JPH01156470A - Manufacture of sputtering target - Google Patents

Abstract

PURPOSE:To obtain a target reduced in oxygen content and causing no distribution of composition in the film-forming plane by placing a powder of rare earth- transition metal alloy and an ingot of this alloy in a mold, heating this mold at a temp. between the melting points of both, and then working the resulting formed body after cooling. CONSTITUTION:A powder 4 of rare earth-transition metal alloy and an ingot 3 of rare earth-transition metal alloy are placed in a crucible 1, etc., which is reduced to vacuum. The crucible 1 is heated by means of a high-frequency induction heating coil 2, etc., at a temp. between the melting point of the powder 4 and that of the ingot 3, by which the molten metal of the ingot 3 is infiltrated into the pores of the powder 3 to fill the pores. The ingot after cooling is formed into two phases consisting of the grain 21 of the rare earth-transition metal alloy, a rare-earth single phase 21, and a rear earth-transition metal alloy phase 23. By working an grinding this ingot, a sputtering target is formed. As to the principal composition of the target, it is desirable to incorporate one or more heavy rare earth metals among Gd, Tb, and Dy and one or more transition metals between Fe and Co.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a rare earth transition metal alloy sputtering target.

[Conventional technology]

Conventional sputtering targets for producing a rare earth transition gold elliptic magneto-optical sickle film include a twist casting method, a sintering method, and a semi-melting method. The casting method referred to here is a method in which the cast ingot is used as a target by external diameter processing, and the sintering method is a method in which the cast ingot is crushed and sintered to form a target shape. It is. Also, the semi-melting method is described in Japanese Patent Application Laid-Open No. 1983-1999.
640.

[Problem that the invention seeks to solve]

However, the above-mentioned sintering method is not suitable for rare earth transition metal systems which inherently contain a large amount of oxygen (2000 ppm is the limit) and are easily oxidized. On the other hand, the casting method is preferable because it has a small amount of oxygen (about 50 (about 1 ppm)), but there is a problem that compositional distribution occurs within the film formation surface.

In addition, targets made by the semi-melting method have the advantage that compositional distribution is less likely to occur within the substrate surface, but since the semi-melting method is also basically manufactured by sintering, the target is completely dense. If the target is left in the atmosphere, the surface layer of the target will be oxidized, and the surface layer will become so oxidized that it cannot be cleaned by preliminary sputtering. In addition, since the semi-melting method includes a transition metal simple phase,
The target has a large magnetic permeability, and there is a drawback that during magnetron sputtering, a sufficient leakage magnetic field cannot be generated unless the target is made thin.

The present invention is intended to solve these problems, and its purpose is to overcome the drawback of the conventional cast alloy target that compositional distribution occurs within the film formation surface, and furthermore, to solve the problem of forming a target using a semi-melting method. The objective is to provide a target that overcomes the disadvantages of being easily oxidized and having high magnetic permeability.

[Means for solving problems]

In a method for producing a cast alloy target for producing magneto-optical recording/ill made of a rare earth transition metal alloy by sputtering, rare earth transition metal alloy particles and rare earth transition metal alloy ingots are placed in a mold, and the melting point of the particles is It is characterized by heating the inside of the mold at a temperature between the melting point of the ingot and the melting point of the ingot, and then cooling the molded body.

[Effect]

TM meta-get top R used conventionally in the laboratory
The tendency is opposite to that of a composite target formed by arranging an E-chig to form a film.

In the case of a p-composite target, there are more RRs directly above the target, and more TMs on the sides.

There are more REs as you go directly above, and more TMs on the sides.

On the other hand, in the case of a cast alloy target, there are more TMs directly above the target, and more RBs on the sides.

Looking at these in more detail, the flight of TM was almost the same for both composite targets and cast alloys, with no major difference. On the other hand, it was found that there is a large difference in the way RE flies between the composite target and the cast alloy. In other words, RK in the case of a composite target tends to fly upwards of the target, and R11i in the case of a cast alloy target tends to fly in the lateral direction of the target. In other words, the RE rate appearance and the RE-TM
If a cast alloy target is created by mixing an excessive amount of alloy phase, it will be possible to form a uniform film with a small composition distribution within the substrate surface, and since there is no single TM phase, the magnetic permeability will be low, making it possible to form a cast alloy target even if the target is thick. Magnetron sputtering becomes possible. Furthermore, since it is a cast alloy, the original oxygen content is low, and the preliminary sputtering period is extremely short.

[Example 1] First, T btt (P' eo, ll C0
0,1) ta at % (hereinafter, this ingot is referred to as R+R,T, ingot).The melting point of this ingot is 847°C.
The degree is low.

And then TbIo,s (F eo,o COo,t
) go, g at% ingot was made, and the average particle size was 200.
This ingot is crushed into powder to a size of approximately μm (hereinafter, this powder will be referred to as R1Tl? powder). This R,'r,
? The melting point of the powder is about 1312℃, and the porosity is 14
%.

Place this powder in a crucible with an inner diameter of 4″φ, and place R+
R, T, put the ingot. FIG. 1 is a schematic diagram showing this state. 1 is a crucible, 2 is a high frequency induction heating coil,
3 is R+R, T, ingot, 4 is R, 'r,? It is a powder.

This state is evacuated and then the temperature is raised to 1050°C. At this time, R+R1T, the ingot is melted, and R
1Tl? The granules remain undissolved and remain in the form of granules. R + R, T, the molten metal in which the ingot was melted is "
It penetrates into the pores of the tz'rt'r powder and fills the pores. After that, it was cooled, and the ingot in the crucible was taken out, the outer periphery was machined, and polished to create a sputtering target of 4″φ×6t.The target composition was T b,,F
"to,! Co...at %.A schematic diagram of the surface structure of this target is shown in Figure 2.21
The phase is Rz'r+y particles, the phase 22 is a single Tb textile phase, and the phase 25 is a rare earth transition metal alloy phase containing T'J (Fe6,11 COO). It has two phases: a phase and a rare earth transition metal alloy phase.

This TbFeC0 target was installed in a sputtering apparatus as shown in FIG. 5, a bottom film was formed, and its magnetic properties and composition distribution were investigated. 31 in FIG. 3 is a sputtering target, and 52 is a substrate holder (600φ).

Film forming conditions are Ar pressure 2.5mTU)rr, initial vacuum level 3
1. A friend who works with OA 540V.

FIG. 4 is a diagram showing the composition distribution and magnetic flux distribution in the substrate holder using the target of the present invention. As shown in this figure, the m composition is uniform with RE ranging from 22.0 to 22.5 at%, and the magnetic properties are uniform with Ha ranging from 14.7 to 15.5 KOe. A nearly uniform film was formed inside the substrate holder. Naturally, since this target is a cast alloy, the acid buildup was small (350 ppm).

On the other hand, for comparison, a TbFeC0 target was prepared using a conventional manufacturing method. Ding, namely TbFeC.

The entire composition is TbttF C16,z c ol, @at
% in a crucible at 1650°C, and poured into a mold to form an ingot. and cut the ingot with,
A 4"φX6t12JTbFeCo target was prepared by polishing.

The fifth case is cast alloy TbFeC by this conventional manufacturing method.
2 shows the composition distribution and magnetic property distribution factors within the substrate holder using a zero target. As shown in this figure, the composition has an RE of 22
．． 8 to 19.8 at%, and R increases toward the center of the substrate holder.
There is a lot of E, and on the contrary, the RE decreases toward the outer periphery of the holder. In addition, the magnetic properties are 17 to 11 KOe, and Ha increases toward the center of the holder. This also agrees with the composition distribution. In other words, when casting an alloy TbFaCo target using the conventional manufacturing method, there is no TM (transition metal) in the upper direction of the target, and RE in the lateral direction.
The substrate holder exhibits a characteristic that it is susceptible to oxidation, resulting in compositional distribution within the substrate holder.

Furthermore, compared with a target manufactured by the semi-molten method,
Therefore, the same T bHF as the target composition of the present invention described above
C16, I Co? A target of 4"φ x 3t was prepared using the semi-melting method with a composition of +l a t%.Then, the press sputtering time of the targets of the present invention and the semi-melting product was evaluated.The results showed that the coercive force was 11 KOe. The product of the present invention required only 20 minutes of press sputtering time to reach saturation, while the semi-molten product took 120 minutes.Of course, the process was carried out under the same conditions, with a pressure of 1.0A, 340VAr, and a pressure of 2.5V.
mTorr. This is evidence that the semi-molten product has a larger oxide layer on the target surface, which is disadvantageous in terms of cost during mass production.

Furthermore, in order to compare with the target manufactured by the semi-melting method, T bHF having the same composition as the target composition of the present invention described above was used.
C760, CO? A target of 4"φ x 6t was prepared using the semi-melting method with a composition of , a at%. Then, when the magnetic permeability of the target of the present invention and the semi-melting target was measured, the present product was 3, and the following On the other hand, the semi-molten product had a large value of 55.Then, the semi-molten product was attached to the sputtering device mentioned above and an attempt was made to generate an electric discharge, but no discharge occurred.Therefore, when the target thickness was reduced, , 511111
It started discharging easily at t. The semi-molten material has a high magnetic permeability, so the target needs to be made thinner for magnetron discharge. This means that only a small number of thin films can be produced from one target, which means that the cost of the product is very poor. Naturally, the product of the present invention produces a sufficient leakage magnetic field even at 6@t, and is very advantageous in terms of product cost. It has been confirmed that the present invention is effective even if R6T2g powder, R,T, or R,T, powder is used instead of preparing R,T□ powder other than the second son method shown here.

[Example 2] Next, the effect of the method of the present invention on DyFeCo was confirmed. Manufacturing method μ Same as Example 1, firstly, as raw materials D7tt,w (F 8o,s C0061)ts,s
Make an ingot of at%. The melting point of this ingot is about 890°C. And then D 7+o, s'CF @Io, e
A powder of 200 μm particle size of COo, t)s*, sat% was prepared. The melting point is about 1500℃,
Moreover, the vacancy i of this powder is 14.5%.

This powder is placed in a crucible with an inner diameter of 4″φ, and an ingot is placed on top of it.Then, the temperature is raised to 1050°C in a vacuum.
After the ingot was melted and then cooled, the ingot in the crucible was taken out, the outer periphery was processed and polished to create a sputtering target of 4"φ x 3t. Film formation was then attempted in the same manner as in Example 1. A film with uniform composition and uniform magnetic properties was obtained within the substrate holder.

The oxygen i of this target is 350 ppm, and the target structure is also RE, RE-TM, TM (G5 phase), and the overall composition is D 7zt F @to, *CO
It was y, a a f;

[Example 3] Next, what are the effects of the method of the present invention on TbGclFeCo? li! Approved. The manufacturing method is the same as in Example 1, and first, as raw materials (T bo, s G (io, m) yt,
s (F eo, * COo, t) ts, sat%
Make an ingot. The melting point of this ingot is about 858°C.

And then (T bo,s G(Lo,i)to,s
(F 66, ICo, 1) a*, sat% powder with a particle size of 200 μm was prepared. This melting point is 150
The temperature is about 0°C, and the porosity of this particle is 14.6%.

This powder is placed in a crucible with an inner diameter of 4″φ, and an ingot is placed on top of it.Then, the temperature is raised to 1050°C in a vacuum.
After the ingot was melted, it was cooled, the ingot in the crucible was taken out, the outer periphery was processed and polished, and a sputtering target of 4"φ x 3t was created. Then, when the same film formation as in Example 1 was attempted, the ingot was placed inside the substrate holder. A film with a uniform composition and uniform magnetic properties was obtained.
pm, and the target tissues are R11e, RE-TM,
It has six phases of TM, and the overall composition is u T bl I
Gd, , Fe,. ,.

co, 4at% and friends.

In addition to the composition system shown in Example 1.2.3.4, TbF
e, GdFeCo, TbCo, G4DyFsCo
, GdDyTbFeCo, DyTbFeCo, G
dTbFe, DyCo.

G(L, Tb,
At least one heavy rare earth metal of D7,
Fe.

It was confirmed that the effect of the present invention exists for all composition systems containing at least 1 m of Co and a transition metal.

〔Effect of the invention〕

If the present invention is used in this way, the surface element in the target: 1
While maintaining the characteristic of a cast alloy that there is little oxidation, it still has the effect of not causing compositional distribution within the film formation surface. Moreover, since the press sputtering time is reduced, the product cost of the produced membrane can also be reduced.

Moreover, the target according to the present invention has a low magnetic permeability and is suitable for magnetron sputtering, and the target thickness can be increased, so that the product cost of the produced film can be reduced.

In addition, the present manufacturing method is not limited to the method shown in the examples, and a heat-resistant brick or the like may be used instead of the crucible, and resistance heating or the like may be used instead of high-frequency heating.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the manufacturing method of the present invention. FIG. 2 is a schematic diagram of the surface structure of a target produced by the method of the present invention. FIG. 3 is a schematic diagram of the sputtering apparatus. FIG. 4 is a diagram of the composition distribution and magnetic property distribution in the substrate holder using the target of the present invention. FIG. 5 shows the composition distribution and magnetic property distribution in the substrate holder using a cast alloy target produced by the conventional manufacturing method. 1... Crucible 2... Bulk frequency conduction heating coil 5... R+R, T, ingot 4... R3T! ? Particle powder 21...RtT'tr particle 22...TI) for rare earth alone 23-TbI (Fe(1,,C06,1)! rare earth transition gold ingot alloy phase 61...Sputtering target 32...・・Substrate holder (300φ) Above ground 2 map (γ=15匈)

Claims (2)

[Claims] (1) In a method for manufacturing a cast alloy target for manufacturing a magneto-optical recording layer made of a rare earth transition metal alloy by sputtering, rare earth transition metal alloy particles and a rare earth transition metal alloy ingot are placed in a mold, and the 1. A method for producing a sputtering target, comprising heating the inside of the mold at a temperature between the melting point of the ingot and the melting point of the ingot, and then processing the formed body by cooling. (2) The main composition of the sputtering target includes at least one heavy rare earth metal (HR) among Gd, Tb, and Dy, and at least one transition metal (TM) among Fe and Co. A method for manufacturing a sputtering target according to claim 1, characterized in that: