JPH11335826A - Production of sputtering target material made of al alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a thin film small in warpage and furthermore reduced in particles by subjecting an Al alloy stock to plastic working and heat treatment and thereafter executing cold rolling as final working. SOLUTION: An Al alloy stock is first subjected to plastic working such as pressing and rolling to thin it, and heat treatment is executed, e.g., at 400 deg.C for about 15 min. Next, as final working, cold rolling is executed. In this way, its strength increases, so that the proof stress of a target material at the time of sputtering improves to reduce warpage therein. Simultaneously, the surface toughness in the sputtered face in the target material is reduced to suppress micro-abnormal discharge, by which a thin film small in particles can be obtd. The final cold rolling can be executed similarly to the case in the plastic working, but the working ratio is preferably regulated to 10 to 30%. Moreover, its 0.2%, proof stress after the working is preferably regulated to >=1.5 times that before the working.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an Al alloy sputtering target material,
More specifically, the present invention relates to a method for manufacturing an Al alloy sputtering target material that can form a thin film with less warpage and less particles.

[0002]

2. Description of the Related Art A sputtering target material made of an Al alloy (hereinafter abbreviated as a target material) includes a type in which a backing plate (Cu plate) is bonded to the back surface and a type having no bonding portion and a backing plate equivalent portion. There is an integrated type formed of a target material. All of such target materials are manufactured by subjecting an Al alloy material to plastic working and heat treatment.

[0003] The above-mentioned target material shows high strength due to working strain during plastic working, but finally becomes softened because the working strain is removed by heat treatment for recrystallization. The crystal grain size of the target material varies depending on the purity of Al and the type and amount of the added metal.
The range is from 0 to 250 μm.

[0004] During sputtering, the target material expands due to the high temperature on the sputtered surface side, and the sputtered surface side warps to a convex shape. On the other hand, since the back surface is water-cooled, it contracts when sputtering is completed. Each time the above expansion and contraction are repeated, the residual slight plastic strain accumulates, the warp of the target material gradually increases, and the sputtering surface side becomes convex. In particular, since the integrated target material also has a portion corresponding to the backing plate made of an Al alloy, the mechanical strength is poor and the above-mentioned warpage is large. When the warpage increases, the distance between the target material and the shield plate, which is usually held at about 1 to 2 mm, changes, and the sputter discharge becomes unstable.

[0005] For the reasons described above, when an integrated target material is mounted on a sputtering apparatus designed with the strength of a target material with a backing plate, it becomes impossible to use the target material in the middle of the service life of the target material. Even when a sputtering apparatus is designed based on a target material, there are restrictions due to Al strength.

In the production of a target material, various attempts have been made to reduce the crystal grain size in order to suppress the generation of particles generated during sputtering. That is, by reducing the crystal grain size, the surface roughness of the sputtered surface of the target material is reduced,
As a result, a minute abnormal discharge on the surface of the target material is suppressed, and a thin film with few particles is formed.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing an Al sputtering target material having less warpage. Another object of the present invention is to provide a sputtering target material made of an Al alloy capable of forming a thin film having a small number of particles by using the above-described means for improving the warpage without employing a special means for reducing the crystal grain size. It is to provide a manufacturing method.

[0008]

That is, the gist of the present invention is to provide an Al alloy sputtering target material characterized by subjecting an Al alloy material to plastic working and heat treatment, and then performing cold rolling as final processing. In the manufacturing method.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the present invention, as the Al alloy, Al, Si, C
An alloy to which one or more of additional metal elements such as u, Ti, Sc, Cr, Zr, Y, Nd, and Hf are added is used. As the Al, a higher-purity Al is used in order to form a precise metal thin film, and its purity is usually 99.99% or more. The total amount of the added metal element is usually 0.01 to 10% by weight, preferably 0.1 to 3% by weight.

First, in the manufacturing method of the present invention, the Al alloy material is subjected to plastic working and heat treatment in the same manner as in a conventionally known method. As the Al alloy material, a material ingot (a billet or a slab) is used. Plastic working means giving plastic deformation by processing such as pressing and rolling, and the rate of reduction in material thickness at that time is called the working rate. The plastic working is performed cold, that is, at around room temperature.
The processing rate is usually 50 to 90%. The heat treatment is performed at, for example, about 400 ° C. for about 15 minutes.
Recrystallized grains are formed.

Next, in the manufacturing method of the present invention, cold rolling is performed as final processing. As a result, the strength is increased, and as a result, the yield strength (stress resistance) of the target material during sputtering is improved, and the warpage is reduced. At the same time, the surface roughness of the sputtered surface of the target material is reduced, so that a micro abnormal discharge on the surface of the target material during sputtering is suppressed, and a thin film with few particles is formed.

The above-mentioned final cold rolling can be performed in the same manner as the above-mentioned plastic working, but the working ratio is 10 to 30%.
Is preferable. When the working ratio is less than 10%, the effect of improving the strength is not sufficient, and when the working ratio is more than 30%, the already adjusted crystal grains have too large a distortion and the sputtering characteristics become unstable.

In the present invention, 0.2% proof stress can be used as an index indicating a preferable condition of the final cold rolling. 0.2% proof stress means the deformation stress that gives the material 0.2% plastic strain. In the present invention, it is preferable that the 0.2% proof stress after the final cold rolling is adjusted to 1.5 times or more, preferably 1.5 to 3.0 times, before the final cold rolling. Thereby, strength equal to or higher than that of a Cu plate generally used for a backing plate can be achieved.

The target material obtained as described above is
After cutting into a predetermined shape, the backing plate equivalent part is also an integrated target formed of an Al target material. It is set in an apparatus and used for sputtering. When processing into a backing plate joining type target, after the backing plate is joined to the back surface of the target material as a cooling device by a known method such as a soldering method, the target is beveled into a predetermined shape. The effect of the manufacturing method of the present invention is remarkable in the case of an integrated target.

[0015]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Example 1 An ingot of an Al alloy material containing 1% by weight of Si and 0.5% by weight of Cu was sliced by a continuous casting method.
After pressing to form a disk having a thickness of 37.5 mm (processing rate 85%) at room temperature, heat treatment is performed at 400 ° C. for 15 minutes. A rolling process of 20% was performed. Then the diameter 30
A disk having a thickness of 0 mm and a thickness of 27 mm was cut out, and its surface and peripheral end face were chamfered to obtain a target material.

Sputtering equipment (M manufactured by Nippon Vacuum Engineering Co., Ltd.)
LX3000) with the above target material,
An inch Si wafer is set on the substrate fixing device, and the surface of the target material is irradiated with argon ions for 75 seconds while circulating cooling water through the backing plate device to form an Al alloy thin film having a thickness of about 1 μm on the Si wafer. did. The sputtering was performed with an electric power of 6.5 kW and an integrated electric energy of 3
Up to 00 kWH.

Since the surface of the target before use is chamfered, the preliminary sputtering operation is first repeated on 96 Si wafers in order to eliminate the initial influence of the chamfering. Again, as an example, the sputtering operation was repeated for 12 Si wafers. During the sputtering operation, the fluctuation of the discharge voltage was monitored, and the fluctuation of the discharge voltage of 10% or more was regarded as abnormal discharge, and the total number of abnormal discharges occurred for 12 Si wafers (total processing time 15 minutes) was calculated as the number of abnormal discharges. And

After the completion of the sputtering of 12 sheets, the number of particles and the like in the Al alloy thin film formed on each Si wafer was measured. To measure the number of such particles and the like, use a laser type particle counter (TENC).
OR INSTRUMENTS “SF-642”
0 ”), and the number of particles having an outer diameter of 0.3 μm or more is used as the number of particles.
The average number of particles per wafer was defined as the number of particles.

After a series of sputtering operations is completed, the target material is removed from the sputtering apparatus, the average grain size of the crystal grains on the surface of the target material is measured by the quadrature method, and further the measurement is performed according to JIS B-0601. The surface roughness Ra value and Rmax value of the surface were measured according to the standards, and the results are shown in Table 1.

Comparative Example 1 A target was obtained in the same manner as in Example 1 except that the final cold rolling was omitted. Using this target, a sputtering operation was performed in the same manner as in Example 1, and the number of abnormal discharges, the number of particles, and the surface roughness R
The a value, the Rmax value, and the grain size of the crystal grains were measured. Table 1 shows the results of these measurements.

[0022]

[Table 1]

[0023]

According to the present invention described above, there is provided a method for producing an Al alloy sputtering target material capable of forming a thin film with less warpage and less particles, and the industrial value of the present invention is great. .

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C22F 1/00 685 C22F 1/00 685Z 694 694A

Claims (3)

[Claims] 1. A method of manufacturing a sputtering target material made of an Al alloy, comprising subjecting an Al alloy material to plastic working and heat treatment, and then performing cold rolling as final processing. 2. The processing rate of the final cold rolling is 10 to 30.
%. 3. The method according to claim 1, wherein the 0.2% proof stress after the final cold rolling is 1.5 times or more that before the final cold rolling.