JP4270971B2 - Manufacturing method of sputtering target - Google Patents

Description

The present invention relates to a method for producing a sputtering target.

  In general, a sputtering method is known as one of methods for forming a thin film. The sputtering method is a method of obtaining a thin film by sputtering a sputtering target, is easy to increase in area, and can be efficiently formed into a high-performance film, and is used industrially. In recent years, as sputtering methods, there are known a reactive sputtering method in which sputtering is performed in a reactive gas, and a magnetron sputtering method in which a magnet is placed on the back surface of a target to increase the speed of thin film formation.

Among the thin films used in such a sputtering method, in particular, an indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ composite oxide, hereinafter referred to as “ITO”) film has high visible light transmittance, and Because of its high conductivity, it is widely used as a transparent conductive film for liquid crystal display devices, heat generation films for preventing condensation of glass, infrared reflective films, and the like.

  For this reason, in order to form a film more efficiently and at a lower cost, improvement of sputtering conditions and a sputtering apparatus are carried out every day, and it is important how to operate the apparatus efficiently.

  In such ITO sputtering, the time from when a new sputtering target is set until the initial arc (abnormal discharge) disappears and the product can be manufactured is short, and how long it can be used after being set (integrated) Sputtering time: target life) is a problem.

  Conventionally, it is said that the initial arc of a sputtering target is reduced as the target surface is polished and smoothed, and a surface polished target having a smooth surface has become the mainstream.

  Further, it is said that when sputtering is continuously performed, black deposits called nodules are generated on the target surface, which causes abnormal discharge or a source of particles. Therefore, in order to prevent thin film defects, periodic nodule removal is required, leading to a problem that productivity is reduced.

  For example, a technique for preventing the occurrence of arcing and nodules by setting the surface roughness of the target within a predetermined range has been developed (see Patent Documents 1 and 2). However, in order to produce an ITO sputtering target having such a predetermined surface roughness, after sintering, the thickness is adjusted by grinding, and then gradually 3 to 4 polishing steps using a fine polishing wheel There is a problem that manufacturing time and cost increase.

  In addition, a technique for preventing generation of nodules and abnormal discharge by cleaning the grinding powder by ultrasonic cleaning of the sputtering target or rubbing and peeling off the adhesive tape (see Patent Document 3). ). However, this technique has a problem that the grinding powder cannot be sufficiently removed.

  Furthermore, for example, even if grinding powder or the like is removed by ultrasonic cleaning or the like, dust or the like adheres to the target surface in a subsequent process of bonding the target onto the backing plate, and the initial arc and particle suppression effect is reduced. is there. In addition, if ultrasonic cleaning is performed immediately before the packaging process, which is the final process of the sputtering target, it is possible to simultaneously remove grinding powder and dust attached by bonding, etc. There is a problem that ultrasonic cleaning after bonding is very difficult.

  On the other hand, by making all or part of the target surface except the bonding surface rough, target particles that did not adhere to the thin film forming substrate during continuous sputtering are trapped as deposits. There is a technique that suppresses particles generated during the period of time and reduces the number of cleanings (see Patent Document 4). However, when this concept is incorporated into the above-described technique, it is necessary to make only the non-erosion portion rough after the smoothing process, and there is a problem that the process becomes extremely complicated.

  Therefore, a technology has been developed that significantly reduces the initial arc by removing burrs, grinding powder, dust, and dust generated during processing by performing surface treatment using a laser beam having a predetermined pulse width (Patent Document 5,). 6).

  However, according to the surface treatment with the laser beam, the initial arc can be almost completely removed.

Japanese Patent No. 2750483 Japanese Patent No. 3152108 JP 11-117062 A Japanese Patent Laid-Open No. 4-301074 JP 2003-55762 A Japanese Patent Laid-Open No. 2003-73821

The present invention has been made in view of such circumstances, and abrasive particles to prevent the generation of particles with effective removal, initial stability significantly improved, and a manufacturing method of a sputtering coater rodents bets it can be manufactured at a low cost The task is to do.

  The inventors of the present invention are mainly caused by micro-cracks or grinding powder generated by polishing or the like, and these can be effectively removed by surface treatment by spraying high-pressure water rather than by polishing. As a result, the present invention has been completed. That is, by performing surface treatment by spraying water onto the target surface at a predetermined pressure, a thermal shock caused by plasma hits the target surface at the start of sputtering, removing microcracks that cause generation of particles caused by the impact, The present invention has been completed based on the knowledge that processing scraps on the surface and dust and dirt adhering before packaging can be removed to prevent generation of arcs and particles.

According to a first aspect of the present invention, there is provided a sputtering target manufacturing method characterized in that surface treatment is performed by spraying water at a predetermined pressure onto the surface of a sputtering target manufactured through a surface grinding step.

In the first aspect, since the water is jetted to the target surface at a predetermined pressure and collides with it, the microcracks are removed and the processing debris, dust and debris on the target surface are removed. Is prevented from occurring.

According to a second aspect of the present invention, there is provided a sputtering target manufacturing method according to the first aspect, wherein pure water is injected as the water.

In this second aspect, pure water is jetted onto the target surface at a predetermined pressure and collides, whereby microcracks are removed and processing waste, dust and dirt on the target surface are removed.

According to a third aspect of the present invention, in the first or second aspect, the water jet pressure is in the range of 1 MPa to 250 MPa.

In this third aspect, water is jetted and collides with the target surface at a predetermined pressure, so that the microcracks are effectively removed, and the processing debris, dust and debris on the target surface are removed, and the initial arc Occurrence is prevented.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the surface treatment is performed at the final stage of the manufacturing process.

In the fourth aspect, the initial arc can be effectively reduced by performing the surface treatment by jetting water at the final stage as much as possible.

According to a fifth aspect of the present invention, there is provided the sputtering target manufacturing method according to any one of the first to fourth aspects, wherein the surface treatment is performed after the target is bonded to a backing plate.

In the fifth aspect, since the surface treatment is performed by jetting water, the surface treatment can be performed after joining to the backing plate, and the initial arc can be reduced more effectively.

A sixth aspect of the present invention, in the first to fifth one embodiment, in the manufacturing method of a sputtering target, characterized in that the target is made of ceramics.

In the sixth aspect, burrs and grinding powder generated during processing such as grinding of the ceramic target are removed by surface treatment by jetting water.

According to a seventh aspect of the present invention, in the sixth aspect, the target is made of an oxide containing at least one of indium oxide and tin oxide.

In the seventh aspect, the initial stability of the ITO sputtering target is remarkably improved by the surface treatment by jetting water.

  In the present invention, since the surface finish of the sputtering target is performed by spraying high-pressure water, dirt such as dust, dust and grease, and burrs and grinding powder generated during processing such as grinding (or polishing), and Microcracks and the like are removed, little initial arc is generated at the beginning of use of the sputtering target, and it is possible to shift to thin film production with little preliminary operation, and the initial stability can be remarkably improved.

  Furthermore, according to the present invention, since the initial arc can be prevented without depending on the surface roughness of the target surface, the non-erosion portion including the erosion portion can be roughened, and when performing continuous sputtering. Target particles that did not adhere to the thin film formation substrate can be effectively trapped as deposits on the rough surface of the non-erosion part, and particles generated from the middle to the latter stage of sputtering can be suppressed and the number of cleaning operations can be reduced. .

  In the present invention, the surface treatment is performed by spraying water at a predetermined pressure on the surface of the sputtering target manufactured through the surface grinding step, so that not only the advantage that there is no need to collect the shot material, but also sputtering. It was completed based on the new knowledge that the microcracks that cause the initial arc can be effectively removed without substantially affecting the surface roughness of the target.

  Here, as water used for the surface treatment, it is preferable to use water that is substantially free of impurities and in which impurities are not dissolved, and so-called pure water such as deionized water or distilled water is used. Is preferred. Of course, a liquid that does not affect the surface of the sputtering target, for example, a hydrophilic solvent such as various alcohols may be mixed and used, and is not limited to pure water. Further, when the high-pressure water is ejected, the gas medium may be ejected simultaneously.

  Moreover, in this invention, the high pressure water injected with respect to the surface of a sputtering target is injected with the pressure within the range of 1 MPa-250 MPa, for example, and it is more preferable to set it as the pressure of 100 MPa-250 MPa. When the water injection pressure is increased, this varies depending on the injection time, but the residual grinding rate after the surface grinding step for the entire surface of the sputtering target is 40% or less, more preferably, the residual grinding rate is 10% or less. can do. Thus, by setting the water injection pressure to a predetermined value, microcracks and the like formed in the surface grinding process can be efficiently removed, so that the initial arc can be greatly reduced and the initial stability can be improved.

  Here, the grinding trace is a trace of movement of the grinding wheel and is usually formed in parallel, but the remaining rate is 40% or less. The degree of unevenness of the grinding trace is 40% or less on average. It means that it was reduced.

  Such a high-pressure water injection method is not particularly limited, and examples thereof include a method using a nozzle or the like that discharges at a predetermined pressure. In addition, the injection time may vary depending on the injection method, the injection pressure, and the like, but it is only necessary that the grinding mark be 40% or less.

  The sputtering target to which the present invention can be applied is not particularly limited, and can be suitably applied to a ceramic target made of an oxide or the like. In the ceramic target obtained by sintering such an oxide powder material, the present invention can be effectively applied because microcracks are easily formed in grinding and surface polishing for thickness adjustment. Among these, an ITO sputtering target made of an oxide containing indium oxide and tin oxide is required to have high initial stability for efficient sputtering, and thus the present invention can be applied particularly effectively.

  An example of the manufacturing method of the sputtering target which concerns on this invention is demonstrated taking a ceramic target as an example.

  First, the raw material powder is mixed at a desired blending ratio, molded using various conventionally known wet methods or dry methods, and fired.

  Examples of the dry method include a cold press method and a hot press method. In the cold press method, a mixed powder is filled in a mold to produce a molded body, which is fired and sintered in an air atmosphere or an oxygen atmosphere. In the hot press method, the mixed powder is directly sintered in a mold.

  As the wet method, for example, a filtration molding method (see JP-A-11-286002) is preferably used. This filtration molding method is a filtration molding die made of a water-insoluble material for obtaining a compact by draining water from a ceramic raw material slurry under reduced pressure, and a molding lower die having one or more drain holes, The filter comprises a water-permeable filter placed on the molding lower mold and a molding mold sandwiched from the upper surface side through a sealing material for sealing the filter. The mold, sealing material, and filter are each assembled so that they can be disassembled, and the mixed powder, ion-exchanged water, and organic additive are added using a filtration mold that drains the water in the slurry under reduced pressure only from the filter surface side. A slurry made of an agent is prepared, this slurry is poured into a filtration mold, and the molded body is produced by draining the water in the slurry under reduced pressure only from the filter surface side. After 燥脱 butter, baking.

  In each method, the firing temperature is preferably 1300 to 1600 ° C., more preferably 1450 to 1600 ° C., for example, in the case of an ITO target. Thereafter, machining for forming / processing is performed to a predetermined dimension to obtain a target.

  In general, after molding, the surface is ground for thickness adjustment, and further, several steps of polishing are performed to smooth the surface. The surface treatment with the high-pressure water of the present invention may be performed after thickness adjustment grinding or after polishing. In any case, after the surface treatment with water, no subsequent treatment such as polishing is performed.

  By performing such a surface treatment with water, even if the surface is not smooth, it is considered that a portion that is easily detached due to microcracks generated during grinding or thermal shock during use is removed. That is, when the present invention is applied, the step of polishing the surface after grinding for thickness adjustment can be omitted, and further, the surface treatment with water without the polishing step after the grinding step is performed. Is preferably performed. In addition, this makes it possible to trap target particles that have not adhered to the thin film formation substrate as an adhering substance when performing continuous sputtering by making all or part of the target surface except the bonding surface rough. There is also an advantage that particles generated from the middle stage to the latter stage of sputtering can be suppressed and the number of cleanings can be reduced.

  Therefore, the surface roughness Ra of the sputtering target of the present invention may be larger than 0.5 μm, which is conventionally preferred, and may be 0.8 μm or more, for example, in the range of 0.8 μm to 10 μm. Of course, it may be smaller than this, for example, 0.05 micrometer or more, ie, 0.05 micrometer-0.8 micrometer, may be sufficient. This is because even if the surface roughness Ra is larger than 0.8 μm, the surface treatment with water is performed, so the microcracks are removed, the initial arc is greatly reduced, and the initial stability is improved. It is. In addition, since the surface roughness Ra tends to increase due to the surface treatment with water, the surface roughness may increase as a result. Furthermore, after the thickness adjustment, a surface that has been roughened by normal blasting may be surface treated with water.

  Conventionally, after the polishing step is completed, the target is bonded to the backing plate to obtain a sputtering target. However, the surface treatment with water of the present invention can be performed after bonding to the backing plate. In consideration of the initial stability of the produced sputtering target, it is preferably performed after bonding to the backing plate. This is for preventing dust and the like from adhering to the surface after the surface treatment with high-pressure water.

  Therefore, it is preferable to package immediately after the surface treatment with water of the present invention. In the case of packing with a resin film, it is preferable to use a resin film that does not contain detachable particles because the particles may be transferred to the surface of the target in contact with the resin film. It is preferable to perform packing so that nothing touches.

  As described above, according to the surface treatment using high-pressure water, not only the advantage that there is no need to collect the shot material but also the cause of the initial arc without affecting the surface roughness of the sputtering target. There is a new effect that the microcracks can be effectively removed.

  As described above, according to the present invention, microcracks that cause generation of particles are removed by surface treatment by spraying water onto the target surface at a predetermined pressure, and processing waste and packaging on the target surface are removed. It has the effect of removing dust and dirt adhering to the front and preventing arcing and particle generation.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, it is not limited to this.

(Example 1)
A plate material having a density of 99.8% was baked with an ITO (In ₂ O ₃ : SnO ₂ = 90: 10 wt%) target, and a target having a diameter of 4 inches and a thickness of 6 mm was produced from this plate material. In grinding the surface of the target, a # 170 diamond grindstone was mounted on a surface grinder to process the surface. Thereafter, pure water was sprayed onto the target surface at a pressure of 30 MPa. After spraying, it was dried with a vacuum dryer. The dried target was bonded to a copper backing plate with In. Polishing was performed with sandpaper to remove In that protruded around the target after bonding, In that adhered to the backing plate, and oxides of the backing plate. And in order to remove shavings, the surface of the target and the backing plate was wiped off with isopropyl alcohol (IPA), and the target of Example 1 was obtained.

(Example 2)
After surface processing with a diamond grindstone, the surface is simply washed with pure water, and the surface of the target and the backing plate is wiped with isopropyl alcohol (IPA) in order to remove shavings, and then purified at a pressure of 70 MPa. A target of Example 2 was obtained in the same manner as in Example 1 except that water was sprayed onto the target surface.

(Comparative Example 1)
An ITO target similar to that in Example 1 was processed with a # 170 diamond grindstone, washed with pure water in an ultrasonic cleaner, and then dried in a vacuum dryer. Thereafter, the dried target was bonded to a copper backing plate with In and polished with sandpaper to remove In that sticked out around the target after bonding, In adhering to the backing plate, and oxides of the backing plate. Finally, the surface of the target and the backing plate was wiped with IPA to remove shavings from the sandpaper, and the target of Comparative Example 1 was obtained.

(Test example)
The targets of Examples 1 and 2 and Comparative Example 1 were mounted on a sputtering apparatus, and sputtering was performed under the following conditions. The cumulative number of arcing occurrences during sputtering was counted with an arc counter of Landmark Technology. The results are shown in Table 1.

  In addition, the residual rate of surface grinding traces is calculated by area ratio using a 500x scanning electron microscope (SEM) (500 times equivalent for Hitachi SEM) and the area where the grinding traces remain in the observation field of 246 μm x 185 μm. Was measured.

  Further, SEM photographs of Example 1 and Comparative Example 1 are shown in FIGS. 1 and 2, respectively.

Sputtering conditions:
Process pressure (Ar) = 3 mTorr
Oxygen partial pressure (O ₂ ) = 1 × 10 ⁻⁵ Torr
Input power = 3 W / cm ²
Integrated power consumption = 120 Whr / cm ²

  From the above results, it was confirmed that the surface treatment with water significantly reduced the number of accumulated arcs regardless of the surface roughness, greatly improved the initial stability and reduced the arc over the long term. . It was also confirmed that by setting the water injection pressure to a large value, the surface grinding trace residual rate was 40% or less, particularly 15% or less when the injection pressure was 70 MPa, and the cumulative number of arcs was greatly reduced. .

It is a figure which shows the surface state observed with the 500 times scanning electron microscope (SEM) of Example 1 of this invention. It is a figure which shows the surface state observed with the 500-times scanning electron microscope (SEM) of the comparative example 1 of this invention.

Claims (7)

A method for producing a sputtering target, comprising subjecting a surface of the sputtering target produced through a surface grinding process to surface treatment by spraying water at a predetermined pressure. The method for manufacturing a sputtering target according to claim 1 , wherein pure water is injected as the water. 3. The method for producing a sputtering target according to claim 1 , wherein the water injection pressure is in a range of 1 MPa to 250 MPa. In any one of claims 1 to 3, the manufacturing method of a sputtering target which is characterized in that the surface treatment at the final stage of the manufacturing process. In any one of claims 1 to 4, a manufacturing method of a sputtering target and performing the surface treatment after bonding the target to the backing plate. 6. The method for manufacturing a sputtering target according to claim 1, wherein the target is made of ceramics. The method of manufacturing a sputtering target according to claim 6 , wherein the target is made of an oxide containing at least one of indium oxide and tin oxide.

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