JP5065915B2 - Sputtering target, sputtering target material, and manufacturing method thereof - Google Patents

Description

  The present invention relates to a sputtering target, a sputtering target material, and a manufacturing method thereof. More specifically, the present invention relates to a sputtering target in which arcing is effectively reduced, a sputtering target material suitable for the sputtering target, and a manufacturing method thereof.

  Conventionally, it has been known that foreign matters such as grinding powder adhering to the surface of a target material of a sputtering target, in particular, the surface used for sputtering (sputtering surface) cause arcing during sputtering. When arcing occurs frequently, part of the target material melts and scatters in all directions, and splashes called splash are deposited on the substrate and the deposited film, reducing the deposition yield and increasing costs. This is one of the factors.

  Various attempts to remove grinding powder adhering to the sputtering surface of the target material have been proposed so far. For example, a method in which an adhesive tape is applied to the sputter surface of a target material and then peeled off, a method in which the target material is subjected to multiple oscillation ultrasonic cleaning (see Patent Document 1), and a method in which water of a predetermined pressure is jetted onto the target material (Patent Document 2) See).

  However, from the viewpoint of further improving the yield of film formation, the effect of suppressing arcing to the extent achieved by these methods is still not sufficient, and the development of a method for further reducing the occurrence of arcing is desired. It was rare.

  However, in blasting using an abrasive, the abrasive may stick to the sputtered surface of the target material, or may cause damage such as fine cracks or scratches. In the etching treatment to be contacted, the surface composition of the target material is changed, which may affect the physical properties of the formed film.

By the way, cutting of the surface of a metal target material or an alloy target material is generally performed by a milling machine or a lathe. In this case, since oil such as cutting oil is used during cutting, the cutting oil remains on the surface of the target material immediately after the cutting. Therefore, usually, the surface of the target material is wiped with an organic solvent after cutting.
JP 11-117062 A JP-A-2005-42169

  This invention makes it a subject to provide the sputtering target which can reduce generation | occurrence | production of arcing still more effectively, a sputtering target material suitable for this, and these manufacturing methods.

  The inventors of the present invention are one of the causes of arcing because oil remaining in a trace amount on the target material surface after cutting is one of the causes of arcing even after wiping treatment of the target material surface with an organic solvent. It has been found that if cleaning is performed by bringing steam into contact, the oil can be effectively removed to reduce the occurrence of arcing more effectively, and the present invention has been completed.

  That is, the present invention relates to the following matters.

  The sputtering target material according to the present invention is a sputtering target material that has been cut in the presence of oil, and the thickness of the oil film adhering to the surface of the target material before sputtering is 1.5 nm or less. It is a feature.

  The target material is preferably a metal target material or an alloy target material.

  Moreover, the sputtering target according to the present invention is characterized by comprising the sputtering target material and a backing plate.

  Moreover, the sputtering target material manufacturing method and the sputtering target manufacturing method according to the present invention are characterized by having a cleaning step of cleaning the target material surface by bringing steam into contact with the surface of the target material.

  The cleaning step is preferably a step of cleaning the surface of the target material by contacting steam at a temperature of 40 ° C. or higher for 3 seconds or more per 100 mm × 100 mm of the surface of the target material.

  The steam preferably comprises any one of water, an organic solvent, and a mixture thereof.

  Furthermore, the target material is preferably a metal target material or an alloy target material that has been cut in the presence of oil.

  As for the sputtering target material of this invention, the oil component adhering to the surface is removed as much as possible, and the thickness of the oil film is reduced. Therefore, according to the sputtering target equipped with the sputtering target material, the occurrence of arcing during sputtering can be further effectively reduced, and as a result, the occurrence of splash is suppressed and the yield of film formation is dramatically improved. Can be made.

  Moreover, according to the manufacturing method of the sputtering target material of this invention, even if it is the target material to which oil content adhered, this oil content can be removed as much as possible and a clean sputtering target material can be obtained. Moreover, the cleaning process for removing the oil only needs to bring the steam into contact with the surface of the target material for a short time, and no large-scale equipment is required. Therefore, a high-quality sputtering target material can be produced at low cost and high production efficiency. Can be manufactured.

  Further, according to the sputtering target manufacturing method of the present invention, even if the sputtering target includes a target material that has been cut in the presence of oil, the oil that has adhered to the surface of the target material can be obtained. Since it can remove as much as possible, the outstanding sputtering target which can reduce generation | occurrence | production of arcing can be provided. In addition, the cleaning process to remove the oil only needs to bring the steam into contact with the surface of the target material for a short period of time, and no large-scale equipment is required, so a high-quality sputtering target can be produced at low cost and high production efficiency. it can.

FIG. 1 is a graph showing the relationship between the thickness of the oil film adhering to the target material and the number of arcing occurrences.

  Hereinafter, the present invention will be specifically described.

  First, the sputtering target material and the sputtering target of the present invention will be described, and then the manufacturing method of the sputtering target material and the manufacturing method of the sputtering target of the present invention will be described.

<Sputtering target material and sputtering target>
The sputtering target material of the present invention is a sputtering target material that has been cut in the presence of oil, and the thickness of the oil film adhering to the surface of the target material before sputtering is 1.5 nm or less. It is said.

  According to the knowledge of the present inventors, the surface of the target material that has been cut in the presence of oil, such as a milling machine or a lathe, has a small amount of oil even after wiping with an organic solvent. It remains, and the oil component forms and adheres to an oil film having a thickness of about 3.5 to 4.5 nm.

  As the oil content is removed as much as possible and the thickness of the oil film is reduced, the number of occurrences of arcing can be reduced. However, it is practically difficult to reduce the thickness to 0 nm. From the viewpoint of suppressing splash, The thickness is usually 1.5 nm or less, preferably 1.0 nm or less. Moreover, the lower limit of the thickness of the oil film is not particularly limited, but exceeds 0 nm.

  In the present invention, the thickness of the oil film means a detection peak position (maximum value) of carbon measured using a glow discharge emission analysis (GDS) apparatus.

  Of the portions where the oil film is formed, the problem is particularly the sputtering surface of the target material that is actually sputtered, and it is desirable to reduce the thickness of the oil film on the sputtering surface to the above value or less.

  Examples of the target material subjected to cutting performed in the presence of oil include a metal target material or an alloy target material. Since these target materials are generally cut by a milling machine or a lathe, oil remains on the surface and an oil film is formed.

  Specific examples of the metal target material include Mo, Al, Ti, Ta, Cr, W, Ni, Cu, Ag, Au, Pt, Fe, Co, and Mg. Specific examples of the alloy target material include Al—Mg, Al—Ti, Ni—Fe, Ni—Cr, Fe—Co, Fe—Ta, Co—Cr, Co—Cr—Pt, and Co—. Zr, Co—Pt, Pt—Mn, Ir—Mn, Ti—W, and the like can be given. Among these, since the Al target material has a low melting point and is relatively easy to cause splash, the effect of the present invention is remarkably exhibited.

  Moreover, the sputtering target of this invention is provided with the backing plate which is a cooling plate in addition to the said target material, and may be further provided with the bonding material layer as needed.

  Although the backing plate should just be normally used as a backing plate of a sputtering target, from the point with favorable heat conductivity, the backing plate made from copper or a copper alloy is mentioned. Moreover, the shape may be a known one and is not particularly limited.

  The bonding material can be appropriately selected from known bonding materials according to the combination of the target material and the backing plate, and can be used as necessary. Specific examples of the bonding material include a bonding material called In solder, for example, In-based alloys such as In—Sn, In—Pb, In—Ag, and In—Zn, and In. Among these, In is widely used because of good handling, and is preferably mentioned.

In addition, the said sputtering target material and sputtering target can be suitably manufactured with the manufacturing method of a sputtering target material and the manufacturing method of a sputtering target which have the following specific cleaning processes.
<Manufacturing method of sputtering target material, manufacturing method of sputtering target>
The method for producing a sputtering target material and the method for producing a sputtering target according to the present invention are characterized by having a cleaning step of cleaning the surface of the target material by bringing steam into contact with the surface of the target material. Steps other than this cleaning step may be the same steps as known sputtering target materials or sputtering target manufacturing methods and manufacturing conditions, and are not particularly limited.

  Specifically, for example, the target material is a vacuum melting method in which the raw material is melted in the atmosphere or vacuum melted, cast, plastic processed, and then mechanically ground; the raw material powder is HP (hot press method), HIP (hot isolator) Powder metallurgy method in which molding is performed by static pressing (CIP) method or CIP (cold isostatic pressing) method, followed by sintering and plastic processing; other materials are melted, preforms are formed by spray forming, and then plastic processing is performed. It can be manufactured by a grinding method or the like.

  In the method for producing a sputtering target material and the method for producing a sputtering target of the present invention, various target materials produced by these known methods are washed in the washing step.

More specifically, examples of the target material include metal oxide target materials such as ITO (Indium-Tin Oxide), metal target materials, and alloy target materials. Specific examples of the metal target material and the alloy target material are as described above.

  Among these target materials, a target material that has been cut in the presence of oil is preferable because the effects of the present invention are more clearly exhibited. From this viewpoint, a metal target material or an alloy target material, which is generally often cut in the presence of oil, is preferably mentioned. Further, among the metal target materials, the Al target material has a low melting point and is relatively easily splashed. Therefore, the effect of the present invention is easily exhibited and is suitable for applying the present invention.

  In the sputtering target material manufacturing method and the sputtering target manufacturing method of the present invention, the target material surface is cleaned by bringing steam into contact with the surface of any one of these types of target materials in the cleaning step. Therefore, the method for producing a sputtering target material and the method for producing a sputtering target of the present invention also have an aspect as a cleaning method for an existing target material or sputtering target.

  The steam used in the washing step may be generated by a known method, and the method is not particularly limited. For example, a method of generating steam by filling a tank as a raw material for steam and heating it in a pressurized, normal pressure or reduced pressure state by a conventional method may be used. It is desirable that the liquid used as the raw material for steam should be easy to handle in addition to being able to be quickly removed from the target material after being brought into contact with the target material in the state of steam. , An organic solvent, and a mixture thereof. Of these, those containing an organic solvent are more preferable in that they can dissolve the oil and can be expected to improve the removal efficiency of the oil. Considering safety and ease of handling, the organic solvent and the water are preferable. Is more preferable, and a mixed solution of a water-soluble organic solvent and water is particularly preferable.

  The water is preferably water that has undergone a purification process such as distilled water, ion-exchanged water, or purified water. Examples of the organic solvent include water-soluble organic solvents such as ethanol, propyl alcohol, isopropyl alcohol and the like having 2 to 5 carbon atoms, acetone and ethyl acetate; water-insoluble solvents such as toluene, hexane, petroleum benzine and ethylene glycol. An organic solvent.

  The mixing ratio of the organic solvent and water varies depending on the organic solvent used, but it is a mixed solution below the lower explosion limit. For example, when ethanol is used as the organic solvent, the aqueous solution is usually 1 to 4.3 vol%.

  The pressure at which the generated steam is sprayed onto the surface of the target material is not particularly limited, and known means that can achieve the following steam temperature is appropriately employed in consideration of the distance to the surface of the target material that is the object to be cleaned. That's fine.

  The temperature of the steam when reaching the surface of the target material to be cleaned is usually room temperature (25 ° C.) or higher, but the oil is heated to increase its removal effect and reduce the thickness of the oil film. From the viewpoint of effectively suppressing the occurrence of arcing, 40 ° C. or higher is preferable, 60 ° C. or higher is more preferable, and 70 ° C. or higher is even more preferable. The upper limit of the steam temperature when reaching the surface of the target material that is the object to be cleaned is not particularly limited, and higher temperature is better considering oil removal efficiency. However, considering the balance between the oil removal efficiency and the cost, the temperature is usually 90 ° C. or lower. The temperature reached by the steam is obtained in advance by measuring the temperature of the steam that reaches a point at a predetermined distance from the steam injection port with a thermometer.

  The distance between the surface of the target material to be cleaned and the steam injection port is not particularly limited, and may be a distance at which the above steam temperature can be achieved, but is usually about 20 mm to 200 mm.

  Furthermore, in the present invention, it is preferable that the steam having the above temperature is continuously contacted with the surface of the target material of 100 mm × 100 mm for usually 3 seconds or more, preferably 6 seconds or more. Although there is no particular upper limit to the time for which the steam is kept in contact, 60 seconds or less is usually sufficient in consideration of the balance between the oil removal efficiency and the work efficiency.

  Moreover, it is preferable from a viewpoint of production efficiency to provide a drying process after the said washing | cleaning process, and to positively remove the droplet which the steam cooled and condensed from the target material surface. The drying means and its conditions in the drying step may be known means and conditions, and are not particularly limited. For example, it is preferable to use compressed air, which is heated at room temperature or heated, and blown onto the target material that has undergone the cleaning process, use of a dryer, or the like.

  In the method for producing a sputtering target of the present invention, the above-described cleaning step (in the case where a drying step is provided, the cleaning step and the drying step) may be performed at any time before and after the target material is joined to the backing plate. . Among these, when the cleaning process is performed after joining, it is preferable that new oil or dust can be prevented from adhering to the surface of the cleaned target material in the joining process of the target material and the backing plate.

  As a method for joining the target material and the backing plate, a known method can be appropriately employed. The backing plate is not particularly limited as long as it is normally used as a backing plate for a sputtering target. From the viewpoint of good thermal conductivity, a backing plate made of copper or copper alloy can be used. Moreover, the shape may be a known one and is not particularly limited.

  The bonding between the target material and the backing plate is not particularly limited, but a method of bonding via a bonding material such as In solder is preferable from the viewpoint of cost and productivity. Specifically, the target material before cutting or after cutting is heated to a temperature equal to or higher than the melting point of In solder, and the In material melted on the surface of the target material to be bonded to the backing plate is maintained. Solder can be applied, bonded to a backing plate, allowed to cool while being pressurized, and then cooled to room temperature.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.

[Examples 1-7]
After the milled Al target material (5N (99.999%), 590 × 730 × 8 tmm, Al target; manufactured by Sumitomo Chemical Co., Ltd.) was cut into a size of φ152.4 mm × 8 mm, the sputter surface Cutting oil was applied to the surface. Ion-exchanged water is supplied to a steam generating and spraying device (Toshiba Steam Washing Machine JQ-25; manufactured by Nidec Shibaura Co., Ltd.) to generate steam. A nozzle head was mounted, and the generated steam was sprayed from the nozzle head onto the sputtering surface of the Al target material under the conditions shown in Table 1 for cleaning.

Thereafter, air was blown onto the target material from a distance of 20 cm using an air gun (3 kgf / cm ² ) to remove droplets on the surface of the target material. Next, the target material was dried at 80 ° C. for 4 hours.

  The thickness of the oil film remaining on the sputtering surface of the Al target material after drying was measured using a glow discharge emission analysis (GDS) apparatus (JY-5000RF; manufactured by Horiba, Ltd.).

  Further, an Al target material different from that used for GDS was prepared by the same method and conditions as described above, and this Al target material was joined to a copper backing plate via In solder to produce a sputtering target.

  Using this sputtering target, sputtering is performed under the following sputtering conditions, and using a μ arcing monitor (manufactured by Landmark Technology), conditions of arc detection voltage 100V, large / medium arc energy boundary 50 mJ, medium / small arc energy boundary 10 mJ Then, the number of occurrences of arcing for 30 minutes from the start of sputtering was evaluated.

  These results are summarized in Table 1.

<Sputtering conditions>
Equipment: DC magnetron sputtering equipment, exhaust system; cryopump, rotary pump Ultimate vacuum: 4 × 10 ⁻⁴ Pa
Sputtering pressure: 0.5 Pa,
Input power: 2kW
[Examples 8 to 9]
Evaluations were similarly made in the same manner as in Examples 1 to 7 except that a 3 vol% aqueous ethanol solution was supplied to the steam generating and jetting apparatus and the generated steam was jetted onto the sputtering surface of the target material under the conditions shown in Table 1.

  The results are shown in Table 1.

[Reference Examples 1-2]
Cleaning was performed in the same manner as in Examples 1 to 7 except that steam was sprayed onto the sputtering surface of the target material under the conditions shown in Table 1, and evaluation was performed in the same manner.

  The results are shown in Table 1.

[Comparative Example 1]
After applying cutting oil to the sputtering surface of the Al target material, steam was not sprayed, but the target material was wiped off using toluene, and the same evaluation was performed as in Examples 1 to 7.

  The results are shown in Table 1.

[Comparative Example 2]
After applying cutting oil to the sputtering surface of the Al target material, steam was not sprayed, but the same as in Examples 1-7, except that 15 ° C. ion-exchanged water was sprayed onto the sputtering surface of the target material for 60 seconds at a pressure of 30 MPa. And evaluated in the same manner.

  The results are shown in Table 1.

[Comparative Example 3]
After applying cutting oil to the sputtering surface of the Al target material, steam was not sprayed, but 15 ° C. ion exchange water was sprayed from a distance of 50 mm onto the sputtering surface of the target material at a pressure of 30 MPa. And the same evaluation was made.

  The results are shown in Table 1.

[Comparative Example 4]
After applying cutting oil to the sputter surface of the Al target material, steam is not sprayed, and the target material is output with an ultrasonic cleaner (UT-205S; manufactured by Sharp Corporation, maximum output 200 W) using ion-exchanged water. The level was set at 80%, and ultrasonic cleaning treatment was carried out at 35 kHz for 30 minutes.

  The results are shown in Table 1.

[Comparative Example 5]
After applying cutting oil to the sputter surface of the Al target material, steam was not sprayed, and the target material was an ultrasonic cleaner using a 99.5 vol% ethanol aqueous solution (UT-205S; manufactured by Sharp Corporation, maximum output 200 W). Then, except that the output level was set to 80% and ultrasonic cleaning was performed at 35 kHz for 10 minutes, the same evaluation was performed as in Examples 1-7.

  The results are shown in Table 1.

[Comparative Example 6]
After applying cutting oil to the sputter surface of the Al target material, steam was not sprayed, and the target material was an ultrasonic cleaner using a 99.5 vol% ethanol aqueous solution (UT-205S; manufactured by Sharp Corporation, maximum output 200 W). Then, except that the output level was set to 80% and ultrasonic cleaning was performed at 35 kHz for 5 minutes, the same evaluation was performed as in Examples 1-7.

  The results are shown in Table 1.

  It can be seen from Table 1 that when the target material is cleaned by spraying steam, the oil removal effect is high as compared with the toluene wiping cleaning of Comparative Example 1. In addition, from Examples 1 to 9, when the ultimate temperature of the steam is 40 ° C. or higher, and when the organic solvent is contained in the steam, the oil removal effect is further enhanced, thereby suppressing the occurrence of arcing. It turns out that it increases markedly.

  On the other hand, in running water cleaning using ion-exchanged water in Comparative Example 2 and high-pressure water cleaning in Comparative Example 3, the oil removal effect is low and arcing can be effectively suppressed despite the treatment for 60 seconds. I understand that it is not.

  Moreover, in the ultrasonic cleaning of Comparative Examples 4-6, although the oil removal effect and the suppression effect of arcing are recognized, compared with steam cleaning, processing time is long as 5-10 minutes, and production efficiency is inferior. Furthermore, a bath in which the target material is immersed is necessary for ultrasonic treatment, and it is difficult to clean a large target material. When using an organic solvent, a large amount of organic solvent is supplied to the bath. This is not preferable from the viewpoint of safety and environment. On the other hand, the steam cleaning has an advantage that the surface of the target material may be brought into contact with the steam for a short time, and the production efficiency is excellent, and even when an organic solvent is used, a small amount is required.

  Based on the data shown in Table 1, the relationship between the thickness of the oil film adhering to the target material and the number of occurrences of arcing was examined for both axes. As shown in FIG. Correlation was observed.

Claims (13)

  A sputtering target material that has been cut in the presence of oil, wherein the thickness of the oil film adhering to the surface of the target material before sputtering is 1.5 nm or less.   The sputtering target material according to claim 1, wherein the target material is a metal target material or an alloy target material.   A sputtering target comprising the sputtering target material according to claim 1 or 2 and a backing plate.   A method for producing a sputtering target material, comprising: a step of cleaning the surface of the target material by bringing steam into contact with the surface of the target material.   5. The cleaning step is a step of cleaning the surface of the target material by bringing steam at a temperature of 40 ° C. or more into contact with the surface of the target material 100 mm × 100 mm for 3 seconds or more for 5 seconds or more. Manufacturing method of sputtering target material.   The method for producing a sputtering target material according to claim 4, wherein the steam comprises any one of water, an organic solvent, and a mixture thereof.   6. The method of manufacturing a sputtering target material according to claim 4, wherein the target material is a metal target material or an alloy target material that has been cut in the presence of oil.   The method for producing a sputtering target material according to claim 6, wherein the target material is a metal target material or an alloy target material that has been cut in the presence of oil.   A method for producing a sputtering target, comprising: a step of cleaning the surface of the target material by bringing steam into contact with the surface of the target material.   10. The process according to claim 9, wherein the cleaning step is a step of cleaning the surface of the target material by contacting steam at a temperature of 40 ° C. or more for 3 seconds or more per 100 mm × 100 mm of the surface of the target material. A method for manufacturing a sputtering target.   The method for producing a sputtering target according to claim 9 or 10, wherein the steam comprises any one of water, an organic solvent, and a mixture thereof.   The method of manufacturing a sputtering target according to claim 9 or 10, wherein the target material is a metal target material or an alloy target material that has been cut in the presence of oil.   The method of manufacturing a sputtering target according to claim 11, wherein the target material is a metal target material or an alloy target material that has been cut in the presence of oil.

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