JPH10330931A - Sputtering cathode and sputtering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering cathode preventing the diffusion of H2 O into a vacuum side and capable of satisfactorily maintaining sputtering performance. SOLUTION: In a sputtering cathode, the sealing part of a coolant in the cathode 15 provided on the air side, concretely, a background electrode 13 to be arranged on the back side of a target is formed into a solid shape opened to the air side, particularly, into a bottomed cylindrical shape, and by this background electrode 13, the coolant circulating path of the sputtering target is separated to isolate from the vacuum side. Then, the opening part of the background electrode 13 is covered with a cathode flange 14 and forms a cylindrical space, the coolant is circulated at the inside, furthermore, the background electrode 13 is provided with a flange part, with the contact part with the cathode flange 14 circled, a coolant sealing member 15a is fitted, and moreover, a magnet 21 is arranged within the cylindrical space.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering cathode and a sputtering apparatus, and can be applied to not only a general sputtering apparatus but also various application apparatuses such as a thin film manufacturing apparatus using a sputtering method and an LCD manufacturing apparatus. Can be.

[0002]

2. Description of the Related Art Conventionally, a sputtering apparatus is often used as a means for forming a thin film on a surface of a substrate or the like. In a sputtering apparatus, DC or high-frequency power is applied between a substrate and a target which are opposed to each other in a vacuum vessel, and is applied in the presence of a predetermined inert discharge gas (usually 3 × 1).
Ar gas having a pressure of about 0 ^-3 to 10 × 10 ^-3 torr is used.) Glow discharge is caused. At this time, gas ions generated by the discharge enter the target, and target atoms are sputtered, and these atoms adhere to the substrate to form a thin film.

Since Ar gas is usually used as a discharge gas, gas ions are positive ions and the target is on the cathode side. This cathode side structure is called a sputtering cathode, and is bonded to the back surface of the target, and a back plate electrode (backing plate) for applying a negative potential thereto,
It is composed of a permanent magnet for controlling the trajectory of gas ions, a cooling liquid circulation path for cooling the cathode, and the like.

A conventional sputtering cathode is configured, for example, in the following (A) or (B).

(A) FIG. 3 shows a specific example of a conventional sputtering cathode in which an O-ring seal for cooling water is formed in a vacuum chamber. A sputtering cathode 30 is formed on a vacuum chamber wall 31. .
A flat back plate electrode (backing plate) 33 is placed on the back surface of the target 32, and a shallow cylindrical cathode flange 34 is joined to the other surface (atmosphere side) of the back plate electrode 33 to form the cathode flange 34. A permanent magnet 36 is disposed in the space. A flow path for circulating cooling water to the back plate electrode 33 is provided in the cathode flange 34,
In the figure, a cooling water inlet 34a and an outlet 34b are shown. The cathode flange 34 has a flange portion 34f,
The flange portion 34f is formed such that the back plate electrode 33 and the cathode flange cylindrical portion 34t extend from the vacuum chamber wall 31 to a predetermined gap g.
Is fixed to the vacuum chamber wall 31 via the insulating flange 38. The gap g communicates with the vacuum side. 37 is a high frequency shield cover. 35a, 35
Reference numerals b and 35c denote sealing means such as an O-ring for securing a seal between the vacuum side and the atmosphere side.
3, 34, 34, 38, 38, 31 are sealed.

(B) Further, the backing plate itself is
A system in which a three-dimensional structure in which a tubular cooling water channel is formed inside and a permanent magnet or the like is arranged outside the three-dimensional structure has also been proposed.

[0007]

In case (A), if a cooling water seal is formed in a vacuum chamber, diffusion of H2 O into the vacuum occurs. That is, the space between the gap g communicating with the vacuum side and the cooling water circulation path is sealed by the O-ring 35a, but the O-ring polymer constituting the O-ring has a small but constant water absorption. The H ₂ O absorbed by the ring 35a diffuses to the gap g, and thus to the vacuum side. When the sputtered film is a pure metal thin film, for example, an Al wiring film for a semiconductor, even if a trace amount of H ₂ O, the oxidation reaction becomes a requirement for inhibiting purity and adversely affects the characteristics of the film.

In the case (B), if a cooling water circulation path is formed inside the backing plate itself, the thickness of the backing plate member increases and the distance between the magnet and the target increases, thereby weakening the effect of the magnet.
As a result, the sputtering efficiency such as the utilization efficiency of the target material deposited on the substrate and the deposition rate is impaired.

An object of the present invention is to provide a target cathode which can prevent the diffusion of the cooling liquid (H ₂ O) into a vacuum and maintain good sputtering performance as described above.

[0010]

In order to achieve the above object, a sputtering cathode according to the present invention is a sputtering cathode in which sputtering is performed in a vacuum, wherein a cooling liquid sealing portion in the cathode is provided on the atmosphere side. .

[0011] Thus, the sealing member absorbs the cooling liquid (water), and even if these molecules diffuse to the atmosphere side, they are prevented from diffusing to the vacuum side.

In order to achieve the above object, a sputtering cathode according to a second aspect of the present invention has a specific structure for realizing the above invention, in which glow discharge is performed by using a target opposed to a substrate in a vacuum as a cathode side. The backing plate (backing plate) disposed on the back of the target is formed in a bottomed cylindrical shape that opens to the atmosphere side, and the back plate electrode causes the cooling liquid circulation path of the sputtering cathode to be on the vacuum side. It was separated and cut off from With this configuration, contamination of the coolant component on the vacuum side is basically eliminated.

A third invention is a sputtering cathode of the first or second invention, a sputtering apparatus arranged substrate facing a vacuum vessel, thereby, H ₂ O
The diffusion of the cooling liquid into a vacuum can be prevented, and a sputtering apparatus that maintains the expected and efficient sputtering performance can be realized, and a sputtering film free of H ₂ O contamination can be efficiently achieved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS By forming a backing plate for bonding a target into a three-dimensional shape and forming a cooling water seal between the backing plate and the atmosphere, diffusion of H ₂ O into a vacuum is prevented.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a schematic configuration of a sputtering apparatus using the sputtering cathode of the present invention.
The structure of the sputtering cathode 10 is arranged on a part 21 of the wall surface of the vacuum chamber 20. The cross section of each part of the sputtering cathode 10 is circular, and forms a part of the wall of the vacuum vessel. A target 12 made of a material for film formation is placed on the sputtering cathode 10, and a substrate 22 is arranged to face the target 12. The substrate 22 is held by a substrate holder 23 fixed to the vacuum chamber 20 and connected to a ground 24. On the other hand, the sputtering cathode 10 is
5, for example, connected to a high frequency power supply. 20a, 20
Reference symbol b denotes a discharge gas inlet / outlet pipe connected to a discharge gas source such as Ar via a valve or the like.
The pipes 20a and 20b are also connected to the vacuum pump side, and can switch between vacuum exhaust and introduction and discharge of discharge gas by a switching valve.

FIG. 2 is a cross-sectional view of a more detailed configuration of the sputtering cathode 10 in FIG. 1, and reference numeral 12 denotes a target formed of a substance for forming a film on a substrate 22;
Reference numeral 3 denotes a back plate electrode (backing plate) for applying a potential to the target 12, and is formed using a conductor such as Cu or Al. The back plate electrode 13 is formed in a three-dimensional shape open to the atmosphere side, preferably a cylindrical shape with a bottom open to the atmosphere side, and the target 12 is joined to the surface of the bottom portion 13b. Further, a flange portion 13f is provided at an open end (lower end in the figure) of the cylindrical portion 13t of the back plate electrode 13.

Reference numeral 18 denotes an insulating flange formed of an electrically insulating material such as PTFE or a ceramic material in a ring shape.
The flange portion 13 f of the back plate electrode 13 is fixed to the atmosphere-side surface of the vacuum chamber wall 21 via the insulating flange 18. At this time, an annular gap g communicating with the inside of the vacuum chamber 20 is formed between the outer surface of the cylindrical portion 13t of the back plate electrode 13 and the inner surfaces of the vacuum chamber wall 21 and the insulating flange 18, while the other flange portions 13f, 13f are formed. The periphery of the insulating flange 18 is configured to be exposed to the atmosphere.

Reference numeral 14 denotes a flange portion 13f of the back plate electrode 13.
Is a flat-plate-shaped cathode flange that covers the atmosphere side surface and constitutes a lid of the bottomed cylindrical back plate electrode 13 and is made of a conductor such as metal or a resin material, and has a cylindrical shape together with the bottomed cylindrical back plate electrode 13. To form a closed space. A permanent magnet 16 for bending the trajectory of ions at the time of sputtering to improve the film formation efficiency and a magnetic plate 16a for forming a magnetic path thereof are accommodated in the cylindrical closed space.

Reference numerals 14a and 14b denote coolant inlets and outlets provided on the cathode flange, respectively, for circulating a coolant (usually water) in the space, and for the entire sputtering cathode, especially the back plate. It is used for cooling the electrode 13 and the target 12. This coolant circulation path
As is clear from the figure, the back plate electrode 13 completely separates and blocks the vacuum side.

Numeral 15 (15a, 15b, 15c) is a sealing means for cooling liquid and vacuum, and usually uses an O-ring and is made of a material such as NBR or FPM. The sealing means 15a seals the space between the coolant and the atmosphere between the flange 13f of the back plate electrode 13 and the cathode flange 14. On the other hand, 15b vacuum seals between the flange portion 13c and the insulating flange 18, and
c seals the vacuum between the insulating flange 18 and the outer surface of the vacuum chamber wall 21. This coolant seal (O-ring 1)
5a) communicates with the atmosphere side, but is completely separated and cut off from the vacuum side by the back plate electrode 13;
Even if 5a absorbs moisture, it has no effect on the vacuum side.

The back plate electrode 13 is electrically connected to the power supply system 25. Since the outer edge of the flange 13f is exposed to the atmosphere, the back plate electrode 13 may be directly connected to the power supply system 25. When a conductor is used as the cathode flange 14, the cathode flange 14 may be connected to the power supply system 25 via the conductor. Further, the back plate electrode 13 also plays a role of a main strength member constituting the sputtering cathode 10.

According to the above-structured sputtering cathode, the back plate electrode is formed in a bottomed cylindrical shape opened to the atmosphere side, so that the coolant circulation path and the vacuum side are completely separated and cut off by the back plate electrode itself. Since the mating surface sealed by the O-ring 15 communicates with the atmosphere side but does not communicate with the vacuum side at all, that is, since the O-ring seal portion for the coolant is formed in the atmosphere, even if the cooling water O
Even if the ring 15 absorbs moisture, diffusion of H ₂ O into the vacuum can be completely prevented.

Further, since the distance between the target 12 and the permanent magnet 16 does not increase, the magnetic force is
The effect of the permanent magnet on the ion trajectory in the glow discharge space between the target and the glow discharge space can be effectively maintained, and good sputtering performance can be secured.

[0025]

The cooling water circulation path and the vacuum side are completely separated from each other by the back plate electrode itself, and the O-ring sealing portion of the cooling water is formed in the atmosphere, so that H ₂ O diffuses into the vacuum chamber. And a sputtering cathode capable of effectively maintaining the action of the permanent magnet on the ion orbit can be constructed. As a sputtering apparatus, it is possible to efficiently obtain a good sputtering film free of contamination of a coolant component such as H ₂ O. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a sputtering apparatus of the present invention.

FIG. 2 is a cross-sectional view of one embodiment of the sputtering cathode of the present invention.

FIG. 3 is a cross-sectional view of a configuration example of a conventional sputtering cathode.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Sputtering cathode 12 Target 13 Back plate electrode 14 Cathode flange 14a, 14b Cooling water inlet / outlet 15 (15a, 15b, 15c) Sealing means (O-ring seal) 16 Permanent magnet 18 Insulating flange 21 Vacuum chamber wall

Claims (3)

[Claims] 1. A sputtering cathode for performing sputtering in a vacuum, wherein a cooling liquid sealing portion in the cathode is provided on the atmosphere side. 2. A sputtering cathode for generating a glow discharge with a target disposed in a vacuum facing a substrate facing a cathode, wherein a back plate electrode (backing plate) disposed on the back surface of the target is open to the atmosphere. 3. The sputtering cathode according to claim 1, wherein the sputtering plate is formed in a bottom cylindrical shape, and the cooling liquid circulation path of the sputtering cathode is separated and blocked from the vacuum side by the back plate electrode. 3. A sputtering apparatus, wherein the sputtering cathode according to claim 1 is arranged in a vacuum chamber so as to face a substrate.