JPH0215167A - Magnetron sputtering target - Google Patents

Abstract

PURPOSE:To remarkably improve film-forming velocity and also to obtain a thin uniformly distributed film by forming a target so that (111) crystal plane comprises >=50% of the surface area of the target. CONSTITUTION:A target composed of single crystal properly arranged in the (111) crystal plane is prepared by a solidification process by using high-purity aluminum or its alloy. Further, the single crystal properly arranged in the (111) crystal plane is worked by means of rolling and then subjected to the prescribed heat treatment, by which a target in which the proportion of the (111) crystal plane is regulated to that it comprises >=50% of the surface area is prepared. By this method, efficiency of adhesion to substrate, that is, film-forming velocity can be remarkably improved without increasing electric power and a contribution toward productivity can be made, and further, uniform distribution can be attained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a magnetron sputtering target made of high-purity aluminum or its alloy, which has improved adhesion efficiency to substrates such as wafers and compact disks, so-called film formation speed. It is related to.

[Problems to be solved by conventional techniques and inventions] With the development of the electronic industry, the demand for ICs and LSIs has increased significantly. The wiring used inside these elements is mainly made into a thin film by sputtering using high-purity aluminum or its alloy as a target. In addition, reflective films for compact disks, magneto-optical disks, etc. are also increasingly formed of high-purity aluminum and its alloys by sputtering.

It is known that in the lithobatter method, which is different from the vapor deposition method using evaporation of molten metal, the surface and internal crystal structure of the target greatly influences the characteristics of emitting atoms from the target.

For example, Webne, which uses single crystals of silver and copper,
t) experiments (Phys, Rev,
) 102.699 (1956)) describes that the density of atoms emitted from the target is high in the <110> direction, which is the closest-packed direction of the crystal structure, and a spot-like distribution is obtained on the wafer.

Therefore, targets for IC and LSI wiring materials made of high-purity aluminum or aluminum alloy, and targets for reflective films used in compact discs are made with as fine crystals as possible to avoid the effects of crystal orientation and to obtain a uniform thin film. Moreover, they have been manufactured so that the crystal orientation is random. (Proceedings of the 25th Symposium of the Light Metals Society, 33
(1984)) On the other hand, in order to improve the productivity of ICs and LSIs as well as the formation speed of reflective films, there is a need to increase the speed of forming thin films by sputtering, which has so far been addressed by increasing the capacity of power supplies. Ta.

However, this not only increases power consumption, but also raises the temperature of the target, wafer, and compact disk substrate, and has been accompanied by other difficult problems, such as making the cooling equipment more complex.

[Means to solve the problem]

In view of these circumstances, the inventors of the present invention have conducted intensive studies on the orientation of crystal planes of high-purity aluminum and its alloys, and have found that:
Using a magnetron sputtering device, the target (11
The present inventors have discovered that when the No. 11 crystal plane accounts for 50% or more of the surface area of the wafer, the film formation rate can be increased without showing any scratches or 1- to 1-like adhesion distribution on the wafer, leading to the completion of the present invention.

That is, in the present invention, in a target made of high-purity aluminum or its alloy, 50% of the surface area of the target is
The above provides a magnet I long sputtering target I composed of 11N crystal planes.

The present invention will be explained in detail below.

What is high-purity aluminum used as target material?J
It means 99.95% or more aluminum as specified in IS H2111, and its alloys include S+ + Cu, T+ + Cr, which are usually added for sputter targets.
W+ refers to high-purity aluminum containing 10% by weight or less of one or two types of metal elements such as Mo and Mg.

The +1111 crystal plane includes not only the (1111 crystal plane itself) but also a crystal plane tilted within ±10° from the N11 crystal plane, for example, a plane similar to the (1111 crystal plane) with a high index such as (7751).

In addition, (the 1111 crystal plane is more than 50% of the surface area) means that not only the surface but also the inside of the crystal has +11
This includes cases where 11 crystal faces account for 50% or more of the area. Furthermore, +1111 crystal planes account for 50% or more of the surface area when counted using an X-ray diffraction device (the intensity ratio of the 1111 crystal planes and similar planes to the total counted intensity is 50% or more).

When the +1111 crystal face accounts for 50% or more of the surface area, the film formation rate is significantly improved, but when it is less than 50%, the film formation rate cannot be sufficiently improved and therefore productivity cannot be expected.

The target used in the present invention may be a single crystal material produced by a solidification method such as the Bridgman method or the Djochralski method, a single crystal material produced by plastic working and heat treatment, a single crystal material produced by the so-called recrystallization method, or a single crystal material formed by an aggregation of polycrystals. It may be one in which the (111) crystal plane is oriented over 50% or more of its surface area by adjusting the orientation. The reason why the (111) crystal plane improves the film formation rate is not clear, but in aluminum, which has a face-centered cubic lattice, the (1111 crystal plane is a close-packed plane, and the sputtering efficiency with ions is high, and the magnetic It is presumed that the surface radiation of I.ron causes a uniform distribution on the wafer.

The target thus obtained can be used as a target for all magnetron sputtering devices currently in practical use.

〔Effect of the invention〕

As described in detail above, the present invention provides that the surface of the magnetron sputtering target occupies 50% or more of the surface area (1
111 crystal plane, it greatly improves the adhesion efficiency to the substrate, that is, the film formation speed, without increasing the electric power, contributing to productivity, and uniform distribution, making it suitable for the industry. Its value is enormous.

[Examples] The present invention will be explained below using Examples, but the present invention is not limited thereto.

Examples 1 and 2, Comparative Examples 1 to 3 A single-crystal cougette aligned to the N crystal plane was produced by a solidification method (Bridgeman method) using high-purity aluminum (purity 99.999%) (1). Also mentioned above (111
A single crystal aligned in one crystal plane is processed by 28% by rolling,
By heat treatment at 300'C, the ratio of (111) crystal faces was reduced to 64.
A target adjusted to % was prepared. These pieces are 3 inches in diameter and 5 mm thick.

As comparative examples, high-purity aluminum similar to the above was used and subjected to the solidification method (Brifgeman method) (110) and [001
A single-crystal target aligned with the crystal plane was fabricated. In addition, the single crystal aligned with the 111 crystal plane was processed by 60% by rolling, and a target with the proportion of the 11,11 crystal plane adjusted to 13% was prepared by heat treatment at 350°C.

These three types of targets are also the same as the target described in 1.

Using the above two types of targets of the present invention and three types of comparative targets, a thin film of about 2 μm was formed on a 3-inch diameter wafer using a DC magnetron spackling device.
The deposition rate and film thickness distribution on the wafer were measured. The film formation rate was calculated as a percentage based on the weight increase of the wafer after sputtering for a certain period of time based on that of Comparative Example 3, and the film thickness distribution was calculated from the measurement of electrical resistance by the four-terminal method. The measurement results are shown in Table 1.

The input power during sputtering was 500W, the Ar pressure was 8X10'-3Torr, and the Targera 1~/
There were 80 fences between wafers.

Table 1

Claims (1)

[Claims] A magnetron sputtering target made of high-purity aluminum or its alloy, in which 50% or more of the surface area is composed of {111} crystal planes.