JPH07310181A - Dc magnetron sputtering method and device therefor - Google Patents

Abstract

PURPOSE:To uniformly form metallic thin films of an aluminum alloy, etc., and thin films of ITO (indium-tin oxide) on a large-area glass substrate, etc., by a DC magnetron sputtering method. CONSTITUTION:A sputtering chamber 10 is internally provided with the glass substrate 11 to be formed with the required films and a conductive target 13 in a position facing the substrate 11 and is provided with a permanent magnet 16 which oscillates on the rear surface of the target 13 and forms magnetron magnetic fields. The substrate 11 is provided with a mask 14 set at floating potential near the substrate. Two grounding electrodes 15 are disposed between this mask 14 and the target 13 in such a manner that these electrodes are aligned to the positions facing both ends of the permanent magnet 16 and the oscillation direction. As a result, the fluctuation in the plasma density according to oscillation of the permanent magnet is obviated and the uniform films are formed on the large-area glass substrate 11 of>=350mmX450mm with which the formation of the uniform films is heretofore infeasible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC magnetron sputtering apparatus, and more particularly to a metal thin film such as an aluminum alloy or an IT.
Thin film of O (Indium-Tin Oxide, tin-doped indium oxide) is formed by a DC magnetron sputtering method in a large area and uniformly, for example, for making various conductive thin films for large-screen liquid crystal displays. The present invention relates to a suitable DC magnetron sputtering device.

[0002]

2. Description of the Related Art In recent years, liquid crystal displays have been used as display devices for computers and word processors. In a liquid crystal display, an ITO thin film is used as a transparent electrode for transmitting visible light and applying a voltage to liquid crystal molecules, and a metal thin film such as an aluminum alloy is used for wiring between the electrodes. The DC magnetron sputtering method is often used to form these conductive thin films.

The sputtering method is a physical film forming method in which ions in plasma are made to collide with a mass of a material to be formed (referred to as a target), and particles scattered from the target are deposited on an opposing substrate.

Particularly, in the DC magnetron sputtering method, a negative voltage is applied to the target to cause discharge between the target and the ground electrode, and secondary electrons emitted from the target are confined by using a magnetic field, so that the target surface is covered. A high density plasma can be formed. Therefore, it has characteristics such as a high film forming speed and a small heat input to the substrate, and is widely used for forming a thin film in a large screen liquid crystal display manufacturing process.

Regarding the DC magnetron sputtering method, "Basics of Plasma Processing" (Brian N. Chapman
As described in detail in the book (Translated by Yukio Okamoto, Denki Shoin), electrons drift on the surface of the target in a racetrack shape, so that high-density plasma concentrates on the racetrack and the speed at which the target is sputtered is also high. Significantly higher in the racetrack area.

[0006]

Since the magnetic field on the target surface causes electrons to drift in a racetrack shape,
Racetrack-shaped high-density plasma is generated on the target surface, and the speed at which the target is sputtered is also extremely high in this racetrack portion. Furthermore, there is a distribution of plasma density even in a racetrack-shaped high-density plasma,
In particular, in the part where the electrons drift and hit the straight part from the straight part, and the part that goes out from the corner part to the straight part,
A difference in plasma density is likely to occur. Therefore, when the magnet is moved in parallel and the film is formed while moving the racetrack-shaped plasma on the target, the film thickness becomes uneven at the end of the diagonal line of the large-area substrate. If the target size is made sufficiently large with respect to the size of the substrate, nonuniformity of the film thickness distribution is unlikely to occur, but it is not economical to use a large target. There is a problem that the plasma density distribution in the high-density plasma must be made uniform in order to secure the uniformity of the film thickness distribution in the large area substrate and minimize the target size.

The present invention has been made in view of the above points,
An object of the invention is to provide a DC magnetron sputtering apparatus capable of forming a uniform film even on a large-area substrate.

[0008]

According to the present invention, two ground electrodes are provided in parallel with the swinging direction of the permanent magnet on the back surface of the target, and the potential of the mask used during mask sputtering is set to a floating potential. Can be achieved.

[0009]

Since the ground electrodes are always opposed to both ends of the racetrack-shaped high-density plasma even when the permanent magnet is swung, the inflow of electrons to the ground electrode can be kept constant. Therefore, even if the permanent magnet is swung, the plasma density distribution is kept constant, and a uniform film can be formed on a large-area substrate.

[0010]

【Example】

(Embodiment 1) As one embodiment of the present invention, an apparatus for forming an aluminum alloy thin film by a DC magnetron sputtering method will be described below.

The structure of a DC magnetron sputtering apparatus is shown in FIGS. 1 and 2. The present apparatus is provided with a transfer chamber (not shown) and a plurality of vacuum containers required for the sputtering chamber 10 as a basic unit. The glass substrate 11, which is a substrate on which a film is to be formed, is transferred from the transfer chamber to the sputtering chamber 10 after performing necessary processing such as heating in the previous process. 0.4P in sputter chamber 10
The argon gas (Ar) of a is supplied, and the flow rate of the argon gas is adjusted and the vacuum pump 12 exhausts the gas so that the gas pressure becomes constant. The sputtering chamber 10 has a target 13 made of an aluminum alloy facing the glass substrate 11.
In addition, an earth shield 18 is provided around the target 13 so that a place other than the target 13 is not sputtered. A mask 14 and a ground electrode 15 are provided near the glass substrate 11 to prevent the film from adhering to the peripheral portion of the substrate. Further, a permanent magnet 16 for generating a magnetron magnetic field is provided on the back surface of the target 13.
Further, there is a DC power supply 17 necessary for applying a DC high voltage between the target 13 and the ground electrode 15 to cause discharge.

FIG. 2 shows the structure as seen from the direction AA 'in FIG. 1. The mask 14 has a frame shape when viewed from above, and the ground electrode 15 extends along one side of the opening of the mask 14. Place it. Below the mask 14 is the glass substrate 11 which is the object of film formation.

In FIG. 2, the permanent magnet 16 is the ground electrode 1
5 and is indicated by a broken line in FIG. On the surface of the target 13, a racetrack-shaped high-density plasma is generated by the magnetic field of the permanent magnet 16 on the back surface. There are many argon ions in the high density plasma, and the argon ions sputter the target 13 to form an aluminum alloy thin film on the opposing glass substrate 11. Further, since the high-density plasma is formed in a racetrack shape, the target 13 is sputtered only at the racetrack portion. Therefore, when the area of the glass substrate 11 is larger than that of the permanent magnet 16, the film cannot be formed on the entire surface of the glass substrate 11.

Therefore, the permanent magnet 16 is swung (reciprocating) in the direction of the arrow in FIG.
Similar to 6, the target surface is moved. Permanent magnet 1
By moving 6 the film can be formed over the entire area of the glass substrate 11. However, the film thickness uniformity on the substrate 11 cannot be ensured only by moving the permanent magnet 16. This is because the racetrack-shaped high density plasma also has a density distribution, which affects the film thickness distribution. In particular, the film thickness distribution in the peripheral portion of the substrate 11 is affected. As described below, the potential of the mask 14 and the arrangement of the ground electrode 15 are important factors for controlling the plasma density distribution and ensuring a uniform film thickness distribution.

The mask 14 is set to a floating potential, and the ground electrode 15 is placed on the mask 14 to make the target 1
The electrons generated by the high-density plasma on 3 are permanent magnets 1
Even if 6 is swung in the direction of the arrow, it can be collected by the ground electrode 15. Therefore, even if the permanent magnet 16 is swung to move the racetrack-shaped high-density plasma, the density distribution in the racetrack-shaped high-density plasma can be kept substantially uniform. Here, since the glass substrate 11 is made of an insulating material, it is difficult to apply a constant potential, and the glass substrate 11 has a floating potential. The mask 14 has the same potential as the glass substrate 11,
It is insulated from the surroundings and is also set to a floating potential. This allows
The electrons from the target 13 mainly flow into the ground electrode 15 and do not flow into the glass substrate 11 and the mask 14.

As a result, even if the permanent magnet 16 oscillates in the direction of the arrow in FIG. 2, the same magnetron plasma is always obtained, so that a uniform film thickness distribution is achieved in the area surrounded by the mask 14 on the glass substrate 11. Was realized.

(Embodiment 2) FIG. 3 shows a structure in which the ground electrode 25 is extended along the mask 14 and is structurally simplified as compared with the embodiment 1.

(Embodiment 3) In FIG. 4, the frame-shaped floating potential electrode 34 is provided in place of the mask 14 of FIG. 2, and as shown in the figure, the opening of the floating potential electrode 34 is larger than that of the glass substrate 11. Thus, there is an effect that a film can be uniformly formed on the entire area of the glass substrate 11 by sputtering. Here, the floating potential electrode 34 and the ground electrode 15 are provided between the glass substrate 11 and the target 13.
However, it is also possible to dispose the floating potential electrode 34 farther from the substrate 11 with respect to the target 13 so that unnecessary dust or the like does not come to the glass substrate 11.

(Embodiment 4) FIG. 5 shows a structure in which the potential of the mask 14, which is a floating potential, can be monitored outside the sputtering chamber 10. A large amount of a conductive film adheres to the mask 14 to cause the mask 14 to grow. Is the ground electrode 15 or the sputtering chamber 10
It is for detecting whether or not it has made electrical contact with the wall surface of.

By using the DC magnetron sputtering apparatus of this embodiment as described above, the glass substrate 350 mm ×
It was possible to form an aluminum alloy thin film of 400 nm in a large area of 450 mm, which is larger than the conventional one, with a film thickness distribution variation of ± 5% or less.

[0021]

According to the DC magnetron sputtering apparatus of the present invention described above, two ground electrodes parallel to the swinging direction of the permanent magnet on the back surface of the target are provided, and the potential of the mask used during mask sputtering is set to the floating potential. Therefore, even if the permanent magnet is swung, the ground electrodes are always opposed to both ends of the racetrack-shaped high-density plasma, so that the inflow of electrons to the ground electrode can be kept constant, Therefore, even if the permanent magnet is swung, the plasma density distribution is kept constant, and there is an effect that a uniform film can be formed on a large-area substrate.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a DC magnetron sputtering apparatus of the present invention.

FIG. 2 is a view seen from the direction AA ′ in FIG.

FIG. 3 is a view corresponding to FIG. 2 showing another embodiment of the present invention.

FIG. 4 is a view corresponding to FIG. 2 showing still another embodiment of the present invention.

FIG. 5 is a view corresponding to FIG. 1 showing still another embodiment of the present invention.

[Explanation of symbols]

10 ... Sputtering chamber, 11 ... Glass substrate, 13 ... Target, 14 ... Mask, 15, 25 ... Ground electrode, 16 ... Permanent magnet, 17 ... DC power supply, 18 ... Earth shield, 34 ...
Floating potential electrode.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Chahara 7-1-1, Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory

Claims (4)

[Claims] 1. A vacuum container, a substrate on which a required film is to be formed in the vacuum container, a conductive target arranged at a position facing the substrate, and a place other than the target around the target. An earth shield that prevents sputtering, and a mechanically movable magnet for forming a magnetron magnetic field, in a DC magnetron sputtering apparatus that applies a DC voltage to the target, in the order close to the target, A DC magnetron sputtering apparatus, wherein an electrode having a ground potential different from the ground shield and an electrode electrically insulated to have a floating potential are provided. 2. A floating potential electrode according to claim 1, wherein an inner opening of the floating potential electrode is smaller than that of the base body, and the dimension of the floating potential electrode in the magnet moving direction is such that the moving magnet is a floating potential electrode. While making it larger than the trajectory projected to
The DC magnetron is characterized in that two or more electrodes including two at the end are provided along the moving direction of the magnet so as not to be shaded by the inner opening of the floating potential electrode. Sputtering equipment. 3. A DC magnetron sputtering apparatus, wherein an inner opening of the floating potential electrode according to claim 2 is equal to or larger than the base, and a film is formed on one entire surface of the base. 4. The DC magnetron sputtering apparatus according to claim 1, 2, or 3, wherein the potential of the floating potential electrode is measured outside the vacuum container,
A DC magnetron sputtering device characterized by being able to monitor the potential of a floating potential electrode.