JPH05195215A - Ceramic sputtering target - Google Patents

Abstract

PURPOSE:To provide such a ceramic sputtering target that splashing of powder from the target can be prevented. CONSTITUTION:This target consists of a ZnS sintered body 13 joined with Al2O3 12 of specified thickness to the upper surface of a copper backing plate 11. This ZnS sintered body 13 is used as a sputtering target for EL. Measurement of the number of abnormal particles on the surface of a film formed by sputtering, by using this target, results in a definitely reduced number of the abnormal particles. Namely, by using the target of this structure, scattering of powder from the target can be prevented and a good film can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is directed to ceramic sputtering targets such as electroluminescence (E).
L) A ZnS sintered body sputtering target for a device.

[0002]

2. Description of the Related Art Conventionally, Zn for forming a light emitting layer of a thin film EL element
As an S-based target, for example, JP-A-3-11078
There is one disclosed in Japanese Patent Publication No. 7. As shown in the publication,
The thin film EL device produced using this type of target has a drawback that it exhibits dielectric breakdown at a relatively low voltage. This is because there are many abnormal particles in the thin film EL element. The abnormal particles adhere to the light emitting layer when the light emitting layer is formed.

That is, since ZnS is a sublimable substance and does not melt even if it is heated, ZnS which constitutes the target by electric repulsive force due to charge-up during vapor deposition or bumping due to thermal energy. This is because the crystal particles are scattered and adhere to the film. Then, the publication discloses a technique for reducing the adhesion of abnormal particles by increasing the particle size of this ZnS sintered body target.

[0004]

However, even with such a conventional technique, there is a problem in that the adhesion of particles to the light emitting film cannot be completely eliminated. Therefore, when an EL element is manufactured, the particles may cause dielectric breakdown at a low voltage. In addition, since the current gradually leaks in this abnormal particle portion, the amount of mobile charge flowing through the light-emitting layer during light emission is smaller than that in a film with few abnormal particles. Has been a cause of shortening the life, and eventually shortening the life.

[0005]

DISCLOSURE OF THE INVENTION Therefore, the inventors of the present application have found that the reason why the powder is scattered from the sputtering target is that the ZnS particles constituting the target are left behind during the sputtering, and the particles are charged with a negative electric charge. It was thought that this is because the repulsive force scatters from the negatively charged target to the positively charged substrate (film) side. In this case, the structure of the conventional sputtering target is a planar type in which a target material is directly bonded onto a metal backing plate using a brazing material or the like. Therefore, electric charges are easily accumulated on the surface of the target during sputtering, and the electric repulsive force is large. Therefore, it has been conceived that by improving the structure of the sputtering target, it is possible to reduce the electric repulsion force and prevent the powder from scattering.

[0006]

OBJECTS OF THE INVENTION It is an object of the present invention to provide a ceramics sputtering target capable of preventing the scattering of powder from the sputtering target.

[0007]

The invention according to claim 1 of the present application is a ceramics sputtering target held on a metal backing plate, wherein an insulator is interposed on the surface of the ceramics target facing the backing plate. This is a ceramics sputtering target.

In the invention according to claim 2, the ceramics target is a semiconductor ceramics sintered compact target or a conductive ceramics sintered compact target having a specific resistance of 10 ⁵ Ω · cm or less. For example, a ZnS sintered body target, ITO (In _1-x Sn _x O, x = 0.02-
0.20) _{target, MSi x (M = W,} Mo, T
i, Zr, Hf, Nb, and Ta: x = 2.0 or more and 4.0 or less) target.

In the invention according to claim 3, the ceramics target is a ZnS sintered body target.

[0010]

According to the present invention, since the insulator is interposed between the metal backing plate and the ceramic target, the amount of charge accumulated on the surface of the ceramic target can be greatly reduced, and the scattering of powder can be prevented. You can Further, this insulator is preferably smaller than the ceramic target. This is to prevent sputtering of the insulator itself. Further, as the insulator, a heat resistant ceramic insulator is preferable. Since this is not in direct contact with the water-cooled metal backing plate, when the sputtering target is heated to a high temperature and the insulator is also heated to a high temperature, its melting or the like is prevented. Therefore, as the insulator, a material that is electrically insulating and has high strength at high temperature, such as Al ₂ O ₃ ,
AlN and the like are preferable. When the ceramics target is a ZnS sintered body for EL device formation, the Zn
It is preferable to use the above-mentioned ceramics having a thermal expansion coefficient substantially equal to S as an insulator.

The above-mentioned ceramics sputtering target may be integrally formed with an insulator by hot pressing, or may be separately formed and then joined by a brazing material. The former method is preferred from the viewpoint that the target can be prevented from peeling due to melting of the brazing filler metal during heating. Then, for example, when a ZnS sintered body is manufactured by hot pressing, it is necessary to use a ceramic insulator powder that can be sintered at a ZnS hot pressing sintering temperature (1200 ° C.) or lower. For example, Al ₂ O ₃ , Mg
O or the like is used. Furthermore, using a ceramic plate, Zn
When performing hot pressing simultaneously with the S powder, it is advisable to prepare the bonding surface of the ceramic plate by shot blasting or the like in advance in order to increase the bonding strength between them.

The insulator has a specific resistance value of 10 ¹⁰
It is preferably Ω · cm or more. Furthermore, the thickness of the insulator is preferably 0.5 mm or more.

[0013]

EXAMPLES Examples of ceramic sputtering targets according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the structure of a ceramic target according to an embodiment of the present invention. As shown in this figure, a ZnS sintered body 13 is bonded to the upper surface of a copper backing plate 11 via a ceramic insulator 12 of a predetermined thickness. This ZnS sintered body 13 will be used as a sputtering target for EL.
Although not shown, the backing plate 11 is water-cooled by a water-cooling structure in the sputtering device.

The sputtering target having the above structure was manufactured as follows. That is, ZnS
Powder (average particle size 3 μm) and 4 wt% TbF ₃ powder (average particle size 2 μm) were mixed by a ball mill for 1 hour and Z
An nS-4 wt% TbF ₃ mixed powder is prepared. Next, a graphit mold having an inner diameter of 125 mm was first filled with a predetermined amount of Al ₂ O ₃ powder (average particle size 0.5 μm), an upper punch was inserted, and a press pressure of 18.4 ton (150 kg
Perform cold pressing at f / cm ² ). Once the upper punch was removed, the above ZnS-4 wt% was added to this mold.
Fill with TbF ₃ mixed powder, insert the upper punch again, temperature 1000 ° C., 3 hours (temperature increase 10 ° C./min, temperature decrease furnace cooling),
Hot pressing is performed under the conditions of a pressure of 18.4 ton (150 kgf / cm ² ) and a vacuum. As a result, the target,
An integral sintered body of insulator is produced. The density of this ZnS sintered body portion was 3.8 g / cm ³ (relative density 91%), A
The density of the 1 ₂ O ₃ sintered body portion was 3.3 g / cm ³ (relative density 83%). The thickness of the ZnS sintered body portion is 5
mm, and the thickness of the Al ₂ O ₃ sintered body portion was 2 mm.

The sintered body integrally molded in this manner is processed into a predetermined size, and is formed on the copper backing plate 11 by A
The 1 ₂ O ₃ sintered body portions 12 were brought into contact with each other and bonded using In—Sn solder. This is the sputtering target shown in FIG. Using this sputtering target, sputtering was performed under the following conditions to obtain a size of 10
A ZnS-Tb thin film of x10 was prepared. Then, the number of abnormal particles existing on this thin film was measured using a particle counter. For comparison, Z without an insulator
sputtered under the same conditions using a target in which bonded directly nS-TbF ₃ sintered body to a copper backing plate, it was measured in the same manner by the particle counter number abnormal grains. Table 1 shows the measurement results. Further, FIG. 2 shows the result of this sputtering. As shown in FIG. 2, the number of abnormal particles (50
(particles above μm) are clearly reduced.

The sputtering conditions are as follows. That is, target: ZnS-4wt% TbF ₃ insulation type target (φ125 × 5t) Substrate: glass (10 × 10 × 1t) Input power: RF200, 300, 400W Gas pressure: Ar 2 × 10 ^-2 Torr Substrate temperature: 300 ° C S-T distance: 50 mm Time: 30 minutes.

[0017]

[Table 1]

Table 2 shows the measurement results of the number of abnormal particles when a sputtering target manufactured by a method other than the above is used. That is, as for this target, only the above ZnS-4 wt% TbF ₃ mixed powder was filled in the mold, and the temperature was 1000 ° C. for 3 hours (temperature increase 10
(° C / min, cooling in a cooling furnace), pressure 18.4 tons, hot pressing under the conditions of vacuum to produce a sintered body. Then, this ZnS-4 wt% TbF ₃ sintered body was applied onto an Al ₂ O ₃ sintered body disk (density 3.9 g / cm ³ , relative density 99%) of size φ120 × 3 using In—Sn solder. Bonded. Furthermore, this disk is joined to a copper backing plate by soldering. Sputtering was performed under the same conditions as above using this target.

[0019]

[Table 2]

[0020]

According to the present invention, it is possible to prevent the powder from scattering from the sputtering target and obtain a good film.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a sputtering target according to an embodiment of the present invention.

FIG. 2 is a diagram showing abnormal particles of a ZnS thin film formed by sputtering using a sputtering target according to an example of the present invention.

[Explanation of symbols]

 11 backing plate 12 insulator 13 ZnS sintered body (ceramic target)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Soichi Fukui 12-6 Techno Park, Mita City, Hyogo Prefecture Mitsubishi Materials Corporation Mita Factory

Claims (3)

[Claims] 1. A ceramics sputtering target held on a metal backing plate, wherein an insulator is interposed on the surface of the ceramics target facing the backing plate. 2. The ceramic sputtering target according to claim 1, wherein the ceramics target is a semiconductor ceramics sintered body target or a conductive ceramics sintered body target having a specific resistance of 10 ⁵ Ω · cm or less. 3. The ceramics sputtering target according to claim 1, wherein the ceramics target is a ZnS sintered body target.