JP2001040471A - Sputtering target and sputtering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the peeling of a coated film by specifying the C chamfered shape or rounded shape of a corner formed by the erosion face, facing a wafer, of a cylindrical or discoid target and the side wall or side face of the target and also specifying the surface roughness of the resultant C chamfered or rounded part and the side wall of the target. SOLUTION: The corner part is formed into a C chamfered or rounded shape of 1.0-4.0 mm, and also the surface roughness of the resultant C chamfered or rounded part and the side wall of a target is regulated to 2-8 Ra. The surface area of the film coated part can be increased and the thickness of a coated film per unit area can be decreased to prevent the peeling of the film, and the infiltration of plasma into the periphery of the corner part can be facilitated by the modification of shape and erosion in this region can be activated to prevent the re-adhesion of sputtered particles. It is preferable to regulate the surface roughness of the erosion part, in the region where a sputter film is allowed to adhere, to <1 μm to suppress the delamination of the coated film. By this method, the number of particles can be minimized and an unexpected occurrence of particles can be practically reduced to zero, by which product yield can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a sputtering target which generates less particles during film formation and a film formation method using the same.

[0002]

2. Description of the Related Art In recent years, a sputtering method using a sputtering target has been widely used as a method for forming a semiconductor thin film or the like. In this sputtering method, an impact is applied to a sputtering target with charged particles, particles are knocked out of the sputtering target by the impact force, and this is attached to a substrate such as a wafer, which is set up against the target, to form a thin film. This is a film forming method.

By the way, in sputtering, a substance sputtered from a target is re-attached to a non-erosion portion or a region where the erosion is weak on the target during sputtering, and a film having a thickness of about several mm is formed in the case of several microns to severe. There are cases. Reattachment to the target is not only weak due to the small kinetic energy of the sputter particles that adhere to the target in the first place. Known and problematic.

Conventionally, in order to eliminate the problem due to film peeling, measures have been taken to change the magnet or change the plasma region by an electric operation so that the target is entirely eroded to prevent film adhesion. However, complete erosion is difficult, and there are cases where it is impossible to perform erosion for various reasons and a re-adhesion film must be formed, which is not sufficient as a solution. It is.

Further, a method of roughening the non-erosion portion of the target in order to prevent the adhesion film from peeling has been known. However, this method may also cause the adhesion film to peel, and there is a sufficient solution. I can't say that.

[0006]

SUMMARY OF THE INVENTION
An object of the present invention is to provide a sputtering target that can sufficiently prevent peeling of an adhered film by simultaneously examining the shape and surface roughness of a portion where the film of the sputtering target is adhered. An object of the present invention is to provide a sputtering method with less generation of particles.

The present inventors have conducted intensive studies in order to achieve the above object, and have obtained the following findings. That is,
After careful examination of the sputtering target during use, the adhered film was peeled off, and cracks occurred in the adhered film at the corner between the erosion surface facing the wafer of the disk-shaped target and the side wall or side surface of the target. It has been found that the cracks serve as starting points to cause film peeling. This is considered to be due to the stress concentration of the film stress due to the change in the shape of the edge portion.

In order to reduce stress concentration, sputtering was performed by using a target whose corners were subjected to C processing and R processing by machining, and the film thickness adhered to the processed part was smaller than before the processing. It has been found that the peeling of the film is reduced as the amount decreases, but in the part where the film adheres, although it is a part of the processed part and the target side wall and the erosion part, the minute peeling still occurs,
The effect was not enough. For this reason, as a result of further research, it was found that roughening of the surface in the C-processed portion, R-processed portion, and the side wall of the target can prevent film peeling by roughening the surface in a certain range, and conversely, smoothing the surface in the erosion portion. It was found that film peeling could be prevented.

The edge of the target as described above is subjected to C chamfering or R processing, and the C chamfered or R processed portion and the side surface of the target are roughened. It has been found that sudden spikes of particles can be almost completely solved in sputtering using a smoothed target.

[0010]

SUMMARY OF THE INVENTION The present invention has been made based on the above findings and the like. "The erosion surface of a cylindrical or disk-shaped target facing a wafer and the side wall or side surface of the target are formed. Corner is 1.0 ~
4.0mm C chamfered shape or R processed shape,
A target characterized in that the surface roughness of the C-chamfered portion or the R-processed portion and the side surface of the target is Ra = 2 to 8 μm. And a C-chamfered shape or a rounded shape in which a corner formed between an erosion surface of a cylindrical or disk-shaped target facing a wafer and a side wall or a side surface of the target is 1.0 to 4.0 mm. The surface roughness of the C-chamfered portion or the R-processed portion and the side surface of the target is Ra = 2 to 8 μm, and the surface roughness of the erosion portion at least in a range where the sputtered film adheres is Ra <1 μm. And a corner formed between the erosion surface of the cylindrical or disk-shaped target facing the wafer and the side wall or side surface of the target is 1.0 to 4.
Opposes a target having a 0 mm C-chamfered shape or R-processed shape, and having a C-chamfered or R-processed portion and a target side surface roughness of Ra = 2 to 8 μm, or a cylindrical or disk-shaped target wafer. The corner formed between the erosion surface to be formed and the side wall or side surface of the target has a C-chamfered shape or an R-processed shape of 1.0 to 4.0 mm, and the surface roughness of the C-chamfered portion or the R-processed portion and the target side surface is Ra. = 2 to 8 μm, and a sputtering method using a target having a surface roughness of Ra <1 μm in a range where at least the sputtered film adheres to the erosion portion ”.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, in the sputtering target according to the present invention, the corner between the erosion surface of the cylindrical or disk-shaped target facing the wafer and the side wall or side surface of the target is 1.0 to 4.0 mm.
C chamfered shape or R processed shape. As described above, the reason why the C processing or the R processing is performed on the corner portion is that, by performing these processings, the degree of stress concentration is reduced, and the surface area of the film-deposited portion is increased to reduce the deposited film thickness per unit area. By making the film difficult to peel off, and by changing the shape, it is easy to wrap around the corner of the plasma, activate erosion in this region, and make it difficult for redeposition of sputtered particles to occur,
An object of the present invention is to reduce the thickness of an adhered film per unit area, reduce the film stress, and make it difficult to cause film peeling.

The C-shape and R-shape dimensions of the corners are specified to be "1.0 to 4.0 mm".
When the thickness is less than the above, the film stress is not sufficiently reduced by the above effect, and the film is partially peeled. When the thickness is more than 4.0 mm, the sputtered particles are more likely to wrap around the target side wall, and the side wall is likely to be peeled. It is because it becomes. Further, this is because the machinability deteriorates and the production cost of the target increases.

Further, in the sputtering target according to the present invention, the surface roughness of the C chamfered portion or the R processed portion and the target side surface is specified to be Ra = 2 to 8 μm. The reason for specifying the surface roughness is that if Ra is less than 2 μm, the effect of preventing film peeling due to surface roughening is small.
If the thickness exceeds 8 μm, extreme unevenness in the thickness of the deposited film occurs due to the shadowing effect at the time of film deposition, so that the film is liable to peel. is there.

Further, in the sputtering target according to the present invention, the surface roughness of the erosion portion at least in a range where the sputtered film adheres is specified as Ra <1 μm.
In this part, the directionality of the sputtered particles flying from the above-mentioned processed part and the target side wall part is much more concentrated, and the adhered film grows in an oblique direction toward the center of the target, so that the adhered surface is rough. In this case, the effect of shadowing is so great that discontinuous growth of the deposited film is liable to occur, and delamination of the deposited film occurs at the discontinuous portion. In other words, roughening the surface of the erosion surface to which the film adheres is effective in preventing peeling of the adhered film, but adversely affects delamination. The reason for specifying this portion as Ra <1 μm is that delamination of the film is not observed in this range, and delamination occurs when the range is exceeded.

Further, by performing sputtering using a target having the above-described characteristics, a film can be formed with almost no sudden occurrence of particles. The target of the present invention is particularly effective for refractory metals and alloys thereof, silicide, silicon and the like.

[0016]

Examples and Comparative Examples Next, the present invention will be described with reference to Examples and Comparative Examples. (Example 1) Target 1 WS of φ300 × 6.35t prepared by powder metallurgy
After bonding the i disk to the backing plate made of pure copper with indium, and then tapering the corners of the target to C3, masking the tapered part and the parts other than the side of the target, and blasting using SiC particles Processing was performed.

(Example 2) Target 2 The target of Example 1 was prepared by masking the blast portion and then polishing the erosion surface of the target.

Example 3 Target 3 Vacuum-melted Ti ingot is forged and rolled, heat-treated to produce a φ300 × 6.35t Ti disk, brazed to a pure copper backing plate with indium, and joined. After performing R processing of R4 on the corner of the target, masking the parts other than the R processing part and the side of the target,
A blast treatment was performed using SiC particles to produce a target.

(Example 4) Target 4 A disk produced in the same manner as the target of Example 3 was similarly joined to a backing plate, and the corners of the target were placed at C1.
After performing the taper processing of No. 5, a part other than the tapered part and the target side surface was masked, and blast processing was performed using SiC particles. Thereafter, the target was produced by polishing the erosion surface of the target.

(Comparative Example 1) Target 5 A target similar to that of Example 1 was produced except that no C processing was performed on the target corners and no blasting was performed.

(Comparative Example 2) Target 6 The same target as in Example 1 was prepared except that no blast treatment was performed.

(Comparative Example 3) Target 7 A target similar to that of Example 3 was prepared except that no blast treatment was performed.

Sputtering was performed using these targets, and the average number of particles and the number of sudden occurrences of particles when one target life was used were examined. Table 1 shows the characteristics of the targets of the examples and comparative examples.
The average number of particles in the target life and the number of sudden occurrences of particles (50 or more wafers) are shown.

[0024]

[Table 1]

As shown in Table 1, in the targets of Comparative Examples 5 to 7, the average number of particles of 0.3 μm or more was 36 to 36 μm.
In contrast to 41, the number of targets in Examples 1 to 4 is 19 to 29, which is reduced to about half in the present invention. In addition, the number of sudden occurrences of particles
(50 wafers / wafer or more), the targets of Comparative Examples 5 to 7 are 8 to 12 times, but the targets of Examples 1 to 4 are zero or at most 2 times, and decrease significantly. You can see that it is. As described above, the target of the present invention is excellent in film forming properties and has excellent characteristics that can greatly improve the yield of products.

[0026]

According to the present invention, a certain range of C processing or R processing is applied to a corner portion of a target according to the present invention, and sputtering is performed by using a target in which a specific range of surface roughness of the processed portion and the target side wall and the erosion surface is specified. In addition, the number of particles is small and the occurrence of sudden particles can be reduced to almost zero, so that the product yield can be improved.

Claims (3)

[Claims] 1. A cylindrical or disk-shaped target, wherein a corner formed by an erosion surface facing the wafer and a side wall or a side surface of the target has a C-chamfered shape or an R-processed shape of 1.0 to 4.0 mm. The surface roughness of the chamfered or R-processed portion and the side surface of the target is Ra = 2
A sputtering target having a thickness of about 8 μm. 2. The sputtering target according to claim 1, wherein the surface roughness of the erosion portion at least in a range where the sputtered film adheres is Ra <1 μm. 3. A sputtering method using the target according to claim 1.