WO2021024896A1

WO2021024896A1 - Divided sputtering target

Info

Publication number: WO2021024896A1
Application number: PCT/JP2020/029196
Authority: WO
Inventors: 矢野　智泰; 打田　龍彦; 享祐寺村
Original assignee: 三井金属鉱業株式会社
Priority date: 2019-08-08
Filing date: 2020-07-30
Publication date: 2021-02-11
Also published as: JP7419379B2; JPWO2021024896A1; CN113811633A; KR20220039648A; JP2024028973A; TW202108795A

Abstract

[Problem] To provide a divided sputtering target that can suppress a constituent material of a backing plate from contaminating a thin film being formed during sputtering processing. [Solution] A divided sputtering target is provided with: a substrate; a plurality of target members disposed on the surface of the substrate so that neighboring target members are separated from each other by gaps; a joining material disposed between the surface of the substrate and the plurality of target members; and a protective member disposed on the surface of the substrate to cover at least the gaps so that the substrate surface is not sputtered from the gaps between mutually neighboring target members. The protective member comprises: a first portion that extends in a first direction; a second portion that extends in a direction that intersects the first direction; and a third portion that links the first portion and the second portion.

Description

Split sputtering target

The present invention relates to a split sputtering target, and more particularly to a split sputtering target in which a protective member is provided in a gap between adjacent target members so that the backing plate is not exposed.

In recent years, the sputtering method has been widely used in manufacturing electronic components such as information equipment, AV equipment, and home appliances. For example, in a display device such as a liquid crystal display device, a semiconductor element such as a thin film transistor is subjected to the sputtering method. It is formed. This is because the sputtering method is extremely effective as a manufacturing method for forming a thin film constituting a transparent electrode layer or the like in a large area with high accuracy.

By the way, in recent semiconductor devices, oxide semiconductors typified by IGZO (In-Ga-Zn-O) are attracting attention instead of amorphous silicon. As for this oxide semiconductor, it is desired to form an oxide semiconductor thin film by using a sputtering method as in the case of amorphous silicon. However, in the sputtering target of the oxide semiconductor used for sputtering, since the material is ceramic, it is difficult to construct a large-area target with a single target member. Therefore, a plurality of oxide semiconductor target members having a certain size are prepared, each oxide semiconductor target member is arranged on a substrate called a backing plate having a desired size, and the substrate and each target member are joined. By doing so, a large-area oxide semiconductor sputtering target is manufactured (see, for example, Patent Document 1).

The backing plate of this sputtering target is usually made of copper or a copper alloy, and low melting point solder having good thermal conductivity such as In-based or Sn-based metal is used for joining the backing plate and the target member. .. For example, when manufacturing a large-area oxide semiconductor sputtering target, a backing plate having a desired area is prepared, the surface of the backing plate is divided into a plurality of sections, and an oxide semiconductor target member having an area suitable for the sections is provided. Prepare more than one. Then, a plurality of target members are arranged on the backing plate, and each target member is joined to the backing plate via low melting point solder. At the time of this joining, in consideration of the difference in thermal expansion between the backing plate and the target member, the adjacent target members are adjusted and arranged so that a gap of 0.1 mm to 1.0 mm is formed at room temperature. Will be done.

In such a split sputtering target in which a plurality of oxide semiconductor target members are joined, a gap is provided between the target members as described above, so that the backing occurs from the gap between the target members during the sputtering process. The plate is also sputtered, and there is a concern that the backing plate material may be mixed in the thin film of the oxide semiconductor to be formed. Therefore, the end cross section of each target member is processed so as to be inclined so that the plasma does not reach the backing plate surface during the sputtering process (for example, Patent Document 2 and the like), and the gap between adjacent target members is prevented. A protective member is provided on the backing plate to prevent the backing plate from being exposed (for example, Patent Document 3 and the like).

Japanese Unexamined Patent Publication No. 2005-232580 Japanese Unexamined Patent Publication No. 2-254164 International Publication No. 2012/0653524 Pamphlet

In the split sputtering target as described above, the method proposed in Patent Document 2 and the like is simple because it is not necessary to provide a protective member in the gap between the split target members, but it is necessary to process the end portion of the split target member. It cannot be said that it is a simple method. Therefore, the method proposed in Patent Document 3 and the like is generally applied.

In the method proposed in Patent Document 3 and the like, that is, in the method of providing a protective member in the gap between adjacent target members, when the single-wafer target member is arranged on the surface of a rectangular large-area backing plate, it is long. A protective member having a shape is prepared, cut to a desired length, and as shown in FIG. 3, for example, the protective member of the first portion extending in the first direction and the direction intersecting the first direction. A second part of the protective member extending to the surface is manufactured. Next, each protective member is attached to the backing plate so that the gap between the target members corresponds to the portion where the protective member is provided, and each target member is attached via the bonding material to manufacture a sputtering target. be able to.

In the split sputtering target manufactured as described above, as shown in FIG. 3, the first portion and the second portion of the protective member are not joined, and strictly speaking, a gap (interface) exists. .. Therefore, even when the target members are bonded together, the gaps between the protective members are exposed, and the constituent material of the backing plate may be mixed in the thin film to be formed during the sputtering process.

Therefore, an object of the present invention is to provide a split sputtering target capable of suppressing the constituent materials of the backing plate from being mixed into the thin film during sputtering.

As a result of examining such a problem, the present inventors have found that by providing a third portion connecting the first portion and the second portion of the protective member, the constituent material of the backing plate is contained in a thin film during the sputtering process. It was found that it can be suppressed from being mixed in. The present invention is based on such findings. According to the present invention, the following split sputtering targets are provided.

The split sputtering target according to the present invention
With the base
A plurality of target members in which adjacent target members are arranged with a gap on the surface of the substrate, and
A bonding material provided between the surface of the substrate and the plurality of target members,
A protective member provided on the surface of the substrate so as to cover at least the gap so that the surface of the substrate is not sputtered from the gap between the target members adjacent to each other.
It is a split sputtering target equipped with
The protective member includes a first portion extending in the first direction, a second portion extending in a direction intersecting the first direction, and a third portion connecting the first portion and the second portion. It has.

According to the present invention, a first portion extending in the first direction, a second portion extending in a direction intersecting the first direction, and a third portion connecting the first portion and the second portion. By using the protective member having the above, it is possible to prevent the constituent material of the backing plate from being mixed into the thin film during sputtering.

The perspective view which shows one Embodiment of the split sputtering target of this invention. FIG. 5 is a plan view showing a state before bonding the target members when manufacturing the split sputtering target of FIG. 1. The plan view of the part where the 1st part and the 2nd part of the protection member intersect with each other in the conventional split sputtering target. FIG. 3 is an enlarged plan view of a portion where the first portion and the second portion of the protective member intersect in the split sputtering target of the present invention. An enlarged plan view showing another embodiment of a portion where the first portion and the second portion of the protective member intersect. An enlarged plan view showing another embodiment of a portion where the first portion and the second portion of the protective member intersect. FIG. 5 is an enlarged cross-sectional view showing another embodiment of a portion where the first portion and the second portion of the protective member intersect. FIG. 3 is a perspective view showing another embodiment of a portion where the first portion and the second portion of the protective member intersect. AA'cross-sectional view of the split sputtering target shown in FIG. The external view which shows the shape of the protective member produced in Example 1. FIG. FIG. 3 is a perspective view illustrating a state in which the protective member produced in the first embodiment is attached to the surface of the backing plate. The perspective view of the split sputtering target produced in Example 1. FIG. The external view which shows the shape of the protective member produced in Example 2. FIG.

The split sputtering target according to the embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the split sputtering target of the present invention, and FIG. 2 is a top view of a state before bonding the target members when manufacturing the split sputtering target of FIG. It is a plan view. The split sputtering target 1 of the present invention includes a substrate 10 and a plurality of

target members

20a, 20b, 20c, and 20d in which adjacent target members 20 are arranged on the surface of the substrate 10 with a gap 30. There is. The split sputtering target shown in FIG. 1 is composed of four target members, but may be composed of six or more target members depending on the size of the substrate 10.

The width of the gap provided between the four

target members

20a, 20b, 20c, and 20d is adjusted in consideration of the difference in the coefficient of thermal expansion between the substrate 10 and the target member, but is generally 0.1 to 1.0 mm. Each target member is arranged with a gap of about.

The four

target members

20a, 20b, 20c, and 20d are arranged on the surface of the substrate 10 with a constant gap 30, but as shown in FIG. 2, the surface of the substrate 10 covers at least the gap 30. Protective members 40 (401, 402, 403) are provided on the top. Since the protective members 40 (401, 402, 403) are provided on the surface of the base material 10, it is possible to prevent the base material 10 from being sputtered from the gaps 30 of the target members 20 adjacent to each other. The protective member 40 can be attached to the surface of the substrate 10 by using low melting point solder, conductive double-sided tape, or the like at a position corresponding to the gap 30 formed between the target members 20.

Each target member 20 is bonded to the substrate 10 using a bonding material (not shown). As the bonding material, a known bonding material can be used without particular limitation, and for example, low melting point solder of In or Sn can be preferably used. To join the base 10 and each target member 20, the base 10 and each target member 20 are heated to a temperature at which the joining material melts, the joining material is applied to the surface of the base 10, and each target member 20 is melted. It is carried out by placing it on the bonded material and cooling it to room temperature.

FIG. 4 is an enlarged plan view of a portion where the first portion and the second portion of the protective member intersect in the split sputtering target of the present invention. As shown in FIG. 4, the protective member 40 extends in a direction intersecting the first direction (vertical direction in FIG. 4) with the first portion 401 extending in the first direction (horizontal direction in FIG. 4). It has a second portion 402 that exists and a third portion 403 that connects the first portion 401 and the second portion 402. In the conventional split sputtering target, for example, when manufacturing the split sputtering target as shown in FIG. 1, a protective member (first member) corresponding to the protective member 401 and a protective member (first member) corresponding to the protective member 402 ( The second member) was prepared and bonded to the surface of the substrate as shown in FIG. Therefore, even if the first member and the second member of the protective member are not connected and both are arranged so as not to generate a gap, a gap (interface) is provided between the first member and the second member of the protective member. Was present, and when sputtering was performed, the constituent material of the backing plate was sometimes mixed in the thin film. In the present invention, as shown in FIG. 4, by providing the third portion 403 that connects the first portion 401 and the second portion 402, the gap (interface) between the first portion 401 and the second portion 402 is eliminated. , It is possible to prevent the constituent material of the backing plate from being mixed into the thin film during sputtering.

The protective member as shown in FIG. 4 can be formed, for example, by connecting the first portion 401 and the second portion 402 by the third portion 403. The protective member can be formed by using a ceramic material or a polymer material as described later, but the third part 403 is formed by welding the first part 401 and the second part 402 made of the ceramic material with the same type of ceramic material. The first portion 401 and the second portion 402 made of the polymer material may be connected by the third portion 403 by melting the same kind of polymer material.

Further, in one embodiment, as shown in FIG. 5, the protective member may be integrally formed with the first portion 401, the second portion 402, and the third portion 403. The integrally formed protective member as shown in FIG. 5 can be obtained, for example, by cutting out a flat plate-shaped ceramic material or a polymer material so as to have a cross-shaped shape as shown in FIG. When the protective member is integrally formed by cutting out from a flat plate-like material, as shown in FIG. 6, the third portion 403 connecting the first portion 401 and the second portion 402 is processed so as to have a rounded portion R. It is preferable to do so. By rounding the intersection of the first portion 401 and the second portion 402, it is possible to further suppress the constituent materials of the backing plate from being mixed into the thin film.

In addition, in FIGS. 4 to 6, as a protective member, an embodiment (that is, a cross-shaped protective member) in which the extending direction of the first portion and the extending method of the second portion intersect so as to be orthogonal to each other is used. Although shown, the shape is not limited to this, and can be a shape corresponding to the shape of the gap 30 formed between the target members 40.

Further, as another embodiment of the protective member, as shown in FIG. 7, a third portion 403 connecting the first portion 401 and the second portion 402 may be integrally formed with the second portion 402. .. That is, at the intersection of the first portion 401 and the second portion 402, the third portion 403 may be integrally formed with the second portion 402 so as to cover the first portion 401. As the protective member according to the embodiment as shown in FIG. 7, for example, two long protective members (401 and 402) are prepared, and two protective members (401 and 402) are stacked so as to form a cross shape. Can be made to match. In this case, the portion where the two protective members overlap can be regarded as the third portion 403. Note that FIG. 7 is an enlarged cross-sectional view showing another embodiment of the portion where the first portion and the second portion of the protective member intersect with each other, but is low when the substrate 10 and the protective member 40 are attached. Adhesive materials such as melting point solder and conductive double-sided tape are not shown.

In the protective member shown in FIG. 7, since the third portion 403 is integrally formed with the second portion 402 so as to cover the first portion 401, the upper surface of the second portion 402 and the upper surface of the third portion 403 There is a step between them. Since the target member is arranged on a part of the protective member 40 as shown in FIG. 2, if there is a step, it is necessary to apply the joining material to the extent that the step is filled.

As described above, when two long protective members (401 and 402) are prepared and the two protective members (401 and 402) are overlapped so as to form a cross shape, the first part 401 and the second As shown in FIG. 8, a notch 401A is formed in a part of the first member 401, and a notch 402A is also formed in a part of the second member 402 so as to eliminate the step at the intersection with the portion 402. The integrated protective member 40 may be formed by fitting the

notches

401A and 402A to each other.

FIG. 9 shows a cross-sectional view taken along the line AA'of the split sputtering target 1 shown in FIG. As described above, the protective member 40 (first member 401) is attached to the surface of the substrate 10 (the adhesive material is not shown), which is the same as the thickness of the protective member 40 (first member 401). The bonding material 50 is provided so as to be about the same, and the

target members

20a and 20b are arranged on the bonding material 50 with a predetermined gap.

The substrate 10 is also called a backing plate, and as the material thereof, the same material as the backing plate used for a known sputtering target can be used without particular limitation. For example, a copper-based material, a titanium-based material, or aluminum can be used. A material having excellent conductivity and excellent thermal conductivity, such as a system material, can be used. Although not shown in FIG. 9, a cooling mechanism is provided on the back surface side of the base 10 (that is, the side opposite to the side where the

target members

20a and 20b are provided) to indirectly connect the

target members

20a and 20b via the base 10. It may be configured so that it can be cooled.

The split sputtering target in the present invention is not limited to the flat plate shape shown in FIG. 1 and the like, and may have a cylindrical shape. The flat plate-shaped split sputtering target is formed by arranging a plurality of flat plate-shaped target members having a substantially rectangular shape on a flat plate-shaped substrate and joining them. On the other hand, in the case of a cylindrical sputtering target, a plurality of cylindrical target members (hollow cylinders) are penetrated around the cylindrical base, and the cylindrical base is arranged in multiple stages in the direction of the cylinder axis and joined, or hollow. A plurality of curved target members obtained by vertically dividing a cylinder in the direction of the cylinder axis are arranged and joined to the outer surface of the cylindrical substrate in the circumferential direction. These flat plate-shaped or cylindrical split sputtering targets can be suitably used for large-area sputtering equipment.

When arranging a plurality of split sputtering targets, the gap between the adjacent split sputtering targets depends on the difference in thermal expansion between the base material (backing plate) used and the sputtering target and the size of the split sputtering targets. Usually, it is adjusted and arranged so that a gap of 0.1 mm to 1.0 mm is formed at room temperature.

The shape of the target member is not limited, but when a flat plate-shaped split sputtering target is used, it is preferable to use a plurality of flat plate-shaped target members having a substantially rectangular shape. Further, the composition of the target member is not particularly limited, and for example, oxides such as IGZO, ZTO and ITO and metals such as Al can be applied, and the composition thereof is also not limited.

Materials constituting the protective member include metal materials such as Zn, Ti, Sn, oxides containing one or more of In, Zn, Al, Ga, Zr, Ti, Sn, Y, and Mg, nitrides, and foot. Ceramic material consisting of compound or oxyfluoride, phenol resin, melamine resin, epoxy resin, urea resin, vinyl chloride resin, polyethylene, polypropylene, polyvinyl chloride, polypropylene, polystyrene, polyvinyl acetate, ABS resin, AS resin, acrylic resin , Polyacetal, Polycarbonate, Polyester, Polyphenylene ether, Polyarylate, Polysulfone, Polyphenylene sulfide, Polyether ether ketone, Polyimide resin, Fluororesin and other polymer materials. Among these, ceramics material and polymer material are preferable. Can be used.

The protective member of the split sputtering target shown in FIG. 9 is a single layer, but the protective member may have a laminated structure of two or more layers. In that case, it is preferable that the outermost surface layer of the protective member is composed of the above-mentioned ceramic material or polymer material. For example, it may be a protective member having a two-layer structure of a lower layer made of a metal material such as Zn, Ti, Sn, Cu, and SUS and an upper layer made of a ceramic material or a polymer material. When a ceramic material is used for the upper layer, an upper layer made of the ceramic material can be formed on the lower layer made of the metal material by using a vapor deposition method, a sputtering method, a plasma spraying method, a coating method, or the like.

When the protective member has a laminated structure of two or more layers made of different materials as described above, a third portion 403 connecting the first portion 401 and the second portion 402 is formed by welding as shown in FIG. When doing so, it is preferable to monitor the temperature rise while cooling the protective member so that the protective member is not affected by heat as much as possible. By joining in this way, even when dissimilar materials are laminated, it is possible to suppress delamination between the layers due to the difference in thermal expansion between the two materials. When the protective member is partially peeled off, the base material is exposed, the lower layer of the protective member is exposed, and in some cases, when sputtering is performed, a thin film formed by the constituent material of the base material or the lower layer of the protective member. There is a risk of mixing inside.

The thickness of the protective member is preferably 0.0001 mm to 1.0 mm. The width of the protective member is not particularly limited as long as it can cover the gap formed between the adjacent target members, but is preferably 5 mm to 20 mm in consideration of workability and the like. ~ 20 mm is more preferable.

The split sputtering target of the present invention can be applied to both the DC sputtering method and the high frequency sputtering method, but is particularly suitable for the DC sputtering method because it can suppress the generation of particles.

Next, the embodiments of the present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

<Preparation of backing plate>
As a backing plate, a copper plate having a diameter of 110 mm and a thickness of 6 mm was prepared.

<Preparation of target members>
The raw material powders of In ₂ O ₃ , Ga ₂ O ₃ , and Zn O were weighed and mixed so as to have a molar ratio of 1: 1: 2, and mixed by a ball mill for 20 hours. Next, an aqueous polyvinyl alcohol solution diluted to 4% by mass as a binder was added so as to be 8% by mass with respect to the total amount of the mixed raw material powder, mixed, and then molded at a pressure of 500 kgf / cm ² . .. Then, it was fired in the air at 1450 ° C. for 8 hours to obtain a plate-shaped sintered body. Both sides of the obtained sintered body were polished with a surface grinder to prepare an IGZO target member having a diameter of 101 mm and a thickness of 5 mm. The obtained circular target member was cut so as to form an arc having a central angle of 90 degrees, and was divided into four arc-shaped members.

<Preparation of protective material>
A copper plate having a thickness of 0.3 mm was prepared, and ZrO ₂ was sprayed on one surface of the copper plate to prepare a protective member 1 having a two-layer structure in which the upper layer was ZrO ₂ and the lower layer was Cu.

<Example 1>
As the protective member 1 obtained as described above, one having a width of 20 mm and a length of 110 mm and two having a width of 20 mm and a length of 45 mm were prepared. Subsequently, these three protective members were arranged so as to form a cross as shown in FIG. 10, and the longer protective member and the shorter protective member were joined by welding. Welding was performed carefully while using a welding rod that can narrow the welding width and monitoring the temperature listing of the protective member.

Next, as shown in FIG. 11, the protective member 1 having a cross shape as described above was attached to the surface of the backing plate via an adhesive.
Subsequently, as shown in FIG. 12, four target members were joined on the backing plate via a low melting point solder (not shown) made of In to prepare a split sputtering target. At this time, the target members were arranged so that the gap between the target members was 0.5 mm.

<Example 2>
A split sputtering target was produced in the same manner as in Example 1 except that a protective member cut out from the protective member 1 so as to have a cross-shaped shape as shown in FIG. 13 was used.

<Example 3>
In the production of the protective member 1, the protective member 2 was produced in the same manner except that Al ₂ O ₃ was sprayed instead of spraying ZrO ₂ on one surface of the copper plate. Next, a split sputtering target was produced in the same manner as in Example 1 except that the protective member 2 was used instead of the protective member 1.

<Comparative example 1>
A split sputtering target was produced in the same manner as in Example 1 except that the longer protective member and the shorter protective member were not joined by welding. The gap between the longer protective member and the shorter protective member at this time was 0.8 mm.

<Sputter evaluation test>
The following sputtering evaluation tests were performed on each of the split sputtering targets obtained as described above.
First, an IGZO thin film having a thickness of 14 μm was formed on a glass substrate (EAGLE XG (registered trademark), manufactured by Corning Inc.) using a sputtering apparatus (EX-3013M, manufactured by Vacuum Equipment Industry Co., Ltd.). Subsequently, a portion directly above the crossed portion of the crosses of the split sputtering target was cut out from the formed glass substrate.
Atomic absorption analysis was performed on the thin film on the surface of the cut glass substrate, and the amount of Cu mixed in the IGZO thin film was measured. The amount of Cu in the IGZO thin film formed by using each split sputtering target is as shown in Table 1.

As shown in Table 1, a first portion extending in the first direction, a second portion extending in a direction intersecting the first direction, and a third portion connecting the first portion and the second portion are formed. In the case of using such a protective member (Examples 1 to 3), the amount of Cu mixed in the IGZO thin film was less than 2 mass ppm (below the detection limit of atomic absorption spectrometry). On the other hand, in the case of using a conventional protective member having no third portion connecting the first portion and the second portion (Comparative Example 1), the amount of Cu mixed in the IGZO thin film is 15 mass ppm at the intersecting portion. there were.

From the above evaluation results, it can be seen that the split sputtering target of the present invention can effectively prevent impurities from being mixed into the thin film to be formed. Therefore, it can be said that the split sputtering target of the present invention is useful when forming a thin film having a large area.

1 split sputtering target 10 substrate (backing plate)
20, 20a, 20b, 20c, 20d Target member 30 Gap 40 Protective member 50 Joining material 401 First part of protective member 402 Second part of protective member 403 Third part of protective member 401A Notch of first part 402A Second Partial cutout

Claims

With the base
A plurality of target members in which adjacent target members are arranged with a gap on the surface of the substrate, and
A bonding material provided between the surface of the substrate and the plurality of target members,
A protective member provided on the surface of the substrate so as to cover at least the gap so that the surface of the substrate is not sputtered from the gap between the target members adjacent to each other.
It is a split sputtering target equipped with
The protective member includes a first portion extending in the first direction, a second portion extending in a direction intersecting the first direction, and a third portion connecting the first portion and the second portion. Has a split sputtering target.
The split sputtering target according to claim 1, wherein the first portion, the second portion, and the third portion are integrally formed.
The first aspect according to claim 1, wherein the first part and the second part are made of the same material, and the third part is made of a material different from the first part and the second part. Split sputtering target.
The split sputtering target according to claim 1 or 2, wherein the extending direction of the first portion and the extending method of the second portion intersect so as to be orthogonal to each other.
The split sputtering target according to any one of claims 1 to 3, wherein the third portion connecting the first portion and the second portion has a rounded portion.
The split sputtering target according to any one of claims 1 to 5, wherein the protective member has a laminated structure of two or more layers.
The sputtering target according to claim 6, wherein the outermost surface layer of the protective member is made of a ceramic material or a polymer material.
The ceramic material is an oxide, nitride, fluoride, or oxyfluoride containing at least one selected from the group consisting of In, Zn, Al, Ga, Zr, Ti, Sn, Y, and Mg. The split sputtering target according to claim 7.
The split sputtering target according to any one of claims 1 to 8, wherein the target member is a flat plate having a substantially rectangular shape.