JP3076311B2 - Oxide sintered body sputtering target assembly - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ITO, ZnO-based, In ₂ O _3-
The present invention relates to an oxide-sintered-body sputtering target assembly that can reduce the amount of expensive target materials made of ZnO-based or MgO-based oxide sintered bodies and can easily manufacture large-sized products that are difficult to integrally mold.

[0002]

2. Description of the Related Art ITO, ZnO, I
Thin films such as n ₂ O ₃ —ZnO-based and MgO-based are widely used as transparent electrodes for display devices such as liquid crystal displays, touch panels, and EL displays. In many cases, an oxide thin film for forming a transparent conductive film such as ITO is formed by sputtering. At the beginning of the development of the sputtering apparatus, a bipolar sputtering apparatus was used. However, this bipolar sputtering apparatus has drawbacks such as a high applied voltage, a rise in substrate temperature, and a low deposition rate. For this reason, three-pole and four-pole sputtering devices have been devised, and high-frequency sputtering devices have been developed, but they have not been satisfactory. For this reason, a magnetron sputtering device has recently been developed in which a magnet is placed on the back side of the target, the plasma is restrained by the magnetic flux generated from this magnet, ionized ion gas is focused on the target, and the sputtering efficiency is increased. Was. This is the mainstream of the current sputtering apparatus for forming a transparent conductive film such as an ITO thin film.

[0003] This magnetron sputtering apparatus can form a film at a high speed and at a low temperature. However, since the plasma is confined by a magnetic field, sputter ion gas concentrates only on a certain portion of the target, whereby the target is locally eroded. The phenomenon occurred. Generally, this local erosion is called an erosion, but when the erosion is local, there is a disadvantage that most of the target remains unused. That is, when the eroded portion by sputtering reaches a position (a certain depth) near the backing plate, the life of the target has expired, and it is necessary to replace the target. In other words, as the local erosion progresses, the local erosion determines the lifetime of the entire target. Since a target such as ITO, which forms a transparent conductive film, often has a large area, the local erosion as described above causes a great decrease in the use efficiency of the target.

In order to solve such a problem, an integrated target has been proposed in which a ceramic target for magnetron sputtering is divided into an erosion region and a non-erosion region, and the material of the erosion region is made thicker and the non-erosion region is made thinner. (JP-A-6-172991). Also, a proposal has been made of a doughnut-shaped sputtering target for a transparent conductive film in which a material is intensively arranged in an erosion region (Japanese Patent Laid-Open Publication No. 1-21-2).
No. 90764). The above two types of improved targets are:
Although it has a certain effect of increasing the thickness of the target in the locally eroded area and extending the life of the target, it is necessary to form a step at the center or edge even though the target is an integrated type. Therefore, cracks may be generated during the manufacturing process, that is, during a processing process such as pressure sintering or grinding. Therefore, they are effective for relatively small targets, but are not suitable for targets requiring a large area.

[0005] As a split type magnetron sputtering target, there is also a proposal of forming a thick donut-shaped target around the periphery and a thin disk target at the center (Japanese Patent Laid-Open No. 3-287773). However, in this case, the concept of division is mainly only between the inner disk target and the donut-shaped target, and it is difficult to manufacture a large-sized target having such a shape as long as the donut-shaped target arranged in the erosion region is of an integral type. There is the same problem as above.

[0006]

SUMMARY OF THE INVENTION The present invention enables efficient sputtering capable of coping with local erosion due to magnetron sputtering, and does not affect sputtering performance, and is expensive for an oxide sintered body such as ITO. Provided is an oxide-sintered-body sputtering target assembly made of ITO or the like that can reduce the amount of target material used as much as possible and can easily produce a large product that is difficult to integrally mold.

[0007]

SUMMARY OF THE INVENTION According to the present invention, there is provided: 1. An oxide sintered body target assembly for magnetron sputtering, wherein an oxide sintered body is not present in a central non-erosion portion, and the central non-erosion portion is not provided. The surface of the backing plate is covered with an element constituting the target material or a brazing material containing the element constituting the target material, and the thickness of the most susceptible portion of the target is thicker than that of the non-erosion portion. Each part of the oxide sintered body target divided so as to have a race track shape that is thick is combined, and the oxide sintered body target assembly further has a rectangular end portion in plan view, and a portion between them. It is composed of a pair or a plurality of pairs of parallel parts arranged, and the central non-erosion where there is no oxide sintered body between both end parts and the parallel parts. 2 is characterized in that it has a horseshoe-shaped thick part and a thin part around it, and is formed in a parallel part. 2. The oxide according to claim 1, wherein the thick part and the thin part are aligned with the horseshoe-shaped thick part and the end of the thin part, respectively, to form a race track shape when assembling the oxide sintered body target. 3. The sintered oxide target assembly according to item 1 or 2, wherein the thick portion has a substantially trapezoidal cross-sectional shape, and the average slope of the slope is 5 ° or more and less than 90 °. Bonded sputtering target assembly 4 Between the thick portion and the thin portion or on the periphery of the thick portion, select from a straight slope, an upper arc surface, a lower arc surface, a combination thereof, or a combination of these with a flat surface or a vertical surface. Little 5. The oxide sintered compact sputtering target assembly according to any one of the above 1 to 3, wherein each of the intersections includes a horizontal plane, a slope, an arc plane, and a vertical plane. The oxide sintering sputtering target assembly according to 4 above, wherein the ridge portion or the corner portion is chamfered by R 0.1 mm or more. 6. The erosion profile when a flat target is sputtered. The distance between the virtual intersection with the slope of the target having a substantially trapezoidal thick portion and the top surface of the thick portion is 5 m.
m, the center line average surface roughness Ra of the sputtered surface is 4 μm or less, and the relative density of the target is 80% or more. And an oxide sintered compact sputtering target assembly as described in any one of the above items 1 to 6, wherein the target has a density distribution within 0.04%.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In manufacturing a sputtering target assembly (part) made of an oxide sintered body, for example,
Explaining based on the TO sintered body, an indium oxide powder having an average particle size of 2 μm and a tin oxide powder having the same particle size have a weight ratio of 90: 1.
It is weighed so as to be 0, and a molding binder is added thereto and mixed uniformly. Next, this mixed powder is filled in a mold,
After pressure molding, it is obtained by sintering at a high temperature. Generally, ITO
The target mainly contains at least 70% by weight of indium oxide and tin oxide, but a third component may be added in addition to the above components in order to improve the conductivity or transparency of the transparent conductive film. The particle diameters and the mixing ratios of the indium oxide powder and the tin oxide powder in the ITO sputtering target assembly are merely examples, and the present invention is not limited thereto. Further, the present invention can be applied not only to ordinary ITO but also to all oxide sintered body target materials such as ZnO-based, In ₂ O ₃ -ZnO-based, and MgO-based, and the present invention includes all of them. I do.

Continuing with the above example, the ITO sputtering target sintered body obtained as described above is ground by a surface grinder to obtain a material for an ITO target assembly part. In the finishing step, the surface of the ITO target assembly part is polished and smoothed with sandpaper, polishing cloth or the like. Sandblasting may be used in this finishing step. For example, by using glass beads, alumina beads, zirconia beads, or the like as a blast material, it is possible to reduce irregularities having edges of the target surface and to remove grinding dust between these irregularities. Next, a cleaning process such as air blowing or washing with running water is performed. Ultrasonic cleaning can also be used. In addition, a method of removing particles adhering to the sputtered surface together with peeling off the adhesive tape (tape peeling method)
May be used.

FIG. 1 shows the appearance of the ITO sputtering target assembly manufactured as described above. When the ITO target assembly 1 is viewed in a plan view, both ends 3 are rectangular,
It is composed of a pair or a plurality of pairs of parallel portions 4 arranged therebetween, and assembled so that a central non-erosion portion where no ITO exists is formed between these rectangular end portions 3 and the parallel portions 4. The race track of this assembly has a substantially elliptical planar shape. The ITO target assembly 1 is composed of a total of four parts including both end parts 3 when the parallel part 4 is a pair, and is composed of a total of six parts when the parallel part 4 is two pairs. The parallel part 4 can furthermore consist of more pairs of assembled parts. Thus, simply increasing the number of parallel parts 4 of the same shape,
A long and large ITO target assembly can be obtained. Although the racetrack may be curved with a constant curvature, the assembly in this case is limited to an elliptical shape for that curvature.

On the backing plate 2, a metal In solder 7
Is applied to the entire surface, and the ITO target assembly 1
And put them together. Therefore, the structure is such that the metal In solder 7 is exposed at the central non-erosion portion where no ITO exists. When the metal In solder 7 is applied only to the back surface of the ITO target assembly 1 to be joined, the exposed surface of the backing plate 2 is coated with another metal In. As described above, when the metal In solder 7 is applied to the entire surface of the backing plate 2, the metal I
The feature is that the process can be simplified since only one coating of n is required. As a result, since there is no expensive ITO in the central non-erosion portion, the raw material cost can be significantly reduced. Even if the central non-erosion portion is sputtered, the metal In only comes flying, so that it does not become a contamination source for ITO film formation.
Note that another brazing material can be used depending on the film forming conditions (the type of the thin film). That is, an element constituting the target material or a brazing material containing an element constituting the target material can be used for the central non-erosion portion. As described above, it is a condition that these brazing materials use a material that does not contaminate a film formed by sputtering, but there is no particular limitation as long as the conditions are satisfied.

Each of the rectangular end portions 3 of the ITO target assembly 1 has a horseshoe-shaped thick portion 5 and a thin portion 6 surrounding the thick portion.
It has. The parallel portion 4 also has a parallel thick portion 5 and a thin portion 6 sandwiching the same. When the ITO target of the parallel portion 4 is assembled, the horseshoe-shaped thick portion 5 and the thin portion 6 of the both end portions 3 are formed. The end portions of the thick portion 5 and the thin portion 6 of the parallel portion 4 or the end portions of the thick portion 5 and the thin portion 6 of the parallel portion 4 are aligned to form an endless race track.
The end portions 3 of the ITO target assembly 1 have a horseshoe-shaped thick portion 5 and a thin portion 6 around the entire portion, and are generally rectangular in plan view, so that the processing is easy. Also has the advantage of requiring at least one. Also, as shown in the figure, since it has a relatively compact shape, no cracking occurs during sintering or handling, and the processing yield is greatly improved. The parallel portions 4 made of one or more pairs of the ITO target assembly 1 can also have basically the same shape. As in the case of the above-mentioned both end portions 3, only a minimum of one powder molding die is required, no cracking occurs during sintering or handling, and the processing yield is greatly improved. As described above, the ITO target assembly has been described here, but it goes without saying that the present invention can be applied to all oxide sintered body target materials. Further, the brazing material applied to the backing plate and the central non-erosion portion described above can be appropriately selected according to the type of the oxide sintered body target material.

The cross-sectional shape of the thick portion 5, that is, the race track is substantially trapezoidal, and both slopes 8 have a slope of 5 ° to less than 90 °, preferably 10 ° to 60 °, more preferably 15 ° to 45 °. Good angle. The portion of the target that is most likely to be sputtered, that is, the thick portion 5 is intensively sputtered. Although the erosion part is mostly formed also on the inclined surface 8, the amount of erosion is smaller than that of the thick part 5, and the amount decreases as approaching the edge. Thus, the inclined surface can reduce the local progress of the erosion. The thin portion 6 may also be sputtered, but the amount is small. The width of the thin portion 6 is designed in consideration of the safety of the sputtered area.

FIG. 2A shows a cross-sectional shape in which the thick portion of the target is substantially trapezoidal. The center is a thick part and both ends are thin parts. FIGS. 2 (b) to 2 (c) and FIG. 3 (d) show cross sections of a target race track as another example of the present invention.
To (f) and FIGS. 4 (g) to (i). In FIG. 2B, the top surface (upper surface) of the thick portion of the target is flat, and the slope (straight slope) is continuously inclined to the edge of the target.
In the case where the slope or the arc surface continues to the edge of the target in this manner, the thin portion may not be formed, but a thin portion may be formed around the slope or the arc surface for more safety. The top surface of the thick part of the target shown in FIG. 2 (c) is flat, and both ends are continuously inclined with an upper arc surface, smoothly continue to the edge of the target, and the end point. At both ends of the target shown in FIG. 3D, straight slopes are formed in two steps with a horizontal plane in between. Those having a step form a discontinuous slope as shown in the figure. FIG. 3 (e)
The top surface of the thick portion of the target shown in (1) is flat, and both end portions have slopes (straight slopes) continuously inclined to the edge of the target. The top surface of the thick part of the target shown in FIG. 3 (f) is flat, and both ends are continuously curved to the edge of the target with lower arc surfaces. The cross section of the target shown in FIG. 4 (g) is a convex upper arc surface, which has no flat portion and continues to the outer end of the target. FIG. 4H shows an example in which the cross section of the target is reduced stepwise (in this case, two steps) from the thick part to the thin part. The joining of each step is an example having a vertical surface. The cross section of the target shown in FIG. 4 (i) is an example having a discontinuous surface which is joined from a thick part to a thin part by an inclined surface and a vertical surface.
2 (b) to 4 (g) show examples other than trapezoidal thick portions (including those approximating trapezoids). The thick part, the thin part, and the inclined part (plane) between them are at least selected from the above-mentioned straight inclined plane, upper arc plane, lower arc plane, a combination thereof, or a combination of these plane and vertical planes. It can be appropriately formed using one kind of continuous or discontinuous surface. Although details of the junction (corner) between the slope of the target and the thick portion or the thin portion shown in FIGS. 2 to 4 (a) to (g) are not shown, if these corners are steep. Since irregularities may occur during molding or sintering of the target material, and there is a risk of damage during the handling operation, it is desirable that the corners be formed to have a gentle curved surface as shown in FIG. . FIG.
Is a typical example of this, in which a rounded corner is formed and the inclined portion is curved. The hatched portion in the figure indicates the target material. As described above, chamfering the ridge or corner at each intersection of the horizontal plane, the inclined plane, the arc plane, and the vertical plane with R 0.1 mm or more is effective in preventing the above-described defects.

FIG. 5 is an explanatory cross-sectional view of a target showing an erosion profile when a flat target is sputtered and a profile of a target having a trapezoidal thick portion according to the present invention. In FIG. 5, the horizontal axis is the target dimension (mm), and the vertical axis is the erosion depth (Er).
osion Depth) or the height (mm) of the thick portion of the trapezoid. The distance between the imaginary intersection A between the erosion profile 9 when a flat target is sputtered and the inclined surface 10 of the target having the trapezoidal thick portion of the present invention and the top surface 11 of the thick portion is 5 mm or less. , Preferably 2 mm or less, more preferably 0.4 mm or less. As a result, it is possible to reduce the amount of a target material for an oxide sintered body such as ITO corresponding to the erosion profile.

The center line average surface roughness Ra of the sputter surface of the assembly 1 of an oxide sintered body target such as ITO is 4 μm.
Or less, preferably 1 μm or less, the relative density of the target is 80% or more, preferably 90% or more, and the density distribution of the target is within 0.04%, preferably 0.02%.
%. Since the target assembly 1 of an oxide sintered body such as ITO is composed of a plurality of divided parts, it is necessary to avoid variations in the manufacturing process. In the range of the above numerical values, a sputtering target assembly 1 of an oxide sintered body such as a preferable ITO can be obtained. In particular, when the density distribution of the target is in the above range, a uniform sputter film can be obtained.

[0017]

According to the present invention, efficient sputtering capable of coping with local erosion due to magnetron sputtering is enabled, and the amount of the target material of an expensive oxide sintered body such as ITO can be used without affecting the sputtering performance. Provided is an oxide sintered compact sputtering target assembly that can save as much as possible and can easily produce a large product that is difficult to integrally mold. Both ends of an oxide sintered body target assembly such as ITO have a horseshoe-shaped thick part and a thin part around it are easy to work because they are almost rectangular in plan view. The advantage is that only one mold is required. In addition, since it has a relatively compact shape, no cracking occurs during sintering or handling, and the processing yield is greatly improved. Similarly, the parallel portions made of one or more pairs of oxide sintered body target assemblies such as ITO can have basically the same shape. As in the case of the above both ends, only one powder molding die is required,
Since it has a relatively simple shape, cracking does not occur during sintering or handling, and the processing yield is greatly improved. Also, by increasing the number of pairs of parallel parts,
The shape of the oxide sintered body target assembly such as ITO can be made larger, and the dimensions of the oxide sintered body target assembly such as ITO can be easily exchanged according to the film forming conditions. A). The cross-sectional shape of the race track is substantially trapezoidal, and erosion occurs intensively in the thick portion of the trapezoid. The sloping surface also partially becomes an erosion portion, and the sloping surface can reduce local progress. Also, if necessary, the cross-sectional shape of the race track, for example, between the thick portion and the thin portion,
It can be modified to have at least one continuous or discontinuous slope selected from a straight slope, an upper arc face, a lower arc face, or a combination thereof, or a combination thereof with a flat or vertical surface. Thereby, it is possible to obtain a target shape that can cope with various erosion. The non-erosion portion located at the center of the race track has a material that does not contaminate a sputtering thin film of an oxide sintered body such as an element constituting a target material such as a metal In braze or a brazing material containing an element constituting the target material. Since the (metal) is exposed, even if the central non-erosion portion is sputtered, a harmless material such as metal In only flies, which is a source of contamination for oxide film formation such as ITO. Can be prevented. Thus, a sputtered film of stable quality can be obtained by a simple process. As described above, ITO corresponding to the erosion profile
By arranging thick portions of the oxide sintered body target such as intensively, waste can be omitted as a whole, and the efficiency of the oxide sintered body target such as ITO can be greatly improved and the raw material can be saved.

[Brief description of the drawings]

FIG. 1 is an external explanatory view of a sputtering target assembly of an oxide sintered body such as ITO of the present invention.

FIG. 2 is a schematic explanatory view showing various examples of a thick portion of a target of the present invention, that is, a cross-sectional shape of a race track.
(C).

FIGS. 3 (d) to 3 (f).

FIGS. 4 (g) to (i).

FIG. 5 is an explanatory view of a cross section of a target showing an erosion profile when a flat target is sputtered and a profile of a target having a trapezoidal thick portion of the present invention.

FIG. 6: R-shape so that the corner becomes a gentle curved surface,
It is explanatory drawing which shows the example which curved the inclined part.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Oxide sintered compact sputtering target assembly of ITO etc. 2 Backing plate 3 Both ends of target assembly 4 Parallel part of target assembly 5 Horseshoe-shaped thick part or parallel thick part of race track 6 Thin part of race track 7 Exposed portion of metal In (wax) 8 Inclined surface between thick portion and thin portion 9 Erosion profile when flat target is sputtered 10 Profile of target having trapezoidal thick portion of the present invention 11 Trapezoid thick portion 12 The angle of the inclined surface 8 A The virtual intersection point between the erosion profile when a flat target is sputtered and the inclined surface of the target having a trapezoidal thick portion

Claims (7)

(57) [Claims] 1. An oxide sintered body target assembly for magnetron sputtering, wherein an oxide sintered body does not exist in a central non-erosion portion, and a surface of a backing plate in the central non-erosion portion is the target material. Is covered with a brazing material containing the element constituting the target material or the target material, so that the thickness of the most easily sputtered portion of the target becomes a race track shape which is thicker than the non-erosion portion. Each portion of the oxide sintered body target divided into two is combined, and the oxide sintered body target assembly further has a rectangular end portion as viewed in plan, and a pair or a plurality of parallel pairs disposed therebetween. And a central non-erosion portion between the two end portions and the parallel portion where the oxide sintered body does not exist. Oxide sintered body sputtering target assembly. 2. Both ends of a rectangular shape have a horseshoe-shaped thick portion and a thin portion surrounding the horseshoe-shaped portion, and the thick portion and the thin portion formed in parallel portions are formed in the horseshoe shape when assembling the oxide sintered body target. 2. The oxide sintered body sputtering target assembly according to claim 1, wherein the sputtering target assembly has a racetrack shape aligned with each of the thick portion and the end portion of the thin portion. 3. 3. The oxide sintered body according to claim 1, wherein a cross-sectional shape of the thick portion is substantially trapezoidal, and an average slope of the slope is 5 ° or more and less than 90 °. Sputtering target assembly. 4. At least a portion selected from a straight slope, an upper arc surface, a lower arc surface, a combination thereof, and a combination thereof with a flat surface or a vertical surface, between the thick portion and the thin portion or on the periphery of the thick portion. The oxide sintered compact sputtering target assembly according to any one of claims 1 to 3, comprising one kind of continuous or discontinuous slope. 5. The oxide sintering according to claim 4, wherein the ridges or corners at the intersections of the horizontal plane, the inclined plane, the arc plane, and the vertical plane are chamfered with R of 0.1 mm or more. Body sputtering target assembly. 6. A distance between an imaginary intersection between an erosion profile when a flat target is sputtered and a slope of a target having a substantially trapezoidal thick portion and a top surface of the thick portion is 5 mm or less. The oxide sintered compact sputtering target assembly according to claim 4 or 5, wherein: 7. A center line average surface roughness Ra of a sputtered surface.
The oxide sintered compact sputtering target according to any one of claims 1 to 6, wherein the target has a relative density of 4 µm or less, the target has a relative density of 80% or more, and the target has a density distribution within 0.04%. Assembly.