JP2878299B2 - Ion plating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to efficiently forming a high-quality thin film with low internal stress at high speed by using plasma generated from a composite cathode plasma gun. It relates to an effective ion plating method.

[Prior Art] Conventionally, vacuum deposition has been widely used for optical thin films, decorative purposes, and the like. Further, a technique called ion plating for improving a film quality by introducing a hollow cathode and high-frequency excitation into vacuum deposition to generate glow discharge is also known.
However, there is a problem in efficiently depositing a high-quality and low-internal-stress film on a large-area substrate such as a window glass of an architectural building or a glass for an automobile using these methods. For example, in the hollow cathode method, since the cathode portion is exposed to plasma, it has been difficult to perform stable continuous vapor deposition due to melting or deformation. In addition, there is a possibility that ions may flow back to the cathode side, and there is a problem in performing high-power discharge for a long time. In the high-frequency method, it is necessary to use a ring-shaped antenna or the like to generate a discharge, and to arrange a metal plate or the like on the substrate side to apply a bias, making it difficult to create a uniform discharge area over a large area. In addition, since the discharge is affected by the gas pressure in the vacuum chamber, the discharge is unstable, and it has been difficult to uniformly and continuously perform stable vapor deposition on a large-area substrate at a high speed.

[Problem to be Solved by the Invention] As described above, it is extremely difficult to form a large-area and uniform thin film with low internal stress by the conventional hollow cathode or the ion plating method using high-frequency excitation. Had.

Means for Solving the Problems The present invention has been made for the purpose of solving the above-mentioned disadvantages, and the He gas is an arc discharge by performing an arc discharge using a gas containing He as a main component as a discharge gas. Generating a plasma process, directing said arc discharge plasma stream by a magnetic field onto a metal oxide tablet placed below said arc discharge plasma stream to evaporate said metal oxide tablet,
It is intended to provide an ion plating method comprising forming a transparent conductive film on a substrate placed above the metal oxide tablet. Further, an arc discharge is performed by using an He gas or a gas containing He as a main component as a discharge gas to generate an arc discharge plasma flow, and a magnetic field is applied to form the sheet plasma in which the arc discharge plasma flow is deformed into a sheet shape. The sheet-like plasma was guided on a metal oxide tablet by a magnetic field generated by an elongated permanent magnet extending in the width direction of the sheet-like plasma to evaporate the metal oxide tablet, and was placed above the metal oxide tablet. An object of the present invention is to provide an ion plating method characterized by forming a transparent conductive film on a substrate.

 Hereinafter, the present invention will be described in detail.

FIG. 1 is a schematic diagram showing a basic configuration of an example of an apparatus used for performing ion plating by the method of the present invention. FIG. 1 shows an example in which a base on which a transparent conductive film is formed is fixed. FIG. 2 is a cross-sectional view of an area shown in FIG.

In the present invention, a plasma flow by arc discharge is used. The arc discharge plasma flow is generated by applying a plasma generating DC power supply 4 between the arc discharge plasma flow source 1 and the anode (hearth) 2 to perform arc discharge.

As such an arc discharge plasma flow generation source 1, a composite cathode type plasma generation device, a pressure gradient type plasma generation device, or a plasma generation device combining the both is preferable. Such a plasma generator is described in Vacuum Vol. 25, No. 10, issued in 1982.

The composite cathode type plasma generating apparatus has a small auxiliary cathode heat capacity and a main cathode made of LaB _6, to concentrate initial discharge to the auxiliary cathode, by using it to heat the main cathode LaB _6, This is a plasma generator in which a main cathode LaB ₆ performs an arc discharge as a final cathode. For example, there is an apparatus as shown in FIG. Examples of the auxiliary cathode include coils or pipes of a high melting point metal such as W, Ta, and Mo.

In such a composite cathode type plasma generator,
A small auxiliary cathode 52 of the heat capacity and heated at intensive initial discharge, is operated as an initial cathode, the main cathode 51 indirectly LaB ₆
Heating the so eventually is in a manner to be shifted to the arc discharge by the main cathode 51 of LaB _6, the main cathode 51 of LaB ₆ before the auxiliary cathode 52 affects the service life at a high temperature above 2500 ° C.
Is heated to 1500 ° C. to 1800 ° C., a large electron current can be emitted, and a further increase in the temperature of the auxiliary cathode 52 is avoided.

A pressure-gradient plasma generator is a device in which an intermediate electrode is interposed between a cathode and an anode, and discharges while maintaining the cathode region at about 1 Torr and the anode region at about 10 ^-3 Torr. There is no damage to the cathode due to backflow of ions from the region, and the gas efficiency of the carrier gas for creating the discharge electron flow is dramatically higher than that of the discharge type without the intermediate electrode, enabling large current discharge. Has the advantage that

The composite cathode type plasma generator and the pressure gradient type plasma generator each have the above-mentioned advantages, and a plasma generator combining both of them, that is, a composite cathode is used as a cathode and an intermediate electrode is also provided. The plasma generator described above is very preferable as the arc discharge plasma flow generation source 1 of the present invention because it can obtain the above advantages at the same time.

FIG. 1 shows an arc discharge plasma source 1
An example is shown in which a composite cathode 21 as shown in the figure, a first intermediate electrode 22 including an annular permanent magnet, and a second intermediate electrode 23 including a second intermediate electrode including an air core coil are used.

In the present invention, the anode (hearth) 2 is disposed so as to be located below the plasma generation source 1, and the air-core coil 6
A high-density plasma flow generated by the arc discharge generated from the plasma generation source 1 is drawn into the vacuum chamber 3. further,
In order to make the drawn plasma into a sheet shape, the pair of permanent magnets 5 are sandwiched between the hearth 2 and the base 7 with the N pole faces facing each other, and the N pole of the permanent magnet or
The S pole face is two hearths or the substrate 7 on which a coating is formed
The sheet plasma 8 is formed by pressing the plasma in a direction parallel to the hearth 2 or the substrate 7.

In FIG. 1, the sheet plasma 8 deformed into a sheet shape by a pair of permanent magnets 5 has a thickness from the top to the bottom in FIG. 1 and a direction perpendicular to FIG. 1 as shown in FIG. It has a width.

The sheet plasma 8 is bent at about 90 ° by the magnetic field generated by the permanent magnet 9 placed under the hearth 2, focuses on the hearth 2, evaporates the raw material 10 in the hearth 2, and evaporates the particles. A transparent conductive film is formed on the substrate 7 placed above the substrate.

In the present invention, as shown in FIG. 2, the permanent magnet 9 preferably has at least the same length as the hearth 2 in the width direction of the sheet plasma 8. This is because the sheet plasma 8 is evenly incident on the evaporation material in the hearth 2, and the evaporation material can be used effectively.

In the present invention, the permanent magnet 9 and the hearth 2 are
As shown in FIG. 2, the sheet plasma 8 preferably has at least the same length as the base 7 in the width direction. The reason is that the evaporation raw material evaporated from the hearth 2 can be evenly and uniformly attached to the base 7 in the width direction of the sheet plasma.

In the present invention, the hearth 2 and the permanent magnet 9 are the first
In the direction of arrow A in the figure, that is, in the direction perpendicular to the width of the sheet plasma when the translational motion is performed in a plane parallel to the base 7,
The evaporation material evaporated from the hearth 2 is uniformly adhered to the base 7, and the film thickness can be prevented as much as possible from the portion just above the hearth 2 of the base 7 and the portion apart from the hearth 2. Very good.

In the present invention, for example, as shown in FIG. 5, a permanent magnet 9 thinner than the hearth 2 is used, and the permanent magnet 9 is moved relative to the hearth 2 as shown by an arrow B in FIG.
The operation can be performed so that the plasma is uniformly incident on the substrate. By doing so, the use efficiency of the evaporation raw material is increased. This is particularly effective because the evaporation source is an expensive material such as a metal oxide. This operation is performed by the arrow A in FIG.
It can be performed in combination with the translational movement.

As shown in FIG. 7, the evaporation material hearth 2 and the base 7 for forming the transparent conductive film are arranged in the vacuum chamber 3 and the elongated rectangular permanent magnet 9 is placed outside the vacuum chamber 3 and on the evaporation material hearth 2.
To perform ion plating. In this case, the evaporation material hearth 2 on the bottom of the vacuum chamber 3
It is necessary that the portion sandwiched between the magnet and the permanent magnet 9 be made of a material that does not shield the magnetic field. As described above, the width, thickness, plasma density, and the like of the sheet plasma 8 can be controlled outside the vacuum chamber as desired by changing the permanent magnet 9 via the bottom surface of the vacuum chamber 3. it can. The width, length, and plasma density of the sheet plasma vary depending on the power applied to the evaporation raw material hearth 2, the permanent magnet 9, the arc discharge plasma flow source 1, and the like. If the intensity can be freely changed, sufficient control of the sheet plasma becomes possible. As described above, if the permanent magnet 9 is arranged outside the vacuum chamber 3, the type and shape of the permanent magnet 9 can be changed without changing the inside of the vacuum chamber 3,
It is possible to change the distance between the permanent magnet 9 and the evaporation material hearth 2. This greatly contributes to multilayering of films of different materials and stabilization for continuous production.

Further, a discharge gas is introduced from the discharge gas inlet 11. Further, it is desirable that the vacuum chamber 3 is maintained at about 10 ⁻³ Torr or less by the exhaust means.

As the evaporation raw material 10 used in the present invention, a tablet made of a metal oxide is used. When a metal oxide tablet is used in forming a metal oxide film, a film of good quality can be obtained with easy control of film forming conditions. In particular, when an indium oxide film containing tin is formed, a tablet of indium oxide containing 5 to 10% by weight of tin is preferable because a very low-resistance film can be obtained.

A feature of the present invention is that He is used as a discharge gas introduced from the gas inlet 11 into the vacuum chamber 3.

Ar gas is usually used as a gas used to generate an arc discharge and generate a plasma flow. This is used to facilitate arc discharge because the ionization degree of Ar gas is good and the ionization voltage is as low as 15 to 16 V. But,
When Ar gas is used for arc discharge, the plasma flow is introduced into a vacuum and mixed into a film deposited on a substrate. When Ar gas is mixed into the film, the internal stress may increase, and a material having a high internal stress, for example,
When a thick film is formed, cracks and film peeling are likely to occur. In the case of He gas, the atomic radius of He is smaller than that of Ar, so that even if it is mixed in the film, it does not easily cause internal stress. It has also been found that the use of He gas can achieve a higher evaporation rate than Ar gas. This is because the He gas has a higher arc discharge voltage of 24 to 25 V than the Ar gas, so the particles of the plasma flow applied to the deposition material (metal oxide tablet) on the hearth are accelerated, and the evaporation rate of the deposition material is increased. Is thought to be faster. In the present invention, it is particularly preferable to use a discharge gas composed of 100% He. However, in consideration of the degree of internal stress of the film to be formed, the film thickness, and the like, a discharge gas containing He as a main component and mixing Ar is used. A use gas may be used.

The gas atmosphere in the vacuum chamber 3 is not only an inert gas such as He or Ar but also a gas introduction means provided in the vacuum chamber 3.
According to 12, O ₂ , N _2, etc. as a reaction gas, 0 to 50% by volume
It may be added.

As the substrate 7 on which a thin film is formed in the present invention, a substrate or a film made of glass, plastic, or metal can be used, and is not particularly limited. However, in the method of the present invention, even if the substrate is not heated. Since a high quality film can be obtained, those having low heat resistance, such as a substrate or film made of plastic or a glass plate having an organic polymer film in advance, such as a glass substrate for a liquid crystal color display having a color filter film, etc. Applicable enough.

In the present invention, a thin film made of a metal oxide is formed as the thin film formed on the base 7. The method of the present invention is suitable for obtaining a transparent conductive film having low resistance and high transmittance. Suitable examples of such a transparent conductive film include an indium oxide film containing tin, a tin oxide film containing antimony, and a zinc oxide film containing aluminum.

Also, the present invention uses He as a discharge gas,
The method of the present invention can reduce the internal stress of the film as compared with the case of using Ar, a transparent electrode for a display such as a liquid crystal display element, an electrode such as a solar cell, a heat ray reflective glass, an electromagnetic shielding glass, a low emissivity ( Low-Emissivity) can be applied to the production of glass and the like. In the present invention, during film formation, the substrate 7 may be stationary or may be transported. In particular, the first
In the figure, from left to right, or from right to left, that is, in FIG.
It is preferable that the film is formed while being transported vertically from the back side to the front side, since a uniform film can be continuously formed in the width direction of the sheet plasma.

In the present invention, if the length of the DC power supply 4 applied to the arc discharge plasma flow source 1 and the length of the permanent magnet 5 for transforming the plasma flow into a sheet, the strength of the magnetic force, and the like are adjusted, the thickness is reduced.
A sheet plasma having a width of about 0.5 to 3 cm and a width of about 10 to 50 cm can be easily formed, and the width of the sheet plasma on the hearth 2 and the shape of the plasma can be changed by changing the length of the permanent magnet 9 and the strength of the magnetic force. , The density can be changed.

Further, as shown in FIG.
A large-area sheet plasma is formed by adjoining the sheet plasma deformed into a sheet shape by magnetic field means (specifically, the permanent magnet 5 in FIG. 4) in the same plane to form a large-area sheet plasma, and placed below the sheet plasma. It is also possible to bend onto the hearth 2 and evaporate it. FIG.
FIG. 2 is a diagram showing a case where three devices as shown in FIG. When a plurality of sheet plasmas are adjacent to each other, the permanent magnet 5
In order to maintain the symmetry of the magnetic field component B _x in the width direction of the sheet plasma, on an extension of a line connecting a plurality of permanent magnets 5, and on the outside of both ends of the sheet plasma, one by another set permanent magnets
Need to arrange 15

The hearth 2 may be an elongated one as shown in FIG. 4 or a plurality of relatively short hearths having different evaporation materials. In either case, the substrate on which the thin film is formed may be stationary or may be transported. In this case, when the substrate is transported in the direction of arrow C, a large-area thin film can be formed very uniformly at high speed.

In addition, by incorporating the film forming apparatus as shown in Fig. 1 into a part of the in-line type film forming apparatus, it is possible to continuously produce a multilayer film in combination with other film forming apparatuses such as a sputtered film and a vapor deposited film. It is. When forming a multi-layer film, it is important to form a multi-layer material by the most suitable method.Especially, in the case of a large area, the film thickness distribution has been a problem in the vapor deposition method. The use of a sheet plasma as in the invention greatly improves the performance.

Further, as shown in FIG. 6, a plurality of hearths may be provided, and ion plating may be performed in which different evaporation raw materials 10A, 10B, and 10C are put. In FIG. 6, each hearth 2A, 2B, 2
It is desirable that each of C and the permanent magnets 9A, 9B, 9C have at least the same width as the base 7 as shown in FIG.
By selecting the switches 13A, 13B, and 13C as desired, a film having one or more compositions can be formed on the substrate 7. FIG. 6 shows that only the switch 13B is turned ON,
The sheet plasma 8 is concentrated on the top,
10B shows a case where a film is formed by evaporating 10B.
In particular, in the case of an in-line type apparatus, a job change for changing the type of the evaporation raw material is not required, and a significant cost reduction can be achieved. Also, switch two or more of the switches
By turning on and applying the desired power to the DC power supplies 4A, 4B, 4C, the density of the sheet plasma incident on the corresponding evaporating material is adjusted, the evaporation rate is controlled, and the composition of the multi-component film is controlled. It can also be formed. If the thickness of the hearths 2A, 2B, and 2C (the length in the left-right direction in FIG. 6) is reduced and various hearths are brought close to each other, a film composed of multiple components having a specific composition can be formed uniformly. In particular, it is more preferable to transport the substrate 7 in the direction of the arrow D or D '.

As described above, in the ion plating method of the present invention, the case where the arc discharge plasma flow is deformed into a sheet shape by the magnetic field means has been described, but the ion plating using the arc discharge plasma flow generated by using He as the discharge gas of the present invention has been described. The singing method does not necessarily require that the arc discharge plasma flow be sheeted.

In the present invention, when Ar is a discharge gas, 3000 to
A higher film formation rate of about 5,000 to 15,000 Å / min can be obtained as compared with 10,000 Å / min, and a film with much lower internal stress can be formed at a much higher speed than the conventional ion plating method.

For example, when forming an ITO film using a tablet made of indium oxide containing tin as an evaporation material, a low-resistance IT having a specific resistance of 3 × 10 ⁻⁴ Ω · cm or less at a film forming rate of about 10,000 Å / min.
An O film is obtained. This film formation rate is about twice as large as 5000 ° / min when Ar is used as the discharge gas, and is extremely high.

[Operation] In the present invention, since the plasma used is an arc discharge, the density of the plasma is 50 to 100 as compared with the glow discharge type plasma used in the conventional magnetron sputtering or ion plating. The ionization degree of the gas is several tens%, and the ion density, electron density and neutral active species density are very high. By converging such a high-density plasma on the evaporation material, it is possible to take out a very large number of particles from the evaporation material, and to form a film 3 to 10 times as fast as the conventional ion plating method. Can be realized. Furthermore, many of the atmospheric gases such as oxygen and argon take reactive high ions and neutral active states, and in addition, evaporated particles pass through a high-density plasma before reaching the substrate. It is a highly active neutral active species. As a result, the reactivity on the substrate increases, and even without substrate heating,
A transparent conductive film having a low specific resistance can be formed at a higher film forming speed than before.

As described above, in the present invention, since a high-density arc discharge plasma is used, a discharge gas is easily taken into a film to be formed, but high-speed film formation can be performed by using He having a small atomic radius as a discharge gas. A film having low internal stress can be formed while having advantages.

Further, by changing the gas for arc discharge from Ar gas to He gas, the discharge voltage is increased, the plasma particles are further accelerated, and the raw material evaporation rate is increased. Compared with the case where Ar gas is used, the amount of current for generating the same velocity in He gas may be smaller.

[Example] A glass plate was used as the substrate 7, and an ITO film of a conductive oxide was vapor-deposited by a method described below. First, the degree of vacuum in the vacuum chamber 3 is reduced to 2 × 10 ⁻⁵ Torr, and then O ₂ gas is introduced to 4.0 × 10 ⁻⁴ Torr, as shown in FIG. 1 having a composite cathode as shown in FIG. DC power supply 4 was set to 150 A and 110 V using a simple plasma generator, and H
Arc discharge was performed by introducing e gas. The distance between the hearth 2 and the substrate 7 was about 60 cm, and the substrate was fixed. Film thickness 1680
0Å, specific resistance 2.85 × 10 ^-4 Ωcm, internal stress 3.0 × 10 ³ kg / cm
^2. A film having a visible light transmittance of 70% (substrate glass 92%) was obtained.
This is a film formation rate of 12000Å / min, which is extremely faster than a method using an EB (electron beam) gun or the like. As the deposition performed without heating the substrate, one having a considerably low specific resistance was obtained.

[Comparative Example] A glass plate was used as the substrate 7, and an ITO film of a conductive oxide was deposited as a deposition material by the following method. First, the degree of vacuum in the vacuum chamber 3 is reduced to 2 × 10 ⁻⁵ Torr, and then O ₂ gas is introduced to 4.0 × 10 ⁻⁴ Torr, as shown in FIG. 1 having a composite cathode as shown in FIG. Using a suitable plasma generator, the DC power supply 4 was set to 250 ° C. and 70 V, and Ar gas was introduced to perform arc discharge. Approximately 60cm distance between Haas 2 and substrate 7
The test was performed with the substrate fixed. 14800mm thick, specific resistance 3.05
A film having × 10 ⁻⁴ Ω · cm and a visible light transmittance of 70% (substrate glass 92%) was obtained. This is a film formation rate of 5000 l / min, which is extremely faster than a method using an EB gun or the like. As the deposition performed without heating the substrate, one having a considerably low specific resistance was obtained.

[Effects of the Invention] According to the present invention, it is possible to form a film having a low internal stress at a high speed without heating a thin film of various compounds to a substrate. This is particularly advantageous when a film having a high internal stress or a thick film having a thickness of several μm is formed. Further, since an optimum plasma flow can be generated by using an appropriate magnetic field means according to the type of the thin film, an optimum film can be formed. That is, by increasing the width of the sheet plasma, for a large-area substrate, the film thickness distribution on the substrate 7 can be reduced to form a uniform film. Conversely, a small permanent magnet 9 can be used. By making the sheet plasma small and dot-like, the degree of concentration on the hearth 2 is increased,
Materials that are difficult to evaporate can be easily evaporated.

Further, in the present invention, it is possible to further improve the film thickness distribution over a large area by translating the hearth 2 and the magnet 9, and it is possible to apply a plurality of hearths 2 to a large-area multilayer film. Becomes

Further, by moving the hearth 2 and the permanent magnet 9 relatively, the utilization efficiency of the evaporating substance 10 in the hearth can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a basic configuration of an example of an apparatus used for performing ion plating according to the present invention, FIG. 2 is a cross-sectional view of an arc in FIG. 1, and FIG. 3 is an arc discharge plasma used in the present invention. FIG. 4 is a cross-sectional view of an example of a composite cathode as a cathode of a generator, FIG.
The figure is a schematic explanatory view when the hearth and the permanent magnet are relatively moved, FIG. 6 is a schematic explanatory view when a plurality of hearths are provided, and FIG. 7 is for performing the ion plating of the present invention. FIG. 6 is a schematic diagram showing a basic configuration of another example of the device used for the above. 1: Arc discharge plasma flow source 2: Hearth (anode) 3: Vacuum chamber 4: DC power supply for plasma generation 5: Permanent magnet 6: Air-core coil 7: Substrate 8: Sheet plasma 9: Permanent magnet 10: Evaporated raw material 11 : Discharge gas inlet 12: Reaction gas inlet 13: Switch 21: Composite cathode 22: First intermediate electrode with built-in annular permanent magnet 23: Second intermediate electrode with built-in air core coil 51: LaB ₆ main cathode 52: Ta pipe Auxiliary cathode 53: Disk made of W for protecting the cathode 54: Cylinder made of Mo 55: Disk shaped heat shield made of Mo 56: Cooling water 57: Cathode support made of stainless steel 58: Gas inlet

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-57767 (JP, A) JP-A-59-47381 (JP, A) JP-A-57-172742 (JP, A) (58) Field (Int. Cl. ⁶ , DB name) C23C 14/00-14/58

Claims (2)

(57) [Claims] An arc discharge is performed by using an He gas or a gas mainly composed of He as a discharge gas to generate an arc discharge plasma flow, and a magnetic field is formed on a metal oxide tablet placed below the arc discharge plasma flow. Ion-plating, wherein the metal oxide tablet is evaporated by guiding the arc discharge plasma flow to form a transparent conductive film on a substrate placed above the metal oxide tablet. 2. An arc discharge plasma flow is generated by using a He gas or a gas containing He as a main component as a discharge gas to generate an arc discharge plasma flow, and a sheet-like plasma is formed by applying a magnetic field to transform the arc discharge plasma flow into a sheet shape. Is formed, and the sheet-like plasma is guided onto the metal oxide tablet by a magnetic field generated by an elongated permanent magnet extending in the width direction of the sheet-like plasma to evaporate the metal oxide tablet. An ion plating method comprising forming a transparent conductive film on a placed substrate.