KR20170032427A - Sputtering target structure and sputtering target structure manufacturing method - Google Patents

Abstract

Reduce particles. The sputtering target structure includes a sputtering target and a backing plate for holding the sputtering target. At least one of the surface of the sputtering target and the surface of the backing plate has a region including a plurality of recesses having an average diameter of 50 mu m or more and 300 mu m or less and an average depth of 5 mu m or more and 30 mu m or less. The arithmetic average roughness Ra of the surface of the region including the plurality of recesses is 10 占 퐉 or more and 20 占 퐉 or less.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target structure and a sputtering target structure,

One aspect of the invention relates to a sputtering target structure and a method of manufacturing the sputtering target structure.

In an electronic device including a semiconductor device or a liquid crystal display device having a fine structure, reduction of dust such as particles generated by a manufacturing process has been progressing in order to improve the yield. Particles are one of the factors that deteriorate the yield.

Along with high integration, as the internal structure becomes finer, the width of metal wiring such as Al, Cu, etc. becomes narrow. For example, the memory wiring width is narrowed to 19 nm to 15 nm, further to 10 nm. When the wiring width is narrow, fine particles having a diameter of 0.2 占 퐉 or less, which have not been noticed in the past, may cause wiring defects or device defects. Along with this, the generation of finer particles (size of 0.2 탆 or less) than conventional ones must be reduced.

In a sputtering target structure used in a sputtering apparatus, constituent components of a sputtered target are reattached to a sputtering target itself to form a coating. The film peels off and falls off as a particle on a semiconductor substrate or the like. As described above, the particles are one of the causes of failure of electronic parts.

As a countermeasure for preventing the reattachment of the reattachment film, for example, a method of roughening the surface of the sputtering target and the backing plate in a region where the constituent components are reattached by blasting to improve adhesion adhesion of the reattachment film, Vapor deposition (PVD), or chemical vapor deposition (CVD) to increase the adhesion of the reattached film by forming a coating on a region where the target component is reattached.

In the conventional blasting process, a sharp grain having a sharp angle portion collides with the surface of the material to be treated, or the spherical medium is crushed at the surface. Therefore, the abrasive grains are likely to be eroded into the material to be treated, and scratches such as a fractured layer are likely to be generated on the surface of the material to be treated. Therefore, although the surface is rough, a plurality of scratches remain. Therefore, it is difficult to eliminate generation of fine particles.

Japanese Patent Laid-Open No. 9-287072 Japanese Patent No. 3895277 Japanese Patent No. 3791829 Japanese Patent No. 4820508

One of the problems to be solved by one embodiment of the present invention is to reduce particles.

The sputtering target structure of the present embodiment includes a sputtering target and a backing plate for holding the sputtering target. At least one of the surface of the sputtering target and the surface of the backing plate has a region including a plurality of recesses having an average diameter of 50 mu m or more and 300 mu m or less and an average depth of 5 mu m or more and 30 mu m or less. The arithmetic average roughness Ra of the surface of the region including the plurality of recesses is 10 占 퐉 or more and 20 占 퐉 or less.

Fig. 1 is a schematic cross-sectional view showing a structural example of a part of a sputtering target structure. Fig.
2 is a schematic cross-sectional view showing a structural example of another part of the sputtering target structure.
3 is a schematic cross-sectional view for explaining an example of a ball shot process.
4 is a schematic cross-sectional view for explaining another example of the ball shot process.

1 is a schematic cross-sectional view showing an example of the structure of a part of a sputtering target structure. The sputtering target structure shown in Fig. 1 has a sputtering target 1 and a backing plate 2 for holding the sputtering target 1. As shown in Fig.

At least one surface of the surface of the sputtering target (1) and the surface of the backing plate (2) has a region (3) comprising a plurality of recesses. The region 3 is a region where the constituent components of the sputtering target 1 are reattached at the time of sputtering. In the sputtering target structure shown in Fig. 1, the sputtering target 1 has the area 3a on the side surface, and the backing plate 2 has the area 3b on the upper surface. The region 3a and the region 3b may be formed to be continuous.

At least one planar shape of the plurality of recesses may have, for example, a circular shape. At least one of the plurality of recesses may have, for example, a partially spherical shape or a cup shape. At this time, the bottom surface of the concave portion is a curved surface convex downward. The plurality of concave portions may be provided in at least one of the region 3a and the region 3b.

The arithmetic average roughness Ra of the region 3 is 20 占 퐉 or less. When the arithmetic average roughness Ra is 20 탆 or less, adhesion of the deposit adhering to the region 3 can be enhanced. Therefore, the peeling of the reattached film can be effectively suppressed, and the particles can be reduced. When the arithmetic average roughness Ra exceeds 20 占 퐉, the film projection of the reattachment film due to the sharp convexity of the surface tends to be formed. In the vicinity of the membrane protrusion, unstably deposited fine particles are exposed. The fine particles are removed due to the thermal change caused by the plasma during the sputtering, and particles are liable to be generated. It is more preferable that the arithmetic average roughness Ra of the area 3a and the area 3b is 10 占 퐉 or more and 20 占 퐉 or less.

The average diameter of the plurality of concave portions is preferably 50 탆 or more and 300 탆 or less. The average depth of the plurality of concave portions is preferably not less than 5 탆 and not more than 30 탆. The area 3a and the area 3b having the arithmetic mean roughness Ra of 20 m or less can be formed on the surface of the sputtering target 1 and the surface of the backing plate 2 by controlling the shape and the number of the recesses.

2 is a cross-sectional schematic diagram showing an example of the structure of another portion of the sputtering target structure. The sputtering target structure shown in Fig. 2 differs from the sputtering target structure shown in Fig. 1 in that the backing plate 2 has the thermal sprayed film 4. In the sputtering target structure shown in Fig. 2, the thermal sprayed film 4 has a region 3b on its surface. The thermal sprayed coating 4 may be provided on at least one surface of the main body of the sputtering target 1 and the main body of the backing plate 2.

The thickness of the thermal sprayed coating 4 is preferably 50 탆 or more. When the thickness of the thermal sprayed coating 4 is less than 50 탆, the function of relaxing the difference in thermal expansion between the region 3b and the adherend is degraded. As a result, the adherend is peeled off from the backing plate 2 and is likely to fall off, resulting in an increase in the amount of particles. More preferably, the thickness of the thermal sprayed coating 4 is not less than 100 탆 and not more than 500 탆, and more preferably not less than 150 탆 and not more than 250 탆.

The thermal sprayed coating 4 has, for example, a structure containing a plurality of particles. The average particle diameter of the plurality of particles is preferably 5 占 퐉 or more and 150 占 퐉 or less. The relative density of the thermal sprayed coating 4 is preferably 75% or more and 99% or less.

When the relative density exceeds 99% or the average particle diameter is less than 5 占 퐉, cracks are likely to occur between the particles due to the stress applied to the thermal sprayed coating 4. Therefore, the stress relaxation ability is lowered and the coating film may peel off. When the relative density is less than 75% or when the average particle diameter exceeds 150 탆, the surface of the thermal sprayed film 4 becomes uneven. Therefore, depending on the state of the surface of the thermal sprayed film 4, dust (particles) attributed to the projections are liable to be generated from the deposited deposit surface. It is more preferable that the relative density of the thermal sprayed coating 4 is 97% or more and 99% or less.

The relative density of the thermal sprayed coating 4 is obtained by the following method. The cross-sectional structure cut in the film thickness direction of the thermal sprayed coating 4 is observed with an optical microscope at a magnification of 500 times. The area of the pores is measured in a field of 210 mu m in length and 270 mu m in width. (%) From the following expression (1). The average value of the relative density of the 10 fields is the relative density of the thermal sprayed film 4.

Relative density (%) = {(S1-S2) / S1} x 100 (One)

(Where S1 is an area (mu m ² ) of a field of view of 210 mu m in length x 270 mu m in width and S2 is a total area (mu m ² ) of vacancy in a field of view of 210 mu m in width x 270 mu m in width)

The thermal sprayed coating 4 is formed by appropriately selecting plasma spraying or arc spraying. The spraying material may be powder or wire. At this time, a material having a powder particle size or wire diameter adjusted to control Ra to 20 탆 or less is used.

In the spraying method, the thermal spraying film 4 having a film structure in which flat particles are deposited by melting a powder or a wire by a heat source by a plasma discharge or an arc discharge can be obtained. By controlling the plasma spraying conditions of the feed powder, a porous thermal sprayed film 4 in which the feed powder is present as particles or elliptical particles can be obtained. The present invention is not limited to this, and a thermal sprayed film may be formed by using a flame sprayed with a combustion gas as a heat source and spraying a powder or a wire in a molten state.

As described above, the sputtering target structure has a region having a plurality of concave portions on at least one surface of the surface of the sputtering target 1 and the surface of the backing plate 2. The arithmetic average roughness Ra of the area is 20 mu m or less.

The inventors of the present invention analyzed the components of fine particles, investigated and verified the generation position of fine particles in the sputtering target, repeatedly started trial work and reviewed them. As a result, it was found that factors of generation of fine particles are related to the state of the target surface (surface roughness, surface shape), the type of the medium used for the blast treatment, and the unstable point of the reattached film in the solvent film.

In the sputtering target structure, generation of fine particles is reduced, and occurrence of wiring defects and element defects is suppressed. Therefore, the production yield of the electronic component can be remarkably improved. Further, since the peeling of the film of the film forming material is effectively suppressed over a long period of time, the frequency of cleaning the film forming apparatus and replacing the constituent parts is reduced, and operation control of the film forming apparatus becomes extremely easy. Further, the productivity of the film product can be increased, and the film forming cost can be reduced.

Next, an example of a manufacturing method of the sputtering target structure including the step of manufacturing the sputtering target structure will be described. The manufacturing process includes a step of forming a plurality of recesses by performing a sintering process on at least one surface of the surface of the sputtering target 1 and the surface of the backing plate.

The surface roughness of the thermal sprayed coating 4 can be adjusted to a predetermined range only by thermal spraying. However, fine irregularities and cavities are likely to be formed on the surface of the thermal sprayed film 4, and abnormal growth portions of the reattached film are likely to be formed starting from these irregularities and cavities. Since the abnormal growth portion is unstable, it is easily removed from the surface portion of the thermal sprayed film 4, and particles are liable to be generated. Therefore, it is preferable that the surface of the thermal sprayed coating 4 is subjected to plastic working to remove defects such as irregularities and cavities.

As the plastic working, for example, a ball shot treatment can be mentioned. The ball shot treatment is a treatment of colliding a spherical ball-shaped metallic fine grain with a high-pressure fluid against the surface of a material to be treated (a sputtering target, a backing plate, a thermal spray coating, etc.). In the ball shot treatment, the recess can be formed without leaving abrasive grains on the surface of the material to be treated and without damaging the surface of the material to be treated (formation of a crushed layer). The shape (diameter, depth, etc.) of the plurality of recesses is adjusted by controlling processing conditions such as, for example, the ball diameter of the ball type abrasive grain, the jetting distance of the ball type abrasive grain,

3 is a schematic cross-sectional view for explaining an example of a ball shot process. The hard ball 5 is ejected from the injection nozzle 6 on at least one surface of the surface of the sputtering target 1 and the surface of the backing plate 2 as shown in Fig. 4 is a schematic cross-sectional view for explaining another example of the ball shot process. The hard ball 5 is injected from the injection nozzle 6 onto the surface of the thermal sprayed film 4. In this case,

As the hard ball 5, for example, a spherical ball made of ordinary steel, stainless steel or ceramics material can be mentioned. The spherical balls are less prone to breakage even when they are subjected to a strong impact force by injection. Therefore, it can be used repeatedly.

The diameter of the hard ball 5 is preferably, for example, 2 mm or less, more preferably 0.4 mm or more and 0.8 mm or less. When the diameter of the hard ball 5 exceeds 2 mm, for example, it is difficult to impinge the ball to the concave portion of the surface of the thermal sprayed film 4, and a portion in which the thermal spray form remains remains, It does not become uniform.

The injection pressure in the ball shot process may be a pressure that allows the hard ball 5 to be sprayed while having a uniform momentum. The injection pressure is preferably 5 kg / cm 2 or less. When the injection pressure exceeds 5 kg / cm 2, for example, the surface of the thermal sprayed coating 4 is extremely plastic-deformed, making it difficult to obtain a desired surface roughness. If the injection pressure is excessively lowered, the hard ball 5 is not stably ejected, so that the surface of the thermal sprayed coating 4 is not completely smoothed and the thermal sprayed coating remains on the surface of the thermal sprayed coating 4 Resulting in a nonuniform shape, and the productivity of the film is deteriorated.

The thermal sprayed film 4 is subjected to plastic working by the ball shot treatment, whereby the stress is relaxed. Therefore, it is possible to lengthen the service life of the parts and reduce the particles.

By performing ball shot processing, the surface portion of the thermal sprayed film 4 is deformed to form a large number of recesses 7 having curved surfaces corresponding to the outer surface shape of the balls as shown in Fig. The diameter D and depth d of the concave portion 7 can be controlled by adjusting shot conditions such as the ball diameter and the ejection pressure. This is also true in the case where there is no thermal spray film shown in Fig.

The average diameter and the average depth of the plurality of concave portions are defined as follows. In the photograph of the cross-sectional structure obtained by observing the cross-sectional structure of the region 3 by an electron microscope or the like, five concave portions 7 adjacent to each other in the unit region were arbitrarily selected and the diameter of each concave portion 7 (D) and depth (d) are measured. The average value of the measured diameter D is the average diameter, and the average value of the measured depth d is the average depth.

The ball shot processing and the dry ice shot processing may be used in combination. The dry ice shot treatment is a treatment of spraying dry ice pellets to clean the surface. In dry ice shot processing, it is possible to remove foreign matter remaining when the ball shot processing is performed on the surface of the ball shot target material (target, backing plate, thermal sprayed film) with the sublimation energy of dry ice in a short time, It is possible to maintain the concave portion by the convex portion.

By using the ball shot processing and the dry ice shot processing together, it is possible to easily remove, for example, adherents remaining on the surface of the thermal sprayed film 4 before the ball shot processing, protrusions (irregular portions), and the like. Therefore, it is possible to eliminate defects which are the cause of minute particles and to perform almost complete cleaning. Therefore, fine particles having a diameter of about 0.1 占 퐉 can be reduced, and both the life of the target and the particle reduction effect can be realized.

The dry ice shot processing may be performed after spraying. On the surface of the thermal sprayed coating 4, particles that are likely to be peeled off, such as scattered particles, may be present. Therefore, in the case where the ball shot processing is performed in the state as it is, there is a possibility that the ball shot processing surface has a highly peelable coating on which scattered particles are crushed. Therefore, by performing dry ice shot processing for the first time on the thermal sprayed film 4, it is possible to eliminate the scattered particles which are likely to fall off, and to reduce the formation of the abnormal part which is likely to be peeled off even after the ball shot processing.

<Examples>

(Examples 1 to 6)

The sputtering target structures of Examples 1 to 6 were fabricated. The material of the sputtering target and the thickness of the thermal sprayed coating are as shown in Table 1. The materials of the backing plate used in Examples 1 to 6 are aluminum alloys.

In the fabrication of the sputtering target structures of Examples 1 and 2, a region including a plurality of recesses was formed on the surface of the sputtering target and the surface of the backing plate by ball shot processing without forming a sprayed film.

In the fabrication of the sputtering target structures of Examples 3 and 4, an arc Al sprayed film was formed on the surface of the main body portion of the backing plate, and a plurality of Thereby forming a region including the concave portion.

In the fabrication of the sputtering target structures of Examples 5 and 6, an arc Al sprayed film was formed on the surface of the body portion of the backing plate, and the surface of the sputtering target and the surface of the backing plate A surface including a plurality of concave portions was formed on the surface of the substrate.

In the ball shot processing, a ball made of stainless steel having a diameter of 0.8 mm was ejected from an injection nozzle at a jetting pressure of 5 kg / cm 2 to collide with the surface of the sputtering target and the surface of the backing plate.

(Comparative Examples 1 to 6)

The sputtering target structures of Comparative Examples 1 to 6 were fabricated using sputtering targets and backing plates of the same materials as in Examples 1 to 6. In the fabrication of the sputtering target structures of Comparative Examples 1 and 2, no sprayed film was formed, and in the fabrication of the sputtering target structures of Comparative Examples 3 to 6, an arc Al sprayed film was formed on the surface of the main body portion of the backing plate. The material of the sputtering target and the thickness of the thermal sprayed coating are as shown in Table 1. In the production of the sputtering target structures of Comparative Examples 1 to 6, the ball shot treatment and the dry ice shot treatment were not performed. In the production of the sputtering target structures of Comparative Examples 2 and 5, blast treatment was performed with SiC abrasive grains. In the fabrication of the sputtering target structures of Comparative Examples 3 and 6, a wire shot process, which is a blast process using a cut wire, was performed. The blast processing and the wire shot processing are processing for roughening the surface which has conventionally been done.

Table 2 shows the arithmetic mean roughness Ra (concave portion Ra), concave portion average diameter, and concave portion average depth of concave portions of each sputtering target obtained. In the sputtering target structures of Examples 1 to 6 and Comparative Examples 1 to 6, the number of dusts having a diameter of 0.2 mu m or more and mixed on the surface of a 12-inch wafer was measured with a particle counter (WM-3). The measurement results are shown in Table 2.

As is apparent from Table 2, in the sputtering target structure of the embodiment having a region including a plurality of recesses and having an arithmetic average roughness Ra of 20 m or less, the amount of generated particles can be significantly reduced as compared with the sputtering target structure of the comparative example. In addition, the generation of particles can be effectively and stably prevented by the thermal sprayed film formed in each of the embodiments. The materials of the backing plates used in Examples 1 to 6 and Comparative Examples 1 to 6 were aluminum alloys, but similar effects were obtained when copper alloys were used as backing plates.

It is possible to effectively remove the adhering matter remaining on the surface of the thermal sprayed film immediately after the formation of the thermal sprayed coating or immediately after the construction of the thermal sprayed shot by using the two post treatments of the ball shot treatment and the dry ice shot treatment together. Therefore, the dropout of the abnormally grown deposit can be effectively prevented. Therefore, it has been demonstrated that the number of dust particles or the like incorporated on the wafer can be further reduced. The relative density of the thermal sprayed films of the sputtering target structures according to Examples 3 to 6 was measured and found to be within the range of 91% to 99%.

Claims (14)

A sputtering target,
And a backing plate for holding the sputtering target,
Wherein at least one of a surface of the sputtering target and a surface of the backing plate has a region including a plurality of recesses having an average diameter of 50 mu m or more and 300 mu m or less and an average depth of 5 mu m or more and 30 mu m or less,
Wherein the arithmetic mean roughness Ra of the surface of the region including the plurality of recesses is 10 占 퐉 or more and 20 占 퐉 or less. The method of claim 1, wherein at least one of the sputtering target and the backing plate comprises:
A body portion,
And a sprayed film provided on a surface of the main body portion and having a region including the plurality of recessed portions. The method according to claim 2, wherein the thermal sprayed coating comprises a plurality of particles,
Wherein the plurality of particles have an average particle diameter of 5 占 퐉 or more and 150 占 퐉 or less. The sputtering target structure according to claim 2, wherein the relative density of the thermal sprayed coating is 75% or more and 99% or less. The sputtering target structure according to claim 2, wherein the thickness of the thermal sprayed coating is 50 μm or more and 500 μm or less. 3. The sputtering target structure of claim 2, wherein the thermal spray coating comprises aluminum. 3. The sputtering target structure of claim 2, wherein the sputtering target comprises titanium. 3. The sputtering target structure of claim 2, wherein the backing plate comprises at least one of an aluminum alloy and a copper alloy. A manufacturing method of a sputtering target structure comprising the step of manufacturing the sputtering target structure according to claim 1,
Wherein the manufacturing process includes a step of performing at least one of a ball shot process and a dry ice shot process on at least one surface of the surface of the sputtering target and the surface of the backing plate to form the plurality of recesses , And a method for manufacturing a sputtering target structure. A manufacturing method of a sputtering target structure comprising the step of manufacturing the sputtering target structure according to claim 2,
Wherein the step of manufacturing comprises:
Melting the sprayed material by arc spraying, plasma spraying or flame spraying to form the sprayed film on the surface of at least one of the sputtering target and the backing plate;
And performing at least one of a ball shot process and a dry ice shot process on the thermal sprayed film to form the plurality of recesses. The method according to claim 10, wherein the step of forming the plurality of recesses comprises:
Forming the plurality of concave portions on the surface of the thermal sprayed film by the ball shot processing;
And removing the foreign matter remaining in the region including the plurality of concave portions by the dry ice shot processing after the ball shot processing. The method according to claim 10, wherein the step of forming the plurality of recesses comprises:
Removing at least a part of the particles remaining on the surface of the thermal sprayed coating by the dry ice shot treatment;
And forming the plurality of recesses on the surface of the thermal sprayed coating by the ball shot processing after the dry ice shot processing. 11. The method of claim 10, wherein the spraying material is powder or wire. The method of manufacturing a sputtering target structure according to claim 10, wherein in the ball shot processing, the diameter of the ball to be collided is 2 mm or less and the injection pressure is 5 kg / cm 2 or less.

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