JP2017222906A - Method for depositing film by high frequency plasma cvd - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for depositing a film by high frequency plasma CVD using capacitive coupling plasma, having a speedy film deposition rate and capable of forming a dense film on the surface of a base material.SOLUTION: In the method for depositing a film by high frequency plasma CVD, capable of depositing a film on the surface of a film-like base material held on a power supply electrode or a counter electrode by plasma generated by applying a high frequency voltage to the power supply electrode while supplying a raw material gas to a space between the power supply electrode and the counter electrode and holding a pressure reduced between the electrodes, the supply pipe of the raw material gas is extended to a plasma emission region between the electrodes and blows the raw material gas in the plasma emission region to form a film.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for forming a film on a substrate by a chemical vapor deposition method (CVD method) using high-frequency plasma.

  Chemical vapor deposition (CVD) is a technology that deposits reaction products on the surface of a substrate by vapor phase growth in a high-temperature atmosphere using a source gas (reaction gas) that does not react at room temperature. It is widely used for the production of metal and surface modification of metals and ceramics, but recently it is also being used for surface modification of plastic moldings.

  As a film forming technique using CVD, a thermal CVD method in which a reaction gas is decomposed and reacted by thermal energy is widely known. However, since the thermal CVD method involves deformation due to heat, the heat resistance of a plastic molded body or the like. It is difficult to form a film on a substrate having a low density. For this reason, various plasma CVD methods using a plasma reaction capable of forming a film at a low temperature have been proposed as film forming means on the surface of a plastic molded body.

  The plasma CVD method is a method in which a thin film is grown using plasma. Basically, a gas containing a source gas is discharged under a reduced pressure with electric energy by a high electric field, decomposed, and a substance to be generated is generated. It consists of a process of depositing on a substrate through a chemical reaction in the gas phase or on the substrate. The plasma state is realized by glow discharge. For example, high-frequency plasma CVD in which film formation is performed by generating plasma derived from a source gas by high-frequency glow discharge can form an insulating thin film. Are most commonly used industrially (see, for example, Patent Documents 1 and 2).

  However, the conventional film formation method using high-frequency plasma CVD tends to cause film defects and lacks film density. For example, when a gas barrier film is formed on a substrate such as a plastic film, the film deposition method is high. The barrier property cannot be obtained, and its improvement is demanded.

  In order to form a dense film without defects, for example, there is a method of blowing a source gas toward a substrate using a source gas blowing device shaped like a shower head (see Patent Document 3). . However, the denseness of the film obtained by this method is still inadequate, and the film forming speed is also slow, so that establishment of a better film forming method has been demanded.

  In Patent Document 4, as a high-frequency plasma CVD film forming apparatus for avoiding film defects, a plurality of upper nozzles for ejecting a rare gas and a plurality of lower nozzles for ejecting a source gas are provided in a vacuum chamber. There is disclosed a film forming apparatus in which a nozzle is positioned immediately above a base material and a plurality of nozzle holes are provided in a portion facing the base material. According to this apparatus, oxygen introduced into the upper part of the chamber first becomes oxygen plasma to generate active oxygen, and this active oxygen reacts with dichlorosilane in the lower part of the chamber to form a precursor, and the precursor adheres to the wafer. Thus, a film is formed on the substrate. However, the high-frequency plasma CVD apparatus of Patent Document 4 is based on inductively coupled plasma instead of capacitively coupled plasma, that is, a gas is turned into a plasma by applying a high voltage, and a vortex is generated inside the plasma by a high-frequency magnetic field. This is based on a mechanism that generates Joule heat due to electric current, and may not be applicable to film formation of a plastic substrate having poor heat resistance. Furthermore, although the apparatus of Patent Document 4 is for forming a uniform film on the surface of a base material, it has been studied at all about the formation of a dense film without defects by suppressing the formation of a SiOH structure or the like. There wasn't.

  In addition, the present inventors previously related to a capacitively coupled high-frequency plasma CVD film forming method, wherein a base material is positioned on a power supply electrode, and a gas outlet is disposed in the vicinity of the power supply electrode to supply a source gas. Then, the film defects were effectively suppressed by performing film formation, and a patent application was filed for this film formation method (Patent Document 5). However, there is room for improvement with respect to the film formation rate.

JP 2008-189964 A JP 2009-97061 A JP2012-151278 JP 20029065 JP 2014-177688 A

  Accordingly, an object of the present invention is to provide a high-frequency plasma CVD film forming method using capacitively coupled plasma, which forms a dense film having a high film forming speed and no defects on a substrate surface.

  According to the present invention, by supplying a raw material gas between the electrodes between the power supply electrode and the counter electrode (earth electrode), and applying a high frequency voltage to the power supply electrode while maintaining a reduced pressure between the electrodes. In a high-frequency plasma CVD film forming method for forming a film on the surface of the film-like substrate held on the power supply electrode or the counter electrode by the generated plasma, the source gas supply tube is placed in the plasma emission region between the electrodes. There is provided a high-frequency plasma CVD film forming method characterized in that the film is formed by blowing and blowing the source gas in the plasma emission region.

In the high frequency plasma CVD film forming method of the present invention,
(1) The source gas supply pipe extends to an intermediate portion between the electrodes,
(2) blowing out the source gas toward the electrode opposite to the electrode on which the film-like substrate is held;
(3) Exhaust is performed from a position closer to the electrode on the opposite side than the electrode on which the film-like substrate is held,
(4) The tip of the source gas supply pipe has an annular nozzle part, and
(5) holding the film-like substrate on the feeding electrode;
Is preferred.

  In this specification, the plasma emission region means a region where plasma emission occurs when a high-frequency voltage is applied to the power supply electrode and the source gas is blown out from the source gas supply pipe. The area | region except the area | region (non-light-emission area | region) where a sheath generate | occur | produces near each electrode (base material) among these spaces is meant.

The high-frequency plasma CVD film forming method of the present invention forms a dense film having no defects and is excellent in productivity because the film forming speed is high. For example, a gas barrier film is formed on the surface of a plastic substrate. Is suitable.
That is, using a mixed gas of a gas such as an organosilicon compound and oxygen gas as a raw material gas, a metal such as a silicon oxide film (SiOx film, 1 <x <2) on the surface of a plastic substrate (PET film) In the case of forming an oxide film, as shown in a comparative example described later, when a film is formed by providing a showerhead-shaped source gas blowing nozzle on the electrode side on which the base material is not held, the formation is performed. The film speed is slow, and more OH groups are present in the metal oxide film. On the other hand, as shown in the examples described later, according to the present invention, when the source gas supply pipe is extended inside the plasma emission region between the electrodes, that is, when the source gas is blown out in the plasma emission region, the film is formed. It can be seen that the speed is remarkably higher than that of the comparative example (conventional), and further, the amount of OH groups in the film is suppressed, and a dense film without defects is formed.

Although the reason why a dense film having no defect can be formed in a short time by the film forming method of the present invention has not been clarified accurately, the present inventors have estimated as follows.
That is, conventionally, when a film is formed by capacitively coupled high-frequency plasma CVD, a substrate is held on a power supply electrode, and a voltage is applied to the power supply electrode to generate an electric field between the electrodes. A method has been employed in which a raw material gas is blown out from a raw material gas outlet provided on the outside toward the substrate. However, in the plasma emission region, the input source gas is decomposed by plasma, and ions and radicals are generated one after another. That is, the plasma emission region has more particles flying in the space than the surroundings, and it has a relatively positive pressure, and the gas injected into the vacuum is likely to diffuse to the low pressure side, so it is supplied from outside the plasma emission region. The raw material gas was easily diffused to other regions where the atmospheric pressure was low while avoiding the plasma light emitting region where the atmospheric pressure was high.
However, according to the film forming method of the present invention, since the source gas is supplied inside the plasma emission region, the supplied gas can be decomposed into ions and radicals necessary for forming the film with a high probability. That is, the supplied source gas is efficiently decomposed before diffusing out of the plasma emission region, so that the film formation rate can be increased. In addition, the film is quickly formed on the surface of the base material, and the supplied source gas is highly activated from beginning to end, so that OH group contamination (for example, formation of SiOH structure) in the film is effectively suppressed. As a result, a dense film without defects is formed.

In the present invention, as shown in the examples described later, the source gas is blown out from the source gas supply pipe extending into the plasma emission region toward the electrode on which the substrate is not held. Is preferred. According to this aspect, it has been found that the film forming speed is further increased and further excellent film quality can be obtained. In addition, it has been found that the thermal load on the substrate during film formation can be reduced.
The reason why the above-mentioned effect can be obtained by blowing the raw material gas toward the electrode on which the film-like substrate is not held is estimated as follows.
That is, the gas is blown from the nozzle with a velocity vector in the blowing direction and diffused in the plasma, but when blown parallel to the substrate surface, it has a velocity vector parallel to the substrate surface. Spread. That is, since the gas is blown out with a velocity vector to the outside of the plasma region, the gas is likely to diffuse out of the plasma region. When blown out perpendicularly to the substrate surface, the blowout is carried out without having a velocity vector outside the plasma region, so that diffusion of gas outside the plasma region is suppressed and the film formation rate can be increased. In addition, if blown toward the base material, there is a risk of collision with the base material even if it is unnecessary for film formation. However, if the raw material gas is blown in the direction opposite to the base material surface, Since only the ions and radicals that are sufficiently decomposed and diffused in the vicinity of the base material, the film formation reaction on the base material becomes active, and a film with few OH groups, that is, a dense film without defects is formed. Can do.
Furthermore, it is known that radicals other than ions and electrons exist in the plasma emission region, which contributes to the reaction. Particularly, when an excessive amount of oxygen radicals collide with the substrate, heat is applied to the substrate. Gives a load. Since this radical is electrically neutral, it is not affected by the electric field generated between the electrodes. Therefore, if the source gas is blown vertically toward the counter electrode, the radicals move in the opposite direction to the base material along the gas flow at the time of supply of the source gas. It is possible to reduce the heat load on the base material by moving to another region having a low temperature. In the high-frequency plasma CVD film forming method, since a plastic substrate having poor heat resistance is often used, the effect of reducing the thermal load on the substrate is very advantageous.

The figure which shows an example of schematic structure of the film-forming apparatus used for implementation of the high frequency plasma CVD film-forming method of this invention. The figure which shows the other example of schematic structure of the film-forming apparatus used for implementation of the high frequency plasma CVD film-forming method of this invention. FIG. 2 is a schematic partial enlarged perspective view showing an example of the shape of a nozzle that can be used in the film forming apparatus of FIG. 1 (particularly, a portion A surrounded by a broken line).

  In FIG. 1 showing an example of the schematic structure of an apparatus used for carrying out the film forming method of the present invention, the film forming apparatus denoted by 1 as a whole has a CVD film forming chamber 3. A power supply electrode 7 connected to the high-frequency power source 5 is provided on the ceiling of the film, and a grounded counter electrode (earth electrode) 9 is provided below the film forming chamber 3.

A plasma emission region exists between the feeding electrode 7 and the counter electrode 9. In the film forming method of the present invention, the source gas supply tube 11 extends into the plasma emission region. This is because the source gas can be efficiently converted into plasma by blowing the source gas inside the plasma emission region. The method of disposing the source gas supply pipe 11 in the apparatus is not particularly limited as long as the tip of the source gas supply pipe 11 exists in the plasma emission region. From the viewpoint of maximizing the activation of the source gas, It is preferable that the gas supply pipe 11 is disposed so as to exist in an intermediate portion between the electrodes. If the source gas blowing position is too close to the base material 20 held on the power supply electrode or the counter electrode, the raw material gas before being converted into plasma is sprayed on the base material 20 as it is, and the film formation speed is reduced. This is because if the blowing position of the source gas is too far from the base material, positive ions necessary for film formation may flow out of the plasma emission region before reaching the base material. Specifically, as shown in FIG. 1, the distance between the tip of the feeding electrode 7 surface and the raw material gas supply pipe 11 (outlet 15) and L _1, a raw material gas supply pipe 11 leading end (outlet 15) It is preferable to provide the source gas supply pipe 11 so that L ₁ : L ₂ = 1: 4 to 6: 1 when the distance from the surface of the counter electrode 9 is L ₂ . From the viewpoint of film formation speed, L ₁ : L ₂ = 1: 2 to 2: 1 is more preferable, or from the viewpoint of forming a dense film without defects, L ₁ : L ₂ = 1: 1. 1-6: 1 is more preferable.

  Moreover, it is preferable that the raw material gas supply pipe 11 extends until the tip 15 thereof is located immediately above the central portion of the base material from the viewpoint of improving the uniformity of the film.

Furthermore, the nozzle part 13 can be attached to the source gas supply pipe 11 as necessary. The method of attaching the nozzle 13 is not particularly limited as long as the source gas is blown out in the plasma emission region, but it is based on the viewpoint that the ion component is more reliably kept between the electrodes and the film forming speed is increased, and radicals are excluded. From the viewpoint of reducing the thermal load of the material, it is preferable that the material gas is blown out toward the electrode opposite to the electrode on which the film-like substrate 20 is held (see FIG. 2).
One or a plurality of nozzles 13 can be attached to one source gas supply pipe 11. From the viewpoint of uniformly forming the film, the nozzle 13 is more preferably annular, for example, as shown in FIG. 3, and when a plurality of source gas supply pipes 11 are used, It is preferable that the nozzles 13 provided in the supply pipe are coupled to each other to form an annular shape. One nozzle is provided with one or a plurality of gas outlets 15.

In the high frequency plasma CVD film forming method of the present invention, the film-like substrate 20 to be formed is held on the surface of the feeding electrode 7 or the counter electrode 9. This is because a sheath having a high ion density is formed in the vicinity of the substrate surface. In particular, from the viewpoint of making it difficult to bring radicals and molecules unnecessary for film formation into contact with the base material 20, it is preferable that the base material 20 be held on the feeding electrode 7 in the apparatus of FIG. 1. That is, it is particularly preferable to hold the base material 20 so that gravity works in the direction opposite to the base material 20 depending on the structure of the apparatus.
The film-like substrate 20 can be held on the electrode by appropriate locking means (for example, fixing by fitting, locking by a nail or the like) depending on the form.
Further, when the base material 20 is a long film, when the long film is wound up by the take-up roller from the original roll on which the film is wound, the wound long film passes over the feeding electrode 7. The film can also be formed.

  Furthermore, according to the film forming method of the present invention, in the film forming apparatus 1 having such a structure, it is preferable to exhaust by providing the exhaust port 17 at a position close to the electrode on which the film-like substrate 20 is not held. . As will be described later, the exhaust port 17 is mainly used to depressurize the inside of the CVD film forming chamber 3, but if the air is exhausted near the electrode on which the film-like substrate 20 is held, it is not necessary for film formation. Molecules, radicals, and the like are likely to move toward the base material 20 on the air flow caused by the exhaust, and this may impair the film quality or prevent the heat load on the film from being effectively reduced. is there. Specifically, the position closer to the electrode on which the base material 20 is not held is, as shown in FIGS. 1 and 2, the electrode side holding the base material is upward, and the electrode side not holding is downward. This means that the exhaust port 17 is provided below the tip of the source gas supply nozzle 13 (blower port 15).

When film formation is performed by the above-described apparatus, the film formation chamber 3 is depressurized by exhaust from the gas exhaust port 17, and then the film formation chamber has a degree of vacuum (for example, about 10 ^{2 to 1} Pa) such that glow discharge is generated. 3, while supplying the plasma CVD source gas to the gas supply pipe 11, the source gas is blown out from the gas outlet 15, and a metal mold having a diameter of 300 mm and a height of 450 mm, depending on the volume of the film forming chamber. In the cylinder forming film chamber, when a high frequency voltage is applied to the power supply electrode with a predetermined output (for example, 100 to 1000 W), plasma of the raw material gas is generated, and the reaction product is deposited on the surface of the base material 20 on the power supply electrode 7. Thus, a CVD deposited film is formed.

  When performing CVD film formation using high-frequency plasma as described above, the frequency of the high-frequency voltage applied to the power supply electrode 7 is particularly limited as long as glow discharge occurs in the region between the power supply electrode 7 and the counter electrode 9. Although it is not a thing, it is desirable that it is a high frequency area | region rather than 13.56 MHz generally used, and it is more desirable that it is a VHF area | region of 27.12 MHz or more. That is, as the frequency is higher, the polarity (+, −) of the potential of the feeding electrode 7 changes more drastically, so that collision of ions with the base material 20 is reduced. As a result, film formation is performed at a frequency of 13.56 MHz, for example. Compared with the case where it is performed, the temperature rise of the base material 20 due to film formation can be reduced, and film formation at a lower temperature is possible. This is advantageous in terms of suppressing thermal deformation.

The supply amount of the source gas varies depending on the surface area of the substrate to be treated. For example, when a silicon oxide film (SiOx film, 1 <x <2) is formed using an organic silicon compound gas and an oxygen gas, It is desirable to introduce the organic silicon compound gas into the film formation chamber at 1 to 20 sccm and oxygen gas at 10 to 300 sccm. The supply amount of oxygen gas must be such that the organosilicon compound can be completely oxidized. For example, when hexamethyldisiloxane is used as the organosilicon compound, the supply amount of oxygen gas is relative to the supply amount of hexamethyldisiloxane. Is preferably 15 times or more. In the case where an organic zirconium compound gas and an oxygen gas are used, it is preferable to introduce the organic zirconium compound gas into the film formation chamber at 1 to 10 sccm and oxygen gas at 25 to 300 sccm. The supply amount of the oxygen gas needs to be an amount capable of completely oxidizing the organic zirconium compound. For example, when zirconium tetra-t-butoxide (composition formula; C ₁₆ H ₃₆ O ₄ Zr) is used as the organic zirconium compound, the oxygen gas is used. Is preferably 24 times or more the supply amount of zirconium tetra-t-butoxide.

  In the high frequency plasma CVD film forming method of the present invention, the substrate 20 is held on the power supply electrode 7 or the counter electrode 9, whereby a sheath is formed in the vicinity of the surface of the substrate 20 and the ion density in the vicinity of the surface is increased. . Further, the outlet 15 of the source gas supply pipe is in the plasma emission region between the feeding electrode 7 and the counter electrode 9, that is, since the source gas is blown out in the plasma emission region, the source gas is converted into plasma with high probability. Thus, ions necessary for film formation can be efficiently collided with the film-like substrate 20. Therefore, a dense film having no defects can be formed on the surface of the film-like substrate 20 in a short time.

  According to the above-described high-frequency plasma CVD film forming method of the present invention, since the film forming speed is high, it is possible to form a highly productive and dense film without defects. Therefore, the film forming method of the present invention is used to form a CVD deposited film on various substrate surfaces, to form a thin silicon film, to form a thin film transistor element in a display such as a liquid crystal, and to form an interlayer insulating film for a VLSI. In particular, it is effectively applied to the formation of a gas barrier film on a plastic substrate. According to the present invention, since it is possible to form a dense film having no defects, in which mixing of OH groups in the film is suppressed, such a film can improve the gas barrier property of the plastic substrate. Because.

When the present invention is applied to the formation of a gas barrier film, the plastic constituting the substrate 20 may be formed from a known thermoplastic or thermosetting resin, such as low-density polyethylene, Polyolefin such as random or block copolymer of α-olefins such as density polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene or ethylene, propylene, 1-butene, 4-methyl-1-pentene , Cyclic olefin copolymer, etc., ethylene / vinyl acetate copolymer, ethylene / vinyl alcohol copolymer, ethylene / vinyl compound copolymer such as ethylene / vinyl chloride copolymer, polystyrene, acrylonitrile / styrene copolymer , ABS, α-methylstyrene / styrene copolymer, etc. Tylene resin, polyvinyl chloride, polyvinylidene chloride, vinyl chloride / vinylidene chloride copolymer, polyvinyl compounds such as polymethyl acrylate, polymethyl methacrylate, nylon 6, nylon 6-6, nylon 6-10, nylon 11 , Polyamides such as nylon 12, thermoplastic polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate (PEN), polycarbonate, polyphenylene oxide, polyimide resin, polyamideimide resin, polyetherimide resin, fluorine Resin, allyl resin, polyurethane resin, cellulose resin, polysulfone resin, polyethersulfone resin, ketone resin, amino resin, biodegradable resin such as polylactic acid, etc. To, or blends thereof, may be one of these resins are modified by appropriate copolymerization. Moreover, the base material itself may have a multilayer structure made of the above resin.
In particular, in applications where transparency is required, polyester resins such as PET and PEN are suitable among the above, and polycarbonates and polyimide resins are preferable in applications where heat resistance is also required.

  Moreover, the form of the base material 20 is a film from the viewpoint that the advantages of the present invention can be utilized to the maximum, and the thickness thereof is a characteristic required for each application (for example, flexibility, flexibility, Strength etc.).

  As a raw material gas for forming a gas barrier film, those capable of forming a film of an inorganic compound having a high degree of oxidation, for example, an organoaluminum compound such as trialkylaluminum, an organotitanium compound, an organozirconium compound, and an organosilicon compound An organosilicon compound is preferred, and an organosilicon compound is particularly preferred in that the reaction is relatively mild and the film structure can be easily controlled. From the viewpoint of utilizing the characteristics of the present invention, an organic zirconium compound is also suitable. That is, since organic zirconium is a compound that is difficult to vaporize, it tends to be liquefied when blown out from the source gas supply pipe. However, according to the present invention, it is converted into plasma immediately after being blown out. It can be suppressed.

  Examples of organosilicon compounds include hexamethyldisilane, vinyltrimethylsilane, methylsilane, dimethylsilane, trimethylsilane, diethylsilane, propylsilane, phenylsilane, methyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, tetramethoxy Organic silane compounds such as silane, tetraethoxysilane, phenyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, octamethylcyclotetrasiloxane, 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane, etc. And organic siloxane compounds. Besides these, aminosilane, silazane and the like can also be used.

  In addition, the organometallic compound mentioned above can be used individually or in combination of 2 or more types.

  In the present invention, the above-mentioned organometallic compound gas is used as a raw material gas by mixing with an oxidizing gas such as oxygen in an appropriate amount. It is also possible to use an active gas as a carrier gas.

  When the gas barrier film is formed on the plastic base material 20 as described above, for example, the base material 20 is formed by first performing film formation at a low output and then switching to film formation at a high output. It is possible to form a film having a high gas barrier property.

In addition to conventional food and pharmaceutical packaging materials, the plastic substrate 20 on which a gas barrier film is formed in this way is also used in areas where extremely high water vapor barrier properties are required, such as thin film solar cells and organic EL. Applicable.
In the film forming method of the present invention, since the source gas supply pipe is extended to the inside of the plasma emission region, the present invention can be suitably applied to the case where a compound that hardly vaporizes such as a zirconium compound is used as the source gas. This is because according to the film forming method of the present invention, liquefaction after being blown out from the source gas supply pipe is effectively prevented.

The present invention will be described in the following examples, but the present invention is not limited to the following examples in any way.
Various measurements performed in Examples and Comparative Examples were performed as follows.

<Measurement of SiOH / SiO ratio>
The SiOH / SiO ratio represents the quality of the film. The smaller the value, the smaller the number of defects in the film and the denser the film. This is because when the SiOH structure is formed during film formation, the structure is hydrophilic and thus the barrier property against moisture is lowered. The SiOH / SiO ratio is calculated by measuring the film formation surface of the substrate on which the CVD film is formed with a Fourier transform infrared spectrophotometer. As a result of measuring the infrared absorption spectrum by the difference spectrum method, the silicon oxide film has an infrared absorption peak near 930～1060Cm ^-1, the absorption peak height of the SiOH groups in the vicinity of wave number 930 cm ^-1 to (A1) Further, the absorption peak height (A2) of the SiO group near the wave number of 1060 cm ⁻¹ was obtained, and the infrared absorbance ratio (A) of SiOH / SiO was obtained from A1 / A2.

<Measurement of film thickness uniformity>
The amount of Si on the film-forming surface of the substrate on which the CVD film was formed was measured with an X-ray fluorescence spectrometer (ZSX100e, manufactured by Rigaku Corporation), and the SiOx film based on the Si amount of the SiOx film having a known film thickness (100 nm) Converted to thickness. As an index of film thickness uniformity, the film thickness difference between the central part and the edge part of the base material is excellent if it is less than 1%, good if it is less than 2%, acceptable if it is less than 10%, if it is 10% or more Impossible.

<Measurement of water vapor barrier properties>
The water vapor permeability at 40 ° C. and a relative humidity of 90% RH of the formed plastic substrate was measured using a water vapor permeability measuring device (manufactured by Modern Control, PERMATRAN-W 3/30).

For samples having a water vapor transmission rate (less than 0.01 g / m ² · day) that is less than the measurement limit of the water vapor transmission rate measuring device, a water-corrosive metal sample is used based on the method described in JP 2010-110196 A. The amount of moisture permeated into the cell was calculated from the amount of corrosion of the thin film. That is, a 300 nm thick thin film of water-corrosive metal is formed on the film-formed surface of the plastic substrate on which the film has been formed by vacuum deposition using a vacuum deposition apparatus (vacuum deposition apparatus JEE-400 manufactured by JEOL Ltd.). Calcium was formed, and an Al vapor-deposited film (water-impermeable metal thin layer) having a thickness of 350 nm was formed so as to cover the calcium thin film, thereby preparing various sample pieces.
The calcium thin film was formed in six circular portions of 1 mmφ by vacuum vapor deposition using a metallic mask as a vapor deposition source and a predetermined mask. Further, the Al vapor deposition film was formed by removing the above-mentioned mask in a vacuum state and subsequently performing vacuum vapor deposition from an Al vapor deposition source in the apparatus.
The sample piece formed as described above was gas-impermeable cup filled with a hygroscopic agent (silica gel) (made of stainless steel: cup inner diameter; 40 mm, cup inner volume; 9.6 cm ³ , sealing of the cup peripheral end face. A fluororubber O-ring) and fixed with a fixing ring to obtain an evaluation unit.
The evaluation unit thus prepared was held in a thermostatic chamber having an atmosphere adjusted to 40 ° C. and a relative humidity of 90% RH for 500 hours, and then a sample piece was taken out from the evaluation unit and a laser microscope (Carl Zeiss) The corrosion state of the Ca thin film was observed with a laser scanning microscope (LSM 5 PASCAL), the image was binarized to calculate the black spot area, and the water vapor permeability was calculated from the result according to the calculation formula.

<Calculation formula>
From the sunspot area, the number of moles X of the metal hydroxide produced by corrosion is calculated according to the following formula.
X (number of moles)
= [Spot area (cm ² )] × [Thin film thickness (cm)] × [Molecular weight of corrosive metal hydroxide]
From this result, the water vapor permeability can be determined by the following equation.
Water vapor transmission rate (g / m ² · day)
= X · 18 · m · (10000 / A) · (24 / T)
Where X is the number of moles of metal hydroxide produced by the corrosion calculated above,
m is the valence of a water corrosive metal (for example, Ca),
A is the area (cm ² ) of the water-corrosive metal thin film,
T is the holding time (hour) of the evaluation unit in an atmosphere containing water vapor
The

Example 1
High frequency output power source with a frequency of 27.12 MHz and a maximum output of 2 kW, a matching box, a metal cylindrical plasma film forming chamber having a diameter of 300 mm and a height of 450 mm, a source gas supply pipe 11, and an oil rotary vacuum pump that evacuates the film forming chamber The CVD apparatus shown in FIG. The tip of the source gas supply pipe 11 was adjusted to a position such that L ₁ : L ₂ = 1: 1 so as to be located immediately above the center of the substrate. A polyethylene terephthalate (PET) film having a 120 mm square and a thickness of 100 μm was used as the plastic substrate. A plastic substrate is installed on the feeding electrode 7 in the film forming chamber, and while exhausting from the exhaust port 17 with an oil rotary vacuum pump, 3 sccm of hexamethyldisiloxane and 45 sccm of oxygen are used as the source gas from the source gas supply pipe 11. After the introduction, a high frequency was oscillated with an output of 300 W by a high frequency oscillator, and plasma treatment was performed for 50 seconds to coat a silicon oxide film on one surface of the plastic substrate.

(Example 2)
In Example 1, a plastic substrate coated with a silicon oxide film in the same manner as in Example 1 except that the tip position of the source gas supply pipe 11 was adjusted to be L ₁ : L ₂ = 1: 2. Got.

(Example 3)
In Example 1, a plastic substrate coated with a silicon oxide film by the same method as in Example 1 except that the tip position of the source gas supply pipe 11 was adjusted to be L ₁ : L ₂ = 1: 4 Got.

Example 4
In Example 1, a plastic substrate coated with a silicon oxide film in the same manner as in Example 1 except that the tip position of the source gas supply pipe 11 was adjusted to be L ₁ : L ₂ = 2: 1 Got.

(Example 5)
In Example 1, a plastic substrate coated with a silicon oxide film in the same manner as in Example 1 except that the tip position of the source gas supply pipe 11 was adjusted to be L ₁ : L ₂ = 4: 1 Got.

(Example 6)
In Example 1, a plastic substrate coated with a silicon oxide film in the same manner as in Example 1 except that the tip position of the source gas supply pipe 11 was adjusted to be L ₁ : L ₂ = 6: 1 Got.

(Example 7)
In Example 1, the nozzle 13 is attached to the tip of the source gas supply pipe 11 so that the source gas is blown out toward the electrode opposite to the electrode on which the film substrate 20 is held. A plastic substrate coated with a silicon oxide film was obtained in the same manner as described above.

(Example 8)
In Example 1, the nozzle 13 was attached to the tip of the source gas supply pipe 11 so that the source gas was blown out toward the electrode on which the film substrate 20 was held. A plastic substrate coated with an oxide film was obtained.

Example 9
In Example 7, a plastic substrate coated with a silicon oxide film was obtained in the same manner as in Example 7 except that evacuation was performed from a position close to the electrode on which the film substrate was held.

(Example 10)
In Example 7, a plastic substrate coated with a silicon oxide film was obtained in the same manner as in Example 7 except that the nozzle 13 was an annular nozzle as shown in FIG.

(Example 11)
In Example 7, a plastic substrate coated with a zirconium oxide film was obtained in the same manner as in Example 7 except that 3 sccm of zirconium tetra-t-butoxide and 80 sccm of oxygen were introduced as source gases.

(Comparative Example 1)
In Example 1, a plastic substrate coated with a silicon oxide film was obtained in the same manner as in Example 1 except that the tip of the source gas supply pipe 11 was located outside the plasma generation region.

(Comparative Example 2)
In Example 11, a plastic substrate coated with a zirconium oxide film was obtained in the same manner as in Example 11 except that the tip of the source gas supply pipe 11 was located outside the plasma generation region.

(Comparative Example 3)
In Example 1, the raw material gas supply pipe 11 was not used, and a film was formed by providing a showerhead-shaped raw material gas outlet on the electrode side on which the base material was not held. A plastic substrate coated with a zirconium oxide film was obtained.

Table 1 shows the measurement results of the SiOH / SiO ratio, film thickness uniformity, and water vapor barrier properties of the plastic substrates coated with the oxide films obtained in the above Examples and Comparative Examples.
In the examples, all the evaluations showed good results, and in particular, in Example 10, the SiOH / SiO ratio was the smallest, there were few defects, a good quality film, a thick and uniform film, and good water vapor barrier properties. . In the case of the comparative example in which the front end portion of the source gas supply pipe 11 was installed outside the plasma generation region, the film thickness was thin and non-uniform, and the film had a large SiOH / SiO ratio and many defects, indicating a poor water vapor barrier property. .

DESCRIPTION OF SYMBOLS 1: Film-forming apparatus 3: CVD film-forming chamber 5: High frequency power supply 7: Feed electrode 9: Counter electrode 11: Source gas supply pipe 13: Nozzle 15: Air outlet 17: Exhaust port 20: Film-like base material

Claims (6)

By supplying a source gas between the electrodes between the power supply electrode and the counter electrode and maintaining a high pressure between the electrodes while applying a high frequency voltage to the power supply electrode, the power supply electrode or In a high-frequency plasma CVD film forming method for forming a film on the surface of a film-like substrate held on the counter electrode,
A high-frequency plasma CVD film forming method, wherein a film is formed by extending a source gas supply pipe to a plasma light emitting region between the electrodes and blowing the raw material gas in the plasma light emitting region.   The high-frequency plasma CVD film forming method according to claim 1, wherein the source gas supply pipe extends to an intermediate portion between the electrodes.   The high frequency plasma CVD film-forming method of Claim 1 or 2 which blows off the said source gas toward the electrode on the opposite side to the electrode with which the said film-form base material is hold | maintained.   The high frequency plasma CVD film-forming method according to any one of claims 1 to 3, wherein evacuation is performed from a position closer to an electrode on the opposite side than the electrode on which the film-like substrate is held.   The high frequency plasma CVD film-forming method according to any one of claims 1 to 4, wherein a tip portion of the source gas supply pipe has an annular nozzle portion.   The high frequency plasma CVD film-forming method in any one of Claims 1-5 which hold | maintains the said film-form base material on the said electric power feeding electrode.