JPH0234778A - Embedded target for sputtering - Google Patents

Abstract

PURPOSE:To prolong the service life of a composite film to be obtained and also to reduce fluctuations in composition by dividing a cruciform chip into an upper projected part and a lower flat part in a discoid composite target formed of the above cruciform chip and four quadrantlike materials. CONSTITUTION:The embedded target for sputtering is a discoid composite target 3 and formed by allowing four quadrantlike formed bodies consisting of a second sputtering material 2 to adhere to a cruciform chip of projected sectional form consisting of a first sputtering material. The above chip is formed so that its upper part is exposed and its lower part is embedded. Further, this chip is separated into an upper projected part 5 forming a projected sectional form and a lower flat part 6.

Description

[Detailed Description of the Invention] [Summary] Regarding a target for forming a composite film on a substrate to be processed by a sputtering method, we have developed a convex A cross-shaped chip made of the first sputtered material has a cross section of 174
In a disk-shaped composite target formed by four semicircular molded bodies made of the second sputtering material, with the upper part exposed and the lower part buried, the target is formed in close contact with the first sputtering material. The embedded target for sputtering is constructed by separating the chip into an upper protruding part and a lower flat part which have a convex cross-sectional structure.

[Industrial application field]

The present invention relates to a buried target for sputtering that forms a composite film with a fixed composition ratio.

Due to the need to process large amounts of information at high speed, information processing equipment has made remarkable progress, leading to miniaturization and high-density packaging of components and devices.These miniaturizations and higher performance are due to advances in thin film formation technology. I owe a lot to

For example, regarding optical disks, optical disks can be divided into optical disks and magneto-optical disks in the narrow sense, but their structure is that they are made by sputtering or other methods on a glass disk about 1.2 mm thick or on a substrate made of synthetic resin. , a base film, a recording film, and a protective film each having a thickness of about 1,000 layers are formed to form a unit optical disk element.

In this case, the base film and protective film are made of materials with excellent moisture resistance and light transmittance, such as silicon dioxide (SiO□), silicon nitride (5iJn), and titanium dioxide (Ti0z), and the recording film is made of tellurium for optical discs.・tR(Te-Sn).

Arsenic, tellurium, selenium (As-Te-3e) + arsenic,
Low melting point amorphous solid solutions such as tellurium germanium (As-Te-Ge) are used.

Regarding magneto-optical disks, terbium iron (Tb-
Fe), terbium-iron-cobalt (Tb-Fe-C
o) Gadolinium-terbium-iron (Gd-Tb-Fe
) are used as magnetic thin films made of rare earth and transition metals.

Next, the method for forming these thin films is vacuum evaporation.

Various methods have been used, such as electron beam evaporation and high-frequency sputtering, but when forming a composite film, sputtering is often used because of its characteristic that there is little change in the composition ratio; The present invention relates to the configuration of a target for sputtering a composite material having a composition ratio of .

[Conventional technology]

Conventionally, as a method of forming a thin film with a certain composition ratio on a substrate to be processed by sputtering, a circular target is formed using a material with a large composition ratio, and this is cooled with water on a banking plate. It was customary to fix it on the top and place a chip made of a material with a small composition ratio on top of it in the required area ratio.

Hereinafter, in order to facilitate understanding, the present invention will be explained using the formation of a base film on a magneto-optical disk as an example.

In an optical disk, information is recorded by irradiating a recording film, which is made up of a base H/recording film/protective film on glass or transparent resin, with a laser beam focused to a diameter of about 1 μm. .

Here, the necessary conditions for the material constituting the base film are: ■ not oxidizing the recording film, ■ having excellent light transmittance, and ■ having low moisture permeability. 5i02 is a material that satisfies these requirements. It is used.

However, when using 5iOt as a target and sputtering it onto a substrate to be processed, a part of SfQ'z dissociates into SiO and 0, so there is a problem that the recording film is slightly oxidized by this 0. There is.

Therefore, as a method to eliminate this free O, the inventors proposed an O
It is proposed to add a rare earth element such as terbium (Tb), which is easy to bond with and has an excellent optical transmittance of an oxide.

The method for constructing the composite target is to create a disk-shaped target using 5i02, place a Tb chip on top of it, and perform sputtering while keeping the exposed area of SiO□ and the area of Tb at the composition ratio of the composite film. Ta.

However, in this method, while the Sin is sufficiently cooled by the backing plate, the Tb chip has poor thermal conductivity and the contact is not perfect, so the composition ratio in the composite film fluctuates and the Tb composition ratio changes. There is a problem that the amount of energy decreases gradually.

That is, Tb is oxidized due to poor heat dissipation, which reduces the spuck rate.

Therefore, the inventors have proposed a target having a structure whose cross section is shown in FIG.

(Patent Application No. 1984-199446, issued on August 10, 1986) Figure 1 is a plan view of the target according to the present invention (A
) and a cross-sectional view (B), but there is no difference between the two in terms of plan view.

That is, a Tb chip 1 (first sputtering material), which is cross-shaped with a convex cross section, is fitted with four pieces of 5iOz2 (second sputtering material) divided into 174 planes to form a disk-shaped target. Made of indium (I)
n) It was fixed to a backing plate 4 provided at the cathode part of the sputtering apparatus using an adhesive made of metal.

The reason for the convex cross-sectional structure is to prevent spatter caused by the adhesive oozing out.

With such a structure, the Tb chip l (first sputtering material) and 5iOz2 (second sputtering material) are cooled together, thereby eliminating the conventional drawbacks.

However, when performing sputtering using such a composite target,
When creating a base film for an optical disc, the following problems were found.

■ Comparing the sputtering rates of both Tb and 5i02, SiO2 is 90 to 1100 n/min, whereas Tb is 1.5 times larger than 5i02, so Tb chip 1
will wear out quickly.

(2) Since Tb is a metal that is easily oxidized, the surface is already oxidized during the cutting process into a complex shape such as a convex shape.

There were other problems, and improvements were needed.

Therefore, when complex processing is performed, an oxide film is formed on the surface, which hinders sputtering, and a solution needed to be solved.

[Means to solve the problem]

The above problem is that the Tb chip made of the first sputtered material, which has a convex cross section and a cross shape, has its upper part exposed by the Si molded body made of the second sputtered material, which has four 174 semicircular shapes, and the lower part In a disk-shaped composite target that is formed in close contact with a Tb chip embedded therein, a Tb chip made of the first sputtered material is separated into an upper protruding part and a lower flat part forming a convex cross-sectional structure. This problem can be solved by constructing an embedded target for sputtering.

[Problem to be solved by the invention]

As described above, when a composite target is constructed using different metals, metals with a high sputtering rate are consumed quickly, and rare earth metals are easily oxidized. The upper part of the Tb chip, which has a convex cross section, wears out quickly.
As a result, the target lifespan is short.

Therefore, as shown in Fig. 1(B), T
The b-chip is separated into an upper protrusion 5 and a lower flat part 6, so that only the upper protrusion 5 can be replaced as appropriate.

This has the advantage that the upper protrusion 5 made of Tb can be formed in a state where it is only slightly oxidized because it is easy to process, and a composite film with a uniform composition ratio can be formed economically.

〔Example〕

After dividing the Sin disk into 174 semicircles with a diameter of 6 inches and a thickness of 3n, a cross-shaped Tb chip with a convex cross section with a width of the upper protrusion of 2 cm and a width of the lower flat part of 5 cm was obtained. Processed so that they fit together.

Here, the Tb chip is formed with an upper protrusion 5 and a lower flat part 6 separated from each other.

Next, a 174 semicircular lower flat part 6 made of SiO□2 and Tb is bonded and integrated onto a backing plate 4 made of 4 (Cu) having a thickness of 5 fins using an In-based adhesive. On top of this, an upper protrusion 5 made of Tb was installed.

Figure 3 shows the change in Tb concentration in the sputtered film when continuous sputtering is performed using such a composite target.
After evacuation to below, supply argon (Ar) to 0
．． This is the result of continuous sputtering while maintaining a vacuum level of 5 Pa and applying high frequency power of IKW.

In other words, 7M5 in the sputtered film remains for 40 hours.
The degree is constant at 30 atomic weight %, but after that the influence of Tb consumption becomes noticeable, and from then on, as shown by the broken line 7, rbt3
The degree is decreasing.

Therefore, in the embodiment, the step of the upper protrusion of Tb is 2
n or more, and the upper protrusion of the Tb chip was replaced with a new one when the Tb concentration decreased by about 5%.

FIG. 3 shows the state in which this process was repeated four times, and it can be seen that the Tb concentration was maintained at 30 atomic percent by the exchange.

However, after 240 hours have elapsed, the SiO□ substrate is consumed and disappears, so it is necessary to renew the composite target itself.

〔Effect of the invention〕

By implementing the present invention, a composite film having a predetermined composition ratio can be stably obtained even in a composite target made of materials having different sputter rates.

Although Tb was used as the first sputtering material and SiO□ was used as the second sputtering material, the same method can be applied to combinations of other sputtering materials.

In the figure, 1 is a Tb chip (first sputtering material) 2 is a 5i (h
(Second sputtering material) 3 is a target, 4 is a backing plate, 5 is an upper protrusion, and 6 is a lower flat part.

[Brief explanation of the drawing]

Figure 1 is a plan view (A) and cross-sectional view (B) of a target according to the present invention, Figure 2 is a cross-sectional view of a target previously proposed by the inventor, and Figure 3 is a target formed by applying the present invention. This is a transition diagram of the Tb concentration of the composite film. Akira 1 Diagram A (Light bow gd Nodo) [Ryo Mn βU 17”- Night August History Tbh, Izumi, Admiral Osexual Spear Ta 4 et al. 3rd Diagram Z

Claims (1)

[Claims] A cross-shaped chip made of the first sputtered material with a convex cross section is exposed at the top and buried at the bottom by four 1/4 semicircular molded bodies made of the second sputtered material. In the disk-shaped composite target that is formed in close contact with the sputtering material, the chip made of the first sputtering material is formed separately into an upper protrusion and a lower flat part that have a convex cross-sectional shape. An embedded target for sputtering characterized by: