JP2000313955A - Sputtering target and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly form a worked surface free from working strain without hindrance even in the case of a target of irregular shape by using, as a material for finish working of a target, a powder containing, as principal components, one or more kinds among the constituents of the target. SOLUTION: An indium oxide powder is mixed with a tin oxide powder and a binder is further added, and the resultant powder-binder mixture is compression molded, degreased, and sintered, by which a sintered body for target is prepared. The sintered body is formed into the prescribed shape, and a sputter surface is subjected to blasting treatment by using shot material. As to the composition of the shot material, a powder containing, as principal components, at least one or more kinds among the constituents of the sputtering target is used. By this method, even if the shot material remains on the sputter surface of the target after cleaning after blasting treatment, the adverse effect of the remaining of the shot material can be prevented because the principal components of the shot material are the constituents of the target.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target used for forming a thin film by sputtering and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, if residual impurities, projections, stress strains, etc. due to processing and polishing are present on a sputter surface of a sputtering target, arcing during sputtering,
Particles and the like are generated, and as a result, the yield of film formation is greatly reduced. For this reason, as a target used in the sputtering method, a target obtained by smoothing and cleaning the sputtered surface is used, and the less the residual impurities on the target surface, the smaller the surface roughness,
Further, as the processing strain is smaller, the occurrence of arcing, particles and the like during sputtering is reduced.

[0003] ITO, also SnO ₂ based target rather than the exception, the sputtered surface is requested to be smoothly processed. The processing methods of these sputtering targets are described in JP-A-3-257158 and JP-A-5-14.
No. 8,635, JP-A-10-298743 and the like disclose specific techniques.

[0004]

[0005] Currently, the polishing of a sputtered surface is mainly performed by surface polishing using a flat surface polishing machine. In this method, the sputtered surface is polished by using a grindstone. However, in this method, there is a limit in polishing accuracy, and therefore, there is a problem that processing distortion is inevitably generated on the sputtered surface. Furthermore, in this polishing method, it is not possible to perform a polishing process for a so-called irregular-shaped target having an uneven surface formed on a sputtering surface. For this reason, the surface processing of the irregularly shaped target requires a surface processing in a step separate from that of the planar target, which has a problem that this is one of the causes of an increase in manufacturing cost.

[0005] As a polishing processing method in which the processing distortion during polishing is small and is not limited by the surface shape, a processing by blasting in which a shot material is jetted at high speed and collides with a surface to be processed is considered. However, in a conventional blasting process, a shot material as an abrasive is injected at a high speed, so that a phenomenon occurs in which the shot material inevitably bites into a surface to be processed. The shot material thus captured on the surface to be processed is difficult to remove by a general cleaning method, and has a problem that it remains as an impurity.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a process for finishing a sputtered surface of a target, which is smooth and free from processing distortion, regardless of whether the sputtered surface is flat or a so-called irregularly shaped target having an uneven shape. It is an object of the present invention to provide a sputtering target capable of quickly obtaining a surface and eliminating a problem caused by a residual abrasive used for polishing or the like on a sputtered surface.

[0007]

Means for Solving the Problems The present inventors use a powder containing, as a main component, at least one or more of the constituents of a sputtering target as a material for finishing, so that the sputtering surface has a flat surface. Even so,
Even with so-called irregularly shaped targets having irregular shapes, it is possible to obtain a smooth processed surface without processing distortion without any problem,
In addition, the inventors have found that the problem caused by the residual abrasive used for polishing or the like on the sputtered surface can be solved, and have completed the present invention.

That is, in the method for manufacturing a sputtering target according to the present invention, when finishing the sputtering surface of the sputtering target, the sputtering target is processed by using a powder mainly composed of at least one of the constituent components of the sputtering target. Is performed.

As one specific embodiment, a step of blasting the sputtered surface using a shot material made of a powder containing at least one component as a main component among the components of the sputtering target as described above. including.

Further, in a preferred embodiment in this case, after the blast treatment is performed, the method further includes a step of polishing the sputter surface of the sputtering target by a polishing means in which abrasive grains are dispersed on the surface of the elastic body.

Usually, in order to prevent contamination of the surface such as bite of the shot material, it is conceivable to employ a shot material (for example, spherical zirconia powder) having a spherical particle shape that does not adversely affect the surface. According to the knowledge based on the detailed surface analysis by the present inventors, it has been found that the above-mentioned problem caused by the residual impurities cannot be solved even by using such spherical powder.

Further, in another specific embodiment of the present invention, finishing is performed using a powder suspension mainly containing at least one of the components of the sputtering target as described above.

In this preferred embodiment, at the time of finishing, it is also possible to first perform blasting by a conventional method or a conventional method and then perform finishing using the above suspension.

In the case of a planar target or the like, a finishing process can be performed using the above-described suspension in order to remove impurities on the surface after the conventional process polishing.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a method for manufacturing a sputtering target according to the first aspect of the present invention, when finishing a sputtering surface of a sputtering target, at least one of the constituent components of the sputtering target is used as a main component. The blast treatment is performed on the sputtered surface using a shot material made of a powder containing as a material.

The type of the sputtering target to which the present invention is applied is not particularly limited, and can be applied to conventionally known various sputtering targets.

More specifically, ITO used for forming a transparent conductive film or an electrode film of a display device such as a liquid crystal display is used.
_(In 2 _O 3 -SnO ₂₎ based, Al-based, Al-Si-based,
Al-Ti, Al-Cu, Ti, Mo, Mo-
Various types of targets such as Ta-based, Ta-based, W-based, and Cr-based, Co- used for forming a recording film and a protective film of a recording medium such as a hard disk, a magneto-optical recording medium, and a phase change recording medium.
Cr-Pt, Co-Cr-Ta, Co-Ni-Cr
System, C-SiTb-Fe-Co system, Si system, Ge-Sb
-Te system, Ag-In-Sb-Te system, ZnS-SiO
Fe-T used for thin film formation of recording devices such as targets of the ₂ series, magnetic heads, thermal printer heads, etc.
a system, Fe-Al-Si system, Fe-Zr system, Ni-Fe
System, Co-Zr-Nb-based, Fe-N-based, Ta-SiO ₂
System, _Ta 2 _{O 5} system, SiAlON-based, _Si 3 _{N 4} system and the like of the target, Al-S is used for forming the semiconductor electrode
The present invention can be applied to i-type, MoSi ₂ -type, WSi ₂ -type, and Ti-type targets.

As an example, a case of manufacturing a target for forming an ITO film will be described. The ITO target can be manufactured by either a cold press method or a hot press method. In any case, the ITO target is obtained by press-molding and sintering a powder mixture mainly containing indium oxide and tin oxide. Can be

Specifically, in the cold pressing method, indium oxide powder and tin oxide powder are weighed and mixed,
Further, a binder is added, press-formed, degreased, and then sintered to obtain a target sintered body. The obtained sintered body is
Further, processing, grinding and finishing are performed to form a target having a predetermined shape and a predetermined dimension. On the other hand, in the hot press method, indium oxide powder and tin oxide powder are weighed and mixed, mixed by a dry ball mill, and then formed by hot press, and further processed, ground, and finished to have a predetermined shape and predetermined dimensions. Molded to target.

In the present invention, in the finishing process after molding the target, the blasting process is performed on the sputtered surface with a specific shot material. As the blasting method itself in the present invention, a conventionally performed method can be appropriately adopted. Generally, in blasting, a shot material made of a powder material having an abrasive action is sprayed on the surface of the object to be processed together with a gas such as pressurized air or a liquid such as water to adhere to the surface of the object to be processed. Means a surface processing method for removing foreign matter and protrusions.

The blasting apparatus used for blasting in the present invention is not particularly limited, either.
Devices available in the conventional market can be used as appropriate according to the size of the target to be processed. That is, in the present invention, except that the shot material is a specific material described below, there is no particular limitation.For example, the existing blast processing device can be diverted as it is, and special equipment can be used. This is also advantageous in that it is not required.

In the present invention, first, a blast process is used to finish the target surface, and a shot material made of a specific powder is sprayed to polish the surface. However, it is advantageous in that it can be processed quickly without any problem.

Further, in the method of the present invention, the powder containing at least one or more of the constituent components of the sputtering target as a main component is used as a shot material component in finishing the target surface. After the blasting, even if the shot material remains on the sputter surface of the target after cleaning, the main component of the shot material is composed of the constituent components of the target. it can.

In order to prevent such adverse effects due to the residual impurities, it is particularly preferable that the shot material is a powder composed of any one of the constituent components of the target. In this case, even if the shot material inevitably remains, it does not constitute an impurity. More preferably, the shot material is made of powder having the same component as the target. In this case, even if the shot material remains, the shot material does not become an impurity, and composition unevenness due to the shot material remaining can be completely prevented.

For example, in the case of manufacturing a sputtering target for ITO, preferred components of the shot are In ₂ O ₃ -based powder, SnO ₂ -based powder, and In ₂ O-based powder.
₃ -SnO ₂ based _{powder, In 2 O 3 -SnO 2 (} ITO)
Powder, _{an In} 2 ₀ of the same composition as that of the target 3 -SnO
₂ (ITO) powder and the like.

In addition to the components of the sputtering target, the components added to the shot material for improving the properties of the shot material are as long as they enable industrially efficient production of shots suitable for blasting. There is no particular limitation. For example, in the case of a shot material made of SnO ₂ -based powder, iron oxide, cobalt oxide, nickel oxide, or the like can be added as an additional element.

The addition amount of components added to the shot material other than the components of the sputtering target depends on the required purity of the target, but is preferably 1% by weight or less.
More preferably, it is 0.5% by weight or less, and the smaller the amount, the better.

The powder used for the shot material is more brittle than the constituent material of the sputtering target, and it is particularly preferable that the shot material breaks when the shot material collides with the target. This is because the shot material is more brittle than the target, so that the target is not damaged undesirably. The particle size of the powder used for the shot material may be larger than 1 mm, but if the particle size of the shot material is too large, it becomes difficult to jet the shot material in a good state during blasting, so the particle size is 1 mm or less. Is preferred. In addition, with the above-described properties of the powder, there is an advantage that the shot material itself is crushed at the time of collision, so that the impact is absorbed to some extent, so that the processing distortion does not increase.

By using such a material as a shot material, a processed surface having a surface roughness Ra of 5.0 μm or less can be obtained, and a sputtering target with less processing distortion can be obtained regardless of its shape. be able to.

More preferably, when a shot material having a particle size of 710 μm or less is used, a processed surface having a surface roughness Ra of 2.5 or less can be obtained. Further, when the powder used for the shot material is further reduced, the surface roughness is also reduced, processing can be performed more smoothly, and processing distortion is reduced. However, in order to reduce the surface roughness Ra to 0.2 μm or less, a shot material having an average particle size of 45 μm or less must be used. However, it is generally difficult to efficiently pulverize the shot material powder to an average particle size of 45 μm or less. Yes and therefore impractical.

When the shot material has the same hardness or strength as the target or the target is brittle, the powder of the shot is adjusted to have a particle diameter of 500 μm or less, the blast pressure is reduced, or the blasting device is used. By a method such as increasing the distance between the nozzle and the target, it is possible to prevent the occurrence of processing distortion due to the occurrence of an excessive impact. Under normal blast conditions, the blast pressure is 3 to 5 kg / cm ² , and the distance between the nozzle and the target is about 10 to 30 cm.

Further, in the method according to the present invention, after performing the blast treatment as described above, if necessary, furthermore, the sputtering surface of the sputtering target is
It is preferable to employ a step of polishing by a polishing means in which abrasive grains are dispersed on the surface of the elastic body.

As described above, by performing polishing by the polishing means in which abrasive grains are dispersed on the surface of the elastic body, for example, a state in which the surface roughness is about 0.2 to 5.0 μm is reduced to 0.2 μm ≦
Polishing can be efficiently performed up to the range of Ra <1.5 μm. Further, in a method of polishing by a polishing means in which abrasive grains are dispersed on the surface of such an elastic body, in the case of an irregularly shaped target in which an uneven surface is formed on a sputtering surface because the polishing means itself has elasticity. However, polishing can be performed without any problem.

In the above description, the upper limit of the surface roughness by using this method is set to 1.5 μm because the surface roughness is 1.5 μm.
This is because blasting alone is sufficient for processing exceeding μm, while if the surface roughness is to be reduced to less than 0.2 μm, the working time becomes long and is not practical. The elastic body is not particularly limited as long as the elastic body deforms within a pressure at which the target is not deformed or cracked, and urethane, urethane foam,
A sponge or the like can be used. Further, it is preferable to avoid particles that are dispersed in the elastic body from substances that react with the target material. The average particle diameter of the particles to be dispersed depends on the material of the particles. For example, when alumina is used, the average particle diameter is preferably about 7 to 250 μm from the viewpoint of work efficiency. The selection of the particle size can be performed with reference to the particle size standard of the abrasive such as JIS-R600.

The above-described method according to the present invention is particularly useful for low-viscosity metal-based targets and oxide-based targets which are less likely to blast shot material into the target surface.

In the method of the present invention according to the second aspect, the finishing process is performed using a suspension containing a powder mainly composed of at least one of the components of the sputtering target as described above. It can be carried out. In this embodiment, at the time of finishing, the finishing using the above-mentioned suspension may be performed after blasting by a conventional method or an ordinary method.

As the powder used in this case, the above-mentioned materials can be used similarly. The particle size of the powder can be appropriately selected in an optimum range according to the type of the material to be polished, but can be determined with reference to the particle size of the abrasive such as JIS-R6001 described above.

In the case of adjusting the particle size of the powder, preferably, a commercially available powdery material is calcined once and subjected to a particle size adjusting treatment such as particle growth or aggregation (granulation) to obtain a desired particle size. A powder can be obtained. The preferred average particle size range for the secondary particles is from 20 to 250 μm, more preferably from 50 to 150 μm.

To prepare a suspension, this powder is mixed with pure water to form a suspension. In this case, the weight ratio of powder: pure water is from 50:50 to 90:10, and more preferably from 60:40 to 85:15.

It is to be noted that the used suspension can be reused by performing a treatment such as removing coarse particles through a suitable mesh sieve, thereby reducing production costs and saving resources. It is advantageous in the point. However, since the amount of impurities in the suspension may increase as the frequency of use increases, it is desirable to monitor the amount of impurities in the suspension before reuse.

The above-mentioned finishing using the suspension can be performed, for example, by applying the suspension to a portion to be polished and rubbing it with an elastic or flexible material such as a sponge.

[0042]

EXAMPLES Examples of the present invention and comparative examples are shown below, but the present invention is not limited to the following embodiments.

Comparative Example 1 Commercially available alundum, glass, F
e, a flat ITO sputtering target was finished using four types of zirconia, and the sputtered surface was cleaned with ultrasonic waves. As a result, the surface roughness Ra of the sputtered surface was 1.8, 3.3, 4.3, 1.5 μm, respectively.
m. In addition, the impurities on the sputtering surface
Al 2800 ppm, Si 5000 ppm, Fe 2000 ppm, Zr 1800 ppm detected, IT
The product was not sufficient as an O sputtering target.

COMPARATIVE EXAMPLE 2 Finishing processing was performed by a plane processing polishing machine, and sputtering was performed using a flat ITO sputtering target whose sputtering surface was cleaned by ultrasonic waves. As a result, arcing occurred in the initial stage of the sputtering 506 times, and many particles were confirmed on the target.

Example 1 CoO was added to SnO ₂ having an average particle size of 0.8 to 4.0 μm.
The mixture obtained by dry mixing at 00 ppm was directly placed in a commercially available A1203 series pot and heat-treated at 1500 ° C. for 3 hours to cause coagulation.
SnO2 containing 2000 ppm of this aggregated CoO
The powder was pulverized until a 710 μm diameter jaw passed through, and S containing 2000 ppm of CoO having a particle size of 710 μm or less was used.
A shot of nO ₂ powder was obtained. When the shot material thus obtained was rubbed against an ITO sputtering target for finishing, it was found that the shot material was broken first and the shot material was brittle.

The thus obtained CoO was 2,000
By blasting using SnO ₂ powder containing ppm,
Finish processing of a flat ITO sputtering target was performed, and the sputtered surface was cleaned with ultrasonic waves.

As a result, the surface roughness Ra of the sputtered surface was 1.0 μm, no impurities were detected on the sputtered surface, and no Co was detected similarly. Sputtering was performed using this ITO sputtering target. As a result, the arcing in the initial stage of the sputtering was 276 times, and it was recognized that the number of particles on the target was smaller than that in Comparative Example 2.

Example 2 Using an SnO ₂ powder containing 2000 ppm of CoO and obtained in the same manner as in Example 1, an ITO sputtering target having an irregular shape on the sputtered surface was finished by blasting, and an ultrasonic wave was applied. Was used to wash the sputtered surface.

As a result, the surface roughness of the sputtered surface was 1.0
μm, and no impurities on the sputtered surface were detected.
Co was not detected as well. Sputtering was performed using the ITO sputtering target having the irregular shape having irregularities. As a result, the arcing in the initial stage of the sputtering was 290 times, and it was recognized that the number of particles on the target was smaller than that in Comparative Example 2.

Example 3 A flat plate IT was blasted using SnO ₂ powder containing 2000 ppm of CoO and obtained in the same manner as in Example 1.
The O sputtering target was finished, polished with a material in which alumina abrasive grains having an average powder diameter of 50 μm were dispersed on the urethane surface, and the sputtered surface was washed with ultrasonic waves.

As a result, the surface roughness Ra of the sputtered surface was 0.5 μm, no impurities were detected on the sputtered surface, and neither Co nor Al was detected.

Sputtering was performed using the flat ITO sputtering target. As a result, the arcing at the initial stage of the sputtering was 3
It was eight times, and it was recognized that the number of particles also decreased.

Example 4 An ITO sputtering target having an irregular shape on the sputtering surface was finished by blasting using SnO ₂ powder containing 2000 ppm of CoO and obtained in the same manner as in Example 1, and furthermore, Then, the surface of the urethane was polished by a polishing member in which alumina abrasive particles having an average powder diameter of 50 μm were dispersed, and the sputtered surface was cleaned by ultrasonic waves.

As a result, the surface roughness Ra of the sputtered surface was 0.5 μm, no impurities were detected on the sputtered surface, and both Co and Al were 100 ppm or less.

An irregularly shaped IT having irregularities on the sputtered surface
Sputtering was performed using an O sputtering target. As a result, compared to Example 2, the arcing in the initial stage of the sputtering was further performed 67 times, and it was recognized that the number of particles was also reduced.

Example 5 Commercially available SnO ₂ powder having an average particle diameter of 0.4 μm was heated to 1500 ° C.
And calcined to a particle size of 500 μm or less (granulation)
did.

Next, when processing the surface of the ITO sputtering target having an irregular shape on the sputtered surface, the sputtered surface having the irregularity was roughly ground by 0.3 mm using a general blasting method. The blast conditions at this time are as follows.

Projection material: Alundum Particle size range: 74 to 44 μm Projection pressure: 4 kgf / cm ² Next, the SnO ₂ powder prepared by the above method and pure water are mixed in a ratio of 85: 1 (weight ratio). The suspension was applied to the sputtered surface, and polished from above by sponge friction. At this time, since the abrasive obtained by aggregating the SnO ₂ powder by the above-mentioned method is more brittle than the ITO sputtering target to be polished, the polishing is performed finely without damaging the surface of the ITO sputtering target, and the final polishing is effectively performed. I was able to. After the final polishing, the substrate was subjected to ultrasonic cleaning and dried. The surface roughness (Ra) of the obtained sputtered surface was 0.6 μm, and no impurity due to the shot material used in the blasting process was detected from the sputtered surface.

Sputtering was performed using the obtained sputtering target. As a result, the initial arcing of the spatter was 50 times as compared with Example 4, and it was recognized that particles were also reduced.

[0060]

As is clear from the results of the above embodiments, in the method of manufacturing a sputtering target according to the present invention, the sputtering surface is formed by using a powder comprising at least one of the constituent components of the sputtering target. Since the finishing process is performed, an excellent effect is obtained in that the problem caused by the finishing material and the like remaining as impurities can be solved.

In the case where the above powder is used as a shot material for blasting, regardless of the shape of the sputtered surface, even a so-called irregularly shaped target having a flat surface or an irregular shape can be smoothly used. An excellent effect is obtained in that a processing surface free of any processing distortion can be quickly obtained, and a problem caused by the blast shot material or the like remaining on the sputtered surface as an impurity can be eliminated.

Claims (10)

[Claims] An object of the present invention is to perform a finishing process on a sputtered surface of a sputtering target by using a powder containing at least one of the constituent components of the sputtering target as a main component. Production method. 2. The method according to claim 1, further comprising a step of blasting the sputtered surface using a shot material made of a powder containing at least one of the constituent components of the sputtering target as a main component. 3. The method according to claim 2, wherein the particle size of the powder used for the shot material for the blasting treatment is 1 mm or less. 4. The sputter surface of the sputtering target obtained as a result of the blast treatment has a surface roughness Ra of 0.2.
3. The method of claim 2, wherein the thickness is ~ 5.0 [mu] m. 5. The method according to claim 2, further comprising a step of polishing the sputtered surface of the sputtering target by a polishing means in which abrasive grains are dispersed on the surface of the elastic body after performing the blasting. 6. The method according to claim 3, wherein the surface roughness of the sputtering surface of the sputtering target after the polishing step is Ra 0.2 to 1.5 μm. 7. The method according to claim 1, wherein the sputtering target is an ITO or SnO ₂ -based sputtering target, and the shot material for the blasting treatment comprises a SnO ₂ -based powder. 8. The method according to claim 1, wherein the finishing is performed using a suspension of a powder mainly composed of at least one of the components of the sputtering target. 9. The method according to claim 8, wherein a finishing process using the suspension is performed after a conventional blasting process. 10. A sputtering target obtained by the method according to claim 1.