JPH08109472A - Target for sputtering and its production - Google Patents

Abstract

PURPOSE: To produce a homogeneous target high in the using efficiency, high in density and furthermore having resistance to thermal shock into an optional shape at a low cost. CONSTITUTION: On a substrate 3' having a recessed shape corresponding to an erosion region, an undercoat layer 2 composed of metals or alloys and a target layer 1 formed by plasma spraying are successively formed to produce a planar target for magnetron sputtering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar magnetron sputtering target and a method for manufacturing the same.

[0002]

2. Description of the Related Art The planar type magnetron sputtering method has a high film forming rate and is a very important industrial film forming method. In the film formation by the planar magnetron sputtering method, the magnetic field concentrates the plasma on a certain portion, and the target is locally eroded. A region where such local erosion occurs is called an erosion region, and in the case of a general circular target, the erosion region has an annular shape.

As shown in FIGS. 1 to 3, a conventional target is a disk-shaped or divided flat plate-shaped target material 1.
However, the backing plate 3 is bonded to the bonding material 2 such as In.
It is joined and configured by.

Since the above-mentioned erosion occurs locally, only the thickness of the erosion region of the target material is reduced as the sputtering is performed, and finally, the portion of the target material excluding the erosion region is not consumed at all and the target is not consumed. Will run out of life. Therefore, the use efficiency of the target is very low, generally about 10 to 20%.

In Japanese Patent Laid-Open No. 3-287763, in order to solve the high cost of the target due to the low use efficiency of the target material, a thick portion including the erosion region and a thickness not including the erosion region are disclosed. The thin target and the target formed by the division are shown. In such a split target, after the part including the erosion region is eroded, by peeling only the part from the backing plate and replacing it with a new target,
It is said that the cost can be further reduced. A similar division target is also disclosed in Japanese Utility Model Publication No. 63-42157.

Japanese Utility Model Publication No. 63-131755 discloses a target having a thick erosion region.

Japanese Laid-Open Patent Publication No. 1-290764 discloses an ITO target in which 80% or more of the weight of the target is present in the erosion region during sputtering to improve the use efficiency.

However, in the split target as disclosed in JP-A-3-287763 and JP-B-63-42157, it is necessary to arrange a plurality of targets having different thicknesses so that the sputtering surface becomes flat. Special processing such as providing a step on the backing plate is required. Therefore, although the cost of the target material is reduced, the cost of the backing plate increases, and the backing plate has a special shape, which makes it difficult to bond the target material.

If the backing plate is not provided with a step, the difference in thickness appears as a step on the sputtering surface, and there is a problem that abnormal discharge is likely to occur at the edge portion.

Further, in the above-mentioned divided target, only the portion including the erosion region can be exchanged after the portion including the erosion region is eroded. However, as a practical matter, in the case of a target such as ceramics, bonding by low melting point solder is used. However, in order to peel off this joint, it has to be heated to a temperature above the melting point of the low melting point solder. At this time, heat stress occurs, and in most cases,
The thin portion that does not include the erosion region is broken. Since this broken target causes abnormal discharge, it is practically difficult to use repeatedly.

As shown in Japanese Patent Application Laid-Open No. 1-290764, in order to realize a shape in which 80% or more of the target weight exists in the erosion region, it is necessary to make the thickness of the non-erosion portion extremely small. In the case of a ceramics-based target, a target having such a shape is easily cracked during bonding, which makes bonding practically difficult. Therefore, since such a shape must be realized by processing after bonding,
There will be no cost advantage.

[0012]

As described above, the conventional target for planar type magnetron sputtering has low use efficiency, is difficult to reproduce, and is high in cost.

An object of the present invention is to provide a planer type magnetron sputtering target with low cost and high use efficiency, and a method for manufacturing the same.

[0014]

The present invention provides a planer type magnetron sputtering target in which a metal or alloy undercoat layer and a target layer are sequentially formed on a substrate, and the substrate corresponds to an erosion region. Provided is a sputtering target, which is a substrate having a concave shape, and the target layer is formed by plasma spraying on the undercoat layer, and a method for manufacturing the same.

The target of the present invention is a planar type magnetron sputtering target, and the shape thereof includes a disk-shaped or flat-plate-shaped target as shown in FIGS. 4 and 5. In FIGS. 4 and 5, the portion indicated by the dotted line corresponds to the erosion area.

As the substrate used in the present invention, as shown in FIG. 6, a backing plate 3'having a concave shape corresponding to an erosion region (hereinafter referred to as a concave backing plate), or as shown in FIG. It is possible to use the target material 4 itself which has been eroded into a concave erosion shape by spattering (hereinafter referred to as a concave target material) 4.

The concave target material 4 is joined to the backing plate 3 by a bonding material 2 such as In.

The surface of the concave backing plate 3'or the concave target material 4 is roughened by sandblasting or the like, and after the undercoat layer 2'is plasma-sprayed, various sprayed powders to be the target layer are converted into plasma. The target layer 1'is formed by thermal spraying. In the present specification, the target material formed by plasma spraying in the present invention is referred to as a target layer.

The present invention does not require the step of forming into a desired shape, the step of sintering, the step of processing into a complicated structure or various shapes, and the bonding step, which were required in the conventional target. In the present invention, only the steps until obtaining the thermal spray powder to be the target layer are required. For complex compounds that are not easily available, they can be prepared by chemical synthesis or solid-phase reaction, and then crushed or granulated, and then classified to obtain a particle size suitable for thermal spraying that facilitates flow. To be done.

As the thermal spraying powder for forming the target layer used in the present invention, a metal or alloy having a brittle or low melting point is preferable because it is effective in plasma spraying. For example, metals such as Zn, In, Sn, Si and Cr and most metals and alloys such as Zn—Sn, In—Sn and Sn—Ti are selected.

In addition to metals and alloys, TiO ₂ , Al ₂
Most ceramics such as oxides such as O ₃ and ZrO ₂ , silicides such as ZrSi ₂ , MoSi ₂ and borides such as ZrB ₂ , CrB, TiB ₂ and LaB ₆ can also be used.

The thermal spray powder used in the present invention can be prepared by the following method. That is, one or more kinds of various powders having an average particle size of 10 μm or less are weighed in a predetermined amount, and a binder such as PVA and water and / or an organic solvent are used as a dispersion medium and wet-mixed for 3 hours or more in a ball mill to prepare a mud. After producing the ginger, the spray-dried powder can be obtained by spray drying to a particle size of about 20 to 100 μm.

Further, in the above, instead of spray-drying the mud, the mud is dried and calcined at a high temperature in an oxidizing or inert atmosphere, and the obtained lumpy powder is classified to 20 to 100 μm. It is also possible to obtain a degree of thermal spray powder.

If the thermal spraying powder used in the present invention is larger than 100 μm, it is hard to be in a semi-molten state in a high temperature plasma gas, and if it is smaller than 20 μm, it is dispersed in the high temperature plasma gas during plasma spraying and is hard to adhere.

Various metals and alloys such as stainless steel, copper and titanium can be used as the concave backing plate 3'and the concave target material 4 (both collectively referred to as a metal substrate hereinafter).

In the present invention, prior to plasma spraying of the sprayed powder to be the target layer, in order to improve adhesion,
The surface of the metal substrate is preferably roughened by sandblasting using Al ₂ O ₃ or SiC abrasive grains. Alternatively, it is also preferable that after the surface of the metal substrate is processed into a V-groove shape, it is sandblasted by using abrasive grains of Al ₂ O ₃ or SiC to improve the adhesion.

In the present invention, after the surface of the metal substrate is roughened, the difference in thermal expansion between the target layer to be sprayed and the metal substrate is mitigated, and the adhesiveness is to withstand peeling due to mechanical or thermal shock. It is important to form the undercoat layer 2'made of a metal or an alloy in order to increase the temperature.

As the undercoat layer 2 ', a layer having a thermal expansion coefficient intermediate between that of the metal substrate and the material of the target layer (hereinafter referred to as A layer) and / or a thermal expansion coefficient close to that of the material of the target layer is used. The layer which it has (henceforth layer B) is used.

Even if the undercoat layer 2'is only the A layer or the B layer, the metal and the alloy have high elasticity and small brittleness, so that the adhesion with the metal substrate can be enhanced, but both layers are used. It is most preferable to form a metal substrate / A layer / B layer / target material coating layer.

The thermal expansion coefficient of the B layer is optimally within the range of ± 2 × 10 ^-6 / ° C. of the thermal expansion coefficient of the target coating layer.

Further, among the materials of the undercoat layer, an undercoat layer in which a material having a coefficient of thermal expansion close to that of a metal substrate and a material having a coefficient of thermal expansion close to that of the target layer are changed in a gradient composition may be provided. It is preferable because the adhesiveness is further increased.

The material of the undercoat layer 2'is M
o, Ti, Ni, Nb, Ta, W, Ni-Al, Ni-
Cr, Ni-Cr-Al, Ni-Cr-Al-Y, Ni
A conductive material such as —Co—Cr—Al—Y may be used.
The thickness of the undercoat layer 2'is 30 to 30 for both the A layer and the B layer.
About 100 μm is preferable.

The material of the undercoat layer 2'needs to be changed according to the thermal expansion coefficient of the target layer. The coefficient of thermal expansion of copper or stainless steel that can be used as a metal substrate is 17
Is about 18 × 10 ⁻⁶ / ° C., and the coefficient of thermal expansion of titanium is 8.
It is 8 × 10 ⁻⁶ / ° C.

For example, if the target layer is Si, Cr, Z
r, Zr-B system, Ti-B system, Cr-Si system, Sn-S
i type, Zr-Si type, etc. (coefficient of thermal expansion 5-6 × 10 ^-6 /
C), the preferable thermal expansion coefficient of the undercoat A layer is 12 to 15 × 10 ⁻⁶ / ° C., and its material is Ni, Ni—Al system, Ni—Cr system, Ni—Cr—.
Al-based, Ni-Cr-Al-Y-based, Ni-Co-Cr-
An Al-Y system etc. are mentioned. The preferred thermal expansion coefficient of the undercoat B layer is 5 to 8 × 10 ⁻⁶ / ° C., and its material includes Mo, W, Ta, Nb and the like.

The target layer is Ta-B type, Ta-Si
In the case of a system or the like (coefficient of thermal expansion 8 to 9 × 10 ⁻⁶ / ° C.), the preferable thermal expansion coefficient of the undercoat A layer is 12 to 15 × 1.
0 ⁻⁶ / ° C., and its material is Ni, Ni—Al
System, Ni-Cr system, Ni-Cr-Al system, Ni-Cr-
Examples thereof include Al-Y type and Ni-Co-Cr-Al-Y type. The thermal expansion coefficient of the undercoat B layer is preferably 8 to 10 × 10 ⁻⁶ / ° C., and the material thereof is T
i, Nb and the like.

The target layer is Sn-Ti system, Cr-B
In the case of a system, etc. (coefficient of thermal expansion 10-13 × 10 ^-6 / ° C),
The preferred thermal expansion coefficient of the undercoat B layer is 10 to 13
× 10 ⁻⁶ / ° C., and its material is Ni, Ni−
Al-based, Ni-Cr-based, Ni-Cr-Al-based, Ni-C
Examples thereof include r-Al-Y type and Ni-Co-Cr-Al-Y type, and the undercoat A layer can be omitted. When the difference in the coefficient of thermal expansion between the target layer and the metal substrate is small as described above, the undercoat layer may be a single layer. In particular, when the metal substrate is titanium, the difference in the coefficient of thermal expansion between the target layer and the metal substrate is often small, and in many cases only the B layer is formed.

[0037] The thermal spraying powders forming the target layer of the foregoing on the undercoat layer 2 ', Ar and, in a high temperature plasma gas in the reduction under such Ar + H _2, while the semi-molten state,
This gas transports and adheres onto the undercoat layer 2'to form a target layer.

In the present invention, the undercoat layer 2 '
By inserting, a stable target layer having a film thickness of 2 to 10 mm can be formed.

Further, by forming the target layer in the high temperature plasma gas, it is possible to obtain a uniform and high-density target layer with little change in the chemical composition and mineral composition of the target layer.

When forming the undercoat layer 2 ', it is preferable that the undercoat layer 2'is formed by a plasma spraying method in a high temperature plasma gas, preferably in a high temperature plasma gas under reduction.

A plasma spraying method is disclosed in Japanese Patent Laid-Open No. 62-1.
As disclosed in Japanese Patent No. 61945, there is also a water plasma spraying method. In the case of the water plasma spraying method, by adding alcohol to water and spraying it, a metal or alloy that is easily oxidized,
It can be applied to thermal spraying of non-oxides and can be adopted in the present invention.

The target of the present invention is used not only in the DC (direct current) sputtering method but also in the RF (high frequency) sputtering method.

[0043]

In the target of the present invention, the target layer is closely formed on the concave portion as shown in FIG. 6 or 7, and is consumed after sputtering as shown in FIG. 8 or 9. Therefore, the usage efficiency of the target material is significantly higher than that of the conventional target, and 90 to 98% is achieved.

In the present invention, since the target layer is formed in the high temperature plasma gas, a uniform and high-density target layer is formed with little change in chemical composition and mineral composition of the target layer.

Since the target of the present invention has a specific undercoat layer, it has good heat conduction from the target layer to the metal substrate and further to the cathode electrode, and the target layer is firmly adhered to the metal substrate. . Therefore, even if a high sputtering power is applied to increase the deposition rate, sufficient cooling is performed, and there is no peeling or cracking of the target layer due to a rapid heat shock, and a large amount of power is applied per unit area. Is possible.

Even if the erosion zone of the target layer becomes thin, the target layer of the same material can be plasma sprayed to these thinned portions to easily restore the original state.

Furthermore, it is possible to easily give the distribution of the thickness of the target layer depending on the location, thereby making it possible to give the strength of the magnetic field and the temperature distribution on the target surface and control the thickness distribution of the thin film to be formed. It is also possible to do.

[0048]

EXAMPLES Si, Zn, Sn, In as a target layer
A sprayed powder of —Sn, TiO ₂ , ZrSi ₂ or the like was sized to have an average particle size of 20 to 100 μm.

As a metal substrate, a flat Ti target material 4 adhered to the backing plate 3 and eroded in a concave shape by sputtering as shown in FIG. 7 was prepared. After sandblasting the surface of the metal substrate, various undercoat layers 2 ′ shown in Examples 1 to 4 of Table 1 were applied to each metal substrate.

Next, thermal spraying powders of the materials shown in Examples 1 to 4 of Table 1 were sprayed to form target layers.

Further, as a metal substrate, as shown in FIG. 6, a copper backing plate 3'which was dug into a concave shape by a machining center was prepared, and the surface of the substrate was sandblasted. Various undercoat layers 2 ′ were applied respectively, and then Examples 5 to 7 in Table 1 were applied.
Each of the thermal spray powders of the materials shown in 1 was sprayed to form a target layer. The thermal spray powders used in Examples 1 to 7 were each sized to have an average particle size of 20 to 100 μm.

Examples 8 to 9 are comparative examples. Conventional disk-shaped and flat-plate copper backing plates are prepared, sintered bodies of Si and ZrSi ₂ are manufactured as target materials, respectively, processed, and bonded to the above-mentioned backing plates by In bonding materials. The targets shown in Examples 8 to 9 of Example 1 were obtained.

The targets of Examples 1 to 9 prepared as described above were attached to a magnetron sputtering apparatus, used for film formation and used until the erosion due to sputtering reached the backing plate surface, and then the weight loss was measured to determine the target material. The usage efficiency was calculated. Also, the target was checked for cracks, peeling, etc. during sputtering. Table 1 shows the results.

As shown in Table 1, the targets of Examples 1 to 7 of the present invention had high use efficiency and were able to form films stably and at high speed, whereas the targets of Conventional Examples 8 to 9 had use efficiency of 10 to 10. Two
It was about 0%, and cracking and peeling occurred.

[0055]

[Table 1]

[0056]

The use efficiency of the target of the present invention is remarkably higher than that of the conventional target, and the target is homogeneous and high in density and resistant to heat shock. Further, since the plasma spraying method in the high temperature plasma gas is used in the method of manufacturing the target, the conventional molding, firing, processing, bonding, and other steps are not required, and the target of any shape can be easily and inexpensively manufactured. Is created.

The method of manufacturing the target of the present invention is
It is possible to regenerate the target by plasma spraying the sprayed powder of the target material having the same composition on the portion consumed after use, which is economically useful.

When the target of the present invention is used, the cooling efficiency at the time of sputtering is high, and even if the sputtering power is increased, there is no cracking or damage to the target.
Stable high-speed film formation becomes possible. Therefore, the productivity of large-area glass for display elements, CRTs, constructions, automobiles, etc. is remarkably improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing the shape of a conventional target.

FIG. 2 is a perspective view showing the shape of a conventional target.

FIG. 3 is a cross-sectional view showing a worn state of a conventional target.

FIG. 4 is a perspective view illustrating the shape of a target of the present invention.

FIG. 5 is a perspective view illustrating the shape of a target of the present invention.

FIG. 6 is a sectional view of a target of the present invention.

FIG. 7 is a sectional view of a target of the present invention.

FIG. 8 is a sectional view showing the consumption state of the target of the present invention.

FIG. 9 is a cross-sectional view showing the consumption state of the target of the present invention.

[Explanation of symbols]

1: Target material 1 ': Target layer 2: In bonding material 2': Undercoat layer 3: Backing plate 3 ': Backing plate (base) having a concave shape corresponding to an erosion region 4: Corroded into a concave erosion shape Target material (base)

Claims (9)

[Claims] 1. A method of manufacturing a target for planar magnetron sputtering, in which an undercoat layer made of a metal or an alloy and a target layer are sequentially formed on a substrate, wherein the substrate has a concave shape corresponding to an erosion region. Is used to form a target layer on the undercoat layer by plasma spraying, which is a method for producing a sputtering target. 2. The method for producing a sputtering target according to claim 1, wherein a metal or alloy substrate is used as the substrate. 3. The method for manufacturing a sputtering target according to claim 1, wherein a metal or alloy target material having a recessed dug shape that is corroded by sputtering is used as the substrate. 4. The method for producing a sputtering target according to claim 1, wherein a substrate having a rough surface is used as the substrate. 5. A layer having a coefficient of thermal expansion intermediate between the coefficient of thermal expansion of the substrate and the coefficient of thermal expansion of the target layer and / or a layer having a coefficient of thermal expansion close to that of the target layer is used as the undercoat layer. Claim 1 characterized by the above-mentioned.
4. The method for manufacturing a sputtering target according to any one of 4 to 4. 6. A planar magnetron sputtering target in which an undercoat layer made of a metal or an alloy and a target layer are sequentially formed on a substrate, wherein the substrate has a concave shape corresponding to an erosion region, The target layer is on the undercoat layer,
A sputtering target, which is formed by plasma spraying. 7. The sputtering target according to claim 6, wherein the substrate is a metal or alloy substrate. 8. The sputtering target according to claim 6, wherein the substrate is a metal or alloy target material that is corroded by sputtering and has a recessed dug shape. 9. The undercoat layer is a layer having a coefficient of thermal expansion intermediate between the coefficient of thermal expansion of the substrate and the coefficient of thermal expansion of the target layer and / or a layer having a coefficient of thermal expansion similar to that of the target layer. The sputtering target according to any one of claims 6 to 8.