JP2586562B2 - Sputtering target and method of manufacturing sputtering target - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rare earth transition metal alloy sputtering target and a method for producing the same.

[Conventional technology]

A sputtering target for forming a rare earth transition metal based magneto-optical recording film is largely divided into a single phase type in which only a rare earth transition metal alloy phase is present, and a three phase type in which a rare earth metal phase, a transition metal phase and a rare earth transition metal alloy phase are present. Is well known. The three-phase type has two more manufacturing methods,
JP-A-61-99640 discloses a sintered type and Japanese Patent Application No. 62-23277.
2, there is a melting type shown in 62-253001.

Among these, among the three-phase melting type manufacturing methods,
62-315613, the method of placing a rare earth transition metal ingot on the transition metal powder shown in 62-315614, melting the ingot and making it immersed in the powder, the control of the powder becomes important .

[Problems to be solved by the invention]

In other words, since the molten ingot penetrates into the pores of the powder to form the target, the target composition is determined by the porosity of the powder. Therefore, an object of the present invention is to provide various targets having a desired composition by controlling the porosity of the powder.

[Means for solving the problem]

Such an object is achieved by the present invention described below.
That is, the present invention provides a method for preparing a transition metal powder and a rare earth element in a mold.
A method for producing a sputtering target manufactured by placing an ingot of a transition metal alloy, heating it at a temperature equal to or higher than the melting point of the rare earth-transition metal alloy, and impregnating the molten ingot into the pores of the powder. And a porosity of the powder in the mold is set in a range of 30 to 80%.

In this case, the rare earth-transition metal alloy is Sm, Nd, P
At least one light rare earth metal (LR) of r and Ce
And at least one heavy rare earth metal of Gd, Tb, and Dy, and at least one transition metal (TM) of Fe and Co, wherein the powder comprises at least one of Fe and Co. Preferably, it contains a species of transition metal (TM).

Further, the rare earth-transition metal alloy includes at least one heavy rare earth metal (HR) of Gd, Tb, and Dy, and at least one transition metal (TM) of Fe and Co. The powder contains at least one transition metal (T
M).

Further, the present invention is a sputtering target in which porosity of a transition metal powder having a porosity of 30 to 80% is impregnated with a rare earth-transition metal alloy, wherein the structure constituting the target is a rare earth element. Metal phase, transition metal phase, rare earth-
A sputtering target comprising a transition metal alloy phase.

[Operation] In the present invention, a transition metal powder and an ingot of a rare earth-transition metal alloy are placed in a mold, and this is heated at a temperature equal to or higher than the melting point of the rare earth-transition metal alloy to melt the rare earth-transition metal alloy. And
The sputtering target is prepared by impregnating the powder into the pores of the powder. The composition of the obtained target is determined by the porosity of the powder (between each powder of the aggregate of the powder put in the mold). Is determined by the volume ratio of pores formed in the liquid crystal.

That is, since the molten ingot can only penetrate into the pores of the powder, the amount of rare earth metal in the target is determined by the porosity of the powder.

Since the composition of the medium is required to have a rare earth metal content of about 15 at% to 35 at%, the composition of the target must be adjusted accordingly. In order to satisfy this, the target composition is adjusted by changing the porosity of the powder in various ways.

 The details will be described below.

[A] When the porosity of the powder is about 30% As shown in FIG. 1 (a), a transition metal having a porosity of about 30% (near the lower limit) when placed in a mold. A powder is prepared and placed in the bottom of the mold, on which an ingot of a rare earth-transition metal alloy is placed. Next, the inside of the mold is heated to a temperature equal to or higher than the melting point of the ingot to melt the ingot. As shown in FIG. 1 (b), the molten ingot is impregnated in the powder. In this case, the molten ingot enters the vacancies in the powder and is replaced by the vacancies. Therefore, when the porosity is about 30%, a sputtering target having a relatively low content of rare earth metal is produced. it can.

[B] When the porosity of the powder is about 80% As shown in FIG. 2 (a), a transition metal having a porosity of about 80% (near the upper limit) when placed in a mold. A powder is prepared and placed in the bottom of the mold, on which an ingot of a rare earth-transition metal alloy is placed. Next, the inside of the mold is heated to a temperature equal to or higher than the melting point of the ingot to melt the ingot. As shown in FIG. 2 (b), the molten ingot is impregnated in the powder. Also in this case, similarly to the above, the molten ingot enters the pores in the powder and is replaced with the pores. Therefore, when the porosity is about 80%, the content of the rare earth metal is relatively large. A sputtering target can be manufactured.

Thus, the composition of the target can be determined by appropriately adjusting the porosity of the powder between 30% and 80%.

Next, an example of a method for producing a powder will be described. The powder is produced by spraying a molten metal into an inert gas atmosphere and solidifying the gas in a floating state in the gas, a gas atomizing method, a quenching method of spraying the molten metal and rapidly cooling in water, and producing a metal oxide. It can be manufactured by a well-known method such as a reduction method of reducing, a pulverization method of pulverizing a metal lump or a metal particle, or a method of appropriately combining these methods. The desired porosity can be obtained by appropriately selecting the filling conditions (degree of powder compaction) and the like. For example, since the powder produced by the gas atomization method is substantially spherical, it is suitable when the porosity is relatively low as in the above [A]. On the other hand, the powder produced by the reduction method is Since the surface area is increased by deoxidation and the shape having a large number of minute projections is obtained, the above [B]
Is suitable when the porosity is relatively high. The quenching method and the pulverizing method are intermediate between them.

Next, a method for measuring the porosity of the powder will be described. The porosity of the powder can be easily determined by a known method, for example, by measuring the bulk density of the powder. That is, when the porosity of the powder is a, the bulk density is a, and the density of the metal constituting the powder is d, the porosity P of the powder is represented by the following equation.

P = (1−a / d) × 100 (%) In this formula, d is specific to the constituent metal of the powder and is known. Further, a is determined by filling a container having a certain volume with powder and measuring the apparent volume and weight of the filled powder.

(Example 1) First, (Nd _0.2 Dy _0.8 ) _72.2 (Fe _0.8 Co _0.2 ) as a raw material
_{A 27.8} at% ingot is made (hereinafter, this ingot is referred to as R + R ₁ T ₂ ingot). The melting point of this ingot is as low as about 830 ° C. Then, a powder having a powder diameter of 200 μm of Fe ₈₀ Co ₂₀ at% was prepared. The melting point of this powder is as high as about 1500 ° C, and the porosity of this powder is
62.4%.

This powder is put into a 4 ″ φ inner diameter crucible, and R
Add + R ₁ T ₂ ingot. FIG. 3 is a schematic diagram showing this state. 1 is a crucible, 2 high-frequency induction heating coil, 3 is R + R ₁ T ₂ ingot 4 is Fe ₈₀ Co ₂₀ at% powder. The state is evacuated and then the temperature is raised to 1050 ° C. At this time, the R + R ₁ T ₂ ingot is dissolved, and the Fe—Co powder exists in a powder state without being dissolved. That is, the molten metal in which the R + R ₁ T ₂ ingot melts penetrates the pores of the Fe—Co powder and fills the pores. After cooling, the mass in the crucible was taken out, and the outer periphery and the surface were processed to prepare a 4 ″ φ × 3t sputtering target. The target composition was Nd _5.5 Dy.
_22.0 Fe _58.0 Co _14.5 at%. FIG. 4 shows a schematic diagram of the surface texture of this target. The phase 21 is Fe-Co particles, the phase 22 is a single phase of Nd-Dy rare earth, and the phase 23 is (NdDy) ₁ (Fe
Co) _{2 is} a rare earth transition metal alloy phase. In other words, there are three phases: a rare earth single phase, a rare earth transition metal alloy phase, and a transition metal single phase.

This NdDyFeCo target was mounted on a sputtering apparatus as shown in FIG. 5, and a film was formed, and its magnetic properties and composition distribution were examined. In FIG. 5, 31 is a sputtering target, and 32 is a substrate holder (300φ). The film formation conditions were as follows: Ar pressure 2.5 mTorr, initial vacuum degree 3 × 10 ^-7 Torr, input power was
The test was performed at 340 V at 1.0 A using a DC power supply. FIG. 6 shows a composition distribution and a magnetic characteristic distribution diagram in the substrate holder using the target of the present invention. As shown in this figure, the composition is uniform with a rare earth metal (RE) content of 28.0 to 28.5 at% in the film, and the magnetic properties are uniform with a coercive force Hc of 9.7 to 10.5 KOe. The more uniform the film is, the better the film can be placed in the substrate holder. Of course, since this target was a molten type, the oxygen content was small and was 500 ppm.

Next, a powder having a different porosity of Fe ₈₀ Co ₂₀ at% powder is prepared,
A target was created in the same manner as in the previous manufacturing method. In other words, FeCo powders with different porosity are laid underneath and (Nd _0.2 D
y _0.8 ) _72.2 (Fe _0.8 Co _0.2 ) _27.8 at%
C. to produce a target. The porosity of the powder used and the resulting target composition are as shown in the table below.

Table 1 Porosity of FeCo powder (%) Target composition (at%) 30 Nd _2.7 Dy _11.6 Fe _68.3 Co _17.4 40 Nd _3.6 Dy _14.2 Fe _65.8 Co _16.4 50 Nd _4.4 Dy _17.6 Fe _62.4 Co _15.6 70 Nd _6.2 Dy _24.7 Fe _55.3 Co _13.8 80 Nd _7.1 Dy _28.3 Fe _51.8 Co _{12.8 Using} these FeCo powder porosity changed targets,
A film was formed by the same sputtering apparatus as in FIG. 5, and the composition distribution in the substrate holder was observed. FIG. 7 shows this, and 71 shows a porosity of 30.
%, A composition distribution formed with a target having a porosity of 72%, a composition distribution formed with a target having a porosity of 70%, and a composition distribution formed with a target having a porosity of 70%. 75 is a composition distribution formed by a target, and 75 is a composition distribution formed by a target having a porosity of 80%. In any of the targets, the composition distribution formed by the target according to the production method of the present invention is extremely small and shows good uniformity. Porosity of 30
Only 30% of the target data is from 80% to 80%
If a powder with a smaller porosity is used, the molten metal does not penetrate sufficiently into the porosity and the composition of the target cannot be made. This makes it difficult to create a target.

As described above, in the present invention, the porosity of the powder is 30 to 80%
By properly setting the range, the desired target composition and film composition can be obtained, and the uniformity is excellent.

Incidentally, the present invention is not limited to NdDyFeCo, but PrTbFeC
o, SmGdFeCo, SmDyTbFeCo, NdTbFeCo, NdGdFeCo, NdPrD
yFeCo, NdPrDyTbFeCo, PrDyFeCo, NdSmGdFeCo, CeNdDyF
eCo, CeNdPrDyFeCo, etc., at least one light rare earth metal of Sm, Nd, Pr, Ce, at least one heavy rare earth metal of Gd, Tb, Dy, and at least one of Fe, Co It is clear from Japanese Patent Application No. 62-315613 that the method of the present invention is effective for all composition systems containing various transition metals.

Example 2 Next, the effect of the method of the present invention on TbFeCo was confirmed.
The production method is the same as in Example 1, and first, Tb ₇₂
(Fe _0.9 Co _0.1 ) Make a ₂₈ at% mother alloy ingot. The melting point of this mother alloy is as low as about 847 ° C. And then Fe ₉₀ Co ₁₀ at% 2
A powder having a particle size of 00 μm and a porosity of 43.2% was prepared. The melting point of this powder is as high as 1500 ° C.

This powder is placed in a 4 ″ φ inner diameter crucible, a master alloy ingot is placed thereon, heated to 1050 ° C., the mother alloy is melted and infiltrated into the pores of the powder, and then cooled to form a target shape. was processed to. the target tissue also RE, RE-TM, has a three-phase TM, the overall composition had a _{Tb 22 Fe 70.2 Co 7.8 at%} . using this TbFeCo target, Figure 5 Fig. 8 shows the composition distribution and the magnetic characteristic distribution in the substrate holder formed by the same sputtering apparatus as that shown in Fig. 8.
It can be seen that the composition distribution and the magnetic characteristic distribution in the holder are small and excellent even in the FeCo target.

Next, a powder was prepared by changing the porosity of the powder of Fe ₉₀ Co at ₁₀ at%, and a target was prepared using ₂₈ at% of Tb ₇₂ (Fe _0.9 Co _0.1 ) as the mother alloy ingot in the same manner. The porosity of the powder used and the resulting target composition are as shown in the table below.

Table 2 FeCo powder porosity (%) Target composition (at%) 30 Tb ₁₅ Fe _76.5 Co _8.5 50 Tb _25.5 Fe _67.0 Co _7.5 60 Tb _30.5 Fe _62.6 Co _6.9 70 Tb _35.5 Fe _58.0 Co _6.5 80 Tb _40.7 Fe _53.4 Co _5.9 FIG. 9 shows the distribution of the film composition in the substrate holder using these targets with different porosity of FeCo powder and the same sputtering apparatus as that of FIG. 81 is a composition distribution formed with a target having a porosity of 30%, 82 is a composition distribution formed with a target having a porosity of 50%, 83 is a composition distribution formed with a target having a porosity of 60%, and 84 is a composition distribution formed with a target having a porosity of 60%. A composition distribution formed with a target having a porosity of 70% and a composition distribution 85 formed with a target having a porosity of 80% are shown.

It can be seen that also in this embodiment, there is sufficient compositional uniformity. The reason why the porosity is less than 30 or more than 80% and the target is not shown is the same as in Example 1.

Incidentally, the present invention is not limited to TbFeCo, and DyFeCo, Tb
GdFeCo, TbFe, GdFeCo, GdDyFeCo, GdDyTbFeCo, DyTbFe
Particularly effective for all composition systems containing at least one heavy rare earth metal of Gd, Tb, and Dy such as Co, TbCo, GdTbFe, and TbDyCo and at least one transition metal of Fe and Co. This is also evident from Gan-62-315614.

〔The invention's effect〕

As described above, according to the present invention, the porosity of the powder is reduced.
By appropriately setting the content in the range of 30 to 80%, a sputtering target having a desired composition or a film produced therefrom can be obtained, and the composition can be made uniform.

[Brief description of the drawings]

FIG. 1 (a) is a schematic diagram in which an ingot is placed on a powder having a porosity of 30%. FIG. 1 (b) is a schematic view of a state in which a molten metal has penetrated into powder having a porosity of 30%. FIG. 2 (a) is a schematic diagram in which an ingot is placed on a powder having a porosity of 80%. FIG. 2 (b) is a schematic view showing a state in which the molten metal has penetrated into powder having a porosity of 80%. FIG. 3 is a schematic view of the method of the present invention. FIG. 4 is a schematic diagram of the metal composition of the target according to the method of the present invention. FIG. 5 is a schematic diagram of a sputtering apparatus. FIG. 6 shows a composition distribution and a magnetic characteristic distribution in a substrate holder using the NdDyFeCo target of the present invention. FIG. 7 is a film composition distribution diagram of a NdDyFeCo target prepared using various porosity powders. FIG. 8 is a diagram showing a composition distribution and a magnetic characteristic distribution in a substrate holder using the TbFeCo target of the present invention. FIG. 9 is a film composition distribution diagram of a TbFeCo target prepared using various porosity powders. 1 ...... crucible 2 ... high frequency induction heating coil 3 .... R + R ₁ T ₂ ingot 4 ...... Fe ₈₀ Co ₂₀ at% powder 21 ... Fe-Co particles 22 ... Nd-Dy rare earth alone phase 23 ... ( NdDy) ₁ (FeCo) ₂ rare earth transition metal alloy phase 31 Sputtering target 32 Substrate holder (300φ) 71 Composition distribution formed on target with porosity of 30% 72 porosity of 40% Composition distribution formed with a target of 73% Composition distribution formed with a target of 50% porosity 74 Composition distribution formed with a target of 70% porosity 75 Target with a porosity of 80% Composition distribution 81 formed with a target having a porosity of 30% 82 Composition distribution formed with a target having a porosity of 50% 83 Composition formed with a target having a porosity of 60% Composition distribution of film 84: Composition distribution formed with a target having a porosity of 70% 85: Formation of film formed with a target having a porosity of 80% Formed distribution

Claims (4)

(57) [Claims] An ingot of a transition metal powder and a rare earth-transition metal alloy is placed in a mold and heated at a temperature equal to or higher than the melting point of the rare earth-transition metal alloy, and the molten ingot is emptied of the powder. A method for producing a sputtering target produced by impregnating pores, wherein a porosity of the powder in the mold is set in a range of 30 to 80%. . 2. The rare earth-transition metal alloy comprises Sm, Nd, P
at least one kind of light rare earth metal (LR) of r and Ce, and G
at least one heavy rare earth metal of d, Tb, and Dy;
e, at least one transition metal (TM) of Co, and the powder contains at least one transition metal (TM) of Fe and Co. Production method. 3. The rare earth-transition metal alloy comprises Gd, Tb, Dy.
At least one heavy rare earth metal (HR), Fe,
2. The method for producing a sputtering target according to claim 1, comprising at least one transition metal (TM) of Co, and wherein the powder contains at least one transition metal (TM) of Fe and Co. 3. . 4. A sputtering target in which vacancies of a transition metal powder having a porosity of 30 to 80% are impregnated with a rare earth-transition metal alloy, wherein the structure constituting the target is a rare earth metal. A sputtering target comprising a phase, a transition metal phase, and a rare earth-transition metal alloy phase.