JPH08291382A - Bonding structure of target for high-frequency sputtering - Google Patents

Abstract

PURPOSE: To eliminate minute discharge generated between a target and a target electrode at the time of forming a film by high-frequency sputtering, to improve the yield by effectively preventing the generation of abnormal discharge and fine arcing, and to reduce a producing cost and improve the reliability. CONSTITUTION: The target 3 for high-frequency sputtering and the target electrode 5 mutually joined through a bonding material 4 have joining surfaces 11 arranged in the inside ranges at some interval from their outer peripheral edges. The target electrode has a difference of step 10 at the outer side of the joining surface 11 and an annular member 12 composed of an electric conductive material 1 is fitted in a gap formed between the target and this difference of step so as to contact with the target and the target electrode, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding structure for joining a target to a target electrode in a high frequency sputtering technique used for forming an oxide insulating film such as an IC and a thin film magnetic head.

[0002]

2. Description of the Related Art Conventionally, insulators such as silicon dioxide (SiO2) and aluminum oxide (Al2O3) have been widely used as protective films and insulating films for ICs, thin film magnetic heads and the like. Generally, a high frequency sputtering method is used as a method for forming these thin films, and a target made of an insulator is integrally bonded to a target electrode by using a bonding material,
The insulating material is sputtered by causing a discharge with the substrate side in an inert gas such as argon gas.

If abnormal discharge or minute arcing occurs during film formation by high frequency sputtering, it may cause pits, contamination, etc. in the film to be formed, resulting in low yield, high manufacturing cost, and high reliability. Will have a negative effect such as As a measure against such abnormal discharge and minute arcing, a method of reducing the degree of arcing by stopping energization for a very short time (several microseconds) during the flow of a high frequency current is performed.

[0004]

Recently, when a protective film having a film thickness of 5 to 100 μm is formed in the manufacture of a thin film magnetic head, the film forming time is extremely shortened or the number of wafers processed at one time is increased. For example, in order to meet this demand, the target used for high-frequency sputtering is increased in size, or the power consumption is increased in order to increase the film formation rate. However, the above-described conventional measures against abnormal discharge and minute arcing cannot sufficiently cope with an increase in target size and an increase in power consumption. For example, in forming an oxide insulating film, film forming conditions such as the flow rate of the sputtering gas, the gas pressure thereof, the incident power on the target side, and the voltage on the substrate side are controlled, and the supply of the high frequency current is stopped for a short time. However, there is a problem that abnormal discharge or minute arcing occurs. The main reason for this is that between the target and the target electrode, a minute discharge occurs during film formation in the vicinity of the bonding layer that joins them.

Therefore, an object of the present invention is to eliminate the minute discharge generated between the target and the target electrode during film formation in the high frequency sputtering, effectively prevent the occurrence of abnormal discharge and minute arcing, or reduce the degree thereof. Another object of the present invention is to provide a target bonding structure capable of reducing the yield, improving the yield, reducing the manufacturing cost, and improving the reliability.

[0006]

SUMMARY OF THE INVENTION The present invention is to achieve the above object, and a bonding structure for a high frequency sputtering target according to claim 1 is a target and a target to be bonded to each other via a bonding material. Each of the target electrodes is characterized in that a bonding surface is provided inside the outer peripheral edges of the target electrodes at a certain interval.

In the bonding structure for a high frequency sputtering target according to a second aspect of the present invention, in addition to the characteristic features of the first aspect, the distance outside the joint surface between the target and the target electrode is determined by the distance between them on the joint surface. It is characterized by being formed large. Furthermore, the bonding structure according to a third aspect is characterized in that a step is formed between the bonding surface and the outer peripheral edge of the target electrode.

Further, the bonding structure according to claim 4 is characterized in that a conductive material is provided in a gap between the target and the target electrode outside the bonding surface so as to be in contact with the target and the target electrode, respectively.

[0009]

Therefore, according to the bonding structure for a target for high frequency sputtering according to the first aspect of the present invention, the respective bonding surfaces of the target and the target electrode, which are bonded to each other by the bonding material, are located inside at a certain distance from their outer peripheral edges. By providing the gap between the target and the target electrode, a gap region where no bonding material is present is formed between the target and the target electrode. The present inventor configures the target bonding structure in this manner to prevent abnormal discharge and minute arcing between the target and the target electrode around the conventional bonding layer, which causes abnormal discharge or minute arcing during film formation. We have found that the incidence is reduced.

In the bonding structure for a target for high frequency sputtering according to a second aspect of the present invention, a large gap is formed between the target and the target electrode on the outer side of the bonding surface of the target electrode. It can be more difficult to generate.

According to the bonding structure of the third aspect, the step provided on the target electrode can easily form a large gap between the target outside the bonding surface and the target electrode.

Furthermore, according to the bonding structure for a target for high-frequency sputtering according to a fourth aspect, at least the target is formed by filling the gap formed between the target and the target electrode along the outer periphery thereof with a conductive material. Since the potential on the surface of the target electrode side in the outer peripheral portion can be made equal to the potential of the target electrode, it is possible to more reliably eliminate the occurrence of minute discharge.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 schematically shows the configuration of a high frequency sputtering apparatus to which the present invention is applied. A plate-shaped target 3 for forming a thin film on the surface of the substrate 1 is arranged above the substrate holder 2 on which the substrate 1 is placed. The target 3 is joined to the lower surface of the target electrode 5 by a known indium-based bonding material 4, for example. The substrate holder 2 and the target electrode 5 are
High frequency power supplies 8 and 9 are connected via matching boxes 6 and 7, respectively. Further, the target electrode 5 is
It has a cooling structure that allows cooling water to flow inside.

On the lower surface of the target electrode 5, a step 10 having a certain width and depth is formed along the outer periphery of the target electrode 5, and a bonding surface 11 is provided on the inner side of the step 10 with the step 10 therebetween. The target 3 having substantially the same planar shape as the target electrode 5 is
It is bonded to the bonding surface 11 of the target electrode 5 via the bonding material 4 with the bonding surface being a region that is inside the outer peripheral edge and separated by a distance corresponding to the step 10. An annular member 12 made of a conductive material such as copper, aluminum, or nickel is formed in the annular gap formed between the target electrode 5 and the target 3 by the step 10 and along the outer circumference thereof.
Are fitted so as to be in contact with the target 3 and the target electrode 5, respectively. The outer peripheral surface of the annular member 12 is coated with a nickel coating 13 having a film thickness of 2 to 5 μm.

Using the high-frequency sputtering apparatus having the target bonding structure configured as described above, an alumina film was formed on the substrate under the following conditions, and an experiment was conducted on the occurrence of abnormal discharge and minute arcing. As target, purity 99.9%, size 425 x 425
A target electrode made of oxygen-free copper was used, in which sintered alumina having a size of 6.5 mm was used, and a step having a width of 5 mm and a depth of 5 mm was provided on the outer circumference. The target and the target electrode were bonded by using an indium-based bonding material so that the thickness thereof was 0.05 mm or less. At this time, the area ratio of the bonding area to the total area of the target upper surface is 9
It was 7.7%. The outer peripheral surface of the annular member was plated with a nickel coating having a film thickness of 5 μm.

Target power: 7.5 kW Sputtering gas: Ar gas flow rate: 140SCCM Sputtering gas pressure: 20 mTorr Negative negative voltage on substrate side: -130V

As a result, the number of occurrences of abnormal discharge and minute arcing during film formation as shown in FIG. 2 (A) can be greatly reduced as compared with the conventional case shown in FIG. 2 (B). It was

[0018]

Since the present invention is configured as described above, it has the following effects.

According to the target structure of the bonding for high frequency sputtering of the first aspect, the gap region is provided between the target and the target electrode along the outer periphery thereof so that the bonding material does not intervene outside the bonding surface. Since the minute discharge generated during the film formation can be reduced between them, the target can be upsized and the power consumption can be increased, and the film formation speed can be increased and the number of wafers processed at one time can be increased. Because you can
The yield can be improved, the manufacturing cost can be reduced, and the reliability can be improved.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of a high-frequency sputtering device to which a target bonding structure according to the present invention is applied.

FIG. 2A is a diagram showing the frequency of abnormal discharge and minute arcing with respect to film formation time when an alumina film is formed according to the present invention, and FIG. 2B is the frequency of abnormal discharge and minute arcing in the prior art. FIG.

[Explanation of symbols]

 1 Substrate 2 Substrate Holder 3 Target 4 Bonding Material 5 Target Electrode 6, 7 Matching Box 8, 9 High Frequency Power Supply 10 Step 11 Bonding Surface 12 Annular Member 13 Nickel Coating

Claims (4)

[Claims] 1. A bonding structure for bonding a high-frequency sputtering target to a target electrode via a bonding material, wherein the target and the target electrode each have a bonding surface on an inner side at a certain distance from an outer peripheral edge thereof. A bonding structure for a high frequency sputtering target, which is provided. 2. A bonding structure for a high frequency sputtering target, wherein a distance between the target and the target electrode outside the bonding surface is larger than a distance on the bonding surface. 3. The high frequency sputtering target bonding structure according to claim 2, wherein a step is provided along the outer peripheral edge of the target electrode between the target electrode and the bonding surface. 4. A conductive material is disposed in a gap between the target and the target electrode outside the joint surface so as to be in contact with the target and the target electrode, respectively. Item 4. A bonding structure for a high frequency sputtering target according to any one of items 3.