JP4379042B2 - Gas supply member for plasma processing used for formation of vapor deposition film by plasma CVD method, and method for forming vapor deposition film using the gas supply member - Google Patents

Description

  The present invention relates to a plasma processing gas supply member used for forming a vapor deposition film on the inner surface of a container such as a plastic bottle by a plasma CVD method using microwaves, and a vapor deposition film using the gas supply member. The present invention relates to a forming method.

  Chemical vapor deposition (CVD) is a technology that deposits reaction products in the form of a film on the surface of a substrate by vapor phase growth in a high-temperature atmosphere using a source gas that does not react at room temperature. The technology is widely used for surface modification of ceramics and ceramics, and is recently being used for surface modification of containers such as plastic bottles, particularly for improving gas barrier properties.

  Plasma CVD is a method of growing a thin film using plasma. Basically, a gas containing a raw material gas is discharged under a reduced pressure with electric energy by a high electric field, decomposed, and a generated substance is gasified. It consists of a process of depositing on a substrate via a chemical reaction in phase or on the substrate. The plasma state is realized by glow discharge. Depending on the glow discharge method, a method using a direct current glow discharge, a method using a high-frequency glow discharge, a method using a microwave glow discharge, and the like are known. Yes.

  In order to form a deposited film on the inner surface of a container by plasma CVD using microwave glow discharge, the container is held in a plasma processing chamber where microwaves are introduced, and a reactive gas (plasma processing gas) is supplied into the container. A gas supply member is inserted, the inside and outside of the container are evacuated to a predetermined vacuum degree, and a reactive gas is supplied to the inside of the container, while a microwave is introduced into the plasma processing chamber, and a glow discharge is generated inside the container. Although it is a general means to form a vapor deposition film on the inner surface of the container by generating the above, there is a problem that the thickness of the vapor deposition film formed on the inner surface of the container tends to be uneven. In other words, if there is a thin portion of the deposited film, the gas barrier effect due to the deposited film is reduced, so that the deposited film is formed thick overall, but the deposited film is unnecessarily thick. In addition, the productivity is lowered, and the flexibility and flexibility of the film are impaired, and the film is likely to be broken.

As a means for forming a uniform vapor deposition film on the inner surface of the container, it has been proposed to use a metal porous tube as a plasma processing gas supply member (see Patent Document 1).
JP 2003-54532 A

  When the metal porous tube shown in Patent Document 1 is used as the plasma processing gas supply member, the porous material is positioned away from the vicinity of the bottom of the container for electrical compatibility with the microwave. The tip of the tube has to be positioned. For this reason, supply of gas to the bottom of the container becomes insufficient, and there is a problem that it is difficult to form a vapor deposition film having a sufficient thickness on the bottom of the container. In addition, for an axially symmetric container with a circular planar cross-sectional shape of the barrel part, the thickness of the deposited film can be ensured in the circumferential direction of the trunk part, but the uniformity of the axial thickness is still sufficient. In addition, there is a problem that the thickness unevenness of the deposited film in the circumferential direction of the trunk portion is large in a container having an axially asymmetric shape such as a rectangular cross-sectional shape of the trunk portion.

  Accordingly, an object of the present invention is to provide a plasma processing gas supply member capable of forming a vapor deposition film having a uniform thickness over the entire inner surface of the container by plasma CVD using microwaves, and vapor deposition using the gas supply member. It is to provide a method for forming a film.

  Another object of the present invention is to form a vapor-deposited film having a sufficient thickness on the bottom of the container. Further, a vapor-deposited film having a uniform thickness can be applied to a container having an axially asymmetric shape such as a rectangular cross section of the trunk. It is an object of the present invention to provide a plasma processing gas supply member capable of forming a film, and a method for forming a deposited film using the gas supply member.

According to the present invention, a gas supply pipe is provided for supplying a reactive gas for forming a plasma CVD film on the inner surface of a container, which is inserted into a container held in a plasma processing chamber into which microwaves are introduced. In the plasma processing gas supply member,
The gas supply pipe is divided into two regions: a field strength distribution stabilization region and a tip gas induction region located on the tip side with respect to the field strength distribution stabilization region,
In the electric field intensity distribution stabilization region, at least a metal portion that is connected to a shield wall that constitutes the plasma processing chamber and extends from the base portion to the boundary with the tip gas induction region in the axial direction is formed. With
The tip gas induction region is formed of a non-metallic material, and a plasma processing gas supply member is provided.

  According to the present invention, the plasma processing gas supply member is further inserted into the container held in the plasma processing chamber from the gas supply member insertion port into the processing chamber through the mouth of the container. By supplying a reactive gas, a method for forming a plasma CVD film on the inner surface of the container is provided.

In the gas supply pipe for plasma processing in the present invention,
1. The gas supply pipe includes a porous metal pipe and a non-metallic tubular tip joined to the tip thereof, and the porous metal pipe forms the electric field strength distribution stabilization region, and A metal tubular tip forming the tip gas guiding region;
2. The gas supply pipe is a non-metallic porous pipe as a whole, and is a metal that is connected to the shield wall constituting the plasma processing chamber and extends axially from the root portion in the non-metallic porous pipe. A rod made of metal, and the gas supply pipe is divided into two regions, an electric field strength distribution stabilization region and a tip gas induction region, by the metal rod;
3. The non-metallic material is ceramic or fluororesin;
4). The axial length of the tip gas induction region is shorter than λ / 2 when the wavelength of the microwave is λ,
Is preferred.

In the method for forming a vapor deposition film using the plasma processing gas supply pipe,
1. In a state where the gas supply member is inserted into the container, the gas supply member insertion port is sealed with a microwave confinement member, and from the microwave confinement member to the boundary between the electric field intensity distribution stabilization region and the tip gas induction region Is set to (nλ / 2) ± 10 mm (n is an integer of 1 or more) with respect to the wavelength λ of the microwave,
2. The tip of the gas supply pipe is located at a distance of 1 to 40 mm from the bottom of the container;
3. The container is a plastic bottle;
4). The plastic bottle has a body having a plane section that is symmetrical with respect to the center axis of the bottle, or that the body has a plane section that is asymmetric with respect to the center axis of the bottle.
Is preferred.

  In the present invention, the electric field intensity distribution stabilization region and the gas supply member for supplying a reactive gas (plasma gas for plasma processing) into a container held in the plasma processing chamber during chemical plasma processing using microwaves. It is an important feature to use a gas supply pipe that is divided into two regions, a tip gas induction region located on the tip side of the electric field intensity distribution stabilization region.

  In other words, in the electric field intensity distribution stabilization region, at least a metal portion that conducts to the shield wall constituting the plasma processing chamber is formed over the entire axial direction. That is, the metal portion extends from the base portion of the gas supply pipe to the boundary with the tip gas induction region. Therefore, in the simplest embodiment, the gas supply pipe in this region is composed of a metal porous pipe. The electric field intensity distribution stabilization region where such a metal part is formed should be set so that its length has a fixed relationship with the half wavelength (λ / 2) of the microwave used for plasma processing. Thus, the plasma processing region (inside the container) can be made an excellent resonance system, and the electric field strength in the plasma processing region can be stabilized and the electric field strength distribution along the container axial direction to be processed can be stabilized. . Therefore, by forming such a region, the reactive gas (plasma gas for plasma processing) supplied from the gas supply pipe to the inside of the container can be converted into plasma efficiently and uniformly, and the uniform thickness can be obtained. This is advantageous for film formation.

  However, the above-mentioned electric field intensity distribution region brings about the advantages as described above by setting the length so as to satisfy a certain relationship with respect to the half wavelength (λ / 2) of the microwave. . Therefore, when the gas supply pipe is formed only from the above-described electric field intensity distribution stabilization region, the length cannot be adjusted arbitrarily, so that the position of the tip portion is inevitably separated from the bottom of the container. As a result, the gas supply to the bottom of the container becomes insufficient, and it becomes difficult to form a vapor deposition film (CVD film) having a sufficient thickness. However, in the present invention, by forming a tip gas induction region whose tube wall is made of a non-metallic material on the tip side of the electric field strength distribution stabilizing region, the bottom of the container can be sufficiently obtained without affecting the electric field strength distribution. As a result, a CVD film having a uniform thickness can be formed on the inner surface of the container including the bottom. Such an effect of the present invention is clearly shown in FIG. 5 showing experimental results in Examples and Comparative Examples described later.

  In addition, in the present invention, not only for a container (see FIG. 4A) in which the cross-sectional shape of the body portion is an axisymmetric shape such as a circle, the cross-sectional shape of the body portion is rectangular. The container having an axially asymmetric shape (see FIG. 4B) also has an unexpected advantage that a CVD film having a uniform thickness can be formed.

  Normally, the gas supply member (gas supply pipe) is inserted along the container axis, but in a container having an axially asymmetric body section, the distance between the inner surface of the container body wall and the gas supply member is uniform. Therefore, there is a problem that the thickness of the formed CVD film varies depending on the circumferential position of the inner surface of the body wall. That is, on the inner surface of the body portion, there are a portion having a small gap and a large portion with respect to the gas supply pipe. This is because it tends to be thinner. However, in the present invention, the thickness unevenness in the circumferential direction in such an axially asymmetric container is effectively suppressed by using a gas supply pipe in which a predetermined tip gas induction region is formed at the tip of the electric field intensity distribution stabilization region. be able to. Such an unexpected advantage of the present invention is clearly shown in FIG. 6 showing experimental results in Examples and Comparative Examples described later.

In the present invention, it has been experimentally confirmed that the uneven thickness in the circumferential direction in the axially asymmetric container can be effectively suppressed, but the theoretical reason is not clearly elucidated, but the reason is probably The present inventors presume that this is as follows.
That is, conventionally, the tip position of the gas supply member is limited by a function of the half-wavelength of the microwave in order to stabilize the electric field strength, and a large gap is generated between the bottom of the container. However, in the present invention, since the predetermined tip gas induction region is formed at the tip portion of the gas supply member (gas supply tube), the space between the gas supply tube and the container bottom is narrowed by that amount. Yes. As a result, the reactive gas blown to the surface of the bottom of the container circulates in the circumferential direction, and the circulated gas flows particularly into a portion where the gap between the gas supply pipe and the body wall is large. As a result, the axially asymmetric container It seems that uneven thickness in the circumferential direction is effectively suppressed.

  As described above, according to the present invention, a vapor deposition film having a sufficient thickness can be formed on the bottom of the container by a plasma CVD method using microwaves, and the planar shape of the body portion is either axially symmetric or axially asymmetric. With respect to the container having the same, it becomes possible to form a deposited film having a uniform thickness over the entire inner surface thereof.

[Plasma processing gas supply member]
In FIG. 1 showing a typical example of a plasma processing gas supply member of the present invention, this gas supply member comprises a gas supply pipe 2 joined to the tip of a hollow cylindrical support shaft 1 by welding or the like. That is, a structure in which a predetermined reactive gas (plasma processing gas) is supplied to the inside of the gas supply pipe 2 through the hollow portion of the support shaft 1 and the gas is blown out from the pipe wall portion and the tip portion. The reactive gas is supplied to the plasma processing region (inside the container 50) by being inserted into the container 50 held in the plasma processing apparatus of FIG. 3 to be described later.

  In the present invention, the gas supply pipe 2 is divided into two regions, ie, an electric field intensity distribution stabilization region A and a distal gas induction region B located on the distal end side of the region A.

  In the example of FIG. 1, the electric field strength distribution stabilization region A of the gas supply pipe 2 is formed from a metal porous pipe 2 a, and gas is blown out to the surroundings through the pipe wall to While supplying gas to the inside, the plasma processing region (inside the container 50) is made an excellent resonance system, the electric field strength in the plasma processing region (inside the container 50) is increased, and along the axial direction of the container 50 to be processed. Has the effect of stabilizing the electric field strength distribution. Therefore, in this region A, the gas supply pipe 2 is required to be made of metal at the same time as being a porous pipe in order to supply gas to the surroundings. For example, if the tube wall is made of a non-metallic material, the electric field strength adjusting function as described above cannot be expressed. Further, in order to develop the electric field strength adjusting function as described above, the metal porous tube 2a constituting the electric field strength distribution adjusting region A is electrically connected to the shield wall constituting the plasma processing chamber, and The length in the axial direction is set so as to have a fixed relationship with the half wavelength (λ / 2) of the microwave used for the plasma processing (this will be described later). Accordingly, the axial length of the metal porous tube 2a (the axial length of the electric field intensity distribution stabilization region A) cannot be generally defined, but generally, taking a 500 ml plastic bottle as an example, , About 170 to 190 mm.

  In the present invention, the metal porous tube 2a may be formed of any porous metal as long as the above electric characteristics can be ensured. However, in general, from the viewpoint of formability and the like, it is bronze. It is preferably formed from a powder or a stainless steel powder.

  Further, the metal porous tube 2a generally has an opening such that the nominal filtration accuracy is not more than 300 μm, particularly in the range of 2 to 150 μm, in order to uniformly supply the gas through the tube wall. It is preferable. The nominal filtration accuracy is one of characteristic values used when a porous material is used as a filter. For example, the nominal filtration accuracy of 130 μm is the above-mentioned particle size when this porous material is used for a filter. This means that a foreign substance having a diameter can be captured.

  Moreover, although said metal porous pipe | tube 2a may have a fixed opening as a whole, it is also possible to distribute an opening along the axial direction. That is, when performing plasma processing using microwaves, the electric field strength is distributed along the axial direction of the gas supply member (or container). For example, the half-wavelength (λ / 2) of the microwaves is approximately one period, and the electric field strength. However, the tip portion of the metal porous tube 2a tends to be a singular point of electric field concentration and tends to be a thick film. Therefore, in such a case, the thickness of the deposited film formed along the axial direction can be made more uniform, for example, by reducing the opening of the portion.

  The metal porous tube 2a as described above is formed by, for example, forming a ring having a predetermined opening and sintering, and then joining and integrating them by welding or a screw structure. What is necessary is just to join also to the cylindrical support shaft 1 by welding, a screw structure, or the like.

  In the example of FIG. 1, the cylindrical support shaft 1 may be formed of various metal materials as long as it can be electrically connected to the shield wall constituting the plasma processing chamber. It is preferable that the same type of metal as the porous metal constituting the material pipe 2a.

The tip gas guiding region B is composed of a non-metallic pipe 2b formed from an electrically insulating non-metallic material. That is, this region B is formed in order to blow the gas to the bottom of the container without adversely affecting the electrolytic intensity distribution stabilized by the region A. Therefore, the non-metallic pipe 2b may have a mesh opening like the metallic porous pipe 2a, but the leading end of the non-metallic pipe 2b communicates with the inside of the metallic porous pipe 2a. And as long as the through-hole which penetrates to the front-end | tip of this nonmetallic pipe | tube 2b is formed, the thing in which the opening is not formed in the pipe wall may be sufficient.
For example, the embodiment of FIG. 1 (a) is an example in which openings are not formed in the tube wall of the non-metallic pipe 2b. In this case, the through-hole 2c leading to the inside of the metallic porous pipe 2a is a pipe. It penetrates the tip of 2b. 1B is an example in which openings are formed in the tube wall of the non-metallic tube 2b. In this case, the tip of the through hole 2c is closed by the tube wall. Since the openings are formed in the wall, there is no problem in blowing out the reactive gas.

  Examples of the non-metallic material forming the non-metallic pipe 2b include various types of electrically insulating resins and ceramics. From the viewpoint of heat resistance, strength, cost, etc., ceramics such as fluororesin and alumina are used. Is preferred. Such a non-metallic pipe 2b can be molded by a known method such as an injection molding method, an extrusion molding method, a compression molding method, a firing method, a cutting method, etc., depending on the type of material constituting the tube. It joins to the front-end | tip of the metal porous pipe | tube 2a mentioned above using a structure and a suitable adhesive agent if needed.

  The axial length of the non-metallic pipe 2b is determined according to the axial length of the metallic porous pipe 2a and the axial length of the container in which the CVD film is to be formed. In general, it is in the range of less than a half wavelength (λ / 2) of the microwave. That is, the distance between the tip of the metal porous tube 2a and the bottom of the container is usually less than λ / 2. The axial length of the non-metallic pipe 2b is preferably set so that the distance from the container bottom is about 1 to 40 mm. That is, if this interval is larger than the above range, the thickness of the CVD film formed on the bottom of the container tends to be insufficient, and if closer than the above range, compared to the center of the bottom, This is because the thickness of the surrounding CVD film tends to be insufficient.

  The gas supply member of the present invention is not limited to the example of FIG. 1, and may have a structure shown in FIG. 2, for example. That is, in the gas supply member of FIG. 1, the metal portion forming the electric field intensity distribution stabilization region A is formed by the tube wall. In FIG. 2, the metal portion is a member that is completely different from the tube wall. It is greatly different in that it is formed by.

  That is, in FIG. 2A and FIG. 2B showing the II cross section of FIG. 2A, the gas supply member is joined to the tip of the hollow cylindrical support shaft 1. The entire gas supply pipe 2 is formed of a non-metallic porous pipe, and a metal rod 5 (in the example of FIG. 1) defining the electric field intensity distribution stabilization region A is formed inside the supply pipe 2. It has the same electric field strength distribution adjustment function as the metal porous tube 2a).

  That is, the metal rod 5 extends from the base portion of the non-metallic gas supply pipe 2, and the region where the metal rod 5 is provided becomes the electric field intensity distribution stabilization region A. The region ahead of the tip of the metal rod 5 (the region where the metal rod 5 is not provided) is the tip gas guiding region B.

  In this example, the non-metallic gas supply pipe 2 is entirely formed of a non-metallic material (for example, a resin such as a fluororesin or a ceramic such as alumina) similar to the non-metallic pipe 2b of FIG. The electric field intensity distribution stabilization region A has an opening similar to that of the metal porous tube 2a shown in FIG. That is, no opening may be formed in the tip gas guiding region B, and the axial lengths of the electric field intensity distribution stabilizing region A and the tip gas guiding region B are as described with reference to FIG.

  Further, since the metal rod 5 forms the electric field intensity distribution stabilization region A, in the apparatus shown in FIG. 3, it is necessary to be electrically connected to the shield wall constituting the plasma processing chamber. . Therefore, in the example of FIG. 2, the hollow cylindrical support shaft 1 is made of metal, and the metal rod 5 and the shield wall constituting the plasma processing chamber are connected through the metal cylindrical support shaft 1. It is necessary to plan.

  For this reason, the tip portion of the metallic cylindrical support shaft 1 is provided with a rod support portion 1a so as not to impair the communication between the internal passage of the support shaft 1 and the non-metallic gas supply pipe 2. The metal rod 5 is supported on 1a (see especially FIG.2 (b)). The metal rod may be formed of any metal material, but is preferably formed of the same metal material as that of the metal porous tube 2b described above from the viewpoint of oxidation resistance and the like.

[Plasma processing apparatus and method]
The gas supply member described above is used to form a CVD film on the inner surface of a container, particularly a plastic bottle, by microwave plasma treatment. FIG. 3 shows the structure of an apparatus that suitably performs such plasma processing. In FIG. 3, the gas supply member is shown as an example using the structure shown in FIG. 1 for convenience of explanation.

  In FIG. 3, a plasma processing chamber generally indicated by 10 includes an annular base 12, a cylindrical chamber 14 attached to the annular base 12 with pins or the like, and a canopy 16 that closes the upper portion of the chamber 14. It consists of and. These members are all made of a metal material for confinement of microwaves.

  An annular metal bottle holder 18 is also provided in the inner hollow portion of the annular base 12, and the opening of the plastic container 50 is held by the bottle holder 18, and the container 50 is inverted in the chamber 14. Held in a state. Further, an exhaust pipe 22 for holding the inside of the bottle 50 at a reduced pressure is connected to the inner hollow portion of the base 12 and the microwave is confined in the vicinity of the upper end of the mouth of the bottle 50 held in an inverted state. A shield 24 is provided.

  Further, the base 12 is provided with an exhaust pipe 26 for keeping the inside of the chamber 14 (inside the processing chamber 10) at a reduced pressure. The exhaust pipe 26 is also provided with a shield 27 for confining microwaves.

  In the apparatus described above, the chamber 14 is usually cylindrical, and the container 50 is disposed on the axial center of the chamber 14 in order to form a good CVD film.

  The gas supply member 30 including the gas supply pipe 2 having the structure shown in FIG. 1, for example, is provided in the container 50 held in the chamber 14 by the above apparatus from the inner hollow portion of the annular base 12. It is inserted through the mouth. That is, the metal porous tube 2 a of the gas supply tube 2 provided in the gas supply member 30 is electrically connected to the shield wall constituting the chamber 14 through the tubular base 12. The base portion of the metal porous tube 2a is located in the neck portion of the container 50 so that the reactive gas is supplied to the entire body portion of the container 50 as evenly as possible.

  On the other hand, a microwave transmission member 32 such as a waveguide or a coaxial cable is connected to the chamber 14, and microwaves are introduced into the plasma processing chamber 10 from a predetermined microwave oscillator via the microwave transmission member 32. It has come to be. Further, the canopy 16 is provided with an air supply pipe 34 for introducing outside air into the chamber 14 as necessary.

  In addition, the container 50 may have an axially symmetric shape such as a circular shape shown in FIG. 4A or an axially asymmetric shape such as a rectangular shape shown in FIG. In any case, the gas supply member 30 is inserted so that the gas supply pipe 2 is on the container axis in order to form a good resonance system. In the present invention, a uniform CVD film having a small variation in the thickness in the circumferential direction can be formed on the inner surface of the body portion, particularly with respect to the axially asymmetrical container as shown in FIG.

  In the present invention, the gas supply pipe 2 provided in the gas supply member 30 forms an excellent resonance system along the axial direction during plasma processing by microwave supply, and increases the electric field strength and along the axial direction. In order to stabilize the electric field strength distribution, the length L from the shield 24 to the boundary between the electric field strength distribution stabilizing region A and the tip gas guiding region B (corresponding to the tip of the metal porous tube 2a) is The length of the electric field intensity distribution stabilization region A, that is, the metal porous tube 2a, is (nλ / 2) ± 10 mm (n is an integer of 1 or more) with respect to the wavelength λ of the microwave. The length is set. Further, in order to form a CVD film having a uniform thickness even with respect to a container having an axially asymmetric shape as shown in FIG. The axial length of the tip gas guiding region B is preferably set so that the distance between the tip of 2 and the bottom of the container is 1 to 40 mm.

  In plasma processing, first, the inside of the container 50 is maintained in a vacuum state by exhausting from the exhaust pipe 22 by driving a vacuum pump. At this time, in order to prevent deformation of the container 50 due to the external pressure, the inside of the chamber 14 (plasma processing chamber 10) outside the bottle is also decompressed by the exhaust pipe 26.

  The degree of decompression in the container 50 is high so that glow gas is generated when processing gas is introduced from the gas supply pipe 30 and microwaves are introduced. On the other hand, the degree of decompression in the chamber 14 (outside the bottle 20) is such that no glow discharge occurs even when microwaves are introduced.

  After reaching this reduced pressure state, a processing gas is introduced into the container 50 by the gas supply pipe 30 of the present invention described above, a microwave is introduced into the plasma processing chamber 10 through the microwave transmission member 32, and glow discharge is performed. Generate plasma. The electron temperature in this plasma is tens of thousands of K, the temperature of gas particles is about two orders of magnitude higher than that of several hundred K, and is in a thermally non-equilibrium state, compared to a low-temperature plastic substrate. However, plasma treatment can be performed effectively.

  After performing the predetermined plasma treatment, the introduction of the processing gas and the introduction of the microwave are stopped, and cooling air is gradually introduced through the air supply pipe 34 and other gas introduction holes to bring the inside and outside of the container to normal pressure. After returning, the plasma-treated container is taken out of the plasma processing chamber 10.

[Container to be processed]
In the present invention, various plastic containers can be cited as containers for forming the plasma treatment film.

  Examples of the plastic include thermoplastic resins known per se, such as low density polyethylene, high density polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene, or ethylene, pyropyrene, 1-butene, 4-methyl-1 -Random or block copolymers such as pentene and other random or block copolymers, ethylene / vinyl acetate copolymers, ethylene / vinyl alcohol copolymers, ethylene / vinyl chloride copolymers and other ethylene / vinyl compound copolymers Styrene resin such as polymer, polystyrene, acrylonitrile / styrene copolymer, ABS, α-methylstyrene / styrene copolymer, polyvinyl chloride, polyvinylidene chloride, vinyl chloride / vinylidene chloride copolymer, polymethyl acrylate, Polyvinyl chloride such as polymethyl methacrylate Nyl compounds, polyamides such as nylon 6, nylon 6-6, nylon 6-10, nylon 11 and nylon 12, thermoplastic polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, polycarbonate, polyphenylene oxide and the like Any of the resins may be used.

  The shape of the container may be in the form of a bottle, a cup, a tube, etc., but the gas supply pipe described above is most suitable for forming a treatment film on the bottle, and the barrel shape is particularly as shown in FIG. It is a great advantage of the present invention that a CVD film having a uniform thickness can be formed not only in an axially symmetric shape (for example, a circular shape) but also in an axially asymmetric shape as shown in FIG.

[Processing gas]
As the processing gas supplied from the gas supply pipe 30, various gases known per se are used according to the purpose of the plasma processing.

  For example, in order to modify the surface of a plastic substrate, carbon dioxide gas is used to introduce a cross-linked structure on the surface of the plastic substrate, or fluorine gas is used to form the same characteristics as polytetrafluoroethylene on the surface of the plastic substrate. Adhesion, low coefficient of friction, heat resistance, chemical resistance can be imparted.

  For chemical vapor deposition (CVD), it is preferable to use a compound in which a compound containing atoms, molecules or ions constituting a thin film is put in a gas phase and placed on an appropriate carrier gas.

  The raw material compound must be highly volatile, and hydrocarbons such as methane, ethane, ethylene, and acetylene are used to form the carbon film and the carbide film. For forming the silicon film, silicon tetrachloride, silane, an organic silane compound, an organic siloxane compound, or the like is used. Halides (chlorides) such as titanium, zirconium, tin, aluminum, yttrium, molybdenum, tungsten, gallium, tantalum, niobium, iron, nickel, chromium, and boron, and organometallic compounds are used.

  Further, oxygen gas is used for forming the oxide film, and nitrogen gas or ammonia gas is used for forming the nitride film.

  These source gases can be used in appropriate combination of two or more kinds depending on the chemical composition of the thin film to be formed.

  On the other hand, argon, neon, helium, xenon, hydrogen and the like are suitable as the carrier gas.

[Processing conditions]
In the present invention, the processing chamber for performing plasma processing (in the example of FIG. 3, the inside of the container 50 held in the processing chamber 10) should be maintained at a vacuum level at which glow discharge occurs. In view of the efficiency of the plasma treatment, the microwave discharge may be performed while maintaining the pressure within the range of 1 to 500 Pa, particularly preferably 5 to 200 Pa.

  The amount of raw material gas introduced varies depending on the surface area of the substrate to be treated and the type of raw material gas. For example, in the surface treatment of a plastic container, it is converted into the gas volume in a standard state per container. It is desirable to supply at a flow rate of 1 to 500 cc / min, particularly 2 to 200 cc / min.

  When thin film formation is performed by reaction of a plurality of source gases, one source gas can be supplied excessively. For example, in the case of forming a silicon oxide film, it is preferable to supply an excess of oxygen gas compared to the silicon source gas, and in the case of forming a nitride, an excess of nitrogen or ammonia is supplied compared to the metal source gas. can do.

  As the microwave that generates glow discharge, it is preferable to use a microwave whose frequency is allowed to be used industrially 2.45 GHz, 5.8 GHz, 22.125 GHz.

  The microwave output varies depending on the surface area of the substrate to be processed and the type of the raw material gas. For example, in the surface treatment of a plastic container, the power of 50 to 1500 W, particularly 100 to 1000 W, per container. It is desirable to supply as follows.

  The plasma treatment time also varies depending on the surface area of the substrate to be treated, the thickness of the thin film to be formed, the type of the raw material gas, and the like. One second or more is necessary from the viewpoint of the stability of the plasma processing, and a reduction in the time is required from the viewpoint of cost.

  When the plasma treatment is performed using the gas supply pipe in the present invention, as already described, for example, the thickness displacement width on the inner surface of the container is extremely small, and a treatment film having a uniform thickness can be formed.

  The following examples further illustrate the invention, but the invention is in no way limited to the following examples.

(Common conditions)
The experiment of each example was conducted under the following common conditions.
● Treatment substrate The cross-sectional shape has an aspect ratio of 1: 1.3 (see FIG. 6).
Polyethylene terephthalate biaxially stretched rectangular bottle ● Raw material gas for processing Organosilicon compound gas: 2 sccm
Oxygen: 20 sccm
● Degree of vacuum Inside the bottle: 20 Pa, Outside the bottle: 7000 Pa
● Microwave 2. Oscillates with 45GHz microwave power supply
Processed for 10 seconds after plasma ignition with 500W output ● Supporting part of gas supply member: Stainless steel tubing
(Length 35 mm: included in the length of part A in Table 1)

(Evaluation of film thickness distribution)
The film thickness distribution in the height direction (FIG. 5) is obtained by measuring the amount of Si in the film at each measurement site cut out from the vapor deposition sample with a fluorescent X-ray apparatus manufactured by Rigaku Corporation and converting it from the calibration curve to the film thickness. The value at each height is the average value in the four circumferential directions) and the difference between the average film thickness in the 0 & 180 ° direction and the average film thickness in the 90 & 270 ° direction (FIG. 6, height position 60 mm).

(Experimental example)
With respect to the structure and length of the gas supply member, experiments were performed under combinations of conditions shown in Table 1. As Comparative Example 1, a gas supply member in which the entire gas supply pipe was formed of a metal porous pipe was used.

(Result-1)
From Table 1 and FIG. 5, in the experimental conditions (Examples 1 to 3) satisfying the claims of the present invention, the bottle bottom became thick due to the arrival of the raw material gas to the bottle bottom, and at the same time the comparative example It was confirmed that the thick film thickness in the vicinity of 40 to 100 mm seen in 1 was improved, and the film thickness difference (maximum value−minimum value) in the height direction was reduced. The reason why the thick film of the body portion seen in Comparative Example 1 was improved by providing the tip gas induction region is that a part of a constant supply amount of the source gas was guided to the bottom portion, This is thought to be because the flow rate balance of the body has improved.

(Result-2)
From Table 1 and FIG. 6, the film thickness difference between the long side portion (0 & 180 ° direction) and the short side portion (90 & 270 ° direction) is large under the condition of Comparative Example 1 without the tip gas induction region. It was confirmed that this was improved under the experimental conditions (Examples 1 to 3) satisfying the claims.

The sectional side view which shows the typical structure of the gas supply member of this invention. The figure which shows the other example of the gas supply member of this invention. The figure which shows schematic structure of the apparatus which performs a plasma process using the gas supply member of this invention. The figure which shows the example of the plane cross-sectional shape of the container trunk | drum to which this invention is applied. The figure which shows experiment result -1 (film thickness distribution of a bottle height direction) The figure which shows experimental result-2 (film thickness difference of the bottle circumferential direction)

Explanation of symbols

1: hollow cylindrical support shaft 2: gas supply pipe 2a: metallic porous pipe 2b: non-metallic tubular section 5: metallic rod A: electric field strength distribution stabilization area B: tip gas induction area

Claims (11)

A gas supply member for plasma processing, which is inserted into a container held in a plasma processing chamber into which microwaves are introduced and includes a gas supply pipe for supplying a reactive gas for forming a plasma CVD film on the inner surface of the container In
The gas supply pipe is divided into two regions: a field strength distribution stabilization region and a tip gas induction region located on the tip side with respect to the field strength distribution stabilization region,
In the electric field intensity distribution stabilization region, at least a metal portion that is connected to a shield wall that constitutes the plasma processing chamber and extends from the base portion to the boundary with the tip gas induction region in the axial direction is formed. With
The gas supply member for plasma processing, wherein the tip gas induction region is formed of a non-metallic material.   The gas supply pipe includes a porous metal pipe and a non-metallic tubular tip joined to the tip thereof, and the porous metal pipe forms the electric field strength distribution stabilization region, and The gas supply member for plasma processing according to claim 1, wherein a metal tubular tip portion forms the tip gas guiding region.   The gas supply pipe is a non-metallic porous pipe as a whole, and is a metal that is connected to the shield wall constituting the plasma processing chamber and extends axially from the root portion in the non-metallic porous pipe. 2. The plasma processing gas according to claim 1, wherein a rod made of metal is extended, and the gas supply pipe is divided into two regions, a field strength distribution stabilization region and a tip gas induction region, by the metal rod. Supply member.   The gas supply member for plasma processing according to any one of claims 1 to 3, wherein the non-metallic material is ceramic or fluororesin.   5. The plasma processing gas supply member according to claim 1, wherein an axial length of the tip gas guiding region is shorter than λ / 2 when a wavelength of a microwave is λ.   The gas supply member for plasma processing according to any one of claims 1 to 5 is placed inside a container held in the plasma processing chamber from a gas supply member insertion port into the processing chamber via an opening of the container. A method of forming a plasma CVD film on the inner surface of a container by inserting and supplying a reactive gas.   In a state where the gas supply member is inserted into the container, the gas supply member insertion port is sealed with a microwave confinement member, and from the microwave confinement member to the boundary between the electric field intensity distribution stabilization region and the tip gas induction region The length of is set to (nλ / 2) ± 10 mm (n is an integer of 1 or more) with respect to the wavelength λ of the microwave.   The method according to claim 6 or 7, wherein a distal end portion of the gas supply pipe is located at a distance of 1 to 40 mm from a bottom portion of the container.   The method according to claim 6 or 7, wherein the container is a plastic bottle.   The method according to claim 9, wherein the plastic bottle has a body having a plane cross section symmetrical with respect to a central axis of the bottle.   The method according to claim 9, wherein the plastic bottle has a body having a planar cross section that is asymmetric with respect to the central axis of the bottle.

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