JPH06158331A - Coating film forming device - Google Patents

Abstract

PURPOSE:To make the deposition rate high and the residual internal stress low while keeping the film thickness and quality uniform by decreasing the distance between a couple of electrodes to a specified value and making the area of an anode larger than that of a cathode. CONSTITUTION:In a parallel flat sheet plasma CVD device, gaseous hydrogen is introduced at 200 sccm, and a high-frequency power is supplied by 200 W. At this time, a higher self-bias voltage is obtained as the distance 9 between a feeder electrode 3 and a grounded electrode 8 decreases and the reaction pressure lowers. Meanwhile, the distance 9 is decreased to 5-10mm, and a plasma region 10 having a high-brightness emission is locally formed close to the opening of the grounded electrode 8 for supplying the raw gas in the high-reaction pressure region. An electric field is concentrated in this way on the hole part and projecting, acicular and recessed parts, and the deposition rate is remarkably improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming apparatus for forming a film on a substrate at high speed and uniformly.

[0002]

2. Description of the Related Art As a well-known film forming apparatus, there is a parallel plate type plasma vapor phase reaction apparatus using a high frequency of 13.56 MHz. This equipment has a system for exhausting gas, a system for supplying gas (raw material gas), a system for measuring pressure, a system for controlling pressure to a desired value, and a system for heating a substrate, which can be maintained in a depressurized state. Along with the above, a high frequency power supply (13.56 MHz) system is arranged in parallel with a flat plate-shaped power supply electrode (cathode electrode) connected through a matching unit and the flat plate-shaped power supply electrode connected to the ground potential. It has a counter electrode (anode electrode).

When a film is formed using such an apparatus, a substrate is usually placed on the side of the ground electrode at the time of deposition to cause a plasma gas phase reaction to deposit a desired film.
In addition, when forming a specific type of film or a film having a specific performance, for example, when forming a hard carbon-based film, the substrate may be placed on the high frequency power supply electrode side.

When a carbon-based coating having a hardness similar to diamond is formed on the coating-forming surface, molecules, atoms, positive / negative ions, electrons in plasma are generated in the vicinity of the high frequency power supply electrode provided with the substrate having the surface to be formed. Accelerated positive ions are generated by the electric field generated between the self-bias generated by the accumulation of electrons in the high-frequency power supply electrode due to the difference in mobility, mass, etc. It can be made to collide with the carbon-based coating film being formed, and it is formed by reducing the proportion of carbon having a double bond such as C═C and increasing the proportion of carbon having a C—C bond.

Alternatively, by reducing the number of hydrogen atoms bonded to carbon atoms, sp ² hybrid orbitals, so-called trigonal carbons and sp hybrid orbitals, so-called digonal carbons are eliminated as much as possible, and sp ³ hybrid orbitals are provided. That is, it forms a carbon-based coating having a hardness similar to that of diamond, in which the proportion of so-called tetragonal carbon is dominant.

Therefore, in order to obtain a carbon-based coating having a higher hardness, how to increase the above-mentioned self-bias is an important issue, and the method is to set the reaction pressure to a low pressure region. Increasing the high frequency power supply is widely and generally used as a simple method. However, these methods are counter measures against both the rapid deposition which the present invention is trying to solve and the low residual internal stress in the film after the film formation.

[0007]

In forming a carbon-based coating film utilizing a plasma gas phase reaction, the deposition rate is low,
Furthermore, the high residual internal stress of the film is an obstacle to industrial application. For example, with respect to the deposition rate, it is possible to obtain several μm / min or more if the film quality is ignored, but the plasma processing parameters are optimized and the film quality is taken into consideration. m
Achieving a film formation speed of about in is the limit in terms of equipment and hardware. Furthermore, when the raw material gas used is changed, only about a 1.5 times improvement in the film forming rate can be expected.

A simplified cross-sectional view of a conventional device is shown in FIG.
As shown in FIG. 1, in the conventional device, the interval 9 between the opposing electrodes is as wide as 20 to 50 mm. This interval is adopted in consideration of problems in manufacturing the device, stability of discharge, uniformity of the coating within the effective treatment area, and the like. Therefore, in order to improve the deposition rate when such a device is used, the high frequency power supply is increased, or a film is formed by a gas phase reaction in a high reaction pressure range. However, in order to increase the high-frequency power to be supplied, the output from the power source cannot be efficiently used as the power for discharging with a normal wiring path, electrode structure, etc., and there is considerable power loss. In addition, even if a large amount of power is supplied, the etching action is more dominant than the film formation action in a specific condition region, and on the contrary, the phenomenon that the deposition rate on the substrate is reduced appears.

Further, the residual internal stress of the film has a trade-off relationship with the hardening of the film. That is, when the film is hardened, the residual stress of the film increases. Since it is industrially expected to apply a hard film, if the film hardness is prioritized and the film is formed, there is no problem in applying a thin film, but a film thickness of several μm is required. For these, the residual internal stress becomes a major obstacle in the process of thickening the film, causing problems such as film peeling, peeling and long-term adhesion, and a technique for forming a film with low residual internal stress has been desired.

Under these problems, a hardened carbon-based coating is currently obtained by applying a high-frequency power in a low pressure region. However, in terms of deposition rate and residual internal stress of the film, There are problems such as low speed and high residual internal stress.

[0011]

DISCLOSURE OF THE INVENTION The present invention is to solve the above problems at the same time, that is, to achieve high-speed deposition, low residual internal stress, and to satisfy the uniformity of film thickness and film quality. . The point of the technique of the present invention is to realize a high self-bias voltage in a high reaction pressure region.

[First Invention] A coating film forming apparatus having a reaction container capable of holding a reduced pressure state and a pair of opposing electrodes, wherein the pair of electrodes have an interval of 10 mm or less. The film forming apparatus is characterized in that the electrode area on the anode side (ground side) is larger than that on the cathode side (power supply side) of the electrode.

[Second Invention] The film forming apparatus according to claim 1, wherein the anode electrode has a hollow structure, and a linear elongated gas outlet is provided on the electrode surface. Forming device

[Third invention] The coating film forming apparatus according to claim 1, wherein the anode electrode has a hollow structure, and a plurality of gas outlets are provided in a substantially linear shape on the electrode surface. Film forming device.

[Fourth Invention] A coating film forming apparatus having a reaction container capable of holding a reduced pressure state and a pair of opposing electrodes, wherein the pair of electrodes have an interval of 10 mm or less. A film forming apparatus characterized in that a linear local high-intensity light-emitting plasma discharge region generated by the electrode of (1) and a substrate to be processed are relatively moved to form a film.

[0016]

In other words, in order to achieve the above point, the distance between the discharge electrodes is made narrower than usual, so that the self-bias electric field due to the plasma is generated more strongly. The nonuniformity of the film forming process caused by the narrow electrode spacing is generated in a dot-like or linear high-density high-intensity plasma region, and the substrate to be processed is moved relative to the plasma region. This makes the plasma treatment of a large area uniform. In order to obtain these findings,
The present inventors have accomplished the present invention by conducting the following experiments.

In the parallel plate type plasma CVD apparatus as shown in FIG. 2, hydrogen gas was first introduced in an amount of 200 SCCM, and high frequency power of 200 W was applied. At this time,
The distance between the pair of electrodes facing each other is 5, 10, 15, 25 mm
FIG. 3 shows the result of summarizing the relationship between the reaction pressure at that time and the self-bias voltage between the electrodes facing each other.

As is apparent from FIG. 3, it has been found that the narrower the electrode spacing 9 is, or the lower the reaction pressure is, the higher the self-bias voltage can be obtained. Further, in the high reaction pressure region where the electrode interval 9 is as narrow as 5 and 10 mm, the plasma region 10 having locally high-intensity emission near the opening for supplying the source gas of the ground electrode (anode electrode).
Was found to be formed.

Then, when ethylene gas was introduced at a flow rate of 200 SCCM and an attempt was made to deposit a carbon-based coating, a large film thickness distribution difference was found in the coating deposited on the surface to be formed due to the shape of the reactive gas supply opening of the ground electrode 8. Was found to occur. If this raw material supply part is a hole (at this time the diameter is 1 mm
It has been found that φ) is obviously thicker than the other regions, as shown in FIG. 4A.

A high frequency power of 5 is applied to such a reaction system.
When 00 W was charged and a coating film was deposited at a reaction pressure of 100 Pa, the reaction time was 1 minute, and the shaded portion in FIG.
A thick film could be formed. Incidentally, the area other than the shaded area had an average thickness of 0.2 to 0.4 μm. When the existence of the loading effect was confirmed by changing the deposition conditions, it was within a negligible range. The Vickers hardness of the formed film was measured to be 3000 to 4000.
kg / mm ² was obtained. In addition, there was no particular problem with the adhesion between the formed film and the substrate, and it was possible to realize a film with little internal stress without peeling or film peeling.

Next, the shape of the raw material supply portion of the ground side electrode is changed to 1
When the deposition was attempted with a slit (linear) having a width of mm and a length of 15 cm, it was as shown in FIG. 4B, and it was confirmed that the hatched portion 20 was deposited 5 to 10 times thicker than other regions. did it.

From such experimental facts, the discharge electrode interval is 1
When it is set to 0 mm or less, the bias voltage with respect to the substrate can be increased, and particularly preferably when it is set to 5 mm or less, at this time, a bias voltage that is more than twice as large as that in the case of the conventional spacing can be realized. Can be set wider.

Further, it is expected that this local high-intensity discharge region is caused in a portion where electric field concentration occurs between the electrodes facing each other. This electric field concentration occurs in a portion where a hole is provided as described above, a protruding portion, or the like. Therefore, the shape of the gas supply portion can be convex, needle-shaped, or concave.

Therefore, it is also possible to make the anode (ground side) electrode a rod-shaped hollow tube and supply a reactive gas from a hole provided in this hollow tube to generate a locally high-intensity plasma. However, in this case, since self-bias due to plasma discharge must be generated, it is necessary to set the reaction container itself to the ground potential in addition to the ground electrode.

Further, this local high-intensity plasma region does not have to be in one place, and may be in a plurality of places. In particular, it was more effective to have a plurality of locations when forming a film on a large-area substrate.

Furthermore, in order to increase the rate of film formation, it is usually common to increase the reaction pressure. However, in the conventional case, as is clear from FIG. 3, when the pressure at the time of reaction is increased, the amount of self-bias voltage due to plasma discharge tends to decrease, and the coating film formed by this has no denseness and hardness. It could not be performed because it tends to result in a low film. However,
When the electrode interval is set to 10 mm or less, a much larger bias can be obtained than in the conventional case, so that a sufficient bias voltage can be obtained even if the reaction pressure is increased.
This enables high-speed film formation.

[0027]

【Example】

[Example 1] From the experimental facts relating to FIG. 2 described above, a differential exhaust type roll-to-roll system (deposition up type) device as shown in FIG. 5 was prototyped. Known techniques were used for the differential exhaust system and the roll-to-roll transfer method. In the present invention, the roll-shaped film substrate 2 is 50
While passing (sending) at a speed of m, three sheet-like plasma regions 10 were provided, and a film was deposited on the substrate to a thickness of 200Å.

The merit of this embodiment is that the hollow ground electrode 8 of the raw material gas supply unit has a double structure inside, the carbon supply gas is made to flow by the gas supply system 6 in the vicinity of the center, and other parts are provided in the surroundings. By devising such that the hydrogen gas flows through the gas supply system 13, the film substrate 2 starting from the charging chamber 11 is first exposed to the environment where hydrogen plasma is dominant near the end of the discharge electrode. As a result, the surface of the substrate is appropriately cleaned by hydrogen radicals or hydrogen ions, and a clean surface appears.

Next, when the film is guided to the deposition region and a desired film thickness is deposited, the film deposited immediately before entering the extraction chamber 12 is exposed again to the environment where hydrogen plasma is dominant near the end of the discharge electrode. Be done. This time, the film is further densified by being bombarded with appropriate hydrogen ions,
It is characterized in that a high quality film is formed and guided to the extraction chamber 12.

In order to confirm the effect of this hydrogen treatment, a confirmation experiment was conducted to form a film under the same conditions without introducing hydrogen, and the adhesion of the film was worse than that of the hydrogen treatment. There was found.

Further, in the present embodiment, the region where the plasma discharge is locally concentrated is linearly extended over the width of the substrate so that it is perpendicular to the moving direction of the roll-shaped substrate 2. ing. By moving the substrate relative to this plasma region in this manner, it is possible to form a large-area coating film, and if the uniformity of plasma in this linear direction can be ensured, it will be possible to obtain a uniform coating even in a large area. It is possible to realize film formation.

Of course, instead of moving the substrate,
The same effect can be expected by moving the electrode, and the same effect can be expected by moving the region of local discharge within the electrode surface.

[Embodiment 2] FIG. 6 is a schematic view of a known technique, in which an in-line type plasma CVD apparatus or a sputtering apparatus is partially replaced with the technique according to the present invention and modified. Generally known plasma CVD
Alternatively, the sputtering apparatus has a simple structure because the film forming substrate is arranged on the side of the ground electrode, but the carbon-based film according to the present invention is deposited on the side of the high frequency power supply electrode 3, so that the carrying method and the high frequency power supply method are used. Etc. had to be specially devised.

The high-frequency power supply electrode 3 also serves as a substrate holder, and the rails, racks, cloaks, pinions, etc. of the transfer system are all made of an insulating material so that they are galvanically isolated and have a floating structure. Indirect coupling by vacuum gap for high frequency power supply 1
Power is supplied from a power source 5 via 4. In this embodiment,
12 3.5-inch magnetic disks on one side and 24 on both sides
An attempt was made to arrange a single sheet and deposit a hard carbon-based coating with a thickness of 200Å, and it was confirmed that there is no particular problem in increasing the size and treating a large area.

As described above, by narrowing the electrode interval, a high self-bias can be obtained even in a high reaction pressure region, so that the formed film is dense and a film having high hardness can be easily manufactured. done. Furthermore, since the space between the electrodes is narrow, the volume of the plasma discharge space can be reduced, so that the vacuum container itself can be made thin, and a large-area coating surface can be processed with a low volume. The film formation area is not a plasma area that spreads across the entire area between conventional electrodes,
This is a plasma region locally generated in the vicinity of the opening for supplying the source gas of the ground electrode and having high-intensity light emission.

[0036]

By narrowing the electrode spacing, the self-bias necessary for obtaining a hard carbon-based coating can be easily obtained even in a high reaction pressure region. The deposition rate has been dramatically improved by making it possible to effectively utilize the high-intensity luminous plasma region locally in a higher reaction pressure region by forming a film.

Conventionally, in the range where the film quality is not sacrificed, it is 0.
Although the limit was to obtain 2 to 0.3 μm / min, according to the present invention, a value higher by one digit or more was easily obtained. At the same time, it was also found that the residual internal stress can be reduced by about one digit. As described above, the carbon-based coating film coated by the apparatus of the present invention has excellent wear resistance, high smoothness, high hardness, etc. in order to protect the surface of a recording medium such as a magnetic tape, a magnetic disk, or an optical disk. I had one.

[Brief description of drawings]

FIG. 1 is a partial conceptual diagram of a conventional device.

FIG. 2 is a partial schematic view of a film forming apparatus according to the present invention.

FIG. 3 is a graph showing the relationship between pressure and self-bias when the electrode spacing is changed in the above device.

FIG. 4 shows a film thickness distribution when a film is formed on a Si wafer substrate in the above apparatus.

FIG. 5 is a partial conceptual diagram of a differential exhaust type roll-to-roll system (deposition up) for substrates such as films.

FIG. 6 is a partial conceptual diagram of the in-line side deposition method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Reaction container 2 ... Processed substrate 3 ... Power supply electrode (cathode) 5 ... Power supply 6 ... Reactive gas supply system 7 ... Exhaust system 8 ... Ground side electrode (anode ) 9 ... Electrode spacing 10 ... Local plasma region 11 ... Preparation chamber 12 ... Ejection chamber 13 ... Gas supply means

Claims (4)

[Claims] 1. A film forming apparatus comprising a reaction vessel capable of holding a reduced pressure state, and a pair of opposing electrodes, wherein the pair of electrodes have an interval of 10 mm or less, and among the pair of electrodes. A film forming apparatus having a larger electrode area on the anode side (ground side) than on the cathode side (power supply side). 2. The film forming apparatus according to claim 1, wherein
A film forming apparatus, wherein the anode electrode has a hollow structure, and a linear elongated gas outlet is provided on the electrode surface. 3. The film forming apparatus according to claim 1, wherein
A film forming apparatus, wherein the anode electrode has a hollow structure, and a plurality of gas outlets are provided on the electrode surface in a substantially linear shape. 4. A film forming apparatus comprising a reaction vessel capable of holding a reduced pressure state and a pair of opposing electrodes, wherein the pair of electrodes have an interval of 10 mm or less, and the pair of electrodes generate the electrodes. A film forming apparatus, wherein the linear or dot-shaped local plasma discharge region and the substrate to be processed are relatively moved to form a film.