JPH01129965A - Target for sputtering - Google Patents

Abstract

PURPOSE:To obtain a sputtering target causing no component distribution within a film-formation plane and reduced in magnetic permeability by constituting a casting alloy composed of a simple-substance phase of rare earth metal and an alloy phase of rare earth metal and transition metal by using Gd, Tb, Dy, Fe, Co, etc. CONSTITUTION:By sputtering a casting-alloy target having a metallic structure composed of a simple-substance phase of rare earth metal and an alloy phase of rare earth metal and transition metal, a magneto-optical recording layer consisting of an alloy of rare earth metal and transition metal is manufactured. The principal composition of the above sputtering target is regulated so that it contains at least one or more heavy rare earth metals among Gd, Tb, and Dy and at least one or more transition metals between Fe and Co. By this method, the target capable of forming a uniform film minimal in component distribution on a substrate can be obtained. Further, this target is reduced in oxygen content because it is composed of casting alloy, so that presputtering is also facilitated and, moreover, this target is reduced in magnetic permeability and, as a result, it can be applied to effective magnetron sputtering.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the structure and composition of a rare earth transition metal alloy sputtering target.

[Conventional technology]

Conventional sputtering targets for producing rare earth transition metal-based magneto-optical recording films include casting methods, sintering methods, and semi-melting methods. The casting method referred to here is a method in which the cast ingot is used as a target by external diameter and surface processing, and the sintering method is a method in which the cast ingot is crushed and sintered to create a target shape. It is something to do. In addition, the semi-melting method is described in Japanese Patent Application Laid-open No. 1983.
-99640.

However, the above-mentioned sintering method is not suitable for rare earth transition metal systems which inherently contain a large amount of oxygen (approximately 2000 ppm) and are easily oxidized. On the other hand, the casting method is extremely brittle for the TbFe system, and a new composition system is NdDyFeC.
o series is attracting attention. (Unexamined Japanese Patent Publication No. 16822/1983,
62-12941, etc.) [Problems to be solved by the invention] However, the Nd
DyFeCo, NdTbFeCo, PrDyFeCo5
When a film is formed by sputtering using a PrTbFeCo-based casting alloy target, there is a problem in that a compositional distribution occurs within the plane of the substrate.

(ISMO'87 21B-14) Furthermore, a target produced by a semi-melting method has the advantage that compositional distribution is less likely to occur within the plane of the substrate. (The 10th Japanese Society of Applied Magnetics Academic Lecture Abstracts 5aB-7, 5aB-8) However, since the semi-melting method is basically manufactured by sintering, the target is not in a completely dense state. First, if the target is left in the atmosphere, the surface layer of the target will be oxidized, and the oxidized layer will become so thick that it cannot be cleaned by preliminary sputtering. In addition, since the semi-molten method includes a single transition metal phase, the magnetic permeability of the target is large (
During magnetron sputtering, there is a drawback that 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]

A cast alloy target for producing a magneto-optical recording layer made of a rare earth transition metal alloy by sputtering is characterized in that the metal structure in the cast alloy target consists of a rare earth metal elemental phase and a rare earth transition metal alloy phase.

[Effect]

R on the TM target conventionally used in the laboratory.
In the case of a composite target method that uses E-chips to form a film,
The in-plane composition distribution of the substrate exhibits a slope opposite to that of the cast alloy target.

In other words, in the case of a composite target, there are more REs and more TMs on the sides as the position directly above the target increases.

On the other hand, in the case of a cast alloy target, there are more TMs directly above the target, and there are more REs 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, RE when using a compound target is ter.

It is easy to fly upwards of the target, and RE when using a cast alloy target is easy to fly horizontally of the target. In other words, if a cast alloy target with an appropriate mixture of RE single phase and RE-7M alloy phase is created, it will be possible to form a uniform film with a small composition distribution within the substrate surface, and since there is no TM single phase, magnetic permeability This makes it possible to sufficiently perform magnetron sputtering even if the target is made thicker. Furthermore, since it is a cast alloy, the original oxygen content is low, and the preliminary sputtering period is extremely short.

[Example 1] First, as a raw material, T byz (F eo, *COo
,+)gaat% (hereinafter, this ingot will be referred to as R+R)
t Tz ingot). The melting point of this ingot is as low as 847°C.

And then (F eo, q COa, +)s*, sat
% of the ingot is made, and this ingot is ground into powder so that the average particle size is about 200 μm (hereinafter, this powder will be referred to as RtT8
．． powder). The melting point of this RzTtt powder is 1312
It is ℃.

These raw materials, that is, R+ Rr T are combined into an ingot and Rz T
l? Powder (R+R+ Tt): (Rt T,
? )=11.5:50 into the crucible. Thereafter, the temperature of the crucible is raised to 1050°C. In other words, in this state of 1050℃, R+RI T2 ingot is melted and R1Tl? The powder remains mixed in the molten metal without being dissolved. Then, it is poured into a mold in this state, and the finished cast alloy is processed.
A sputtering target of 4#φ×6t was prepared.

The composition of this target is TbztFe-Ho,zCO
-1, sat%. A schematic diagram of the surface structure of this target is shown in FIG. Phase 1 is Tb rare earth [(
R) is a single phase, and the second phase is Tbl (Feo, Co
o, + ) z rare earth transition metal alloy phase (RIT). Also, the phase 3 is 'rbz (F eo, q C06,1)
l? is a rare earth transition metal alloy phase (RzT+t). In other words, there are two main phases: a rare earth single phase and a rare earth transition metal alloy phase.

This TbFeCo target was mounted on a sputtering apparatus as shown in FIG. 2 to form a film, and its magnetic properties and composition distribution were investigated. 21 in FIG. 2 is a sputtering target, and 22 is a substrate holder (300φ).

The film-forming conditions were Ar pressure 2°5 mT or r + initial vacuum level 3 x 10-'T, rr, input power using a DC power supply, and 1. It was performed at OA 340V. FIG. 3 is a diagram showing the composition distribution and magnetic property distribution in the substrate holder using the target of the present invention. As shown in this figure, the composition is uniform with RE of 22.0 to 22.5 at%, and the magnetic properties are also H
c is uniform at 14.7 to 15.5 K Oe. A nearly uniform film was formed inside the substrate holder. Naturally, since this target was a cast alloy, the amount of oxygen was small, 350 ppm.

On the other hand, for comparison, a TbFeCo target was produced using a conventional manufacturing method. That is, the total composition of TbFeC0 is T
The melt was melted in a crucible at 1650°C to give bztF 6BCOs at%, and poured into a mold to form an ingot. Then, this ingot was cut and polished to a Tb of 4#φX6t.
A FeCo target was created. FIG. 4 shows the composition distribution and magnetic property distribution in the substrate holder using a cast alloy TbFeCo target produced by this conventional manufacturing method. As shown in this figure, the composition is 22.8 to 19.8 at% RE.
There is a lot of RE toward the center of the substrate holder, and conversely, RE decreases toward the outer periphery of the holder. Also, regarding the magnetic properties, Hc is 17 to 11 KOe, and Hc increases as you move toward the center of the holder. This is also consistent with the composition distribution, that is, the cast alloy TbFeCo produced by the conventional manufacturing method.
The target is above the target TM (transition metal)
RE is likely to jump in the lateral direction, and a composition distribution occurs within the substrate holder.

Furthermore, in order to compare with a target manufactured by the semi-melting method, Tb! zFe
4 using a semi-melting method with a composition of to, zcOl, @at%.
A target of φX6t was prepared. Then, the magnetic permeability of the targets of the present invention and the semi-molten target was measured.
While the product of the present invention had a score of 3, the semi-molten product had a large value of 55. Then, the semi-molten product was attached to the above-mentioned sputtering device and an attempt was made to generate an electric discharge, but no electric discharge occurred. Therefore, when the target thickness was made thinner, discharge finally began to occur at 3.3 mm. In other words, semi-molten products have high magnetic permeability, and in order to generate magnetron discharge, it is necessary to make the target thin. 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 tmit, and is very advantageous in terms of product cost. Is there any Rt T I method other than the method shown here? RbTzx without creating powder
It has been confirmed that the present invention is effective even when powder or RIT powder or R, T2 powder is used.

[Example 2] Next, the effect of the method of the present invention on DyFeCo was confirmed. The manufacturing method is the same as the product of the present invention shown in Example 1,
First, as raw materials D)'tz (Feo, eCOo, z)
Make an ingot of zsat%. The melting point of this ingot is 890°
C and low. And then Dy+o, s (F eo, sC
Oo, ri 89. An ingot of sat% is made, and the ingot is ground into powder so that the average particle size is about 200 μm. The melting point of this RzT+v powder is 1370°C.

These raw materials, that is, the ingot and the powder, are placed in a crucible at a ratio of 11.5:50. Then add 10 crucibles
5 Raise the temperature to 0°C. Then, we processed the cast alloy that had been cast into a mold, created a 4"φ x 6 sputtering target, and tried to form a film in the same manner as in Example 1. We found that a film with a uniform composition and uniform magnetic properties was formed inside the substrate holder. was obtained.The oxygen content of this target was 3 soppm,
The magnetic permeability was 3.3. This target composition is D)'
zzFe6□, 4Cols, . . . at%.

Further, the metal structure was roughly divided into two phases: a rare earth single phase and a rare earth transition metal alloy phase.

[Example 3] Next, the effect of the method of the present invention on GdTbFeCo was confirmed. The manufacturing method is the same as the product of the present invention shown in Example 1, and first, (Gd, 5Tbo, s)? z (
F ej, *sc Oo, os)gt, sat% ingot is made. The melting point of this ingot is as low as 838°C. And then (G d 6.s T bo, s) + o, s (F
e o, qsCO@, 0'5) aq, sat% of the ingot is ground into powder. The melting point of this powder is 1324°C
It is.

These raw materials, that is, the ingot and the powder, are placed in a crucible at a ratio of 11.5750. Then the crucible is 1050
Raise the temperature to ℃. Then, we processed the finished cast alloy by casting it into a mold, created a sputtering target of 4#φ x 6t, and tried to form a film in the same manner as in Example 1. was gotten. This target had an oxygen content of 360 ppm and a magnetic permeability of 4.0. In addition, the composition of this target is Gd,
.

TbDyFeCo, tcOs, q at%. Furthermore, the metal structure was roughly divided into two phases: a rare earth single phase and a rare earth transition metal alloy phase.

In addition to the composition system shown in Example 1.2.3, TbDy
FeCo, DyGdFeCo, GdFeCo, GdTb
It was confirmed that the effects of the present invention also exist for composition systems such as Fe, TbDyFeCo, etc.

[Effects of the Invention] As described above, when the present invention is used, it is possible to maintain the characteristic of a cast alloy that the amount of oxygen in the target is small, while preventing compositional distribution within the film forming surface. Furthermore, it has low magnetic permeability and is suitable for magnetron sputtering, and the target thickness can be increased, so the product and cost of the produced film can be reduced. −

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the surface structure of the target of the present invention. FIG. 2 is a schematic diagram of a sputtering device. FIG. 3 is a diagram of the composition distribution and magnetic property distribution in the substrate holder using the target of the present invention. FIG. 4 is a diagram of the composition distribution and magnetic property distribution in the substrate holder using a cast alloy target produced by the conventional manufacturing method. 1...Tb rare earth (R) single phase 2...'Tb+ (Feo, q COo, +) z rare earth transition metal alloy phase 3=”rbz (F e(+, 9 COO, I)l?
Rare earth transition metal alloy phase 21...Sputtering target 22...Substrate holder (300φ) Applicants: Seiko Epson Co., Ltd. Representative Patent Attorney Tsutomu Mogami and 1 other person 1. ”;2,2^ °Nini・. 20th

Claims (1)

[Claims] A cast alloy target for manufacturing a magneto-optical recording layer made of a rare earth transition metal alloy by sputtering, wherein the metal structure in the cast alloy target is composed of a rare earth metal elemental phase and a rare earth transition metal alloy phase. The main composition of the sputtering target is characterized by containing at least one heavy rare earth metal (HR) among Gd, Tb, and Dy, and at least one transition metal (TM) among Fe and Co. Target for sputtering.