Continuous film forming apparatus

(54) Title: APPLIANCE FOR CONTINUOUS FILM FORMATION (30) Unionist Priority: 13/02/2007 jp 2007-031585 (73) Holder (s): Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd) (72) Inventor ( es): HiroshiTamagaki (74) Attorney (s): Alexandre Ferreira (86) International Request: pct jP2008050348de 15/01/2008 (87) International Publication: wo 2008 / 099630de 21/08/2008 (57) Summary: apparatus for continuous FILM formation The plasma CVD apparatus of the present invention comprises a pair of deposition cylinders (2 and 3) arranged opposite in parallel so that the substrates (S) wound there are facing each other. other; a magnetic field generator element (12 and 13) provided inside each of the deposition cylinders (2 and 3), which generates a magnetic field to converge plasma to the vicinity of a cylinder's surface facing a space (5 ) between the deposition cylinders; a plasma power supply (14) with alternately inverted polarity between one electrode and the other electrode; a gas supply tube (8) for supplying a film-forming gas in space (5); and evacuation means to evacuate the space. One electrode of the plasma power supply (14) is connected to a deposition cylinder (2), and the other electrode of this to the other deposition cylinder (3).

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PI0806472-5 “APPLIANCE FOR CONTINUOUS FILM FORMATION”

Technical Field

The present invention relates to a plasma CVD apparatus for continuously forming a functional film on a surface of a strip-like substrate, such as a plastic film or sheet.

Background of the Invention

In recent years, several display substrates, which use plastic film or foil as a substrate, have been proposed, and the substrate is required to have water vapor and oxygen barrier properties. To give such barrier properties to the substrate, the substrate is often coated with a transparent SiOx film and, therefore, a productive coating device is desired. Techniques for coating the substrate with SiOx film in the process of conducting the substrate from a cylinder to a cylinder, for example, are known as the physical vapor deposition (PVD) method, such as vacuum evaporation or sputtering, and the plasma CVD method (deposition of chemical vapor enhanced with plasma).

The vacuum evaporation method is used extensively to carry out film formation, mainly for food packaging films, as a production process, but the resulting barrier performance does not meet a required level as a display substrate, with vapor transmission d 'water and oxygen transmission of about 1 g / m²* day and about 1 cc / m²* atm * day. On the other hand, a denser film can be formed by the sputtering method. For example, barrier performances of no more than 0.02 g / m²* day and 0.02 cc / m²* atm * dia, which are detection limits of the MOCON method, can be achieved by forming a 50-100 nm SiOx or SiON film on a substrate in good surface condition. However, the deposition rate is too low to guarantee sufficient productivity. Additionally, since a film formed by the PVD method is inorganic and fragile, the film, when formed in a thickness that exceeds 100 nm, is easily subject to defects or peeling of the film resulting from an internal tension of the film or a difference in the coefficient thermal expansion between the film and the substrate, and additionally resulting from the failure of the film to follow the deformation of the base film.

In contrast, the plasma CVD method is inferior to the vacuum deposition method, but it is superior to an order of magnitude or more in terms of deposition rate over the sputtering method and thus has a possibility that a film with a large barrier can be formed. This method additionally has a feature that a film, as thick as several hundred nm to several pm, that cannot be reached by the PVD method, can be formed in the base film, since a film formed in this way has a certain level of flexibility . Therefore, it is expected that the plasma CVD method will be an unprecedented film formation process that uses these resources.

Various types of film forming apparatus by plasma CVD are conventionally known. As an apparatus adapted to carry out film formation, by winding a film in a deposition cylinder, for example, an apparatus that includes a pair of deposition cylinders for winding and conducting a film, which is a deposition object, is described in the Japanese translation of the international application PCT 2005-504880 (Patent Literature 1), in which a magnetic field is formed to extend between the cylinders, and the pair of deposition cylinders is connected to a high frequency power supply, so that the two deposition cylinders have the same polarity and a high frequency energy of several tens to several hundred kHz is simultaneously supplied to them for cause Penning discharge in a space (discharge area) between the cylinders to confine plasma, and oxygen and a raw material gas, such as HMDSO, they are supplied in the space between the cylinders to consequently carry out the film formation simultaneously with the film in the deposition cylinders on both sides of the discharge area.

In addition, a plasma CVD apparatus is described in Japanese patent 2587507 (Patent Literature 2), and the apparatus comprises a pair of deposition cylinders (metal drums) disposed opposite each other in a vacuum chamber , an AC power source with one electrode connected to one of the deposition cylinders and the other electrode connected to the other deposition cylinder, a discharge chamber arranged in a space between the deposition cylinders with the faces opposite to the deposition cylinders being opened, and a means of supplying monomer gas (raw material) connected to the discharge chamber. According to Patent Literature 2, plasma can be generated in the discharge chamber to effect the formation of film on a film in the deposition cylinders since the interior of the discharge chamber has a reduced degree of vacuum by supplying a monomer gas , compared to the outside, and the contamination of the discharge electrodes can be prevented, since the surfaces of the deposition cylinders that constitute the discharge electrodes are covered with the film conducted there.

However, in the film forming apparatus of Patent Literature 1, because the other electrode of the discharge power supply has to be connected to an annular electrode (counter electrode) provided at a substantially equal distance from the center of the space between deposition cylinders, plasma is also generated at the periphery of the counter electrode, and it is difficult to suppress film deposition perfectly at this periphery. Additionally, changes in discharge associated with deposition of film on the counter electrode and flaking, which are likely to develop defects in the film, are caused during long-term operation.

On the other hand, in the film forming apparatus of Patent Literature 2, although the discharge chamber must be formed in the space between the deposition cylinders, film deposition occurs on the wall of the discharge chamber, and peeling is likely, that occurs from this part, develop defects in the film. Furthermore, to make the interior of the discharge chamber lower in vacuum (or higher in pressure) than the other part of the vacuum chamber, the gas flow must be suppressed by the extreme minimization of clearance between the discharge chamber and the deposition cylinders. However, since the deposition of film also occurs in the vicinity of this gap, the effect of confining the gas in the discharge chamber changes, transmitting the stability of the deposition, and the stability of the quality of the film is consequently reduced.

Patent Literature 1 Japanese translation of the international PCT application 2005504880.

Patent Literature 2 Japanese Patent 2587507

Disclosure of the Invention

From the point of view of such problems, it is an objective of the present invention to provide a plasma CVD device that can reduce the deposition of film inside a vacuum chamber, which causes flaking of the film and adversely affects the stability of the film quality. .

The plasma CVD apparatus according to the present invention for forming a film on a surface of a substrate while continuously conducting the substrate in a vacuum chamber comprises: a pair of deposition cylinders disposed opposite in parallel, or substantially in parallel, in relation to each other, so that the substrates wound on them are facing each other; a magnetic field generator element provided inside each of the deposition cylinders, which generates, in the vicinity of the surface of a cylinder facing a space between the deposition cylinders, a swollen magnetic field from the surface of the cylinder to a surface of the cylinder cylinder on the other side; a plasma power supply with alternately inverted polarity between one electrode and the other electrode; gas supply means for supplying a film-forming gas in the space between the deposition cylinders; and evacuation means for evacuating the space between the deposition cylinders, where one electrode from the plasma power supply is connected to one of the deposition cylinders, and the other electrode is connected to the other of the deposition cylinders.

According to this plasma CVD device, since the magnetic field generating element that generates the magnetic field particularly in the vicinity of the cylinder surfaces facing the space between the deposition cylinders, the magnetic field being swelled from each cylinder surface to the cylinder surface on the other side, and the alternately inverted polarity plasma power supply is provided, the occurrence of electric discharge in the space between the pair of deposition cylinders and the convergence of the plasma generated in this way to the vicinity of the respective surfaces of the deposition cylinder in the space between the deposition cylinders can be achieved without providing a containment to define the space between the deposition cylinders, such as a discharge chamber, or use a discharge electrode other than the deposition cylinders. Therefore, only by supplying the film-forming gas to the gas supply device in the space between the deposition cylinders the film-forming gas is decomposed and activated by the plasma and the decomposed gas is deposited on the surface of the coiled substrate around the deposition cylinders facing the space between the deposition cylinders, according to which, a film can be efficiently formed. Since confinement or discharge electrodes other than deposition cylinders, in which dissociated film-forming gas is adsorbed, are absent, film formation on the substrate can be carried out without film deposition in a part like this, and a high quality film can be formed, still eliminating film defects and deteriorating stability of film formation resulting from film deposition.

Brief Description of Drawings

Figure 1 is an illustrative view of the general scheme of a plasma CVD apparatus according to an embodiment of the present invention;

figure 2 is an enlarged sectional view of the deposition cylinders and the elements generating magnetic field;

figures 3A, 3B and 3C are voltage waveform graphs of a plasma power supply, respectively;

Figure 4 is a general perspective view of an element generating a magnetic field;

figure 5 is an illustrative view of the general scheme of a plasma CVD apparatus according to the other embodiment of the present invention;

figure 6 is an enlarged sectional illustrative view of the deposition cylinders and the magnetic field generating elements showing the other example of a scheme in which the magnetic field generating elements are arranged to form closed magnetic circuits, respectively; and figure 7 is an enlarged sectional illustrative view of the deposition cylinders and the magnetic field generating elements showing an example of a comparative scheme in which the magnetic field generating elements are arranged to form magnetic field lines that extend between the cylinders deposition.

Best Way to Carry Out the Invention

In the plasma CVD apparatus of the present invention, an alternating voltage or pulse type voltage that accompanies the polarity inversion is applied to the position cylinders disposed opposite each other at a reduced pressure to cause the discharge of brightness in a space (deposition zone) between the deposition cylinders disposed in the opposite way, according to which the formation of film by CVD with plasma is carried out on a strip-like substrate wound around the deposition cylinders to face the space between the deposition cylinders. As the substrate, any insulating material that can be taken in a cylinder shape, such as a plastic film or sheet or paper, can be used. Suitable plastic film or foil materials are PET, PEN, PES, polycarbonate, polyolefin, polyimide and the like, and the substrate preferably has a thickness of 5 pm to 0.5 mm that allows conduction in a vacuum. A conductive material can be used as the substrate, depending on the device configuration, as described below.

Figure 1 shows a general configuration of a plasma CVD apparatus according to an embodiment of the present invention, and the apparatus comprises: a vacuum chamber 1; a pair of deposition cylinders 2 and 3 arranged opposite each other in the vacuum chamber 1, so that the respective geometric axes of the cylinder are parallel to each other; a distribution cylinder 4 that holds and distributes a strip-like substrate S taken in a cylinder shape; a plurality of guiding cylinders 6 that drive the substrate S unwound from the distribution cylinder 4, so that the substrate S is wound around the deposition cylinders 2 and 3 which face a space (deposition zone) 5 between a and the other deposition cylinders 2 and 3; a plug cylinder 7 which takes the substrate S after film formation; a film-forming gas supply tube 8 connected to a gas supply device (not shown) and disposed just above the space 5 to be parallel to the cylinder's geometric axes; an evacuation hole 9 opened in the base wall of the vacuum chamber 1; and a vacuum pump 10 connected to the orifice. The film-forming gas supply tube 8 includes a plurality of space-oriented gas ejection nozzles 5, which are supplied in its longitudinal direction, and the evacuation orifice 9 is arranged just below the space 5. The magnetic field generating elements 12 and 13 are provided inside the deposition cylinders 2 and 3, respectively, as shown in figure 2, and a plasma power source 14 is provided to supply a plasma energy in the deposition cylinders 2 and 3. The gas supply device and the film forming gas supply tube 8 constitute the gas supply means of the present invention, and the evacuation port 9 and the vacuum pump 10 constitute the evacuation means of the present invention. ,

As the film-forming gas to be supplied in space 5 from the film-forming gas supply tube 8, raw deposition material gas, reaction gas, conductive gas and discharge gas are used exclusively or together . Examples of the crude deposition gas include HMDSO, TEOS, silane, dimethylsilane, trimethylsilane, tetramethylsilane, HMDS and TMOS to form a film containing Si, methane, ethane, ethylene and acetylene to form a film containing C, and tetrachloride titanium to form a film containing Ti, and an appropriate raw material gas is selected according to the type of film to be formed. As the reaction gas, oxygen, ozone or the like can be used to form an oxide, and nitrogen, ammonia or the like can be used to form a nitride. In this case, too, an appropriate gas is selected according to the type of film to be formed. Like the conductive gas and the exhaust gas, an appropriate gas can be selected from rare gases, such as He, Ar, Ne or Xe and hydrogen.

The space 5 is evacuated by the vacuum pump 10 provided below the space, and is controlled at an appropriate pressure according to the film-forming gas supply from the film-forming gas supply tube 8. It is preferable not to provide a structural element, such as a shielding wall or an electrode, in the vicinity of space 5 to the extent possible in the present invention, since film formation is carried out around space 5, according to what , unnecessary film formation that causes defects in the film can be suppressed. The pressure of space 5 will be described below.

The deposition cylinders 2 and 3 are electrically isolated from the vacuum chamber 1 and additionally electrically isolated from each other. One electrode from the plasma power supply 14 is connected to one deposition cylinder 2 and the other electrode to the other deposition cylinder 3. The plasma power supply 14 transmits a voltage with alternately inverted polarity, the voltage having a waveform, for example, such as the alternating sine wave voltage, as shown in Figure 3A, or a square wave pulse shape, as shown in figures 3B and 3C, and the waveform is slightly distorted by the generation of the discharge during actual operation. Other voltage waveforms can be adopted, as long as they allow the generation of the discharge.

Deposition cylinders 2 and 3 include magnetic field generating elements 12 and 13, which are provided to maintain a fixed positional relationship to space 5, even if the cylinders are rotated. For example, deposition cylinders 2 and 3 can be hollow, and magnetic field generating elements 12 and 13 can be trapped from outside the axial ends of deposition cylinders 2 and 3, thereby fixing their positions relative, and only deposition cylinders 2 and 3 can be rotated in this state. As shown in figures 2 and 4, each of the magnetic field generating elements 12 and 13 includes a central magnet 16 in the length of the axial direction of the cylinder, a circumferential magnet like track 17, and a field short circuit element magnetic 18 that connects these magnets inside the cylinder. The "track type" shape means a shape obtained by arranging a pair of straight lines of the same length in parallel, and by the mutual connection of the end parts on the same side of the pair of straight lines by an outward swollen semicircular arch. , or an athletics track type form (see figure 4).

The magnetic field generating elements 12 and 13 supplied, respectively, in the deposition cylinders 2 and 3 are arranged so that the magnetic poles of the same polarity are opposite to each other. Each of the magnetic field generating elements 12, 13 efficiently guides the lines of the magnetic field that leave the magnetic pole of the central magnet 16 to the magnetic pole of the circumferential magnet 17, and generates an athletic field type R track for magnetron discharge. which has a double peak section and is swelled from the surface of the cylinder to the space 5 in each of the deposition cylinders 2 and 3. Namely, the "R track type magnetic field" means a magnetic field in which the lines of the magnetic field are directed from the central magnet 16 to the circumferential magnet 17, encircling the circumference of the central magnet 16 in an athletic track shape. , and are swollen in the direction of space 5, and the apex of the swollen magnetic field is formed in an athletic track shape along the circumferential magnet 17, viewed from a normal direction relative to a plane on which the center magnet 16 and the circumferential magnet 17 are arranged.

The magnetic field lines formed by the magnetic field generating element 12 provided for a deposition cylinder 2 form substantially closed magnetic circuits, respectively, without extending to the magnetic pole of the magnetic field generating element 13 provided for the opposite deposition cylinder 3 . The state "extending the magnetic field line" means a state in which the magnetic field lines directed from the N pole (pole S) of an opposite magnetic field generating element 12 to the S pole (pole N) of the other magnetic generating element magnetic field 13 are generated. For example, when the other generating element of magnetic field 13 changes so that the central magnetic pole 16 is the pole S and the circumferential magnet 17 is the pole N of figure 2, the magnetic field lines directed from the central magnet (pole N ) 16 from a magnetic field generating element 12 to the central magnet (pole S) 16 of the other magnetic field generating element 13 are generated (see figure 7). This state is the state "extending the magnetic field line".

As described above, the athletic field type R magnetic fields with a double peak section and extending in the axial direction of the cylinder are formed in the vicinity of the cylinder surfaces facing the space 5 between the deposition cylinders 2 and 3, respectively, by the magnetic field generating elements 12 and 13. The shape of this magnetic field is similar to that of a magnetic field formed, for example, by a flat magnetron spray cathode. The magnetic field R works to cause plasma to be generated preferably at the location of the magnetic field and to homogenize the plasma in the longitudinal direction of the cylinders by displacing the plasma or the like. Namely, the plasma generated by the glow discharge is converged in swollen parts of the lines of the magnetic field by the R track type magnetic field, and a P track type plasma is consequently formed in the vicinity of each cylinder surface facing the space 5 between deposition cylinders 2 and 3. Namely, since the apex of the swollen magnetic field in the direction of space 5 is formed in the form of an athletics track, viewed from the normal direction in relation to the plane in which the central magnet 16 and the circumferential magnet 17 are arranged as above. Therefore, the plasma that converges to this apex of the swollen magnetic field (the swollen parts of the lines in the magnetic field) is formed to converge into an athletic track shape, viewed from the normal direction.

The distance between the two deposition cylinders 2 and 3 can be appropriately adjusted by the relationship with the size of the magnetic field generating elements 12 and 13 and with the intensity of the magnetic field, so that the plasma can be trapped.

When alternating voltage at high frequency or pulse type is applied from the plasma power supply 14 in the deposition cylinders 2 and 3, still supplying the film-forming gas in the space 5 between the deposition cylinders 2 and 3 under the magnetic field R and adjusting and maintaining space 5, which constitutes the deposition zone, at an appropriate pressure, the discharge of brightness occurs between the deposition cylinders 2 and 3 through the space 5 and the substrate S coiled around the surface of the deposition cylinders 2 and 3 to thereby form the plasma P. In this way, if the gas film formation is supplied in space 5, the crude material gas is decomposed by plasma in space 5 and a film is formed on the substrate by the plasma CVD process.

Although the plasma current cannot be conducted by applying DC voltage, since the substrate S used in the present invention is an insulating material, the current can be propagated through the insulating substrate S with an appropriate frequency (about 1 kHz or more, preferably 10 kHz or more). The discharge voltage supplied from the plasma power supply 14 is preferably about several hundred to 2 thousand V, as the peak value. Since deposition cylinders 2 and 3 are connected to both electrodes of the plasma power supply 14, which transmit alternating voltage at high frequency or pulse type, respectively, so that a positive voltage is applied to the other deposition cylinder 3 when a negative voltage is applied to a deposition cylinder 2, the current is conducted from the other deposition cylinder 3 to a deposition cylinder 2. And this phenomenon continues as long as it reverses the polarity at high frequency.

Since the magnetic field R that facilitates the discharge of brightness is present only on the surface side of the cylinder facing space 5, although the voltage of the plasma power supply 14 is applied to the entire surface of the deposition cylinders 2 and 3, the discharge of brightness can be caused around the area where the magnetic field is present if the pressure is in the range of about 0.1 Pa to 10 Pa. Therefore, there is no need to provide a discharge chamber in such a way that it confines space 5. When the pressure is below about 0.1 Pa, discharge in the area where the magnetic field is present becomes difficult, and when the pressure exceeds about 10 Pa, the discharge outside the magnetic field area becomes significant, causing undesirable film formation in a part of the deposition cylinders where no substrate is wound.

In the plasma CVD apparatus according to the aforementioned modality, a film is formed on the substrate S supported on the cylinder surfaces facing the space 5 between the deposition cylinders 2 and 3, still placing and conducting the substrate S on the two cylinders deposition 2 and 3. The formation of film on substrate S is accomplished by the decomposition of the film-forming gas supplied in space 5 by the track-type plasma P formed by the track-type magnetic field R formed in the vicinity of the cylinder surfaces by the elements generating the magnetic field 12 and 13 and by the discharge of brightness caused in the space 5 between the deposition cylinders 2 and 3 connected, respectively, in the respective electrodes of the plasma power supply 14, and by depositing the decomposed gas on the substrate S supported on the surfaces of the deposition cylinders 2 and 3 facing space 5, according to which, a film is formed on the surface of the substrate S continuously guided.

Since the discharge of brightness occurs only in areas where there is a magnetic field in the vicinity of the surfaces of deposition cylinders 2 and 3, without the need for an electrode involved in the generation of plasma other than deposition cylinders 2 and 3 or an element of shielding that confines space 5, such as a discharge chamber, the formation of film by CVD with plasma is substantially caused only on the substrate located on the surface of the deposition cylinders 2 and 3. Since the substrate S, which is a deposition object, is wound around deposition cylinders 2 and 3 and is regularly conducted, stable discharge can be carried out over a long period without the generation of a thick film at a location involved in the plasma generation in this device. Harmful splinters are hardly generated during film formation. Additionally, since the plasma generation mechanism consists of only the two deposition cylinders 2 and 3, the plasma generation mechanism can consist of a minimum number of cylinders.

Although a substrate S is wound on two deposition cylinders 2 and 3 and conducted in the aforementioned embodiment, the route of conduction of the substrate is never limited in this way. Distribution cylinders 4 and plug cylinders 7 can be supplied for deposition cylinders 2 and 3, respectively, as shown in figure 5, and substrates S can be wound to be separately supported on the cylinder surfaces facing the space 5 between deposition cylinders 2 and 3. In cases, such as a metal film composed of a metal with low electrical resistance, the device configuration shown in figure 5 is preferred, since the current is conducted through the film to destabilize the discharge when the electrical resistance of the film is low . A conductive material, such as metal, can also be used as the substrate S in the device configuration shown in figure 5. The film formation can be carried out even on the conductive substrate S in the device configuration shown in figure 5, although the application of tension between the deposition cylinders 2 and 3 is necessary.

In the aforementioned modality, the magnetic field type R track for magnetron discharge with a sectional shape with double apex and swelling from the surfaces of the cylinder in the direction of the space between the cylinders is generated in each of the deposition cylinders 2 and 3 by the arrangement of the magnetic poles in the magnetic field generating elements 12 and 13 supplied in the deposition cylinders 2 and 3 arranged in the opposite way, so that the magnetic poles of the same polarity are opposite to each other. However, magnetic poles of the same polarity do not always have to be arranged in the opposite way. In figure 6, in which the magnetic field generating element 12 of one deposition cylinder 2 and the magnetic field generating element 13 of the other deposition cylinder are arranged so that the central magnet 16 and the circumferential magnet 17, with opposite polarities one in relation to the other, they are opposite in relation to the other, the generation of the magnetic field lines that extend between the deposition cylinders 2 and 3 can be prevented by the arrangement of the magnetic field generating elements 12 and 13, still mutually displacing their circumferential positions, and the plasma can be converged to the neighborhoods of the cylinder surfaces facing the space 5 between the deposition cylinders 2 and 3. In this case, when the magnetic field generating elements 12 and 13 are arranged in the opposite way without positional displacement, the lines of the magnetic field that extend between the deposition cylinders 2 and 3, and which connect directly to the different electrode on the opposite side, they are formed as shown in figure 7, and the athletic field-type magnetic field to cause the magnetron discharge is weakened. Although discharge by the Penning effect can be expected, when many lines of magnetic field that connect each other in the cylinders are present, by applying a voltage of the same polarity to the two deposition cylinders, it is preferable to prevent the formation of magnetic field lines in such a way that they extend between the deposition cylinders 2 and 3 up to the limit possible in the present invention in which the discharge of brightness is caused by the application of tension between the two deposition cylinders 2 and 3.

Additionally, although deposition cylinders 2 and 3 are horizontally juxtaposed, and the gas supply means (film-forming gas supply tube) and the evacuation means are arranged above and below the space between the deposition cylinders, respectively, in the aforementioned modality, the layout of the deposition cylinders and the like is never limited to this. For example, the deposition cylinders can be arranged vertically, with the gas supply means and the evacuation means being provided on one side and on the other side of the space between the deposition cylinders, respectively. In short, it is only necessary to supply the gas on one side of the space between the deposition and discharge cylinders on the other side. Certainly, in the aforementioned modality, it is more preferable to arrange these means vertically, as shown in figure 2.

The present invention described above can be summarized as follows.

Namely, the plasma CVD apparatus according to the present invention to form a film on a substrate surface while continuously conducting the substrate in a vacuum chamber comprises: a pair of deposition cylinders disposed in parallel in parallel , or substantially in parallel, with respect to each other, so that the substrates wound there are facing each other; a magnetic field generator element provided inside each of the deposition cylinders, which generates, in the vicinity of the surface of a cylinder facing a space between the deposition cylinders, a swollen magnetic field from the surface of the cylinder to the surface of the cylinder cylinder on the other side; a plasma power supply with alternately inverted polarity between one electrode and the other electrode; gas supply means for supplying a film-forming gas in the space between the deposition cylinders; and evacuation means for evacuating the space between the deposition cylinders, where one electrode from the plasma power supply is connected to one of the deposition cylinders, and the other electrode is connected to the other of the deposition cylinders.

According to this plasma CVD device, since the magnetic field generating element, which generates the swelled magnetic field particularly in the vicinity of the cylinder surfaces facing the space between the deposition cylinders, and the plasma power supply with alternately inverted polarity, are provided, the occurrence of electric discharge in the space between the pair of deposition cylinders and the convergence of the plasma generated in this way to the vicinity of the respective surfaces of the deposition cylinder in the space between the deposition cylinders can be achieved without providing a containment to define the space between the deposition cylinders, such as a discharge chamber, or use a discharge electrode other than the deposition cylinders. Therefore, only by supplying the film-forming gas of the gas supply medium in the space between the deposition cylinders, the film-forming gas is decomposed and activated by the plasma, and the decomposed gas is deposited on the surface of the coiled substrate. around the deposition cylinders facing the space between the deposition cylinders, according to which a film can be efficiently formed. Since confinement or discharge electrodes other than deposition cylinders, in which dissociated film-forming gas is adsorbed, are absent, film formation on the substrate can be carried out without film deposition in a part like this, and a high quality film can be formed, still eliminating film defects and deteriorating stability of film formation resulting from film deposition.

Preferably, the magnetic field generating element provided in each of the deposition cylinders includes a magnetic pole arranged so that each of the magnetic field generating elements forms a substantially closed magnetic circuit without the lines of the magnetic field extending between the element magnetic field generator provided in one of the deposition cylinders and the magnetic field generator element provided in the other of the deposition cylinders. By providing such magnetic field generating elements, the formation of a magnetic field with swollen magnetic field lines can be promoted in the vicinity of the surface of each deposition cylinder voided into the space between the deposition cylinders, and since the plasma is easily converged to the swollen part, the efficiency of film formation can be improved.

In this case, preferably, the magnetic field generator element provided in each of the deposition cylinders has an athletic track-type magnetic pole in the length of the axial direction of the cylinder, and the magnetic pole in each of the elements generating magnetic field is arranged so that the magnetic pole of one of the generating element of magnetic field and the magnetic pole of the other of the generating element of magnetic field opposite the magnetic pole of one of the generating element magnetic field have the same polarity. By providing such magnetic field generating elements, the athletic field-type magnetic field can be easily formed for each magnetic field generating element in the vicinity of the cylinder surface facing the space between the deposition cylinders along the longitudinal direction of the axis geometric shape of the cylinder, without the lines of the magnetic field extending to the generating element of the magnetic field on the side of the opposite cylinder, and plasma can be converged to the magnetic field. Therefore, a film can be efficiently formed using a large substrate wound along the direction of the width of the cylinder.

The gas supply means is preferably provided on one side of the space between the deposition cylinders, and the evacuation means is preferably provided on the other side of the space between the deposition cylinders. Such a scheme of the gas supply means and the evacuation means allows efficient supply of the film-forming gas in the space between the deposition cylinders to improve the film-forming efficiency.

The pressure of the space between the deposition cylinders is preferably set at 0.1 to 10 Pa. Accordingly, the discharge of brightness can be efficiently caused around the area close to the surface of the deposition cylinders where the magnetic fields are gifts, and excellent film forming properties can be obtained.

Industrial Utility

As described above, the film forming apparatus according to the present invention is used as a film forming apparatus to continuously form a functional film on a surface of a strip-like substrate, such as a plastic film or sheet, and can properly form a high quality film on the substrate, still suppressing film deposition inside a vacuum chamber.