JPS61257473A - Target material for sputtering - Google Patents

Abstract

PURPOSE:To enhance the utilization efficiency of the resulting titled target material by producing a mechanical strain in a plastically deformable magnetic material. CONSTITUTION:A mechanical strain is produced in a plastically deformable magnetic material such as 'Permalloy(R)' by a plastic deforming means such as rolling, forging or pressing. At this time, the working temp. is preferably regulated to the recrystallization temp. of the material or below, especially the restoration temp. or below so as to effectively produce the strain. Thus, the coercive force of the material is increased or the magnetic permeability is reduced, and when the resulting target material is fixed in the magnetic circuit of a sputtering apparatus, magnetic flux leaking out of the surface of the material is increased. The material is eroded in an extended region, sputtering is carried out with improved efficiency and the utilization efficiency of the target material can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application This invention relates to a target material made of a soft ferromagnetic material used in a magnetron sputtering device, and more particularly to a target material for sputtering that is highly efficient and inexpensive.

BACKGROUND ART In general, sputtering is performed by applying a voltage between at least two electrodes in which the coating material to be formed is used as a cathode Googet material and the material to which the coating material is to be applied is used as an anode, and the material is introduced into the vacuum container. Argon gas or reactive gas alone or in a mixture is discharged by a sputtering power source to ionize the atmospheric gas, and the resulting positive ions are accelerated by the electric field and collide with the cathode surface with large kinetic energy, sputtering surface atoms. The ejected atoms adhere to the material surface of the anode, forming a thin film.

As a device for performing such sputtering, a magnetic field generating device using a permanent magnet or an electromagnet is installed behind the backing plate 1 that supports the target, and while generating a magnetic field parallel to the target surface, a high-density discharge plasma perpendicular to the magnetic field is generated. A magnetron sputtering device that converges the sputtering material onto the target surface and performs high-speed sputtering is commonly used.

This magnetron sputtering apparatus is often used for depositing thin films on semiconductor wafers, and in many cases, the material to be deposited is a nonmagnetic material such as aluminum and its alloys.

However, magnetic disk substrates in today's computer memories require multiple layers of at least one layer of magnetic material and non-magnetic layers. There is a strong desire to be able to efficiently sputter magnetic materials such as nickel or alloys of iron and nickel.

In magnetron sputtering equipment, when a ferromagnetic material is used for the target material, the magnetic flux of the magnetic field generator is shielded by the ferromagnetic material of this target and is difficult to leak to the target surface. m
It was necessary to increase the leakage magnetic flux by making it as thin as 500 m.

However, in such sputtering equipment, the erosion area of the target during sputtering is originally narrow, so the thin target material mentioned above has a short lifespan.
There have been various problems with sputtering workability and utilization efficiency.

In order to improve the above-mentioned problem of utilization efficiency of the target material, a technique of increasing the thickness of the target material at a specific location including the erosion area (Japanese Patent Laid-Open No. 59-232271)
And, similarly, considering the leakage magnetic flux, Targera! Technology for increasing the thickness of the erosion zone of heel material (Japanese Patent Application Laid-Open No. 60-39158
No.) has been proposed. However, in the case of a ferromagnetic target material, problems arise in its application as described above.

In addition, in order to increase the leakage magnetic flux of the material to the ferromagnetic targeter 1, a large number of targetera 1 to materials are arranged on the backing plate with a gap of 3 mm or less (Japanese Patent Laid-Open No. 57-160
No. 113), 31uf at regular intervals on the ferromagnetic target material.
Invention that explains many deep grooves below fl
No. 1211) has been proposed, but there is a problem in that the machining cost of the material with such grooves increases significantly.

OBJECTS OF THE INVENTION The object of the present invention is to provide a ferromagnetic target material for sputtering which has a wide erosion area during sputtering and has excellent utilization efficiency, and which is easy to manufacture and inexpensive.

Structure of the Invention The present invention is a sputtering target material made of a magnetic material that can be plastically processed, and which applies mechanical strain to the material to increase its own coercive force or decrease its magnetic permeability, and which can be applied to the magnetic circuit of a sputtering device. Sputtering tags 1 to 1 are characterized by increasing leakage magnetic flux from the surface of the target material when attached.

As the target material in this invention, various ferromagnetic metals or alloys are appropriately selected depending on the coating material, and magnetic materials that can be plastically deformed such as Fa, Co, Ni, silicon steel, and permalloy can also be used. You can select and use as appropriate.

In detail, in addition to pure Fθ, pure Co, 1iliNi,
Fs, C.

and a soft magnetic alloy consisting of at least two or more elements among Ni, and Cu, Inn, Cr,
Mo.

W, Nb, Ta, Ding5. Zy, Aρ, Mal
There are soft magnetic alloys containing 0.1 wt% to 17 wt% of at least one of these, and in particular, 40 wt% to 90 v of NL.
yt%, preferably 7 (hvt% to 85wt%) and Co
, CIL, lln, Cr, Mo, W, Nb
, Ta, Ti.

At least one of Zy, △LMc+ o, 1vl
A soft magnetic alloy containing lt% to 15wt% with the remainder being Fi1, and a soft magnetic alloy containing 0.1 to 15 wt% of Sz to Fa. Iwt%~5W[%
Soft magnetic materials such as alloys containing 0.1 to 17 wt% of /V in e can be appropriately selected and used.

In addition, the means of applying mechanical strain are rolling and forging.

All plastic deformation methods normally applied to metal materials, such as pressing and tensioning, can be employed. Furthermore, the processing temperature may be within a general processable range, but in order to effectively apply strain, it must be below the recrystallization temperature of each (A), and the recovery temperature The following is desirable.

DISCLOSURE AND EFFECTS OF THE INVENTION As a result of various studies aimed at creating a ferromagnetic target material for sputtering that has a wide erosion area during sputtering and is highly efficient in use, the present invention has revealed that a target material made of cold-rolled permalloy has a wide erosion area during sputtering and is highly efficient. It was discovered that the leakage magnetic flux is large, the erosion area is wide, and the sputtering efficiency is excellent.

This invention is based on the ratio -Cu permalloy (78Ni-4,5M
.

=3.5Cu-Fe) as an example, M of the same component
.

-Using Cu permalloy, 5mm thickness x 125 book width x
When a target material with a length of 300 mm was prepared and sputtering was performed under the same conditions, as shown in Figure 1,
Sample 1 (hot rolled material) has a narrow erosion zone and is deeply eroded, reaching almost the back surface, whereas Sample 2 (cold rolled material) has a wide erosion zone and is eroded only up to about half of the material thickness. It has not been. Furthermore, when the target material of sample 2 was used until the erosion reached the back surface, like sample 1, sample 2 had a utilization efficiency twice that of sample 1.

This sample 1 is a target (A) made into the required dimensions after hot rolling, whereas sample 2 is a
It is cold rolled at a rolling reduction of 5% and formed into the required dimensions. Figures 2 and 3 show the magnetization curves under direct current for each trial 1!31.
As shown in the figure, sample 1 target 1 ~ air cooled after hot rolling
The material has a coercive force of 0.590e and a maximum permeability of approximately 4500.
The target material of sample 2 that was cold rolled is:
The coercive horn is 5.00s and the maximum permeability is about 250,
Further, the magnetic flux density 850 in a 500θ magnetic field was 7.6 kQ for sample 1 and 4.9 kQ for sample 2.

By the way, the reason for the results shown in Figure 1 above is that permalloy, which has been subjected to large strains in the cold, is a soft magnetic material, but its soft magnetism has deteriorated significantly, and the target lens of the sputtering equipment When used as material No. 1, the magnetic permeability is small and the magnetic flux density under a constant applied magnetic field is low, so leakage magnetic flux from the target/surface increases, the erosion area accompanying sputtering increases, and the sputtering It is thought that the efficiency is improved, and it is thought that the sputtering efficiency of the target material is improved with other magnetic materials by a similar mechanism.

In addition, in this invention, the relationship between the reduction ratio of cold rolling and the sputtering efficiency may be such that an increase in coercive force or a decrease in magnetic permeability of vJ gain can be obtained by applying mechanical strain.
At least 5% is required.

To explain using experimental data, hot rolled M with a thickness of 5 mm
1 from the o-Cu permalloy plate without adding strain.
Cut out small pieces of 5mm x 30mm and add 10% to 50%
When the coercive force of each material was measured by cold rolling at a rolling reduction of 1.5%, the results shown in FIG. 4 were obtained. For example, at a rolling reduction of 10%, the coercive force increases approximately 7 times, and it is thought that the magnetic permeability decreases as the coercive force increases, and the magnetic flux density in a constant applied magnetic field decreases, causing spatter. It is thought that when attached to the magnetic circuit of the apparatus, leakage magnetic flux in the parallel direction of the target surface increases, the erosion area accompanying sputtering increases, and sputtering efficiency improves.

As described in detail, the present invention provides a ferromagnetic target material that can easily improve sputtering efficiency by cold rolling a plastically deformable magnetic material such as permalloy, and has excellent utilization efficiency. It has the advantage of being available at a low price.

Examples Example 1 Mo permalloy (8ONj -5Mo-Fs) Shrine 6
．． Hot rolled to a thickness of 0 mm, then removed with a grinder to a thickness of 5.5 mm, and then rolled to a thickness of 3.0 mm.
It was cold rolled to a thickness of mm to produce a disc-shaped target with a diameter of 200 mm.

Further, the hot-rolled material with a thickness of 5.5 mm from which the black scale had been removed was ground down to a thickness of 3.0 mm using a lathe and a grinder, and then a disk-shaped target with a diameter of 200 mm was produced.

The two types of target materials obtained were mounted on a commercially available 8-inch magnetron sputtering device, and the leakage magnetic flux density in the horizontal direction of the target surface was measured.

The measurement conditions were a permanent fIIt assembled on the yoke (1).
The distance L between the stone (2) and the target (4) fixed to the backing plate (3) (+ is 5 mm, the thickness t of the target is 3 W + m, the center of the magnetic flux density measurement probe (5) and the surface of the target (4) The distance between them was 2.5 mm.

Moreover, the difference in the average value of the thickness measurements taken at six locations was 0.1 mm or less for each target.

The leakage magnetic flux density measurement results are shown in a graph of the relationship between the radial distance from the target center and the leakage magnetic flux density in the horizontal direction of the target surface, as well as a cross-sectional explanation of the magnetic circuit showing the correlation between the radial distance from the center and the target laser 1. Figure 5
As shown in the figure.

As is clear from FIG. 5, the peaks of the leakage magnetic flux density are almost the same between the target of the present invention and the conventional hot-rolled target material, but even in the relatively thin target material of about 3 mm, the leakage magnetic flux The distribution of
It can be seen that the target material of the present invention has a wider distribution of leakage magnetic flux density, expands the region of high plasma density, and can expand the erosion region.

Example 2 Mo-Cu permalloy (78Ni-4,5Mo-
3,5Cu-Fe) material was hot rolled to a thickness of 6.0mm, and then the black scale was removed using a grinder to reduce the thickness to 5.5w+m.
The material was cold-rolled to a thickness of 4.6+ nm without any thickness, and a disk-shaped Targera i~ with a diameter of 100 mm was produced.

Further, the hot-rolled material having a thickness of 5,5+mn from which the black scale had been removed was ground to a thickness of 4.6 mm using a lathe and a grinder, and then disc-shaped Targera 1 to 100 mmφ were produced.

The two types of target materials obtained were attached to a commercially available 4-inch Magne 1 Heron sputtering device, and the leakage magnetic flux density in the horizontal direction of the target surface was measured.

The measurement conditions were a permanent magnet (2) assembled on a yoke (1).
) and the target (4) fixed on the backing plate 1-(3), the distance 1-g is 5 mm, the thickness t to the target plate 1 is 4.6 mm, and the distance between the center of the magnetic flux density measurement probe (5) and the target plate 1 is 5 mm. (4) The distance to the surface was 2.5 mm.

Moreover, the difference in the average value of the thickness measurements at six locations was 0.1+nm or less for the thickness of each target.

As shown in Fig. 6, the measurement results of leakage magnetic flux density are as follows for the target of the present invention and the conventional hot-rolled target material.
Although the peaks of the leakage magnetic flux density are almost the same, the distribution of the leakage magnetic flux is different, and the target material of the present invention has a wider distribution of the leakage magnetic flux density, and the area with high plasma density expands, making it possible to expand the erosion area. I understand.

In addition, it is generally said that a magnetic flux density of 1000 or more is required for sputtering in an AT atmosphere of 5 x 10-3 orr, but in Fig. 6, the area of 1000 or more is It can be seen that the target material of the present invention, which is expanded by 25% compared to the target and cold-rolled at a rolling reduction of about 16%, is extremely effective in improving sputtering efficiency.

Example 3 A pure iron material was hot rolled to a thickness of 5.0 mm, then the black scale was removed using a grinder to a thickness of 4.5 mm, and then cold rolled to a thickness of 3.0 mm to form a disc shape of 100 mmφ. A target was created.

Further, the hot-rolled material with a thickness of 4 to 5 mm from which the black scale had been removed was ground down to a thickness of 3.0 mm using a lathe and a grinder, and then a disk-shaped target with a diameter of 100 mm was produced.

The two types of target materials obtained were mounted on a commercially available 4-inch magnetron sputtering device, and the leakage magnetic flux density in the horizontal direction of the target surface was measured.

The measurement conditions were a permanent magnet (2) assembled on a yoke (1).
) and the target rat (4) fixed to the backing plate (3), the distance Lg is 5 mm, and the thickness t of the target is 3 mm.
mm, and the distance between the center of the magnetic flux density measuring probe (5) and the surface of the target (4) was 2.5 mm.

Moreover, the difference in the average value of the thickness measurements at six locations was 0.1 mm or less for each target.

The leakage magnetic flux density measurement results are shown in a graph of the relationship between the radial distance from the target center and the leakage magnetic flux density in the horizontal direction of the target surface, as well as a cross-sectional explanatory diagram of the magnetic circuit showing the correlation with the radial distance from the target center. As shown in FIG.

As is clear from FIG. 7, the leakage magnetic flux density peaks of the target of the present invention and the conventional hot-rolled target material are almost the same. It can be seen that the distribution of leakage magnetic flux is different, and the target material of the present invention has a wider distribution of leakage magnetic flux density, that the region of high plasma density is expanded, and that the erosion region can be expanded.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional explanatory diagram showing the erosion state of the target. FIGS. 2 and 3 are graphs showing magnetization curves of target materials under direct current, with FIG. 2 showing a target made of a hot-rolled material, and FIG. 3 showing a case of a target according to the present invention. FIG. 4 is a graph showing the relationship between the cold rolling reduction rate and the coercive force of the target vJ yield. Figures 5 to 7 are graphs of the relationship between the radial distance from the target center and the leakage magnetic flux density in the horizontal direction of the target surface, and magnetic circuits showing the correlation between the radial distance from the target center and the magnetic flux density in the horizontal direction of the target surface. FIG. 1...Yoke, 2...Permanent magnet, 3...Backing plate, 4...Tagtsu 1~. 5... Probe. Applicant Sumitomo Special Metals Co., Ltd. Figure 1

Claims (1)

[Claims] 1 A sputtering target material made of a magnetic material that can be plastically processed, which applies mechanical strain to the material to increase its own coercive force or decrease its magnetic permeability, thereby improving the target material when attached to the magnetic circuit of a sputtering device. A sputtering target material characterized by increased leakage magnetic flux from the surface.