JPH01263268A - Production of target for sputtering - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a sputtering target.

(Prior Art) Sputtering targets for producing rare earth-transition metal-based magneto-optical recording films are classified into cast targets, sintered targets, semi-molten targets, etc., depending on the manufacturing method. The casting target referred to here is an ingot that has been completely melted and cast with a predetermined composition, and has been processed into an external shape.
The sintered target is the ingot that has been crushed and sintered into a predetermined shape. The semi-molten target is shown in Japanese Patent Application Laid-Open No. 61-99640.

(Problems to be Solved by the Invention) However, the above-mentioned sintered target inherently contains a large amount of oxygen (2000 pβm is the limit) and is not suitable for rare earth-transition metals that are easily oxidized.

On the other hand, the casting method is preferable because it contains a small amount of oxygen (approximately 500 ppm), but it has the problem that compositional distribution occurs within the film-forming surface.

In addition, targets created by the semi-melting method have the characteristic that compositional distribution is difficult to occur within the substrate surface, but since the semi-melting method is also basically a method by sintering, the metal structure is not in a dense state. Since the surface area is large, the target surface layer is easily oxidized when left in the atmosphere, and the oxidized layer becomes so thick that the surface layer cannot be cleaned by preliminary sputtering.

Therefore, the present invention is intended to solve these problems, and its purpose is to provide a rare earth transition metal target that overcomes the drawback of conventional cast alloy targets that compositional distribution occurs within the film formation surface. It's there.

(Means for Solving the Problems) Therefore, the present invention solves the above-mentioned problem.(1) When the rare earth metal is represented by RE and the transition metal is represented by TM, the atomic ratio of the composition is RExTM+-x. (0,33<x<1) A method for producing a sputtering target, characterized in that the alloy is heated above its melting point and infiltrated into a foamed TM.

(2) The main composition of the rare earth metal (RE) described in the previous section is
Nd, Ce, Pr+ Sm, Gd,
Tb.

Containing at least one or more heavy rare earth metals among Dy,
2. The method for producing a sputtering target according to claim 1, wherein the main composition of the transition metal (TM) includes at least one of Fe, Co, and Ni.

(Function) R on the TM target that has been used in experiments
In the case of a composite target method in which E-chip is placed to form a film,
The composition distribution within the base plane shows a tendency opposite to that of a completely molten cast alloy target.

In other words, in the case of a composite target, the more directly above the target, the more RE there are, and the sides have more TM.

On the other hand, in the case of a cast alloy target, there is more TM right above the target, and more RE on the sides.

This shows that there is a difference in the flight of RE and TM sputtered particles depending on the metal phase appearing in the metal structure of the target.

Therefore, RE, TM single phase and R
By allowing the E-TM alloy phase to appear and mix in an appropriate proportion, it becomes possible to form a uniform film without compositional distribution within the substrate surface.

The targets produced by the manufacturing method of the present invention are RE, T
A single M phase and an alloy phase of RE and TM appear in a moderate proportion.

(Example) (Example 1) The effects of the present invention will be described using an example. First, is the atomic ratio of the raw material composition T b? 2F 828.2CO1,11
Create an alloy. Further, a foamed TM having a composition of F e 918COa, a is prepared. Foamed TM is a metal porous body with a sea-level skeleton and high porosity, as seen in, for example, "Kogyo Materials, October 1987 issue."

Next, the above alloy and powder were prepared so that the atomic ratio was 30°6 for the alloy and 69.4 for the foamed TM.

Further, the foamed TM is pressed and cut into a shape similar to the finished target so that the foamed TM has an appropriate porosity so that the alloy can be infiltrated into the pores of the foamed TM without excess or deficiency.

The crucible containing the alloy prepared in this way and the foamed TM is heated at about 1000° C. in a vacuum atmosphere.

Tb? 2F e 26.2CO+, @alloy has a low melting point, so it melts at temperatures above about 850°C and forms a foamed Fe
s3. It dissolves into aCOs4.

A schematic diagram of the metal structure of the cast alloy thus produced is shown in FIG. 1. The structure contains transition metals (Fe 93.8C
A single phase 101 of Oa, 4), a single phase 102 of rare earth metal (Tb), and an alloy phase 103 of transition metal and rare earth metal are mixed.

A target prepared by externally processing this TbFeCo ingot was mounted on a sputtering apparatus as shown in FIG. 2 to form a film, and its magnetic properties and composition distribution were investigated. In Figure 2, 201 is a sputtering target and 202
is the base holder (300Φ). The film forming conditions were Ar
Pressure 2.5 mTorr, initial vacuum level 3xlO-7 Torr
r. Use a DC power supply for input power. 1. The test was carried out at OA and 340V. FIG. 3 is a diagram of the composition distribution and magnetic property distribution within the substrate using the target of the present invention. As shown in this figure, the composition is uniform with RE of 22.0-22.5 at%,
The magnetic properties of He are 14. It is uniform at 7-15°5 kOe. A nearly uniform film was formed inside the substrate holder. In addition, this target contained a small amount of oxygen, 600 ppm, since the rare earth metal was supplied in the form of an ingot and not made into powder.

(Comparative example 1) On the other hand, for comparison, TbFeC was prepared using the conventional method.

Created a target. First, Tb, Fe, Co metal raw materials are T b22F 6! ? The mixture was melted in a crucible to give 3CO5 and then poured into a mold. The ingot thus prepared was cut and polished to form a target with a diameter of 4 inches and a thickness of 6 mm. FIG. 4 shows the composition distribution and magnetic property distribution in the base holder using a cast alloy TbFeCo target produced by this conventional manufacturing method. As shown in this figure, the composition has an RE of 22.8-19. '8at
%, the closer you go to the center of the base holder, the more RE there is, and conversely, the more you go to the outer periphery of the holder, the less RE there is. Also, regarding the magnetic properties, Hc is 1l-17kOe, and He becomes larger toward the center of the holder. This is consistent with the compositional distribution. In other words, the cast alloy TbFeCo target produced by the conventional method exhibits characteristics in which TM (transition metal) tends to fly upward in the target and RE tends to fly in the lateral direction, resulting in a compositional distribution within the base holder.

(Example 2) Next, as a raw material, the atomic ratio of the composition is D y72F e 2a
, gCo +, @ alloys are created. F jf3 s
a, ec Oa, a Prepare the foam.

Next, the alloy and the foam were prepared so that the atomic ratio was 30°6 for the alloy and 69.4 for the foam.
) and then filled into a crucible.

The crucible containing the alloy prepared in this way and the foamed TM is heated in a vacuum atmosphere.

D'! ? 2F e 28.2CO+, s alloy, has a low melting point, so it melts at temperatures above about 900°C.
Infiltrate z, ac O6,4 foam.

Using this DyFeCo ingot as a sputtering target and using the same film forming apparatus and film forming method as in Example 1, the composition distribution and magnetic property distribution in the substrate holder were evaluated. As a result, the RE was 22.0-22.5 at% and uniform. The magnetic properties were also uniform with He being 12.0-13.0 kOe. The oxygen content was 611 ppm.

(Comparative example 2) On the other hand, for comparison, DyFeC was prepared using the conventional method.

Created a target. First, Dy, Fe, and Co metal raw materials were melted in a crucible to become Dy22Fe73cO5, and the melt was poured into a mold. The ingot thus prepared was cut and polished to form a target with a diameter of 4 inches and a thickness of 6 mm.

Using this DyFeCo ingot as a sputtering target and using the same film forming apparatus and film forming method as in Example 1, the composition distribution and magnetic property distribution inside the substrate holder were evaluated. As a result, the RE was 22.919.5 at% and the closer to the center of the substrate holder There is a lot of RE, and on the contrary, the RE decreases toward the outer periphery of the holder.

In addition, after the magnetic property Hc of 7-18 is treated as described above (Implementation Order 1), it is filled into a crucible.

The crucible containing the alloy prepared in this way and the foamed TM is heated in a vacuum atmosphere. Oe and the closer you go to the center of the holder, the more H
c is getting larger.

(Example 3) Next, as a raw material, the atomic ratio of the composition is T b 38G d 3
An alloy called 6Fe 26.2CO+, e is prepared. Further, a foam having a composition of F e 93.6COa□4 is prepared.

Next, the alloy and the foam are prepared so that the atomic ratio is 30 for the alloy and 70 for the foam, and after being subjected to the treatment described in (Implementation Order 1), the mixture is filled into a crucible.

The crucible containing the alloy prepared in this way and the foamed TM is heated at about 1000° C. in a vacuum atmosphere.

T b 36G d 36F e 28.2CO1,1
1 alloy melts when the temperature exceeds about 900°C and becomes F e 9
3.6 COe, a infiltrate into the foam.

Using this TbGdFeCo ingot as a sputtering target, the composition distribution and magnetic property distribution inside the substrate holder were evaluated using the same film forming apparatus and film forming method as in Example 1.
RE is 22. 0-22. The magnetic properties were uniform at 5 at%, and the magnetic properties were uniform at Hc of 12°0-13.0 kOe. The amount of oxygen contained is small (601 ppm).

(Example 4) Next, as raw materials, the atomic ratio of the composition is N d +e, +D'
! 5a3F e 23. Create an alloy called TCOs, 9. Further, a foam having a composition of Fe5aCOzs is prepared.

Next, the alloy and the foam are prepared so that the weight ratio is 40 for the alloy and 60 for the foam, and after performing the treatment as described in (Implementation Order 1), the mixture is filled into a crucible.

A crucible containing the prepared alloy and foamed TM is heated at about 950° C. in a vacuum atmosphere.

N d +e, +D 515a, 3F e23. vc
The alloy 05.9 melts at temperatures above about 850°C and F
Infiltrate into es 0026 foam.

Using this NdDyFeCo ingot as a sputtering target and using the same film forming apparatus and film forming method as in Example 1, the composition distribution and magnetic property distribution inside the substrate holder were evaluated.
The E was uniform, ranging from 28.0 to 28.5a, and 7%, and the magnetic properties were also uniform, with He ranging from 9.7 to 10.5 kOe.

The amount of oxygen contained is as low as 620 ppm.

In the present invention, the atomic ratio of the composition of the alloy of RE and TM is set to RExTM+-x (0,33<x<1) because the composition of the alloy is not within this range as shown in Fig. This is because RE, TM, and alloy phases of RE and TM do not appear at the same time.

These Examples '1. 2. In addition to the composition system shown in 3.4, SmDyFeCo, PrDyFeCo.

NPrDyFeCo, TbDyFeCo, Dy
It was confirmed that the effects of the present invention also exist for composition systems such as GdFeCo and TbDyFe.

In addition to the above elements, additives and impurities such as Ti,
A1. Si, Cr, Zr, V, M
Even if n, Ca, etc. are contained in the RE-TM gold alloy or foamed TM, the effects of the present invention still exist.

In both of the above-mentioned implementation tables, the starting materials are put in the same crucible, but the RE-TM gold alloy is melted in the crucible,
It can be similarly produced by pouring it into a foamed TM placed in a separate container and infiltrating it.

(Effects of the Invention) As described above, by using the present invention, it is possible to produce a target that has the effect of preventing compositional distribution within the film formation surface while maintaining the characteristic of a cast alloy that the amount of oxygen in the target is small.

Foamed TM can be easily compressed using a press, etc., and the porosity can be easily changed, making it easy to control the TM, RE, and TM-RE gold alloy ratios in the infiltrated metal structure. Furthermore, the foamed TM forms a framework throughout the target ingot, and the toughness of the target ingot is improved. This makes it easier to process and handle than cast alloys.

[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 showing 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. Applicants: Seiko Epson Co., Ltd. Representative Patent Attorney Masayoshi Ueyanagi (and 1 other person) Figure 2

Claims (2)

[Claims] (1) When rare earth metals are represented by RE and transition metals are represented by TM, an alloy with an atomic ratio of RE_xTM_1_-_x (0.33<x<1) is heated above the melting point of the alloy and melted into a foamed TM. A method for producing a sputtering target, the method comprising dipping the target. (2) The main composition of the rare earth metal (RE) described in the previous section is N
d, Ce, Pr, Sm, Gd, Tb, and Dy, and the main composition of the transition metal (TM) is Fe, Co, and Ni. A method for manufacturing a sputtering target according to claim 1.