JP2019035101A - Sputtering target - Google Patents

Abstract

To provide a sputtering target that avoids damage from thermal expansion, is easily manufactured, and protects a backing plate.SOLUTION: A sputtering target of the invention is composed of a plurality of target split pieces 20. At the side face 23 of neighboring target split piece, upper side faces 23a located at the primary surface 21 side are distant from each other, whereas lower side faces 23b located at the rear surface 22 side contact each other. Therefore, a backing plate is not sputtered in a sputtering step. Since the rear surface of the sputtering target is cooled by the backing plate, the lower side faces of the neighboring target pieces which contact each other are hardly damaged by thermal expansion. Further, a target unit or the like is not necessary to be filled in and thus the sputtering target is easily manufactured.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sputtering target, and more particularly, to a large sputtering target composed of a plurality of target divided pieces.

  The sputtering target used in the sputtering apparatus is generally integrally molded. However, since it is not easy to integrally mold a large sputtering target, it may be configured by combining a plurality of target divided pieces. Patent Documents 1 and 2 disclose a sputtering target composed of a plurality of target divided pieces.

  In the sputtering targets described in Patent Documents 1 and 2, the target divided pieces adjacent to each other are separated from each other, thereby preventing breakage due to thermal expansion during sputtering.

Japanese Patent Laid-Open No. 1-2230768 JP 11-61395 A

  However, the sputtering target described in Patent Document 1 has a problem that a manufacturing process is complicated and cost reduction is difficult because adjacent target pieces are bonded via a target unit. It was. Further, the sputtering target described in Patent Document 2 has a problem in that the exposed backing plate is sputtered because the backing plate is exposed from the gap between adjacent target split pieces. Furthermore, since particles accumulate in the grooves formed in the separated portions, there is a problem of causing abnormal discharge. When macro particles are generated due to abnormal discharge, the quality of the film deteriorates, and in the worst case, the target is damaged.

  Accordingly, an object of the present invention is a sputtering target composed of a plurality of target divided pieces, which is prevented from being damaged by thermal expansion, can be easily manufactured, suppresses the occurrence of abnormal discharge, and has a backing plate. It is providing the sputtering target which can protect.

  The sputtering target according to the present invention is a sputtering target composed of a plurality of target divided pieces, and the side surfaces of adjacent target divided pieces are separated from each other on the upper side surface located on the main surface side and on the lower side surface located on the back surface side. It is characterized by being in contact with each other.

  According to the present invention, since the lower side surfaces of the target division pieces adjacent to each other are in contact with each other, it is possible to prevent the backing plate from being exposed. For this reason, a backing plate is not sputtered at the time of sputtering. Moreover, since the back surface of the sputtering target is cooled by the backing plate, even if the lower side surfaces of the adjacent target divided pieces are in contact with each other, damage due to thermal expansion hardly occurs. On the other hand, since the main surface of the sputtering target is far from the backing plate, it becomes the highest temperature and the thermal expansion is the largest, but the upper side surfaces of the adjacent target split pieces are separated from each other, thus preventing damage due to thermal expansion. be able to. Furthermore, since it is not necessary to embed a target unit or the like separately between adjacent target divided pieces 20, it can be easily manufactured. In addition, since the target surface non-erosion region is not adjacent to each other, the target surface non-erosion region does not have a relatively low temperature portion, and there is no reattachment of particles, so that abnormal discharge can be suppressed.

  In the present invention, the thickness of the lower side surface may be 5/8 or less of the thickness of the target segment. According to this, damage due to thermal expansion can be prevented more reliably.

  In the present invention, the thickness of the lower side surface may be 3/8 or less and 1/10 or more of the thickness of the target segment. According to this, damage due to thermal expansion hardly occurs, and the lifetime of the sputtering target can be sufficiently ensured.

  In the present invention, the upper side surface may be chamfered in an arc shape or may be chamfered in a straight line shape. According to the former, the lifetime of a sputtering target can be made longer, and according to the latter, production of a target split piece becomes easier.

  In the present invention, the plurality of target divided pieces may be made of a ceramic material. According to this, it becomes possible to prevent breakage of the target split piece made of a ceramic material that is easily damaged by thermal expansion.

  Thus, according to the present invention, a sputtering target composed of a plurality of target divided pieces, which is prevented from being damaged by thermal expansion, can be easily manufactured, suppresses the occurrence of abnormal discharge, and It becomes possible to provide a sputtering target capable of protecting the backing plate.

FIG. 1 is a schematic plan view for explaining the configuration of a sputtering target 10 according to a preferred embodiment of the present invention. 2 is a schematic cross-sectional view taken along the line AA shown in FIG. FIG. 3 is a flowchart for explaining a manufacturing process of the sputtering target 10. FIG. 4 is a schematic cross-sectional view showing a state in which the sputtering target 10 is mounted on the backing plate 30 of the sputtering apparatus. FIG. 5 is a cross-sectional view of a sputtering target 10 according to a modification.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic plan view for explaining the configuration of a sputtering target 10 according to a preferred embodiment of the present invention, as viewed from the main surface side to be sputtered.

  The sputtering target 10 shown in FIG. 1 is configured by combining a plurality (for example, 10) of target divided pieces 20 in a plane. The planar size of the sputtering target 10 is arbitrary, but is about 130 mm × about 560 mm as an example. The material of the target segment 20 is not particularly limited, but the present invention is more effective when a material that is easily damaged, such as a ceramic material, is used. In the example shown in FIG. 1, the planar shape of the target divided piece 20 is a rectangle. However, the planar shape of the target segment 20 is not limited to the rectangle shown in FIG. 1 and may be a square, a parallelogram, a trapezoid, or a combination thereof. Further, the planar shape of the sputtering target 10 is not limited, and may be a disk shape.

  2 is a schematic cross-sectional view taken along the line AA shown in FIG.

  As shown in FIG. 2, the target segment 20 includes a main surface 21 to be sputtered, a back surface 22 located on the opposite side of the main surface 21, a side surface 23 facing the adjacent target segment 20, and an end of the sputtering target. Side surface 24. The thickness T of each target segment 20 is the same. As shown in FIG. 2, the side surface 24 is substantially perpendicular to the main surface 21 and the back surface 22, while the side surface 23 has a shape in which one corner is chamfered in an arc shape.

  More specifically, the side surface 23 has an upper side surface 23a located on the main surface 21 side and a lower side surface 23b located on the back surface 22 side. The lower side surface 23 b is substantially perpendicular to the main surface 21 and the back surface 22, and is in contact with the lower side surface 23 b of the adjacent target split piece 20. On the other hand, the upper side surface 23a is chamfered in an arc shape, and thus is separated from the upper side surface 23a of the adjacent target segment 20.

  Here, the relationship between the thickness Ta of the portion constituting the upper side surface 23a and the thickness Tb of the portion constituting the lower side surface 23b is preferably Ta ≧ Tb. In other words, the thickness Tb of the lower side surface 23b is preferably 5/8 or less of the total thickness T. Furthermore, the thickness Tb of the lower side surface 23b is more preferably 1/2 or less of the entire thickness T. In particular, the thickness Tb of the lower side surface 23b is 3/8 or less, 1/10 or more of the entire thickness T. Most preferably. The reason will be described later.

  FIG. 3 is a flowchart for explaining a manufacturing process of the sputtering target 10 according to the present embodiment.

  First, target raw materials (such as barium titanate) and necessary additives are weighed, mixed (Step S1), and then dried for granulation (Step S2). Next, the granular raw material is molded using a press molding method, a cold isostatic pressing method, or the like (step S3) and fired (step S4). Next, if processing such as surface grinding, external grinding, and chamfering is performed, individual target divided pieces 20 are completed (step S5). Then, if it bonds to the backing plate 30 so that the lower side surface 23b of the adjacent target division piece 20 may mutually contact, the sputtering target 10 by this embodiment will be completed (step S6).

  FIG. 4 is a schematic cross-sectional view showing a state in which the sputtering target 10 according to the present embodiment is mounted on the backing plate 30 of the sputtering apparatus.

  As shown in FIG. 4, the sputtering target 10 according to the present embodiment is mounted on the backing plate 30 so that the back surface 22 of each target segment 20 faces the backing plate 30. The backing plate 30 holds the sputtering target 10 and cools the sputtering target 10 from the back surface 22 side. Further, the sputtering apparatus generally takes a structure of cooling with cooling water from the side opposite to the back surface 22 side of the backing plate 30, and thereby the temperature of the sputtering target 10 is controlled. On the other hand, a substrate 40 to be deposited is held on the opposite side of the backing plate 30 when viewed from the sputtering target 10. Thereby, the main surface 21 of the sputtering target 10 and the substrate 40 are arranged to face each other through a predetermined space in which plasma is formed.

  And since the lower side surface 23b of the adjacent target division | segmentation piece 20 is mutually contacting, the sputtering plate 10 by this embodiment does not expose the backing plate 30 to plasma space. For this reason, since the backing plate 30 is not sputtered from the gap between the target split pieces 20, damage to the backing plate 30 can be reduced and higher quality film formation can be performed.

  The operation of attaching the sputtering target 10 to the backing plate 30 is performed at room temperature after the backing plate 30 is removed from the sputtering chamber. However, during actual sputtering, since the sputtering target 10 is exposed to high-temperature plasma, thermal expansion occurs in the sputtering target 10. When the thermal expansion occurs, the side surfaces 23 of the adjacent target divided pieces 20 are pressed against each other, so that the higher the temperature, the stronger the stress. However, in this embodiment, since the upper side surface 23a of each target split piece 20 is chamfered in an arc shape, the upper side surfaces 23a that become high temperatures do not contact each other, and this portion is not damaged. .

  On the other hand, stress due to thermal expansion is applied to the lower side surface 23b in contact with each other, but the lower side surface 23b is located in the vicinity of the backing plate 30 having a cooling function, so the temperature is lower than that of the upper side surface 23a. Small thermal expansion. For this reason, the stress applied to the lower side surface 23b is suppressed, and damage due to thermal expansion hardly occurs.

  Damage to the lower side surface 23b due to thermal expansion is less likely to occur as the thickness Tb of the lower side surface 23b is smaller. However, if the thickness Tb of the lower side surface 23b is too small, the backing plate 30 is exposed early due to the thinning of the sputtering target 10 as the sputtering proceeds, and the life of the sputtering target 10 is shortened. Accordingly, the thickness Tb of the lower side surface 23b is preferably designed in consideration of these.

  Specifically, if the thickness Tb of the lower side surface 23b is set to 5/8 or less of the entire thickness T, the occurrence rate of breakage due to thermal expansion can be clearly reduced. If the thickness Tb of the lower side surface 23b is set to 3/8 or less of the entire thickness T, in many cases, damage due to thermal expansion can be completely prevented. On the other hand, even when the thickness Tb of the lower side surface 23b is set to about 3/8 of the entire thickness T, the side surface 23 is less likely to be sputtered compared to the main surface 21, so that the lifetime of the sputtering target 10 is clearly reduced. Absent. In particular, when the shape of the upper side surface 23a is an arc shape as in the present embodiment, the groove formed by the adjacent upper side surface 23a becomes a shape that rapidly narrows toward the back. The rate of thinning is quite slow. Actually, when the upper side surface 23a is arcuate, the lifetime of the sputtering target 10 decreases when the thickness Tb of the lower side surface 23b is less than 1/10 of the total thickness T.

  As an example, when the thickness T of the target segment 20 made of barium titanate is set to 8 mm, damage due to thermal expansion frequently occurs when the thickness of the lower side surface 23b is 6 mm and 7 mm, but the thickness of the lower side surface 23b When the thickness is 5 mm, the occurrence rate of damage due to thermal expansion is clearly reduced, and when the thickness of the lower side surface 23b is 4 mm, the occurrence rate of damage due to thermal expansion is further reduced. When the thickness of the lower side surface 23b was 3 mm, 2 mm, and 1 mm, no damage due to thermal expansion occurred.

  On the contrary, abnormal discharge due to particle reattachment does not occur at all when the thickness of the lower side surface 23b is 4 mm or more, and when the thickness of the lower side surface 23b is 3 mm, 2 mm, and 1 mm, it is a non-erosion region. Particle re-adherence occurred slightly, but abnormal discharge did not occur.

  FIG. 5 is a cross-sectional view of a sputtering target 10 according to a modification. The modification shown in FIG. 5 is different from the above embodiment in that the upper side surface 23a of each target segment 20 is chamfered in a straight line. If the target divided piece 20 has such a shape, the processing of the target divided piece 20 becomes easier.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

DESCRIPTION OF SYMBOLS 10 Sputtering target 20 Target division | segmentation piece 21 Main surface 22 Back surface 23 Side surface 23a Upper side surface 23b Lower side surface 24 Side surface 30 Backing plate 40 Substrate

Claims (7)

  It is a sputtering target composed of a plurality of target divided pieces, and the side surfaces of the adjacent target divided pieces are separated from each other on the upper side surface located on the main surface side and are in contact with each other on the lower side surface located on the back surface side. Sputtering target characterized by the above.   The thickness of the said lower side surface is 5/8 or less of the thickness of the said target division piece, The sputtering target of Claim 1 characterized by the above-mentioned.   3. The sputtering target according to claim 2, wherein a thickness of the lower side surface is 3/8 or less and 1/10 or more of a thickness of the target divided piece.   The sputtering target according to any one of claims 1 to 3, wherein the upper side surface is chamfered in an arc shape.   The sputtering target according to any one of claims 1 to 3, wherein the upper side surface is chamfered linearly.   The sputtering target according to claim 1, wherein the plurality of target divided pieces are made of a ceramic material.   The sputtering target according to claim 6, wherein the plurality of target divided pieces are made of barium titanate.

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