JPH06248444A - Target for sputtering - Google Patents

Abstract

PURPOSE:To provide the target capable of preventing the crack generated by the stress concentration occurring in a difference in thermal expansion at the time of bonding and abnormal discharge, etc., at the time of sputtering. CONSTITUTION:This target 11 for sputtering is formed with a chamfered part 15 having width of 5 to 80% of the thickness of a target body 12 in the angle part between the surface 13 to be sputtered and outer peripheral surface of the target body 12. The angle part between the surface to be sputtered and the chamfered surface and the angle part between the outer peripheral surface and the chamfered surface may be respectively subjected to fine chamfering of 0.1 to 1.0mm radius and the surface of the target body may be subjected to an etching treatment. The surface to be sputtered may be subjected to a mirror finish polishing treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target capable of preventing stress concentration due to a difference in thermal expansion during bonding and cracks caused by abnormal discharge during sputtering.

[0002]

2. Description of the Related Art Conventionally, a Si target is an example of a large-scale sputtering target (hereinafter abbreviated as a target) used for high-speed sputtering. As shown in FIG. 3, the target is a copper plate 2 for cooling a Si plate (target body) 1 obtained by machining disk-shaped Si cut out from a Si single crystal into a predetermined size using a diamond grindstone or the like by bonding. It is joined to and finished. The target 3 is preferably used in manufacturing an antireflection film in a semiconductor manufacturing process, an optical disk, a protective film in a magneto-optical disk, and the like.

[0003]

However, in the target 3 described above, as shown in FIG. 4, the corner 6 between the sputtered surface 4 and the outer peripheral surface 5 of the target main body 1 is sharp, and this corner 3 is sharp. During the bonding (S
When the i-plate 1 and the cooling copper plate 2 are joined), the stress due to the difference in thermal expansion between the Si plate 1 and the cooling copper plate 2 is concentrated in the corners 6 and cracks occur from the minute cracks 7 part. There was a point. When the target 3 is used for sputtering, since the corners of the minute cracks 7 are sharp, abnormal discharge easily occurs at the corners of the minute cracks 7 during sputtering, and the minute cracks also cause the minute cracks. There was a problem that cracking occurred from the 7th part.

The present invention has been made in view of the above circumstances and provides a target capable of preventing cracks caused by stress concentration due to a difference in thermal expansion during bonding or abnormal discharge during sputtering. To provide.

[0005]

In order to solve the above problems, the present invention employs the following targets. That is, in the target according to claim 1, a chamfered surface is formed over the entire circumference at the corners between the sputtered surface and the outer peripheral surface of the target body, and the width of the chamfered surface is equal to the thickness of the target body. It is characterized by being 5 to 80%.

In the target according to the present invention, a chamfered surface is formed over the entire circumference at a corner between the sputtered surface and the outer peripheral surface of the target body, and the sputtered surface and the chamfered surface are formed. And the corners of the outer peripheral surface and the chamfered surface are provided with thread chamfering surfaces, and the radius of each thread chamfer is
It is characterized in that it is 0.1 to 1.0 mm.

The target according to claim 3 is the sputtering target according to claim 1 or 2, characterized in that the surface of the target body is subjected to a corrosion treatment.

The target according to claim 4 is the sputtering target according to claim 1 or 2, wherein the surface to be sputtered is mirror-polished, and the surface roughness (Ra) of the mirror surface is 0.01. .About.0.1 .mu.m.

[0009]

In the target according to claim 1 of the present invention, a chamfered surface is formed over the entire circumference at the corner between the sputtered surface and the outer peripheral surface of the target body, and the width of the chamfered surface is set to the width of the target body. By adjusting the thickness to 5 to 80%, the corners are not sharp and the stress concentration at the corners due to the difference in thermal expansion during bonding is effectively prevented without impairing the mechanical strength of the target body. Therefore, the occurrence of cracks due to stress concentration during bonding is effectively prevented. Further, by forming the chamfered surface, the number of minute cracks generated per unit area of the corner is reduced, and the occurrence rate of abnormal discharge during sputtering is reduced.

Here, the reason why the width of the chamfered surface is set to 5 to 80% of the thickness of the target body is that the effect of preventing stress concentration is not recognized if it is less than 5%, and if it exceeds 80%. This is because the mechanical strength of the main body is lowered and cracks are likely to occur due to the stress associated with the difference in thermal expansion during bonding.

Further, in the target according to claim 2, a chamfered surface is formed over the entire circumference at a corner between the sputtered surface and the outer peripheral surface of the target body, and the sputtered surface and the chamfered surface are formed. Thread chamfers are provided at the corners and between the outer peripheral surface and the chamfer, and the radius of each thread chamfer is 0.1 to 1.0.
By setting the thickness to mm, the corners between the sputtered surface and the outer peripheral surface are not sharpened, and the generation of microcracks is prevented. It also prevents the occurrence of abnormal discharge during sputtering, and thus prevents the target body from cracking during sputtering.

Here, the R of the thread chamfer is 0.1 to 1.
The reason for setting it to 0 mm is that if it is less than 0.1 mm, the minute cracks cannot be removed, and if it exceeds 1.0 mm, the minute cracks conversely increase and it is impossible to prevent the occurrence of abnormal discharge during sputtering. Because.

Further, in the target according to claim 3, the surface of the target body is subjected to a corrosion treatment to remove microcracks caused by surface strain due to mechanical processing such as grinding, and to eliminate abnormalities during sputtering. Prevent the occurrence of discharge.

In the target according to the present invention, the surface to be sputtered is mirror-polished so that the stress due to the difference in thermal expansion during bonding of the corners does not impair the mechanical strength of the target body. Prevents further concentration and cracking. Therefore, the film formation rate during sputtering is improved, and the life of the target is extended.

Here, the surface roughness (Ra) of the mirror surface is 0.0
The reason why it is set to 1 to 0.1 μm is that it is difficult in the actual process because the polishing precision of less than 0.01 μm exceeds the limit of polishing accuracy by machining, and when it exceeds 0.1 μm, the corner bonding is performed. This is because it is not possible to prevent stress concentration due to the difference in thermal expansion.

[0016]

Embodiments of the target according to the present invention will be described below. (First Embodiment) FIG. 1 shows a first embodiment of the target according to the present invention. In this target 11, a disk-shaped target body 12 is bonded to a cooling copper plate 2 by bonding, and the sputtered surface 13 and the outer circumference are provided at the corners of the sputtered surface 13 and the outer peripheral surface 14 of the target body 12. A chamfered surface 15 that is inclined with respect to each of the surfaces 14 is formed.

The present invention is applicable to Si, WSi, MoSi, Ti.
Si, Si ₃ N ₄ , PZT, PLZT, PTO, STO,
It is especially effective for fragile targets such as BSTO and HfB ₂ .

Further, the width of the chamfered surface 15 should be 5 to 80 times the thickness of the target body 12 as long as it can prevent the stress due to the difference in thermal expansion during bonding from being concentrated and cracking.
% Is effective.

Table 1 shows that the width of the chamfered surface 15 is within the above range (Examples: No. 1 to 10), the chamfered surface 15
The target whose width is outside the above range (Comparative example: No.
11 to 14) and a conventional target (conventional example: No. 15) in which the chamfered surface 15 is not formed are shown.

[0020]

[Table 1]

Here, the number of samples of each sample is 20
The number of the target body 12 is 0, and a disk-shaped Si plate having an outer diameter of 200 mm and a thickness of 6 mm, which is a typical target material having weakness, is used.
It was bonded to a cooling copper plate 2 having a thickness of 12 mm and a thickness of 12 mm by bonding. Also, the evaluation is the input power at the time of sputtering,
The erosion depth due to sputtering and the number of microcracks generated per unit area were measured.

Since the input power during sputtering changes depending on the size of the target, the input power per unit area was obtained and evaluated by dividing the input power by the area of the surface 13 to be sputtered. The erosion depth by sputtering was evaluated by placing a straight gauge on the surface 13 to be sputtered and measuring the depth of the deepest erosion portion using the straight gauge as a reference surface using a Depth caliper.

Regarding the number of microcracks generated per unit area, the number of microcracks generated per unit area of the corner portion of the target body 12 after bonding was measured using a microscope.

As shown in Table 1, the target of this embodiment has a power input at the time of sputtering of 3.3 times or more that of the comparative example and 5 times or more of that of the conventional example, and the erosion depth due to sputtering is of the comparative example. Also, it is understood that it is three times or more that of the conventional example. Further, in the comparative example and the conventional example, the number of microcracks generated per unit area was 30 / mm ² or more, whereas in the target of this example, the number was 10 / mm ² or less, which is significantly large. You can see that it is decreasing.

As a result, it is possible to reduce the number of minute cracks generated per unit area of the corner portion of the target body 12 and prevent the generation of cracks due to stress concentration during bonding. It is clear that when sputtering is used, the deposition rate can be improved and the target life can be extended.

The target body 12 is made of a material other than Si, WSi, MoSi, TiSi, Si ₃ N ₄ , PZT,
It was confirmed that even when replaced with PLZT, PTO, STO, BSTO, HfB _2, etc., exactly the same action and effect are exhibited.

As described above, according to the target of this embodiment, the chamfered surface 15 is formed at the corner between the sputtered surface 13 and the outer peripheral surface 14 of the target body 12.
Since the width of 5 is set to 5 to 80% of the thickness of the target body 12, it is possible to prevent stress concentration due to the difference in thermal expansion during bonding of the corners without impairing the mechanical strength of the target body 12. It is possible to prevent cracking. Therefore, the film formation rate during sputtering can be improved, and the life of the target can be extended. Further, by forming the chamfered surface 15, it is possible to reduce the number of minute cracks generated per unit area of the corner portion and reduce the occurrence rate of abnormal discharge during sputtering.

(Second Embodiment) FIG. 2 shows a second embodiment of the target according to the present invention. This target 21 has thread chamfered surfaces 22 and 23 provided at the corners between the sputtered surface 13 and the chamfered surface 15 and the corners between the outer peripheral surface 14 and the chamfered surface 15 of the target body 12 of the first embodiment. Is. The radius (R) of the thread chamfered surfaces 22 and 23 is
It suffices to prevent the generation of minute cracks in the thread chamfered surfaces 22 and 23, and 0.1 to 1.0 mm is effective.

Table 2 shows targets in which the radius (R) of the yarn chamfered surfaces 22 and 23 is within the above range (Example: No. 21).
~ 29), the radius (R) of the yarn chamfered surfaces 22 and 23 deviates from the above range (Comparative Example 1: No. 30 to 3).
5), the target of the first embodiment in which the yarn chamfered surfaces 22 and 23 are not formed (Comparative Example 2: Nos. 36 to 38).
The respective characteristics and evaluation results are shown.

[0030]

[Table 2]

Here, the number of samples of each sample is 20
The number of thread chamfered surfaces 22 and 23 was changed to R as shown in Table 2 for each width of three types of chamfered surfaces 15. In addition, the evaluation methods of the input power during sputtering, the erosion depth due to sputtering, and the number of microcracks generated per unit area were the same as those in the first embodiment.

According to Table 2, the target of the present embodiment has a power input at the time of sputtering which is 1.5 times or more that of Comparative Examples 1 and 2, and the erosion depth due to sputtering is as high as that of Comparative Examples 1 and 2. It can be seen that it is 1.4 times or more. Further, in Comparative Examples 1 and 2, the number of microcracks generated per unit area was 8 / mm ² or more, whereas in the target of this example, it was 2 / mm ² or less, which was further reduced. You can see that

As a result, the occurrence of cracks due to stress concentration during bonding can be further prevented, and when sputtering is performed using the target of this embodiment, the film formation rate can be improved and the life of the target can be increased. It is clear that can be extended.

Also in this embodiment, the target body 12 is made of a material other than Si, WSi, MoSi, TiS.
i, Si ₃ N ₄ , PZT, PLZT, PTO, STO, B
It was confirmed that when replaced with STO, HfB ₂ or the like, exactly the same action and effect were exhibited.

As described above, according to the target of this embodiment, the thread chamfered surface 22 is formed by rounding the corner of the sputtered surface 13 and the chamfered surface 15 of the target 11 and the outer peripheral surface of the target 11 is formed. Since the chamfered surface 23 is formed by rounding the corner portion between the chamfered surface 14 and the chamfered surface 15, the corner portion between the sputtered surface 13 and the outer peripheral surface 14 becomes less sharp, and the corner area per unit area It is possible to reduce the number of micro cracks generated. Therefore, it is possible to prevent abnormal discharge from occurring during sputtering, and to prevent cracking of the target body during sputtering.
As a result, the film formation rate during sputtering can be improved and the life of the target can be extended.

(Third Embodiment) A third embodiment of the target according to the present invention will be described below. This target is obtained by subjecting the surface of the target body 12 of the first embodiment to chemical corrosion treatment. It suffices for this chemical corrosion to be corroded to a depth sufficient to remove microcracks caused by surface strain due to mechanical processing such as grinding of the target body 12. In the case of Si as a corrosive agent, , Hydrofluoric acid, nitric acid, mixed solution of acetic acid and hydrofluoric acid, and Hf
In the case of B ₂ , aqua regia, hydrofluoric nitric acid, etc., and in the case of PZT, hydrofluoric nitric acid etc. are preferably used. In addition, materials other than the above, such as PTO, PLZT, STO, BSTO,
SiO ₂ , Si ₃ N ₄ , WSi, MoSi, PLTO, T
Even in iSi or the like, by selecting an optimum corrosive agent and performing corrosion, it is possible to effectively remove microcracks generated due to surface strain due to mechanical processing such as grinding.

Table 3 shows the target of this example (Example: Nos. 41 to 49) and the target of the first example not subjected to chemical corrosion (Comparative example: Nos. 50 to 5).
2) The respective characteristics and evaluation results are shown.

[0038]

[Table 3]

Here, the number of samples of each sample is 20
The number of chamfered surfaces 15 is 0 and the width of each of the three chamfered surfaces 15 is shown in Table 3.
Chemical corrosion was performed using the corrosive agent shown in. Regarding the microcracks, the entire surface of the target body 12 after bonding was observed with a microscope, and when the sample with microcracks was 20% or more, "x", and the sample with microcracks was 20% or less. The case was "O", and the case where no microcracks were observed was "A". Further, the evaluation method for each of the input power at the time of sputtering and the erosion depth due to sputtering was the same as in the case of the first embodiment.

As shown in Table 3, the target of this example has a power input at the time of sputtering of 1.4 times or more that of the comparative example, and the erosion depth by sputtering is about 1.4 times or more of that of the comparative example. You can see that it is. Further, a slight strain was observed in the comparative example, whereas no strain was observed in the target of this example.

As a result, it is possible to remove the microcracks caused by the surface strain due to mechanical processing such as grinding, and to prevent the occurrence of cracks due to stress concentration during bonding. When sputtering is used, it is apparent that the film forming rate can be improved and the life of the target can be extended.

Also in this embodiment, the target body 12 is made of a material other than Si, WSi, MoSi, TiS.
i, Si ₃ N ₄ , PZT, PLZT, PTO, STO, B
It was confirmed that when replaced with STO, HfB ₂ or the like, exactly the same action and effect were exhibited.

As described above, according to the target of this embodiment, the chamfered surface 15 is formed at the corner between the sputtered surface 13 and the outer peripheral surface 14 of the target body 12, and the surface of the target body 12 is chemically formed. Because it was corroded due to physical corrosion,
It is possible to remove microcracks generated due to surface strain due to mechanical processing such as grinding, prevent cracking due to stress concentration during bonding, and perform sputtering with this target. The film speed can be improved and the life of the target can be extended.

(Fourth Embodiment) A fourth embodiment of the target according to the present invention will be described below. This target is mirror-polished after the chamfered surface 15 is formed in the target body 12 of the first embodiment. This mirror-polishing reduces stress concentration due to the difference in thermal expansion during bonding. In order to prevent cracking, it is effective if the surface roughness Ra is in the range of 0.01 to 0.1 μm.

Table 4 shows targets whose surface roughness Ra of mirror polishing is within the above range (Example: No. 61 to 69) and targets whose surface roughness Ra is out of the above range (Comparative Example 1:
No. 70 to 75), and the target of the above-mentioned first example not subjected to mirror polishing (Comparative Example 2: No. 76 to 78).
The respective characteristics and evaluation results are shown.

[0046]

[Table 4]

Here, the number of samples of each sample is 20
The number of the chamfered surfaces 15 was set to 0, and the surface roughness of mirror polishing was changed as shown in Table 4 for each width of the three types of chamfered surfaces 15. Also, regarding the presence or absence of cracks during bonding, the presence or absence of cracks in the target body 12 after bonding was visually observed.
Further, the evaluation method for each of the input power at the time of sputtering and the erosion depth due to sputtering was the same as in the case of the first embodiment.

From Table 4, the target of the present embodiment has a power input at the time of sputtering which is 1.5 times or more that of Comparative Examples 1 and 2, and the erosion depth due to sputtering is that of Comparative Examples 1 and 2. It can be seen that it is 1.6 times or more. Further, in Comparative Examples 1 and 2, a slight crack at the time of bonding was observed, whereas in the target of this example, no crack at the time of bonding was observed.

As a result, the occurrence of cracks due to stress concentration during bonding can be further prevented, and when sputtering is performed using the target of this embodiment, the film formation rate can be improved and the life of the target can be increased. It is clear that can be extended.

Also in this embodiment, the target body 12 is made of a material other than Si, WSi, MoSi, TiS.
i, Si ₃ N ₄ , PZT, PLZT, PTO, STO, B
It was confirmed that when replaced with STO, HfB ₂ or the like, exactly the same action and effect were exhibited.

As described above, according to the target of this embodiment, after the chamfered surface 15 is formed on the target body 12, mirror polishing is performed, and the surface roughness of this mirror polishing is set to 0.
Since the range is from 01 to 0.1 μmRa, stress concentration due to the difference in thermal expansion at the time of bonding the corners can be further prevented without impairing the mechanical strength of the target body 12, and cracking can be prevented. it can. Therefore, the film formation rate during sputtering can be improved, and the life of the target can be extended.

[0052]

As described above, according to the first aspect of the present invention.
According to the target described above, a chamfered surface is formed over the entire circumference at the corners between the sputtered surface and the outer peripheral surface of the target body, and the width of the chamfered surface is 5 to 80 times the thickness of the target body. %, It is possible to effectively prevent stress concentration at the corners due to the difference in thermal expansion during bonding without impairing the mechanical strength of the target body. It is possible to effectively prevent the occurrence of cracks. Also,
By forming the chamfered surface, it is possible to reduce the number of minute cracks generated per unit area of the corner and reduce the occurrence rate of abnormal discharge during sputtering.

Further, according to the target of the second aspect, a chamfered surface is formed over the entire circumference at the corners between the sputtered surface and the outer peripheral surface of the target body, and the sputtered surface and the chamfered surface are further formed. Since the thread chamfering surface is provided at the corner with the surface and the corner between the outer peripheral surface and the chamfered surface, and the radius of each thread chamfer is 0.1 to 1.0 mm. It is possible to prevent the occurrence of minute cracks.
In addition, it is possible to prevent abnormal discharge from occurring during sputtering, and thus to prevent cracking of the target body during sputtering.

Further, according to the target of claim 3, in the sputtering target according to claim 1 or 2, the surface of the target body is subjected to corrosion treatment. It is possible to remove microcracks generated due to surface strain, and prevent abnormal discharge from occurring during sputtering.

According to the target of claim 4, in the sputtering target of claim 1 or 2, the surface to be sputtered is mirror-polished, and the surface roughness (Ra) of the mirror surface is , 0.01 to 0.1
Since the thickness is μm, it is possible to further prevent the stress concentration due to the difference in thermal expansion at the time of bonding of the corner portion without deteriorating the mechanical strength of the target body, and to prevent the crack. Therefore, the film formation rate during sputtering can be improved, and the life of the target can be extended.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a target according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional view of a target according to a second embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view of a conventional target.

FIG. 4 is a vertical cross-sectional view showing a defective state of a conventional target.

[Explanation of symbols]

 11 target 12 target main body 13 sputtered surface 14 outer peripheral surface 15 chamfered surface 21 target 22,23 thread chamfered surface

Claims (4)

[Claims] 1. A chamfered surface is formed over the entire circumference at the corner between the sputtered surface and the outer peripheral surface of the target body, and the width of the chamfered surface is 5 to 5 times the thickness of the target body.
A sputtering target, which is 80%. 2. A chamfered surface is formed over the entire circumference at the corner between the surface to be sputtered and the outer peripheral surface of the target body.
A thread chamfer is provided at a corner between the sputtered surface and the chamfer and a corner between the outer peripheral surface and the chamfer, and the radius of each thread chamfer is 0.1 to 1.0 mm. Characteristic sputtering target. 3. The sputtering target according to claim 1, wherein the surface of the target body is subjected to corrosion treatment. 4. The sputtering target according to claim 1, wherein the surface to be sputtered is mirror-polished, and the surface roughness (Ra) of the mirror surface is 0.01 to 0.1 μm. A sputtering target characterized by the above.