JP6359901B2 - Sputtering target - Google Patents

Description

  The present invention relates to a sputtering target formed by bonding a target material used in a sputtering method for forming a thin film and a backing plate with a bonding material.

  In general, a sputtering target is obtained by laminating a target material, which is a material for forming a thin film, on a backing plate called a backing plate made of a material having excellent conductivity and thermal conductivity via a bonding material. Yes. Since this target material continues to be impacted by an inert gas or the like in a plasma state during sputtering, heat accumulates in the target material and becomes high temperature, but is cooled through a backing plate.

  In recent years, with the increase in the size of a substrate on which a thin film is formed, there is a demand for a sputtering target as well. For this purpose, for example, as described in Patent Document 1, a plurality of divided target materials are arranged side by side. It has been proposed to use a sputtering target.

  In Patent Document 1, the backing plate is formed in a convex shape having a step at the central portion of the thick portion and the outer peripheral portion of the thin portion, and among the split target materials, the split target material disposed at the end is provided. Formed in an L-shaped cross section so as to contact the stepped portion of the backing plate, the other divided target materials were formed in a flat plate shape, and these were arranged so that the surface of the sputtering target was substantially flush. Are disclosed.

JP 2009-57598 A

  However, in a large-area, long-sized sputtering target composed of a plurality of divided target materials, a temperature difference is likely to occur between the target material side that becomes high during sputtering and the backing plate that is cooled by water cooling or the like. . For this reason, the curvature by the difference of the thermal expansion coefficient of the material of each division | segmentation target material and the thermal expansion coefficient of the material of a backing plate tends to generate | occur | produce. In particular, in a target material made of a brittle material such as silicon, the surface of the target material is likely to be cracked or peeled off during sputtering, and particles are generated from that portion and adhered to the substrate to be processed. Abnormal discharge may occur.

  This invention is made | formed in view of such a situation, and it aims at providing the sputtering target which can prevent the crack of the target material at the time of sputtering, and can prevent generation | occurrence | production of a particle.

The present invention is a sputtering target in which a plurality of divided target materials are arranged in a plane and formed into a long rectangular shape , and a backing plate joined .
Among pre Symbol dividing the target material, at least the target material longitudinal direction of the central portion through you form central dividing target material, which in plan view is formed in an elongated band plate having a predetermined width,
The pre-Symbol central dividing the target material a pair of central division target material aligned butt sides parallel to each other arranged in the lateral direction of the end of the end surface disposed at one end in the longitudinal direction of the central split target material It is formed by combining a plurality of sets, and a position where the end face of the center divided target material is abutted is arranged at the center position in the longitudinal direction of the target material .

  Thus, the sputtering target of the present invention is arranged such that at least the longitudinal direction of each central divided target material forming the central portion in the longitudinal direction of the target material is aligned with the longitudinal direction of the target material, and these central divided targets. The side faces in the short direction are arranged so as to make a pair of materials. For this reason, even if the sputtering target is warped during sputtering, the center-divided target material is easily bent, so that the surface of the target material is not easily cracked. Therefore, it is possible to prevent the generation of particles due to cracks on the surface of the target material.

In addition, by placing the position where the end face in the longitudinal direction of the center divided target material is abutted at the central position in the longitudinal direction where the deflection of the backing plate is the largest, that is, by arranging the divided surface of the target material, crack resistance Can be further improved.

In the sputtering rig target of the present invention, the target material may have a shape in which corner portions of the outer peripheral portion that are not eroded during sputtering are removed.
It is possible to prevent the particles sputtered from the target material from adhering to the non-erosion regions at the corners of the target material that are not eroded and falling off the adhered material.

In the sputtering target of the present invention, the target material may be subjected to a surface treatment for removing microcracks.
By performing in advance a surface treatment for removing the microcracks formed during processing, it is possible to avoid the occurrence of cracks due to the microcracks.

  According to the present invention, it is possible to prevent the target material from cracking during sputtering and to prevent generation of particles.

It is a top view which shows the sputtering target of 1st Embodiment of this invention. It is sectional drawing which shows the example of the sputtering device in which the sputtering target of this invention is used. It is a top view which shows the sputtering target of 2nd Embodiment of this invention. It is a schematic diagram explaining arrangement | positioning with the butting | matching part of a division | segmentation target material, and a process board | substrate. It is a schematic diagram explaining a water pressure test. It is a graph which shows the relationship between the water pressure by the difference in the material of a backing plate, and a displacement, (a) is a result of a backing plate with a diameter of 160 mm, (b) is a result of a backing plate with a diameter of 240 mm. It is a graph which shows the relationship between the water pressure and the displacement of a sputtering target by the difference in the material of a backing plate. It is a graph which shows the difference in the intensity | strength by the presence or absence of surface treatment of a target material, (a) is a result of a bending test, (b) is a result of a hydraulic pressure test. It is a top view which shows the division | segmentation state of the target material of an Example and a comparative example.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 2 shows an example of a magnetron sputtering apparatus in which the sputtering target of the present invention is used. In the magnetron sputtering apparatus 100, a stage 12 that holds a processing substrate 11 in a lower state in a vacuum chamber 10 and a target holder 13 that holds a sputtering target 1 in an upper part of the vacuum chamber 10 are provided. In addition, the surfaces of the processing substrate 11 and the sputtering target 1 (target material 20) are vertically opposed to each other with a space therebetween. In addition, magnets 14 a and 14 b disposed on the back side of the sputtering target 1 are provided inside the target holder 13. The target holder 13 is attached to the wall of the vacuum chamber 10 in an insulated state, and is connected to an external power source 15 for applying a voltage to the sputtering target 1. Further, the vacuum chamber 10 is formed with a gas inlet 16 for introducing an inert gas such as Ar gas, and a gas outlet 17 for exhausting and evacuating. The sputtering target 1 is formed by bonding a target material 20 on a backing plate 30 as will be described in detail later.

  In this sputtering apparatus 100, when the inside of the vacuum chamber 10 is kept in a vacuum state, a voltage is applied between the sputtering target 1 and the processing substrate 11 from the external power source 15, and an inert gas is introduced into the vacuum chamber 10, When the magnetic field from the magnets 14a and 14b on the back of the sputtering target 1 leaks to the surface 20a of the target material 20 as indicated by a two-dot chain line, the discharge plasma is densely formed on the surface 20a of the target material 20 as indicated by a broken line. Then, the ions of the inert gas are accelerated in the plasma and enter the target material 20, whereby the sputtered atoms sputtered from the surface 20 a of the target material 20 reach the processing substrate 11, and the surface A thin film is formed.

The target material 20 used in the sputtering apparatus 100 is made of a metal, an oxide, or the like that is a thin film material. In the present embodiment, the target material 20 is made of columnar crystal silicon. As shown in FIG. 1, the target material 20 is formed in a long rectangular shape by arranging a plurality of divided target materials 21 (center divided target materials in the present invention) in a planar shape.
Each divided target material 21 is formed in an elongated strip shape having a constant width in plan view. Then, the target material 20 includes a pair of divided target materials 21 and 21 that are arranged in parallel with each other, with the side surfaces arranged at one ends of the divided target materials 21 in the short direction, and the length of the divided target material 21. It is formed by abutting end faces arranged at one end in the direction and combining a plurality of sets (four sets in the illustrated example). In addition, a position where the end surfaces of the divided target materials 21 are overlapped is arranged at the center position of the target material 20 in the longitudinal direction, and the divided target materials 21 are arranged symmetrically with the center position of the target material 20 as a boundary. Yes.

In addition, the target material 20 is subjected to surface treatment in advance in order to remove microcracks formed during processing, and generation of cracks due to microcracks can be avoided. Examples of the surface treatment include a method of subjecting the sputtering surface 20a of the target material 20 to precise polishing, sputtering treatment, laser treatment, etching treatment, etc., in which the load and rotation speed of the grinding wheel are strictly controlled.
These divided target materials 21 are integrally joined to the backing plate 30 by a bonding material (not shown).

The backing plate 30 is made of a material having excellent conductivity and thermal conductivity such as oxygen-free copper, copper alloy, and molybdenum, and has a rectangular shape that is slightly larger in plan view than the target material 20 as shown in FIG. Is formed. And the surface of each division | segmentation target material 21 joined on this backing plate 30 is arrange | positioned so that it may become flush | level, and the sputtering target 1 by which the surface flush | aligned to this flush face was used as the sputtering surface 20a is comprised. .
The surface of the backing plate 30 is blasted, and when the reaction product is solidified and adhered during sputtering, the reaction product is prevented from falling off and becomes particles. Can be prevented.

  If an example of the dimension of this sputtering target 1 is shown, the width W1 of the backing plate 30 is formed to 130 mm, the length L1 is 610 mm, and the thickness is 6 mm, and the divided target material 21 is 60 mm in width and L2 in length. 150 mm and a thickness of 5 mm.

The sputtering target 1 configured in this manner is attached to the target holder 13 of the sputtering apparatus 100 with the sputtering surface 20 a on the side where the backing plate 30 is not provided facing the processing substrate 11.
Heat generated in the target material 20 at the time of sputtering is radiated through the backing plate 30. At this time, a temperature difference is likely to occur between the target material 20 side that becomes high temperature and the backing plate cooled by water cooling or the like, and the thermal expansion coefficient of the material of each divided target material and the thermal expansion coefficient of the material of the backing plate. Therefore, the sputtering target 1 is likely to be warped.

However, in the sputtering target 1 of the present embodiment, the longitudinal direction of each divided target material 21 is arranged in accordance with the longitudinal direction of the target material 20, and the short direction so that these divided target materials 21 are paired. The side faces are arranged to face each other. For this reason, even if the sputtering target 1 is warped during sputtering, the split target material 21 is easily bent, so that the surface of the target material 20 is less likely to be cracked. Each of the divided targets 21 is preliminarily surface-treated in order to remove microcracks and the like formed at the time of processing, and avoids promoting the occurrence of cracks due to these microcracks and the like. be able to.
Therefore, it is possible to prevent generation of particles and abnormal discharge due to cracks on the surface of the target material 20.

  Further, by arranging the position where the end face in the longitudinal direction of the divided target material 21 is abutted at the center position in the longitudinal direction where the deflection of the backing plate 30 is the largest, that is, by arranging the divided surface of the target material 20, The cracking property can be further improved.

  In addition, in the sputtering target 1 of 1st Embodiment, although the target material 20 whole was formed with the division | segmentation target material 21 of the same shape used as the elongate strip shape of planar view, the 2nd shown in FIG. Like the sputtering target 40 of the embodiment, both ends of the target material 25 are configured by the rectangular end divided target material 23, and at least the central divided target material 22 that forms the central portion in the longitudinal direction of the target material 25, A pair of centrally divided target materials 22, 22 that are formed in an elongated strip shape having a constant width in plan view and are arranged parallel to each other by abutting the side surfaces arranged at one end in the short direction of the centrally divided target material 22. May be configured such that a plurality of sets are combined by abutting end faces arranged at one end in the longitudinal direction of the center divided target material 22.

  As described above, in the sputtering target 40 according to the second embodiment, even when the sputtering target 40 is warped during sputtering, each center that forms a central portion where the warping amount of the target material 25 is the largest. The longitudinal direction of the divided target material 22 is arranged in accordance with the longitudinal direction of the target material 25, and the lateral side surfaces are arranged so as to make a pair with the central divided target material 22. For this reason, since the center division | segmentation target material 22 of the center part of the target material 25 becomes easy to bend at the time of sputtering, it is hard to produce a crack etc. on the surface of the target material 25. Therefore, similarly to the sputtering target 1 of the first embodiment, it is possible to prevent generation of particles and abnormal discharge due to cracks on the surface of the target material 25.

  In the case where a thin film is formed on a plurality of processing substrates using a sputtering target formed of a plurality of divided target materials, as shown in FIG. 4, the divided surfaces of the target material 28, that is, individual divided target materials 29. It is desirable to arrange the butted portions of the side surfaces in the short direction and the end surfaces in the longitudinal direction so as to avoid the position facing the processing substrate 19. Thereby, the influence of the particle | grains which may generate | occur | produce from the side part of the short direction of the division | segmentation target material 29 and the butt | matching part of the end surfaces of a longitudinal direction can be suppressed to the minimum.

  Moreover, in the said embodiment, although the target material comprised by a division | segmentation target material demonstrated using the thing of the form which makes a planar view rectangular shape, the shape of a target material is not limited to this, As indicated by a two-dot chain line in FIG. 3, the outer peripheral corner 24 that is not eroded during sputtering can be removed. In this case, it is possible to prevent the particles sputtered from the target material from adhering to the corners 24 of the region (non-erosion region) that is not eroded during sputtering and dropping off the adhered material. .

(Examples and Comparative Examples)
In order to confirm the effect of the present invention, various tests were conducted.
[About backing plate]
First, in order to confirm the difference depending on the material of the backing plate, the diameter 160 mm made of oxygen free copper (OFC), copper alloy (CrZr copper: Cr 1 at%, Zr 0.1 at%), molybdenum (Mo), or A disk-shaped backing plate having a diameter of 240 mm and a thickness of 6 mm was formed, and a “water pressure test” was performed on each backing plate.
As shown in FIG. 5, the “water pressure test” is performed by increasing the water pressure in the interior 51 of the water pressure tester 50 in a state where the entire circumference of each backing plate 60 is attached to the water pressure tester 50. The displacement amount of the backing plate 60 was measured and evaluated.
FIG. 6A shows the result of the backing plate having a diameter of 160 mm, and FIG. 6B shows the result of the backing plate having a diameter of 240 mm.

  As can be seen from FIGS. 6A and 6B, regardless of the diameter of the backing plate, the relationship between the water pressure and the displacement is determined by the material. It can also be seen that oxygen-free copper (OFC) is most flexible and molybdenum is most difficult to bend.

  Next, a columnar crystal of 200 × 125 × 5 mm is formed on a 210 × 135 mm backing plate made of oxygen-free copper (OFC) and a copper alloy (CrZr copper: Cr 1 at%, Zr 0.1 at%) and having a thickness of 5 mm or 7 mm. Samples of a sputtering target obtained by bonding a target material made of silicon (B (boron) dope: specific resistance of 3 to 10 mΩ · cm) with indium solder (0.2 mm thickness) are prepared, and the backing shown in FIG. A “hydraulic pressure test” was performed with the same configuration as the hydraulic pressure tester with a single plate.

  In this case, as shown in FIG. 5, with the entire circumference of the backing plate 60 of each sample attached to the water pressure tester 50, the water pressure inside the water pressure tester 50 is increased to bring the surface of the target material 61 to the surface. Evaluation was made on the ultimate pressure until fracture occurred or the peel plate was peeled off. The evaluation was performed by measuring the amount of warpage of the target material 61 at the time of destruction along with the evaluation of the ultimate pressure. The results are shown in FIG.

  As can be seen from FIG. 7, increasing the thickness of the backing plate resulted in an increase in the ultimate pressure.

[Target material]
Next, in order to confirm the difference in strength of the target material depending on the presence or absence of surface treatment on the target material, the target material (untreated) removed by etching microcracks or the like on the surface of the target material formed during processing Then, a target material (treated) in which microcracks and the like were formed without surface treatment after processing was prepared, and a “bending test” and a “hydraulic pressure test” were performed. Each target material was 200 × 125 × 5 mm columnar silicon (B (boron) doped).

The “bending test” was performed by a four-point bending test defined in JIS R 160 for each target material.
As shown in FIG. 5, the “hydraulic pressure test” is a sputtering target sample in which a target material is bonded to a 210 × 135 × 5 mm backing plate made of oxygen-free copper (OFC) with indium solder (0.2 mm thickness). Fabricated and performed on these samples. In this case, the “water pressure test” is performed by increasing the water pressure inside the water pressure tester 50 while the entire circumference of the backing plate 60 of each sample is attached to the water pressure tester 50, and cracking the surface of the target material 61. This is an evaluation of the ultimate pressure (breakdown pressure) until the breakage occurs or when the target material 61 is completely divided.
FIG. 8A shows the result of the “bending test” and FIG. 8B shows the result of the “water pressure test”.

  As can be seen from FIGS. 8A and 8B, the target material subjected to the surface treatment (treated) has a bending strength and a fracture ultimate pressure that are higher than those of the target material not subjected to the surface treatment (untreated). Large and good results were obtained.

Next, a sample of a sputtering target in which the shape of the target material was changed was prepared, and a test for confirming the ease of cracking due to the difference in the shape of the divided target material was performed.
The backing plate constituting the sample of the sputtering target is formed of a copper alloy (Cu-1 wt% Cr-0.1 wt% Zr), and each has a rectangular shape with a width of 135 mm, a length of 210 mm, and a thickness of 5 mm. A thing was used.
Moreover, the target material of each sample was formed of columnar crystal silicon (B (boron) dope), and each used a rectangular material having a width of 125 mm, a length of 200 mm, and a thickness of 10 mm. Further, Comparative Example 1 is a target material 20A having no dividing surface as shown in FIG. 9A, and Comparative Example 2 is a target material 20B that is divided into three in the longitudinal direction as shown in FIG. 9B. 1 is composed of a target material 20C divided into two in the lateral direction as shown in FIG.
And each sample of the sputtering target which bonded each target material 20A-20C to the backing plate 31 was produced, and the "water pressure test" and the "sputtering test" were done using these each sample.

As shown in FIG. 5, in the “water pressure test”, the water pressure in the interior 51 of the water pressure tester 50 is increased in a state where the entire circumference of the backing plate 31 of each sample is attached to the water pressure tester 50, and the target material 20A. It evaluates the ultimate pressure until fracture occurs on the surface of ~ 20C or peels from the backing plate 31, and measures the amount of warpage when the target materials 20A to 20C are destroyed along with the evaluation of the ultimate pressure. And evaluated. The water pressure test was performed three times (n1 to n3) for each sample.
Table 1 shows the results.

In the “sputtering test”, a sputtering target under the same conditions was prepared and used separately from each sample subjected to the water pressure test. In this sputtering test, each sputtering target is sputtered with a DC sputtering apparatus for 1 hour, with a power density of 10 Wh / cm ² and an integrated power amount of 10 WHr / cm ² . In addition, after each bonding, it confirmed that each sputtering target did not have a bonding defect, a crack, etc. by the X-ray transmission image previously. Then, the number of occurrences of abnormal discharge during sputtering, the number of occurrences of cracks in the target material, and the maximum size of the cracks generated in the target material were confirmed.
The results are shown in Table 2.

As can be seen from Table 1, Example 1 configured with the target material divided into two in the short direction had a large displacement at the time of breakage. As can be seen from Table 2, also in the sputtering test, the sputtering target of Example 1 did not cause cracks or the like during sputtering, and abnormal discharge was not confirmed.
In this way, the target material divided into two in the short direction, that is, the longitudinal direction of each divided target material is arranged in accordance with the longitudinal direction of the target material, and the short direction so that these divided target materials are paired By disposing the side surfaces of each other, the surface of the target material is hardly cracked, and particles and abnormal discharge due to the surface crack of the target material can be prevented.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the meaning of this invention, a various change can be added.

1,40 Sputtering target 10 Vacuum chamber 11 Process substrate 12 Stage 13 Target boulder
14a, 14b Magnet 15 External power supply 16 Gas inlet 17 Gas outlet 20, 20A to 20C, 61 Target material 20a Sputtered surface 21 Split target material 22 Center split target material (split target material)
23 End split target material (split target material)
24 Non-erosion portion 30, 31, 60 Backing plate 50 Hydraulic tester 51 Internal 100 Magnetron sputtering device

Claims (3)

A sputtering target obtained by joining a backing plate and a target material formed in a long rectangular shape by arranging a plurality of divided target materials in a planar shape,
Wherein the divided target material, at least the target material longitudinal central portion forming to that in central dividing target material, which in plan view is formed in an elongated band plate having a predetermined width,
A pair of centrally divided target materials, which are arranged in parallel with each other by abutting the side surfaces arranged at one end in the short direction of the centrally divided target material, are struck with the end surfaces arranged at one end in the longitudinal direction of the centrally divided target material. It is formed by combining multiple sets ,
A sputtering target, wherein a position where the end face of the center divided target material is abutted is arranged at a center position in a longitudinal direction of the target material . The sputtering target according to claim 1, wherein the target material has a shape in which corner portions of the outer peripheral portion that are not eroded during sputtering are removed. The target material sputtering target according to claim 1 or 2, characterized in that the surface treatment to remove the microcracks is applied.

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