KR20060006303A - Manufacturing method of al-ti alloy sputtering target for reflection layer of optical disk - Google Patents

Abstract

The present invention provides a method for manufacturing an Al-Ti alloy sputtering target used to form a reflective film of an optical recording medium, the method of manufacturing an Al-Ti alloy sputtering target for forming a reflective film of an optical recording medium by casting, wherein Sputtering target surface during sputtering by applying a vibration force to the liquid Al-Ti alloy, the size of the crystal grains is smaller than in the prior art, the size reduction and uniform dispersion of the second phase Al ₃ Ti, and the refinement of the grain size According to the present invention, there is provided an Al-Ti alloy sputtering target for forming a reflective film of an optical recording medium capable of manufacturing an Al-Ti alloy sputtering target having a uniform thickness uniformity.

Optical record carrier, Al-Ti alloy sputtering target, vibration

Description

Manufacturing method of Al-Ti alloy sputtering target for reflection film formation of optical recording medium {MANUFACTURING METHOD OF Al-Ti ALLOY SPUTTERING TARGET FOR REFLECTION LAYER OF OPTICAL DISK}

1 is a schematic diagram of applying a vibration force to the mold in a mechanical manner according to the present invention.

Figure 2 is a schematic diagram of applying the vibration force electromagnetically to the Al-Ti alloy of the liquid phase in an electromagnetic manner according to the present invention.

3 is a graph showing waveforms of currents applied to FIG. 2;

4 is a schematic diagram showing the shape of a mold to which the electromagnetic method of FIG. 2 is applied;

Figure 5 is a photograph of the microstructure of the Al-Ti alloy sputtering target produced by the prior art by a simple casting without applying a vibration force.

Figure 6 is a photograph of the microstructure of the Al-Ti alloy sputtering target prepared by the method shown in FIG.

Figure 7 is a photograph of the microstructure of the Al-Ti alloy sputtering target prepared by the method shown in FIG.

The present invention relates to a method for manufacturing an Al-Ti alloy sputtering target used to form a reflective film of an optical recording medium. In particular, the present invention relates to the size and uniformity of second phase particles in an Al-Ti alloy by applying vibration force during casting. The present invention relates to a method of controlling the size of grains to be suitable for use as a sputtering target for forming an optical recording medium.

In general, the Al-Si alloy reflective film of the optical recording medium is formed by sputter deposition using an Al alloy target containing Al- (1.3 to 1.7 wt.%) Ti. In the formation of a thin film by sputtering, even if a sputtering target having the same composition is used, the properties of the thin film manufactured by the sputtering method vary depending on the physical properties of the target such as grain size, the size and uniformity of the second phase, and the like.

U.S. Patent No. 5,809,393 discloses the effect of the size of the grains of the sputtering target on the thickness uniformity of the deposited thin film. According to U.S. Patent No. 5,809,393, when the average grain size of the sputtering target is 110 µm or less, thickness uniformity can be obtained in a range of ± 1%, but it is ± 1.5% in the range of 130 µm and ± 2.2% in 150 µm. have. In addition, the grain size of the sputtering target manufactured by the spray forming method is 20 μm or less, and adding an ECAE (Equal Channel Angular Extrusion) steel processing process can reduce the grain size to about 1 μm. do. Furthermore, according to U.S. Patent No. 6,428,638, in the case of Al alloy, when the plastic working speed is 100% or more per second, the grain size can be 20 µm or less, and in the case of 6,000% per second, the grain size can be reduced to 2 µm. do.

However, high quality Al alloy sputtering targets with small grain size can be produced by spray forming process alone, by combining spray forming process and ECAE process, or by high speed plastic working. As a result, the cost of the sputtering target was increased due to the need for expensive additional equipment compared to the simple casting. In addition, in the spray forming process, since droplets formed by atomizing a metal liquid are stacked on a substrate to prepare raw materials, the spray forming process has a large problem of loss of raw materials due to scattering of droplets.

On the other hand, US Patent No. 6,206,958 discloses the effect of the size of the sputtering target second phase particles on the composition of the formed thin film. According to this publication, if the size of the needle-shaped Al ₃ Ti intermetallic compound formed by primary is larger than 200 μm, the composition of the deposited thin film is different from that of the original sputtering target, and thus the size of Al ₃ Ti in the sputtering target. Should be less than 200 μm. Therefore, it is necessary to find a way to make the size of Al ₃ Ti in the sputtering target smaller than 200 μm.

US Patent No. 6,206,958 and Japanese Patent Laid-Open No. 12-178723 disclose the manufacture of sputtering targets produced by a simple casting method. However, such a simple casting method has a problem in that coarsening of the intermetallic compound occurs and the uniformity of the second phase is lowered. More specifically, for example, the liquidus temperature is known as 960 ° C. (see Binary Phase Diagram of TB Masalski, Vol. 1, ASM (page 1986), page 175) Al-1.5 When the temperature is lowered to change the wt.% Ti alloy from the liquid phase to the solid state, Al ₃ Ti intermetallic compounds are formed at 960 ° C. initially, and solidification is completed when the temperature reaches 660 ° C. through the coexistence area of the solid / liquid. . At this time, Al-1.5wt.% Of the co-coagulation segment region of the solid / liquid of the Ti alloy is of the Al ₃ Ti intermetallic compound in passing through the long solidification period is longer approximately two to three times as compared to other Al-alloy the conversation is taking place within the tank, the density of the Al ₃ Ti and the sedimentation to the bottom of the mold by gravity during the solidification of the liquid alloy as the density of 2.3g / cm ³ greater 3.38g / cm ³ than that of the produced sputtering target The uniformity of the two phases was lowered.

The present invention has been made to solve the problems of the prior art as described above, the optical recording, which can improve the uniformity of the composition and thickness of the Al-Ti alloy reflective film of the optical recording medium formed in a simple and economic way It is an object of the present invention to provide a method for producing an Al-Ti alloy sputtering target for forming a reflective film of a medium.

The present invention provides a method of manufacturing an Al-Ti alloy sputtering target for forming a reflective film of an optical recording medium by casting, in order to achieve the object as described above, applying a vibration force to the liquid Al-Ti alloy in the mold To; It provides a method of manufacturing an Al-Ti alloy sputtering target for forming a reflective film of an optical recording medium, characterized in that it comprises a.

This promotes heat transfer and mass transfer to the liquid Al-Ti alloy, thereby suppressing the growth of Al ₃ Ti, which is a second phase particle produced by primary crystals, and allowing the particles to settle under the mold due to density differences. This is to prevent the uniformity of the second phase particles in the casting target from decreasing and to refine the size of the crystal grains.

Here, the vibration force for the mold is to mechanically vibrate the side wall or the bottom wall of the mold to cause vibration in the liquid Al-Ti alloy in the horizontal or vertical direction.

On the other hand, it further comprises a solenoid coil formed on the outside of the side wall of the mold, it is possible to generate a vibration force for the mold by the electromagnetic force induced by applying a current to the solenoid coil.

At this time, the solenoid coil is effectively formed to surround the mold, the winding direction of the coil can be arbitrarily.

In addition, the vibration force is preferably applied by an electromagnetic method by applying an alternating current amount of 20-80A to the solenoid coil.

In addition, the vibration force is effective to be applied in an amplitude of 0.2 mm to 2.0 mm.

In addition, the side wall of the mold is preferably formed of a heat insulating material.

In addition, the Al-Ti alloy is an Al- (1.3 ~ 1.7 wt.%) Ti alloy is effective.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, when the Al-Ti alloy sputtering target is manufactured by a simple casting method, coarsening of the Al ₃ Ti intermetallic compound occurs due to the long solidification section described above, and the density of Al ₃ Ti is a liquid alloy. density of 2.3g / cm ³ and more by gravity during solidification as a large 3.38g / cm ³ sedimentation to the bottom of the mold, the cooling rate in order to prevent the produced sputtering target within the second on the uniformity is lowered The present invention proposes a means for promoting the present invention. Through this, it is possible to increase the nucleation driving force of the second phase of the Al-Ti alloy, or to accelerate the solidification to prevent the generated particles from settling to the bottom.

According to one embodiment of the present invention, by applying a mechanical or electromagnetic vibration force to the liquid Al-Ti alloy in the mold, by promoting the heat transfer and mass transfer in the liquid phase Al ₃ Al of the primary phase produced It suppresses the growth of Ti and improves the uniformity of the second phase particles in the cast target produced by sedimenting the particles to the lower part of the mold by the density difference. At this time, the method of vibrating the mold can be done mechanically and electromagnetically.

1 is a schematic diagram of applying a vibration force to the mold in a mechanical manner according to the present invention. As shown in the figure, the liquid Al-Ti alloy is poured into the mold and solidified while vibrating the water cooling plate 1 using a vibration motor (not shown). At this time, the vibration of the water cooling plate 1 may be in either the vertical direction 4 or the horizontal direction 5, and the two directions may be mixed.

In the case of applying the vibration force by such a mechanical method, the vibration power for the mold is preferably applied in the range of 0.2 ~ 2.0 mm amplitude. This is because when the amplitude is less than 0.2 mm, the effect of vibration is insignificant and the effect of reducing the second phase particles and grain size is not sufficient, and when the amplitude is more than 2.0 mm, the interface between the Al-Ti alloy casting and the mold is not smooth. . On the other hand, since the influence of the vibration frequency on the reduction effect of the second phase particles and grain size is weak compared to the amplitude, it is effective that the range of the vibration frequency is not limited.

Figure 2 is a schematic diagram of applying the vibration force electromagnetically to the liquid Al-Ti alloy in an electromagnetic manner according to the present invention. As shown in FIG. 2, when a current having an AC / DC mixed waveform 27 as shown in FIG. 3 is applied to the solenoid coil 21, the DC component is applied to the metal conductor 26 that the solenoid coil 21 wraps. A corresponding magnetic force B _DC 23 and a magnetic force B _AC 22 corresponding to the alternating current component are induced. Accordingly, AC J _AC 24 is induced in a direction perpendicular to B _AC 22, and finally a vibration force 25 is generated according to Fleming's left hand law. Reference numeral 28 is a schematic diagram showing a state in which the solenoid coil and the mold are coupled, in which case the vibration force is applied to the water cooling plate in the horizontal direction.

In the case of directly applying a vibration force to the liquid alloy by the electromagnetic method, an alternating current amount of 20 to 80 A is applied to the solenoid coil 21 provided on the outside of the side wall 2 of the mold and applied by the electromagnetic method. It is preferable. If the amount of current is less than 20A, the effect of vibration is insignificant, and the effect of reducing the size of the second phase particles and grains is not sufficient, and if the amount of current exceeds 2.0mm, the flow of the melt becomes too severe and the interface between the Al-Ti alloy casting and the mold Because it is not smooth. In addition, similarly to the mechanical vibration method, the influence of the vibration frequency is insignificant from the viewpoint of miniaturization of the second phase particles and the grain size, and therefore, it is effective that it is not particularly limited. At this time, the current amount or the vibration frequency can be adjusted by a commercial inverter.

Meanwhile, the vibration direction indicated by reference numeral 29 may be changed according to the winding direction of the solenoid coil 21. In the solidification of the molten Al-Ti alloy accompanied with the vibrations of Figs. 1 and 2, the side wall 2 of the mold is preferably made of a heat insulating material. This is because if the heat insulating material is installed on the side wall 2 of the mold or around it, one-way solidification of the alloy is possible, so that a solidification shrinkage hole is formed at the center of the last solidification when the alloy is converted from a liquid phase to a solid state, thereby forming a hollow shape. This is to prevent. Therefore, when the side wall 2 of the mold is formed of a heat insulating material, the solid / liquid interface of the alloy is formed parallel to the water cooling plate 1 so that solidification proceeds above the water cooling plate 1, whereby The occurrence is suppressed and the upper part of the manufactured casting becomes smooth.

On the other hand, even in the case of unidirectional solidification, solidification shrinkage pores may be generated directly under the surface by solidification of the surface of the molten alloy in contact with the atmosphere. However, the present invention is directed at the surface by heat and mass transfer to the surface of the molten alloy. Undesired coagulation has the advantage that it can be effectively prevented or at least induced.

Example  One

3 kg of Al- (1.3-1.7 wt.%) Ti alloy was charged into a high frequency induction melting furnace made of alumina crucible and dissolved in a temperature range of 1050 to 1100 ° C. under vacuum atmosphere. And, the mold of the shape shown schematically in FIG. 1 was mechanically vibrated using a vibration motor (not shown). At this time, the vibration frequency was changed in the range of 10 to 60 Hz, and the amplitude was in the range of 0.1 to 5 mm. In addition, the vibration direction was changed up and down or left and right on the basis of the mold. As a result, the frequency effect was hardly observed at the vibration frequency in the range of 10 to 60 kHz, and the average size of primary Al ₃ Ti and grains was less than 100 μm in the amplitude range of 0.2 to 2.0 mm. Photographs of the microstructure of the Ti alloy sputtering target can be seen from FIG. 6.

On the other hand, Figure 5 is a photograph of the microstructure of the Al-Ti alloy sputtering target produced in the prior art by a simple casting without applying a vibration force, it can be seen that the size of Al ₃ Ti and grains are larger than that of FIG. have.

Example  2

As in Example 1, 3 kg of an Al- (1.3-1.7 wt.%) Ti alloy was charged into a high frequency induction melting furnace made of alumina crucible and dissolved at a temperature in the range of 1050 to 1100 ° C. under a vacuum atmosphere, as shown in FIG. 2. Similarly, electromagnetic force was applied around the mold to directly vibrate the liquid alloy. At this time, the vibration frequency was in the range of 5 to 60 Hz, and the applied current was in the range of 10 to 100 A.

As a result, the size of primary crystals and grains was changed according to the change in the amount of current rather than frequency, and more specifically, the average size of primary Al ₃ Ti and crystal grains was 100 μm or less in the range of 20 to 80 A. Fig. 7 shows the microstructure of Al- (1.3 ~ 1.7wt.%) Ti alloy obtained when electromagnetic vibration was applied at a vibration frequency of 30 Hz and a current amount of 50 A, which was obtained by simple casting without applying vibration force. It can be seen that the size of Al ₃ Ti and grains is smaller than the microstructure of the Al-Ti alloy sputtering target prepared in the prior art (FIG. 5).

Although the preferred embodiments of the present invention have been described above by way of example, the scope of the present invention is not limited to these specific embodiments, and may be appropriately changed within the scope described in the claims.

For example, the technical idea of the manufacturing method according to the present invention can be equally applied to an alloy system in which a second phase particle such as an intermetallic compound, as well as an Al-Ti alloy sputtering target for an optical recording medium reflective film. That is, even when producing an alloy-based sputtering target in which Si, Zr, Ti, W, Pt, Au, Nb, Re, Sc, Co, Mo, Hf elements, etc. are added to Al, a higher quality sputtering target can be obtained by applying vibration. It can be produced cheaper. Therefore, the limitation or change of the numerical value about the target alloy system or vibration condition is simply within the protection scope of the present invention as grasped from the claims.

As described above, according to the method for manufacturing an Al-Ti alloy sputtering target for forming a reflective film of an optical recording medium according to the present invention, a method of imparting vibration during solidification of an Al- (1.3 to 1.7 wt.%) Ti alloy liquid phase By improving the casting process, the grain size is smaller than in the prior art, and the abnormal discharge occurring on the surface of the sputtering target during sputtering is reduced due to the size reduction, uniform dispersion, and refinement of the grain size of Al ₃ Ti as the second phase. Accordingly, a method of manufacturing an Al-Ti alloy sputtering target for forming a reflective film of an optical recording medium capable of producing an Al-Ti alloy sputtering target having a uniform thickness uniformity is provided.

Claims (10)

In the manufacturing method of the Al-Ti alloy sputtering target for forming a reflective film of an optical recording medium by casting, Applying a vibration force to the liquid Al-Ti alloy in the mold; A method of manufacturing an Al-Ti alloy sputtering target for forming a reflective film of an optical recording medium, comprising: The method of claim 1, The vibration force for the mold is a method of manufacturing an Al-Ti alloy sputtering target for forming a reflective film of an optical recording medium, characterized in that the vibration of the mold wall surface mechanically. The method of claim 2, And the wall surface is a side wall of the mold. 10. A method of manufacturing an Al-Ti alloy sputtering target for forming a reflective film of an optical recording medium. The method of claim 2, And the wall surface is a bottom wall of the mold. 10. A method of manufacturing an Al-Ti alloy sputtering target for forming a reflective film of an optical recording medium. The method of claim 1, It further comprises a solenoid coil formed on the outside of the side wall of the mold, and generates a vibration force for the mold by the electromagnetic force induced by applying a current to the solenoid coil, Al for forming a reflective film of the optical recording medium -Ti alloy sputtering target manufacturing method. The method of claim 5, And the solenoid coil is formed to surround the mold, wherein the Al-Ti alloy sputtering target for forming a reflective film of an optical recording medium is formed. The method of claim 5, The vibration force is applied to the solenoid coil by applying an alternating current amount of 20-80A, the manufacturing method of the Al-Ti alloy sputtering target for forming a reflective film of the optical recording medium, characterized in that applied. The method according to claim 2 or 5, The vibration force is applied to the Al-Ti alloy sputtering target for forming a reflective film of an optical recording medium, characterized in that applied in an amplitude of 0.2 mm to 2.0 mm. The method according to claim 2 or 5, The sidewall of the mold is formed of a heat insulating material, characterized in that the Al-Ti alloy sputtering target for forming a reflective film of the optical recording medium. The method of claim 1, The Al-Ti alloy is Al- (1.3 ~ 1.7wt.%) Ti alloy manufacturing method of the Al-Ti alloy sputtering target for forming a reflective film of the optical recording medium, characterized in that.

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