JPH11350129A - Magnetron sputtering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the degradation in the uniformity of deposition by adopting a constitution to change the distances between plural permanent magnets and a target by each of the individual permanent magnets according to the consumption of the target by sputtering. SOLUTION: The divided magnets exist on the rear surface of a backing plate 21 and are composed of an upper magnet 11, a middle magnet 12 and a lower magnet 13. Position regulating mechanisms respectively driven by motors are attached to these magnets. When the wear progresses in the target 20 to some extent after the long-time deposition, the middle magnet 12 is moved in the direction parting the magnet from the target 20 in such a manner that the distance from the target 20 is kept nearly constant as the wear in the central part of the target 20 progresses. At this time, the progression of the wear in the upper part and lower part of the target 20 is earlier and, therefore, the upper magnet 11 and the lower magnet 13 are parted more than the middle magnet 12 from the target 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetron sputtering apparatus for forming a thin film on a large-area substrate by a magnetron sputtering method.

[0002]

2. Description of the Related Art In recent years, liquid crystal displays have rapidly become widespread as display devices for personal computers due to their large screens. In particular, a TFT (Thin Film Transistor) liquid crystal display in which a switching transistor is provided for each pixel has excellent image quality, and it is desired to increase the screen size and reduce the cost.

A liquid crystal display basically has a structure in which a liquid crystal material is sealed between two sheets of glass, and the above-described transistor needs to be manufactured as a thin film on a glass substrate.
In addition, it is necessary to form and process various types of thin films on glass, such as electrodes for sending electric signals to transistors, electrodes for applying voltage to liquid crystal molecules, and thin films for insulating them. .

An electrode for transmitting a signal is mainly a metal thin film, and an ITO (Indium-Tin Oxide) thin film is used as a transparent electrode which transmits light and applies a voltage to a liquid crystal. In order to form these thin films, it is common to use a magnetron sputtering apparatus based on the magnetron sputtering method.

[0005] In the magnetron sputtering method, a base material plate, which is a thin film material called a target, is placed in a vacuum, and a magnetic field is applied to the surface to control the movement of electrons to obtain a high-density plasma. The high-density plasma region often has a circular or racetrack shape. Since a large amount of positive ions are present in high-density plasma, the positive ions collide with a target at a negative potential, causing the target material to scatter at the atomic level and deposit as a thin film on the surface of a substrate such as glass. is there. In order to form a magnetic field on the target surface, a permanent magnet is often used on the back of the target, that is, on the atmosphere side. That is, a feature is that plasma control is performed using a magnetic field. Therefore, the plasma density is easily affected by the magnetic field. Generally, up to a magnetic flux density of about 0.1 Tesla, the higher the magnetic flux density, the higher the plasma density.

[0006] As the magnetron sputtering apparatus, two types, an in-line type and a single-wafer type, are used depending on the processing method of the substrate. The in-line method is a method in which a glass substrate is placed on a tray and transported in a vacuum vessel. In a film forming chamber, a plasma serving as a sputter particle source is fixed. That is, the magnet on the back surface of the target is fixed and used. The glass substrate passes in front of the plasma at a constant speed to realize a uniform film thickness.

On the other hand, in an apparatus called a single wafer type, a method in which a substrate is fixed and plasma moves is used. The plasma can be moved by moving the magnet on the back surface of the target having a large area, whereby a film can be formed over a large area. These two methods are used depending on the purpose.

[0008]

In the magnetron sputtering method, a magnetic field is often formed on the surface of a target by using a permanent magnet as described above, but there is a problem therefor. One of them is that the uniformity of film formation varies with time.

The variation in uniformity is caused by the fact that when one target is sputtered for a long time, the target is not uniformly worn. Since the distance between the target and the magnet is reduced more quickly in a portion where the wear is high even a little, the magnetic field intensity is relatively larger than in other portions.
As a result, a vicious cycle occurs in which the plasma density increases and the sputter rate increases. Even if the entire magnet is moved away from the target as the wear of the target progresses, only the overall magnetic field intensity is adjusted,
The magnetic field strength at a portion where the wear rate is relatively high is still higher than that at a portion where the wear rate is low.

[0010] In a portion of the target where wear progresses at a high speed, the sputter rate increases at an accelerated rate, so that the film thickness distribution on the substrate is also affected. That is, the film thickness increases near a portion where the wear proceeds at a high speed, and the film thickness distribution deteriorates as a whole substrate. If the thickness of the target is reduced, the change in the sputtering rate until the life of the target is exhausted is reduced, but the cycle of replacing the target with a new target is shortened. This leads to an increase in target purchase cost and a decrease in the operation rate of the apparatus, resulting in an increase in production cost. Therefore, it is desired to develop a method for improving the uniformity of film formation without increasing the production cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetron sputtering apparatus which suppresses the deterioration of the uniformity of a film with respect to the aging of a target in view of the above-mentioned problems in the prior art.

[0012]

SUMMARY OF THE INVENTION The present invention is characterized in that a magnet for generating a magnetron magnetic field is divided and a mechanism for changing the arrangement of the magnets according to the wear of the target is provided.

That is, in the present invention, as described above, the position of the magnet can be partially changed following the wear of the target. For this reason, the distance between the target and the magnet can be locally increased even in a portion where abrasion easily progresses, so that it is possible to prevent a sputter rate from being acceleratedly increased.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1)
A first example will be described. FIG. 1 shows a cross section of a magnetron cathode to which the present invention is applied to an in-line type sputtering apparatus. Inside the vacuum vessel 25, there is a target 20 bonded to a backing plate 21 with a conductive adhesive. Cooling water circulates through the backing plate 21,
The target 20 is indirectly cooled. On the back side of the backing plate 21, that is, on the atmosphere side, there are divided magnets, which are composed of an upper magnet 11, a middle magnet 12, and a lower magnet 13, respectively. Each of these magnets has a position adjusting mechanism. For example, in the case of the upper magnet 11, the motor 15
Is moved along the linear guide 14 by rotating the shaft 10 via the belt 18 and the pulley 17. Since all magnets are driven via the common pulley 16, they operate in conjunction. The operation is adjusted by changing the diameter of the pulley 17.

A case where a film is formed on the substrate 30 will be described. An insulating spacer 22 is provided between the backing plate 21 and the vacuum vessel 25, and serves to electrically insulate the backing plate 21 from the vacuum vessel 25 in addition to the role of a vacuum seal. On the vacuum side of the target 20, a tunnel-shaped magnetic field is formed by the upper magnet 11, the middle magnet 12, and the lower magnet 13.
When a negative voltage is applied to the target 20, a high-density plasma region 26 is formed inside the tunnel-shaped magnetic field. In the high-density plasma region 26, a large amount of ions are generated, and the ions collide with the target 20. The impact scatters the target material and deposits it on the substrate 30 as a thin film. Substrate 3
Numeral 0 is attached to the tray 31, and the tray 31 is mounted on the transport carriage 32 to perform sputtering while being transported at a constant speed, so that the film thickness distribution of the thin film on the substrate 30 can be made substantially uniform.

The target 20 is a flat plate before use. FIG. 3A shows a positional relationship between the target and the magnet before use, and FIG.
The middle magnet 12 and the lower magnet 13 are arranged in a straight line. FIG. 3B shows the positional relationship between the target and the magnet when the film is formed for a long time and the wear has progressed to some extent. Chubu magnet 12
Is moved in a direction in which the target is separated from the target 41 so that the distance from the surface of the target 41 becomes substantially constant as the wear of the central portion of the target 41 progresses. At this time, since the upper and lower portions of the target 41 wear rapidly, the upper magnet 11 and the lower magnet 13 are separated from the target more than the middle magnet 12.

(Embodiment 2) As a second embodiment, an embodiment of a single-wafer sputtering apparatus for a liquid crystal display will be described. In the first embodiment, the magnet can only change the distance to the target, but in the present embodiment, the magnet can be further moved along the target. Therefore, the magnet table 19 can be moved by the drive shaft 50. At the time of film formation, the substrate 53 is stationary on the heater 52, and the film is formed on the entire surface of the substrate 53 by the plasma 26 moving on the surface of the target 20. The plasma 26 is applied to the magnet table 1 as described above.
This is because the position moves in conjunction with the movement of No. 9. The positions of the magnets 61, 62 and 63 are moved as shown in FIG. 3B in accordance with the wear of the target 54, as in the first embodiment.

[0018]

When film formation was continued using the chromium target using the sputtering apparatus of Example 1, the film thickness distribution was ± 2.8% in the initial stage of using the target.
In the latter period of use, that is, in the state where the wear of the target was advanced, the film thickness distribution was ± 3.9%. When a conventional integrated magnet was used, the film thickness distribution in the initial stage of use of the target was ± 2.9%, but deteriorated to ± 6.3% in the late stage of use.

When a film was formed in the same manner using the sputtering apparatus of Example 2, the film thickness distribution was ± 4.1% in the early stage of use and ± 4.7% in the late stage of use. In the case of the conventional integrated magnet, the film thickness distribution at the beginning of use was ± 4.1%, but at the end of use it was ± 6.0%.

That is, the effect that the deterioration of the film thickness distribution due to the aging of the target can be reduced as compared with the conventional apparatus has been obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a first embodiment of a magnetron sputtering apparatus according to the present invention.

FIG. 2 is a perspective view showing a configuration of a divided magnet used in the magnetron sputtering apparatus shown in FIG.

FIG. 3 is a view showing a method of moving a divided magnet in the magnetron sputtering apparatus shown in FIGS. 1 and 4;

FIG. 4 is a sectional view showing the configuration of a second embodiment of the magnetron sputtering apparatus according to the present invention.

FIG. 5 is a sectional view of a conventional magnetron sputtering apparatus.

[Explanation of symbols]

11: Upper magnet, 12: Middle magnet, 13 ...
Lower magnet, 14: Linear guide, 15: Motor,
16, 17 pulley, 18 belt, 19 magnet base, 20, 54 target, 21 backing plate, 22 insulating spacer, 23 earth shield, 2
4, 51, 53: adhesion-preventing plate, 25: vacuum vessel, 26: high-density plasma, 30: substrate, 31: tray, 32: carrier, 33: wheels, 50: drive shaft, 52: heater,
61, 62, 63: divided magnets, 71: integrated magnet.

Claims (2)

[Claims] 1. A magnetron sputtering apparatus comprising: a vacuum vessel having a substrate disposed therein; a target made of a base material to be a thin film; and means for forming a magnetic field for magnetron discharge on the surface of the target. At
The magnetic field forming means is constituted by a plurality of individually movable permanent magnets, and the distance between the plurality of permanent magnets and the target is changed for each individual permanent magnet according to the degree of wear of the target caused by sputtering. A magnetron sputtering apparatus characterized by being able to perform. 2. The magnetron sputtering apparatus according to claim 1, wherein said plurality of permanent magnets are collectively supported by another member, and the entire magnet portion is movable in parallel with a target surface.