappear. Even if both coatings are melted, fused, and alloyed, the fusion with the target plate remains. In other words, a film that has been heated and fused to 500 ° C or higher in a vacuum, reducing, or inert atmosphere is redissolved in the atmosphere at a temperature of approximately 300 ° C or lower and fused with other alloys. The fusibility of this remains.
This is the greatest feature of the present invention.
In addition, as in the case where one coating is In-based and the other coating is Sn-based, it is heated to a temperature below the melting point of both coatings, and an In melting point lower than both coatings is formed on the contact surface of both coatings. -You may fuse in the form which produces | generates melts, such as Sn-type alloy.
Alternatively, both coatings may be pressurized and bonded by solid phase diffusion at an appropriate temperature below the melting point of both coatings.
The joining temperature is preferably not more than the softening start temperature (approximately 300 ° C.) of the backing metal plate. When the recrystallization temperature is exceeded, the backing metal plate may soften, resulting in insufficient rigidity and strength.
[0010]
According to the joining method of the present invention, when the material of the target plate is carbon or silicon, in the destructive test, the target plate is broken so as to be removed. That is, the bonding strength is the material strength of the target plate. On the other hand, when the material of the target plate is a ceramic single crystal or sintered body with high strength, it may break at the brazing material part, but the shear strength at this time is 50-100 kg / cm ² when using In. is there. In any case, the bonding strength of the method of the present invention is at a level that is too high as the bonding strength of the target plate.
[0011]
【Example】
The examples illustrate the invention.
[Example 1]
Target plate: φ150 × 5 mm thick graphite-backed metal plate: φ180 × 10 mm thick Cu-Cr alloy process 1
Sn-5 wt% Ti alloy powder was mixed with water and organic paste (PVP) to form a paste, and this was applied to the entire surface of one surface (joint surface) of the target plate to a thickness of about 100 μm. After drying, it was heated to 850 ° C. for 10 minutes in a vacuum oven with a vacuum degree of 2 × 10 ⁻⁵ Torr.
A Sn-5 wt% Ti alloy film was fused to the entire surface of one side of the target plate.
The average thickness of the coating was 30 μm.
Process 2
One side of the backing metal plate was heated to 250 ° C., and an In—Pb alloy was plated by 60 μm.
Process 3
The fusion film on the target plate and the molten plating film on the backing metal plate are overlaid and heated to 260 ° C in the atmosphere to melt the fusion film and the molten plating film, and the target plate (top) is rotated to remove excess molten solder. The material was discharged and solidified.
Results Inspection of the joint The joint was inspected with an ultrasonic deep wound device.
No cracking or peeling was observed, and 99% of the joint area was welded.
The product was divided into four parts, and one of the divided pieces was destructively tested with a hammer.
There was no peeling of the joint, and the target plate was only missing.
It was confirmed that the strength of the joint was higher than the strength of the target plate.
Incidentally, after sputtering Ti on the target plate, further sputtering Ni and hot-plating Sn 30 μm, and joining it to the backing metal plate in the same way as this example, peel off at the interface between the target plate and the brazing material There has occurred. The cost was 10 times that of the method of the present invention.
[0012]
[Example 2]
Target plate: Disc-lined metal plate sliced from a silicon single crystal of φ100 x 5 mm thick: Pure copper process 1 of φ120 x 10 mm thick
Sn-30 wt% In-1 wt% Zr alloy powder was mixed with ethanol and organic paste (PVA) to form a paste, which was applied to the entire surface of one side (joint surface) of the target plate to a thickness of about 150 μm.
After drying, it was heated to 900 ° C. for 10 minutes in a vacuum furnace with a vacuum degree of 1 × 10 ⁻⁵ Torr.
A Sn-30 wt% In-1 wt% Zr alloy coating was fused to the entire surface of one side of the target plate.
The average thickness of the coating was 60 μm.
Process 2
One side of the backing metal plate was heated to 200 ° C. and 50 μm indium was hot-plated.
Process 3
The target plate and the backing metal plate are separately heated in the atmosphere, and the molten fused film and the molten plated film are discharged at 200 ° C. by the slide method disclosed in JP-A-6-114549. Then, they were combined and then solidified and fused.
Results Inspection of the joint The joint was inspected with an ultrasonic deep wound device.
No cracking or peeling was observed, and 98% of the bonded area was welded.
The product was divided into four parts, and one of the divided pieces was destructively tested with a hammer.
There was no peeling of the joint, and the target plate was only missing.
It was confirmed that the strength of the joint was higher than the strength of the target plate.
[0013]
[Example 3]
Target plate: φ150 x 5mm thick high purity alumina sintered metal backing metal plate: φ180 x 10mm thick pure copper process 1
Sn-8 wt% Ti alloy powder was mixed with ethanol and organic paste (PVA) to form a paste, which was applied to the entire surface of one side (joint surface) of the target plate to a thickness of about 150 μm.
After drying, it was heated to 1000 ° C. for 10 minutes in a vacuum furnace with a vacuum degree of 1 × 10 ⁻⁵ Torr.
A Sn-8 wt% Ti alloy coating was fused to the entire surface of one side of the target plate.
The average thickness of the coating was 50 μm.
Process 2
One side of the backing metal plate was heated to 250 ° C., and Sn—Pb solder was plated by 100 μm.
Process 3
Both coatings were combined at 250 ° C. in the same sliding manner as in Example 2.
Results Inspection of the joint The joint was inspected with an ultrasonic deep wound device.
No cracks, delamination, or bubbles were observed, and 100% of the bonded area was welded.
The product was subjected to actual use as a sputtering target.
Although the target plate was used up to the usable limit thickness, no problem occurred.
Incidentally, Sn is hot-plated on the target plate by a conventional method (a method in which Ni is sputtered after Ni is flash meshed and sintered at 850 ° C. in vacuum and then Ni is hot-plated). When bonded to the backing metal plate under the same conditions as described above, a strain of 250 μm / diameter was generated after bonding.
It was confirmed that the method of the present invention can reduce the deformation after joining as compared with the conventional method.
[0014]
[Example 4]
Target plate: φ150 x 5mm thick silicon nitride sintered metal backing metal plate: φ180 x pure 10mm thick copper process 1
Sn-5 wt% Al alloy powder was mixed with ethanol and organic paste (PVA) to form a paste, and this was applied to the entire surface of one side (joint surface) of the target plate to a thickness of about 100 μm.
After drying, it was heated for 10 minutes to 1100 ° C. in a vacuum oven at a vacuum degree 4 × 10 ^-5 Torr.
A Sn-5 wt% Al alloy coating was fused to the entire surface of one side of the target plate.
The average thickness of the coating was 30 μm.
Process 2
After 5 μm of Ni was electroplated on one side of the backing metal plate, 100 μm of In was deposited on this.
Plated.
Process 3
The fused film of the target plate and the In film of the backing metal plate were superposed and heated to 140 ° C. while heating in vacuum (5 × 10 ⁻⁴ ) to join the fused film and the In film.
It was confirmed that a melt having a low melting point was generated on the joint surface because the melt protruded from the joint.
Results Inspection of the joint The joint was inspected with an ultrasonic deep wound device.
No cracking or peeling was observed, and 99% of the bonded area was welded.
The product was divided into four parts, and one of the divided pieces was destructively tested with a hammer.
There was no peeling of the joint and only a portion of the silicon nitride portion was missing.
It was confirmed that the strength of the joint was higher than the strength of the target plate.
[0015]
[Example 5]
Target plate: φ150 x 3 mm thick indium-tin oxide sintered backing metal plate: Oxygen-free copper process 1 of φ180 x 10 mm thickness
A foil (thickness 50 μm) made of Sn-5 wt% Ti-10 wt% Ag was affixed to the entire surface of one surface (joint surface) of the target plate using glue mixed with ethanol and an organic paste material.
After drying, it was heated to 900 ° C. for 20 minutes in a vacuum furnace with a degree of vacuum of 2 × 10 ⁻⁵ Torr.
A Sn-5 wt% Ti-10 wt% Ag alloy coating was fused to the entire surface of one side of the target plate.
Process 2
In-Pb solder was 100 μm hot-plated on one side of the backing metal plate.
Process 3
The fusion film on the target plate and the molten plating film on the backing metal plate are overlaid and heated to 270 ° C in the atmosphere to melt and rub the fusion film and the molten plating film to discharge the excess molten brazing material to the outside. Then it was solidified.
Results Inspection of the joint The joint was inspected with an ultrasonic deep wound machine.
No cracking or peeling was observed, and 99% of the bonded area was welded.
The product was divided into four parts, and one of the divided pieces was destructively tested with a hammer.
There was no peeling of the joint, and the target plate was only missing.
[0016]
【The invention's effect】
The method of the present invention has the following effects.
1. A soft film having a low melting point can be fused directly to the target material in a single step.
2. The thermal stress at the joint is small, the deformation is small, and no cracks occur.
3. Can be constructed at low cost.
4). Applicable to carbon, silicon, and ceramics in general.

Claims (2)

Substantially {carbon, silicon, ceramic} on the bonding surface of the sputtering target plate made of a material selected from among the principal components {an In, Sn, Pb} an element selected and active metal elements from the Then, an alloy powder or foil in which the addition amount of the active metal element is in the range of 0.5 to 10 wt% is applied or stuck, and heated to a temperature of 650 to 1200 ° C. in a vacuum, hydrogen, or an inert atmosphere. Step 1 for fusing a coating to the joint surface ,
A step 2 of coating a coating of a low melting point brazing material on the joining surface of the backing metal plate to be joined to the target plate;
And a step 3 of superimposing the target plate and the backing metal plate, and fusing the superposed coatings at a temperature of 300 ° C. or lower . The joining method according to claim 1, wherein the active metal is Ti.