JPH0867981A - Sputtering device - Google Patents

Abstract

PURPOSE: To enhance the practicability and mass productivity of a sputtering device arranged with an anode electrode between a substrate and a target by preventing the generation of abnormal discharge between a substrate tray or the substrate and the anode electrode and executing film formation with high reproducibility, reliability and high stability. CONSTITUTION: This sputtering device has a cathode electrode mechanism 15 which includes the target 18 and a magnet 19 for forming a magnetic field on this target, a gas introducing mechanism 24 which introduces a process gas and a power source 21 which impresses voltage to this cathode electrode mechanism. The process gas is converted to plasma by the magnetic field and the voltage and the target is sputtered by this plasma, by which thin films are formed on the substrate 22 arranged to face the target. The anode electrode 25 impressed with a positive voltage is arranged between the target and substrate of this sputtering device and a grounding electrode 31 held at grounding potential is arranged between the anode electrode and the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering apparatus, and more particularly to a sputtering apparatus for forming a thin film which will be an element or wiring in a semiconductor device, an electronic component or the like.

[0002]

2. Description of the Related Art The structure and operation of a conventional general sputtering apparatus will be described with reference to FIG. A cathode electrode mechanism 15 is provided at a hole 13 in the lower wall of the vacuum container 12 forming the processing chamber 11 via an insulating vacuum seal member 14. The cathode electrode mechanism 15 includes a cathode main body 17 having a back plate 16, a target 18 arranged on the back plate 16, and a magnet 19 provided outside the back surface of the back plate 16. The magnet 19 is a rod-shaped central magnet (upper surface is N pole).
And an annular surrounding magnet (the top surface is the S pole) arranged so as to surround the central magnet. The target 18 is
The inside of the processing chamber 11 is exposed through the hole 13 in the lower wall. Cathode body 1
A DC power supply 21 is connected between 7 and the ground 20, whereby the cathode body 17, the back plate 16, and the target 18 are held at a predetermined negative potential.

A substrate 22 introduced into the processing chamber 11 by a substrate loading / unloading mechanism (not shown) is arranged above the target 18 of the cathode electrode mechanism 15 so as to face the target surface. Substrate 22 is substrate tray 2
Supported by 3. A process gas is introduced into the processing chamber 11 by the gas introduction mechanism 24. Further, a ring plate-shaped anode electrode 25 is disposed between the target 18 and the substrate 22, and the anode electrode 25 is held at a predetermined positive potential by a DC power supply 26. The vacuum container 12 is connected to the ground 27 and is maintained at the ground potential. 28 is a lead wire 2 for applying a voltage to the anode electrode 25.
9 is a terminal portion for passing through.

When the process gas is introduced into the processing chamber 11 and the target 18 is held at a negative potential, plasma is generated on the target 18 corresponding to the magnetic field generated by the magnet 19. When the ions in the plasma collide with the target 18 having a negative potential, electrons are emitted from the target 18, and a part of the emitted electrons are repelled and accelerated by the negative potential of the target 18, and the substrate 22
Collide with

On the target 18, the Lorentz force is applied to the electrons by the action of the electric field and the magnetic field which are orthogonal to each other, and the orbit of the electrons takes a cycloidal orbit. As a result, more collisions and ionizations are repeated in the vicinity of the target 18 as compared with the case where there is no magnetic field. At that time, in the case of argon ion (Ar ⁺ ), electron, reactive sputtering using oxide or oxygen as a target, oxygen ion (O 2
^- , O ₂ ^+, etc.) are generated, and these form plasma. Argon ions repel metal or oxide atoms in the target 18 at negative potential. And
The repelled atoms adhere to the substrate 22 to form a thin film. The electrons and negative oxygen ions, are repelled by the negative potential of the target 18 (V _cath) is accelerated, the floating potential (V _f) or V to the substrate 22 at the ground potential (V _{G) f}
Incident at a voltage difference of -V _cath or V _G -V _cath, re sputtered deposited thin films.

Regarding re-sputtering for negative ions, etc.,
The following issues are raised.

It has been reported that when the thin film on the substrate is a compound, it causes damage such as changing the composition ratio. For example, in the case of an oxide superconducting film, YBaC
An example of uO is SM Rossnagel and JJCuomo, American In
Institute of Physics, 1988, PP106-113, S.Ishibashi, etc., "Proc, 1st Int'l Symp, on
Reported in ISSP '91 Tokyo, 1991, PP 153-158.

Further, when the film was formed, A
It has also been reported that r ⁺ loses its charge, scatters, and again sputters a thin film formed on the substrate as high-speed Ar atoms. For example, DWHoffman and JSBadg
ley, J.Vac.Sci.Technol. A6 (3), May / June, 1988, PP169
Re-sputtering of scatter atoms from the target was reported in 1-1692. Argon ion (Ar ⁺ )
Is the difference between the plasma potential and the floating potential (V _p
Since collisions occur at an energy of −V _f ), Ar ⁺ is also considered to be involved in the film characteristics. For example, Tadahiro Omi, NIKKEI M
In ICRODEVICES, October issue, 1990, PP108-114, there is a report that there is an optimum ion energy for obtaining good film characteristics in Si film formation.

As described above, in the conventional sputtering apparatus, it has been reported that high-energy electrons, high-energy negative ions, and high-energy recoil neutral atoms affect the film quality of the thin film on the substrate by resputtering. ing. Therefore, in order to improve the film quality, (1) remove high-energy negative charged particles, (2) reduce the energy of high-energy particles that collide with the substrate, and (3) optimally control the amount of Ar ⁺ ion energy. The improvement method such as The improvement methods (1) and (2) described above improve the film quality by reducing the damage of the film due to the high energy particles in the thin film on the substrate. The improvement method of (3) improves the film quality by irradiating the substrate with ions having an optimum ion energy.

Further, Japanese Patent Laid-Open No. 4-254579 discloses that
Disclosed is a film forming apparatus having a configuration in which an anode electrode is arranged between a substrate and a target and a positive potential higher than the potential applied to the target is applied to the anode electrode. According to this film forming apparatus, compared to the conventional sputtering apparatus, I
A TO film can be obtained. By disposing the anode electrode between the substrate and the target, (1) collecting negatively charged particles and reducing the number of high-energy negatively charged particles,
(2) The discharge impedance on the target can be lowered, (3) the plasma potential can be controlled, and (4) the plasma density near the substrate can be increased. By thus providing the anode electrode between the substrate and the target, the film characteristics can be improved.

[0011]

In the in-line device having the configuration of the conventional device shown in FIG. 4, the present inventors insert an anode electrode between the substrate and the target, and target the ITO target (In ₂ O 3). ₃ and 10% wtS
nO ₂ ) was used, and a process gas (Ar and O ₂ ) was used to perform a film forming experiment. As a result, when a positive voltage is applied to the anode electrode, an arc-shaped abnormal discharge is continuously generated on the substrate tray or the substrate being transported, and the thin film formed on the substrate may have a change in film thickness or resistivity. The film characteristics changed, and when the substrate was a glass substrate, scratches were generated on the substrate due to abnormal discharge, which caused problems in reproducibility and reliability of film formation. In addition, film peeling occurs during abnormal discharge,
It became one of the causes of particle generation. in this way,
In the in-line device having the configuration of the conventional device, various problems occur only by providing the anode electrode, and there is a problem that the practical production is extremely low in practicality.

In order to solve the above problems, an object of the present invention is to generate an abnormal discharge between the substrate tray and the anode electrode or between the substrate and the anode electrode in the structure in which the anode electrode is inserted between the substrate and the target. Another object of the present invention is to provide a highly practical sputtering device capable of mass-producing thin films having excellent reproducibility, reliability, and stability while preventing the above.

[0013]

In order to achieve the above-mentioned object, a sputtering apparatus according to the present invention introduces a process gas and a cathode electrode mechanism including a target and a magnet for generating a magnetic field on the target. A gas supply mechanism and a power source for applying a voltage to the cathode electrode mechanism are used, and the process gas is turned into plasma by the magnetic field and voltage, and the target is sputtered by this plasma, and a thin film is formed on the substrate placed facing the target. A device, in which a first electrode (anode electrode) to which a positive voltage is applied is arranged between a target and a substrate, and a second electrode (ground electrode) having a ground potential is arranged between the first electrode and the substrate. Is composed of.

In the above structure, preferably, the first electrode and the second electrode are formed in a ring plate shape, and the first electrode and the second electrode are arranged in parallel so that at least a part thereof overlaps.

[0015]

According to the present invention, the first electrode held at the positive potential reduces the number of the negative charged particles absorbing the high energy negative charged particles and colliding with the substrate, and the second electrode held at the ground potential. The electrodes suppress abnormal discharge that occurs between the first electrode and the substrate or substrate tray. By preventing the occurrence of abnormal discharge, the reproducibility, reliability, and stability of the thin film to be produced are improved, and the occurrence of film peeling is suppressed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of a sputtering apparatus according to the present invention. In FIG. 1, elements that are substantially the same as the elements described in FIG. 4 are given the same reference numerals.

A cathode electrode mechanism 15 is provided in a hole 13 in the lower wall of the vacuum container 12 forming the processing chamber 11 via a vacuum seal member (insulating member) 14. Cathode electrode mechanism 15
Is a cathode body 17 having a back plate 16 and a target 1
8 and a magnet 19. Target 18 is IT
In order to form an O film, for example, In ₂ O ₃ and 10% wt.
It is formed of SnO ₂ . The magnet 19 is composed of a rod-shaped central magnet and an annular peripheral magnet. Target 1
8 faces the inside of the processing chamber 11 through the hole 13. Cathode body 17
A DC power supply 21 is connected between the ground and the ground 20, and the cathode body 17, the back plate 16, and the target 18 are held at a negative potential. The substrate tray 2 is located above the target 18.
Substrates 22 supported by 3 are arranged to face each other. A process gas (Ar and O ₂ ) is introduced into the processing chamber 11 by the gas introduction mechanism 24. The vacuum container 12 is connected to the ground 27 and is maintained at the ground potential.

The magnet 1 is provided on the surface of the target 18.
Magnetic field lines 30 are distributed by 9 and a magnetic field is generated. The magnetic field generated on the target surface by the magnet 19 has a ring shape or a donut shape. As the magnet 19, it is preferable to use a magnet having a magnetic field strength on the target parallel to the target surface of about 1000 Gauss or more.

Between the target 18 and the substrate 22, an anode electrode 25 having a ring plate shape, for example, which is held at a predetermined positive potential by a DC power supply 26, is arranged. The conducting wire 29 for applying a voltage to the anode electrode 25 is a current introducing terminal portion 28.
Wired through.

Between the anode electrode 25 and the substrate 22, a ring plate-shaped ground electrode 31 is further arranged. The ground electrode 31 is arranged parallel to the anode electrode 25, and preferably a part of the ground electrode 31 is arranged so as to overlap the anode electrode 25. Ground electrode 31
Is connected to the vacuum vessel 12 by a conductor 32. Since the vacuum container 12 is grounded, the ground electrode 31 is also held at the ground potential. Between the target 18 and the anode electrode 25, and between the anode electrode 25 and the ground electrode 31,
For example, ring-shaped insulating members 33a to 33d are provided, and the target 18, the anode electrode 25, and the ground electrode 31 are provided.
Holds the respective positional relationships of. Insulation member 33a
Ceramics having high heat resistance, for example, alumina ceramics are used for the elements 33d to 33d.

The operation of the above sputtering apparatus will be described. A processing chamber 11 in the vacuum container 12 is provided by an exhaust mechanism (not shown).
Exhaust. After exhausting the processing chamber 11 to a desired pressure,
The gas introducing mechanism 24 introduces the process gas to a predetermined pressure. After that, a desired positive DC voltage is applied to the anode electrode 25 from the DC power supply 26 through the terminal portion 28 and the lead wire 29. While moving the substrate 22 supported by the substrate tray 23 onto the target 18, the sputtered atoms ejected from the target 18 are attached to the substrate 22 to form a thin film. Further, the ground electrode 31 inserted / disposed between the anode electrode 25 and the substrate 22 can prevent abnormal discharge from occurring.

On the other hand, when an anode electrode having a positive potential is arranged instead of the ground electrode 31, as described in the section "Problems to be solved by the invention", the substrate 22,
It was experimentally found that arc-shaped abnormal discharge occurs on each of the thin film on the substrate, the anode electrode 25, and the substrate tray 23, and it is difficult to perform normal film formation.

In the structure shown in FIG. 4 in which the ground electrode 31 is not provided, a positive voltage V ₃ is applied to the anode electrode 25 in a stable discharge state, and a target 18 containing In ₂ O ₃ and 10% wtSnO ₂ is used. When the effects on the target voltage, the target current, and the anode electrode current (I ₃ ) are examined, in the dependence characteristic of the anode electrode current I _{3 on} the anode electrode voltage V ₃ , I ₃ monotonously increases with V _3. Increased,
The result is that the target current increases with the increase of I ₃ . That is, the discharge impedance becomes smaller than the power input from the anode electrode 25, the plasma spreads over the target 18 and is densified, and the increased ions flow into the target 18, so that the target current increases and the target voltage increases. There was a phenomenon that the value decreased. In the above case, the target power is 0.
The pressure was 45 kW, the pressure was 1 to 5 mTorr, and the argon / oxygen flow rate was 105 / 0.5 sccm.

From the above, "conventional art" in the specification
The high-energy negative charged particles described in
It can be suppressed for one reason. First, it reduces the discharge impedance of the target and lowers the target voltage, and secondly, the anode electrode absorbs the negatively charged particles and reduces the amount of high energy negatively charged particles incident on the substrate. That is. Therefore, by providing the anode electrode 25, the collision energy of the negatively charged particles on the substrate 22 can be reduced. Although actually visually observed, it was confirmed that when the potential of the anode electrode 25 was increased, the plasma was spread over the entire shield and the plasma density near the substrate 22 was increased. Therefore, it was confirmed that the number of Ar ⁺ ions colliding with the substrate 22 was increased and the film quality was changed.

In the present embodiment, as shown in FIG. 1, the above-mentioned anode electrode 25 is arranged between the target 18 and the substrate 22, and a plurality of ring-shaped insulating members 33a to 33d are further provided on the anode electrode 25. Since the ground electrode 31 is arranged by means of the ground electrode 31, it is possible to prevent the occurrence of abnormal discharge, improve the reproducibility of film formation, and obtain a low-resistance thin film in a stable state without abnormal discharge. When the target 18 is made of a material composed of In ₂ O ₃ and 10% wtSnO ₂ and Ar and O ₂ are used as the process gas, the thin film produced is an ITO film.

The material of the target 18 is (In ₂ O ₃ +
It is not limited to 10% wtSnO ₂ ). Also,
The shape of the ground electrode 31 and the anode electrode 25 may be the above-mentioned ring-shaped electrode surrounding the erosion portion of the target, or two flat plate-shaped electrodes may be arranged in parallel. The shape of each electrode is set to an optimum shape in consideration of the plasma distribution. In this case, the positional relationship between the ground electrode 31 and the anode electrode 25 can be set arbitrarily.

2 and 3 show another embodiment. Figure 2
In FIG. 3, the ground electrode and the anode electrode are denoted by the same reference numerals as those in FIG. In the embodiment of FIG. 2, the inner edge and the outer edge of the ring plate-shaped ground electrode 31 are the anode electrode 2.
5 extends inward or outward from the inner and outer edges of 5,
An example in which the anode electrode 25 is safely covered is shown. The ground electrode 31 has a wider width than the anode electrode 25. 33
e is, for example, a ring-shaped (rod-shaped or block-shaped) insulating member. In the embodiment of FIG. 3, the ring-shaped ground electrode 3
1 and the anode electrode 25 have the same electrode width.

In the sputtering apparatus according to the present invention, the target mounting position is not particularly limited. That is, even if the mounting position of the target 18 is on the upper side or the horizontal position, the present invention is applied as long as the relative positions of the target, the anode electrode, the ground electrode, and the substrate are maintained in the same positional relationship as in the above embodiment. can do.

As described above, by providing the anode electrode 25, the plasma potential can be reduced, the impedance of the cathode electrode can be reduced, the amount of negative high energy charged particles incident on the substrate can be controlled, and the anode electrode 25 can be provided above the anode electrode 25. By providing the ground electrode 31, abnormal discharge between the substrate tray 23 and the anode electrode 25 and between the substrate 22 and the anode electrode 25 is prevented, reproducibility and reliability in thin film production are improved, and generation of particles is reduced. be able to.

Although the sputtering apparatus has been described in the above embodiments, the electrode structure according to the present invention can be applied to a film forming apparatus such as a CVD apparatus or an etching apparatus.

[0032]

As is apparent from the above description, according to the present invention, the second electrode (ground electrode) of negative potential is provided between the first electrode (anode electrode) to which a positive voltage is applied and the substrate.
It is possible to prevent abnormal discharge from occurring, mass-produce thin films with excellent stability, reproducibility, and reliability, reduce film peeling, and realize a highly practical film forming apparatus. .

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a first embodiment of a sputtering apparatus according to the present invention.

FIG. 2 is a longitudinal sectional view showing another embodiment of the arrangement structure of the anode electrode and the ground electrode.

FIG. 3 is a vertical sectional view showing another embodiment of the arrangement structure of the anode electrode and the ground electrode.

FIG. 4 is a vertical sectional view of a conventional sputtering apparatus.

[Explanation of symbols]

 11 processing chamber 12 vacuum container 15 cathode electrode 17 cathode main body 18 target 19 magnet 22 substrate 23 substrate tray 24 gas introduction mechanism 25 anode electrode 31 ground electrodes 33a to 33e insulating member

Claims (2)

[Claims] 1. A cathode electrode mechanism including a target and a magnet that generates a magnetic field on the target, a gas introduction mechanism that introduces a process gas, and a power source that applies a voltage to the cathode electrode mechanism. In the sputtering apparatus, the process gas is turned into plasma by the voltage, the target material of the target is sputtered by the plasma, and a thin film is formed on a substrate arranged to face the target, between the target and the substrate. A sputtering apparatus, wherein a first electrode to which a positive voltage is applied is arranged, and a second electrode having a ground potential is arranged between the first electrode and the substrate. 2. The sputtering apparatus according to claim 1, wherein
The sputtering apparatus, wherein the first electrode and the second electrode are formed in a ring plate shape, and the first electrode and the second electrode are arranged in parallel so that at least a part of them overlaps each other.