JP2006299353A - Film-forming apparatus and film-forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film-forming apparatus for stably forming a uniform thin film on the surface of a substrate by using a CVD film-forming technique, and to provide a film-forming method therefor. <P>SOLUTION: A chamber 3 has a film-forming chamber 8, a first exhaust chamber 9 and a second exhaust chamber 11 arranged therein, which are separated from each other by barrier plates 5 and 7; and also has the first substrate transfer chamber 15 for sending a substrate 16 to the film-forming chamber 8 and the second substrate transfer chamber 19 for collecting the substrate 16 after having been film-formed, placed therein. The substrate 16 is film-formed in a linear free span section in the film-forming chamber 8. The film-forming chamber 8 has gas supply sections 21 and electrode units 27 installed so as to form a film on both sides of the substrate 16. The gas supply sections 21 spout a film-forming gas to both sides of the top and bottom of the substrate 16. The electrode units 27 have electrodes 55 installed on both sides of the top and bottom of the substrate. A power source 29 supplies an electric power to the electrode units 27 to generate plasma 28 and form the thin film on both sides of the substrate 16. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plasma CVD film forming apparatus (hereinafter referred to as a film forming apparatus) and a plasma CVD film forming method (hereinafter referred to as a film forming method), and in particular, uniformly on a long substrate surface under reduced pressure. The present invention relates to a film forming apparatus and a film forming method for stably and continuously forming a thin film.

  Conventionally, in order to form a thin film on a substrate by plasma CVD, a method using capacitively coupled plasma and inductively coupled plasma is known (see Non-Patent Document 1).

Plasma Electronics Ohmsha, Hideo Sakurai, 1st edition, 1st edition, issued on August 25, 2000, page 106

  On page 106, line 8 of this document, it is described that capacitively coupled plasma can easily generate large-diameter plasma, which can be applied to substrates such as ceramics such as wafers and glass, resin plates, plastic films, metal plates, and metal foils. On the other hand, capacitively coupled plasma is widely used in the field of thin film formation.

In FIG. 6.3 and page 106 of this document, the 13th to 14th lines use two electrodes for plasma discharge when capacitively coupled plasma is used for thin film formation. The film is formed in this state.
In addition, there is an apparatus that has a mechanism for continuously conveying a base material to a roll-shaped base material and forms a film by a capacitively coupled plasma CVD method (Patent Document 1).

JP-A-11-61416

However, when the film is formed by such a method, the electrical flow of the plasma is difficult due to the arrangement of the semiconductor or insulating film-forming substrate, that is, the discharge impedance is increased, and the plasma discharge is difficult to occur. There was a problem that the stability of discharge deteriorated.
Instability of plasma discharge causes abnormal discharge such as arcing, and causes arcing traces with a diameter of several millimeters on the base material, and if this is severe, it causes poor appearance and quality degradation. There was a problem.
In addition, if the plasma is unstable, when forming a film on a long substrate, etc., the substrate conveyance control is also affected, and it is impossible to form a film continuously for a long time. there were.

Further, when the discharge impedance increases, the discharge voltage increases and the discharge current decreases even when the same power is applied. As a result, film formation rate decreases (productivity decrease), film stress increases, damage to the substrate (electric charge-up occurs, poor adhesion due to strong etching of the substrate, substrate coloring occurs Etc.), and deterioration of film quality becomes a problem.
Furthermore, since the discharge impedance differs depending on the base material, there arises a problem that the film thickness and film quality of the formed film differ, and it is necessary to optimize the film forming conditions for each type of base material.

The above problem is that, for example, when an insulating film such as SiO ₂ or TiO ₂ is formed, the discharge impedance is further increased due to the poor decomposability of the film forming material, and the film formation becomes unstable. There is a problem of becoming.
On the other hand, there may be a problem that the film forming impedance is small. When the discharge impedance is small, the discharge voltage is small, the discharge current is large, the ion implantation effect on the substrate is small, and as a result, the adhesion of the film is insufficient, and film peeling may occur.

  The present invention has been made in view of the above problems, and an object of the present invention is to form a film forming apparatus and a composition capable of stably forming a uniform thin film continuously on the surface of a long substrate. It is to provide a membrane method.

  A first invention for solving the above-described problem is a film forming apparatus for forming a thin film on a base material under reduced pressure by a plasma CVD method, the chamber, a transport mechanism for transporting the base material, A gas supply unit configured to supply gas into the chamber; a pair of electrodes that are disposed in the chamber and are electrically floating; and a power source that supplies power between the two electrodes. In the film forming apparatus, the material is held in the chamber so as to have a straight free span portion, and the film is formed in the free span portion of the base material.

  Here, the floating level means that the electrodes are designed and installed using insulating parts and insulating coatings so that insulation from the chamber and other parts of the film forming apparatus installed at the earth level is maintained. Means state.

Moreover, you may enable it to perform the film-forming to a base material in at least 2 or more places with respect to the base material one side surface. In this case, the same seed film may be formed or a different film may be formed in two or more places.
Alternatively, a plurality of sets of electrodes may be provided, and a plurality of sets of electrodes may be installed on both sides of the substrate. In this case, the film formation on the base material may be performed simultaneously on both surfaces of the base material, or may be performed at different times.
By installing them on both sides of the base material, the stress of the base material is reduced, and it becomes possible to form a high-quality film without curling or film peeling. Further, the thermal load generated during the film formation can be reduced by sequentially performing the film formation on the both surfaces of the base material when they are different.

The electrode may include a magnet that concentrates and forms plasma near the substrate. The magnet preferably has a horizontal magnetic flux density on the substrate surface of 10 to 10,000 gauss. The magnet has a magnetron structure.
By providing the magnet, the reactivity in the vicinity of the surface of the substrate is increased, and a high-quality film can be formed at high speed.

  The power supply preferably has a frequency of 10 Hz to 27.12 MHz. The power source is subjected to input power control or impedance control.

The gas supply unit is attached to the electrode side of the substrate and supplies gas toward the substrate surface. A film-forming gas can be uniformly diffused and supplied to the substrate surface, and a uniform film can be formed over a large area.
The gas supply unit may be at an electrically floating level.

The chamber may have a film formation chamber and an exhaust chamber. The transport mechanism includes a first base material transport chamber for feeding the base material into the chamber and a second base material transport chamber for collecting the base material after film formation in the chamber. Is desirable.
In order to form a film having sufficient density and adhesion to the substrate, it is desirable to set and maintain the pressure in the film forming chamber between 0.1 Pa and 100 Pa. It is desirable that the degree of vacuum of the exhaust chamber is in a range of 10 to 10,000 times that of the film forming chamber.
By setting the degree of vacuum in the exhaust chamber in this way, by-products generated on the surface of the film forming substrate can be efficiently removed, and a high-quality film can be generated.

  Further, the degree of vacuum in the first base material transfer chamber and the second base material transfer chamber prevents the film formation chamber plasma from leaking into the base material transfer chamber and makes plasma discharge (film formation) unstable. In order to appropriately control the material conveyance and to protect from the plasma damage to the substrate conveyance mechanism, the degree of vacuum at the time of film formation in the film formation chamber is 10 times or more and 10,000 times or less. It is desirable to set and maintain high within the range.

The base material transfer chamber subsequent to the film formation chamber may include one or more rollers for transferring the base material after film formation. In order to efficiently remove the heat generated at the time of film formation, it is desirable to provide a base material cooling mechanism at least on the roller that first contacts the base material after film formation. Further, in order to efficiently remove the electric charge charged at the time of film formation, it is desirable to set the roller to the ground level or the floating level electrically.
Furthermore, it is preferable to provide a base material charge removal unit for removing base material charge generated during film formation on the roller or in the front stage or the rear stage of the roller in the base material transport chamber downstream of the film formation chamber. The base material charge removal unit is a plasma discharge device or the like.

A second invention is a film forming method for forming a thin film on a base material under reduced pressure by a plasma CVD method. The base material is transported to a straight free span portion provided in the chamber, gas supply, in the chamber, are arranged on the same surface side of the substrate, electrically powering between a pair of electrodes of the floating level, the flop plasma is generated, the on said substrate A thin film is formed at a free span portion.

  According to the present invention, since the film is formed by holding the substrate in a horizontal state with a straight free span portion, it is possible to reduce the film stress of the film to be formed, and there is no curling or bending of the substrate, or peeling of the film A high-quality film can be formed.

In addition, since the base material is not placed between the electrodes to form a film, it is not electrically coupled during plasma discharge, and an increase in discharge impedance can be prevented. As a result, there are advantages such that plasma discharge is easily generated by reducing the discharge start voltage, and plasma discharge can be stably performed by reducing the discharge sustain voltage. In addition, since the discharge impedance is reduced, in plasma CVD film formation, the film formation rate is improved (productivity improvement), film stress is reduced, and damage to the base material is reduced (electric charge-up is suppressed, base material etching is performed). It is possible to improve the degree of adhesion and reduce the coloring of the base material).
Furthermore, since it is not necessary to consider the impedance variation due to the substrate, it is not necessary to optimize the film forming conditions for each type of substrate.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a film forming apparatus 1 according to an embodiment of the present invention. The film forming apparatus 1 includes a chamber 3 that performs a film forming process on the base material 16, a first base material transport chamber 15 that transports the base material 16, a second base material transport chamber 19, and the like. A partition wall 5 and a partition wall 7 are formed in the chamber 3. A film forming chamber 8 is formed in a space surrounded by the partition walls 5 and 7, and an exhaust chamber is formed above the partition walls 5 and below the partition walls 7. A lower side of the partition wall 7 is a first exhaust chamber 9, and an upper side of the partition wall 5 is a second exhaust chamber 11.

The first base material transfer chamber 15 feeds out the base material 16 before film formation, and the second base material transfer chamber 19 performs winding up of the base material 16 after film formation.
In the first base material transfer chamber 15, an unwinding roller 41, a guide roller 43-1 and a pretreatment device 45 are provided. The second base material transfer chamber 19 is provided with a winding roller 47, guide rollers 43-2, 43-3, 43-4, a tension pickup roll 44, and a post-processing device 49.

The unwinding roller 41 winds the base material 16. The base material 16 is a base that is a slit-like horizontal gap through which the base material 16 provided on the wall separating the first base material transfer chamber 15 and the chamber 3 passes from the unwinding roller 41 through the guide roller 43-1. It is fed into the film forming chamber 8 through the material carry-in port 35.
On the other hand, a similar gap is provided as a substrate carry-out port 37 on the wall that separates the chamber 3 and the second substrate transfer chamber 19. It is sent out to the second base material conveyance chamber 19 through the material carry-out port 37 and taken up by the take-up roller 47 through the guide roller 43-2, the tension pick-up roll 45, and the guide rollers 43-3 and 43-4. The tension pickup roller 45 adjusts the tension of the base material 16 and transports the base material 16.

Further, in FIG. 1, the base material transport direction is described so that the base material 16 advances from the unwinding roller 41 to the take-up roller 17. It is also possible to perform processing and to repeat these. From the viewpoint of productivity and film quality, it is preferable to repeatedly form a film without returning the vacuum to atmospheric pressure.
The substrate 16 is a ceramic such as glass, a resin plate, a plastic film, a metal plate, a metal foil, paper, a nonwoven fabric, a fiber, or the like.

In the first base material transfer chamber 15, a pretreatment device 45 is provided between the guide roller 43-1 and the base material carry-in port 35, and in the second base material transfer chamber 19, the base material carry-out port 37 and the guide are provided. A post-processing device 49 is provided between the rollers 43-2.
The pre-processing device 45 and the post-processing device 49 are provided so as to sandwich the base material 16 on both sides of the base material 16. The pretreatment device 45 is, for example, a plasma discharge device, and the posttreatment device 49 is a device that removes the base material charge generated by film formation, and is, for example, a plasma discharge device.

  The chamber 3 is provided so as to be sandwiched between the first base material transport chamber 15 and the second base material transport chamber 19, and the base material 16 is transported horizontally between the base material carry-in port 35 and the base material carry-out port 37. The free span part is configured. The base material 16 is taken up by the take-up roller 47 to move in the film forming chamber 8, during which film forming processing is performed.

In the chamber 3, the gas supply unit 21 and the electrode unit 27 are provided on both the upper surface side and the lower surface side of the base material 16. As a result, film formation on both surfaces of the substrate 16 becomes possible.
On the upper surface side of the base material 16, gas supply units 21-1, 21-2, and 21-3 are provided so as to be sandwiched between the partition walls 5, and the gas supply units 21-1, 21-2, and 21-3 are The gas reservoirs 25-1, 25-2, 25-3 are connected to the gas flow controllers 23-1, 23-2, 23-3.
Further, on the lower surface side of the base material 16, gas supply units 21-4, 21-5, 21-6 are provided so as to be sandwiched between the partition walls 7, and the gas supply units 21-4, 21-5, 21-6 are provided. Is connected to the gas storage units 25-4, 25-5, and 25-6 via the flow rate control units 23-4, 23-5, and 23-6.

The gas storage units 25-1 to 25-6 store a film-forming gas, and the gas storage units 25-1, 25-2, and 25-3 each include, for example, TEOS (tetraethoxysilane) that is a film-forming raw material. Si (OC ₂ H ₅ ) ₄ ), oxygen (O ₂ ) that is a decomposable oxidizing gas, and argon (Ar) that is an ionizing gas for discharge are stored. Similarly, the gas reservoirs 25-4, 25-5, and 25-6 are, for example, TEOS (tetraethoxysilane Si (OC ₂ H ₅ ) ₄ ) that is a film forming raw material, oxygen that is a decomposable oxidizing gas, respectively. (O ₂ ) and argon (Ar) which is an ionizing gas for discharge are stored.
The flow rate controllers 23-1 to 23-6 measure the flow rates of the gases sent from the gas storage units 33-1 to 33-6 to the gas supply units 21-1 to 21-6, respectively.

The gas supply units 21-1 to 21-6 are directed toward the base material 16 at the ejection ports. That is, the jet outlets of the gas supply units 21-1 to 21-3 are directed to the upper surface of the base material 16 and perform gas injection onto the upper surface of the base material 16. On the other hand, the jet outlets of the gas supply units 21-4 to 21-6 are directed to the lower surface of the base material 16, and perform gas injection onto the lower surface of the base material 16.
For this reason, the film forming gas can be uniformly diffused and supplied to both the upper and lower surfaces of the base material 16, and a uniform film can be formed on a large area of the base material 16.

In the upper part of the base material 16, an electrode unit 27-1 including an electrode 55-1 is provided between the gas supply units 21-1 and 21-2, and an electrode is provided between the gas supply units 21-2 and 21-3. An electrode unit 27-2 including 55-2 is provided, and the electrodes 55-1 and 55-2 are connected to a power source 29-1, and power is supplied from the power source 29-1. The electrodes 55-1 and 55-2 are electrically set at a floating level.
On the other hand, the lower surface of the substrate 16 is similarly provided with an electrode unit 27-3 including an electrode 55-3 between the gas supply units 21-4 and 21-5, and the gas supply units 21-5 and 21-6. Is provided with an electrode unit 27-4 including an electrode 55-4, and the electrodes 55-3 and 55-4 are connected to a power source 29-2 and supplied with power from the power source 29-2. The electrodes 55-3 and 55-4 are electrically set at a floating level.

  Here, the electrical floating level refers to the state in which electrodes are designed and installed using insulating parts and insulating coatings so that insulation is maintained from chambers and film deposition equipment parts installed at the ground level. I mean. Despite being designed so that the insulation of the electrode is ensured, the refrigerant necessary for cooling the electrode is used, and this refrigerant and the piping for circulating and supplying these refrigerants have some conductivity. The present invention also includes a case where a resistance of 10 kΩ to 1000 MΩ is provided between the electrode and the ground with reference to the ground level (ground level).

  Further, the gas supply units 21-1 to 21-6 are also set to an electrically floating level. Thereby, it is possible to prevent the deposition power from leaking to the gas supply units 21-1 to 21-6, to increase the deposition input power, and to use the gas supply units 21-1 to 21-6. Efficiency is also increased. That is, it is possible to avoid the problem of forming a film near the gas injection port before the gas is supplied into the chamber 3 and closing the gas injection port.

Each of the first base material transfer chamber 15, the second base material transfer chamber 19, the first exhaust chamber 9 below the chamber 3, the second exhaust chamber 11 above the chamber 3, and the film forming chamber 8 in the chamber 3 A vacuum exhaust pump 33 is provided through each pressure adjustment valve 31.
That is, the first base material transfer chamber 15 is evacuated via a pressure adjustment valve 31-4, and the second base material transfer chamber 19 is evacuated via a pressure adjustment valve 31-5. The pump 33-5 is evacuated to the first exhaust chamber 9 via the pressure adjustment valve 31-3, and the vacuum exhaust pump 33-3 is evacuated to the second exhaust chamber 11 via the pressure adjustment valve 31-1. A pump 33-1 is provided in the film forming chamber 8 via a pressure adjusting valve 31-2.

By the pressure adjusting valve 31 and the vacuum exhaust pump 33 described above, the pressures of the first and second base material transfer chambers 15 and 19 and the film forming chamber 8 and the first and second exhaust chambers 9 and 11 are set to be different from each other. Is possible.
That is, by forming the film forming chamber 11 and the first and second base material transfer chambers 15 and 19 into different spaces in pressure, the plasma 28 in the film forming chamber 8 is changed to the first and second base material transfer chambers 15 and 15. 19, the plasma discharge state of the film forming chamber 8 becomes unstable, the members of the first and second base material transfer chambers 15 and 19 are damaged, and an electric circuit for controlling the base material transfer mechanism is used. Electrical damage is not caused to cause poor control, and stable film formation and substrate transport are possible.

  Specifically, the film forming pressure in the film forming chamber 8 is between 0.1 Pa and 100 Pa. By performing film formation at such a film formation pressure, a stable plasma 28 can be formed.

  Then, the pressure (vacuum degree) in the first and second base material transfer chambers 15 and 19 is made 10 to 10,000 times higher than the pressure (vacuum degree) in the film forming chamber 8. Thus, by setting the pressures in the first and second base material transfer chambers 15 and 19, the plasma 28 in the film formation chamber 8 does not leak into the first and second base material transfer chambers. Plasma CVD film formation in the chamber 8 can be performed stably.

  On the other hand, the first exhaust chamber 9 and the second exhaust chamber 11 are partitioned from the film formation chamber 8 by a partition wall (zone seal) 7 and a partition wall (zone seal) 5, respectively, and have different pressures. The first and second exhaust chambers 9 and 11 have a pressure (degree of vacuum) that is not less than 10 times and not more than 10000 times the pressure at the time of film formation in the film formation chamber 8. By providing such a pressure difference, the by-product generated during film formation can be efficiently exhausted from the vicinity of the surface of the substrate 16.

The post-processing device 49 provided in the second base material transport chamber 19 enables the base material 16 to be stably transported by removing the base material charge due to film formation, and the base material 16 caused by the charge It is possible to prevent breakage and quality deterioration and improve post-processing suitability by improving the wettability of the front and back surfaces of the base material 16.
As the post-processing device 49 serving as a charge removing unit, for example, an arbitrary processing device such as a plasma discharge device, an electron beam irradiation device, an ultraviolet irradiation device, a neutralization bar, a glow discharge device, or a corona treatment device can be used.

  When a discharge is formed using a plasma processing apparatus or a glow discharge apparatus, a discharge gas such as argon, oxygen, nitrogen, helium or the like is supplied in the vicinity of the substrate 16 as a single substance or a mixture, and alternating current (AC) plasma, direct current ( Any discharge method such as DC) plasma, arc discharge, microwave, surface wave plasma, etc. can be used. In a reduced pressure environment, a charging method using a plasma discharge device is most preferable.

  The pretreatment device 45 provided in the first substrate transfer chamber 15 is a plasma discharge treatment device, and this plasma discharge treatment device performs a plasma discharge treatment on the substrate 16 before film formation, thereby forming the substrate 16. It is possible to physically etch the surface of the substrate 16 and to form a concavo-convex shape on the surface of the substrate 16, and by changing the chemical bonding state and functional group, It becomes possible to improve the adhesion of the film.

2 is a cross-sectional view of the electrode unit 27-3, FIG. 3 is a cross-sectional view taken along the direction A in FIG. 2, and FIG. 4 is a cross-sectional view taken along CC in FIG.
An insulating shield plate 53 is provided on the support base 51, and an electrode 55 is provided on the insulating shield plate 53. In order to prevent heat conduction between these, a space may be provided by using an O-ring or a spacer to prevent direct contact. In any case, the electrode 55 has a structure that is electrically insulated from the support base 51. The electrode 55 is provided with a power supply wiring 59 whose exterior is covered with an insulating material, and is connected to a power source 29-3. Inside the electrode 55, a temperature control medium pipe 57 for circulating the refrigerant is provided.
The electrode unit 27-4 can also use the same structure.
As described above, the electrodes 55-3 and 55-4 of the electrode units 27-3 and 27-4 are opposed to the lower surface of the base material 16, and the plasma 28 is generated toward the lower surface of the base material 16. Film formation is performed.

On the other hand, the electrode units 27-1 and 27-2 are those in which the vertical direction of the electrode unit 27-3 is turned over, and basically the same structure can be used.
Therefore, the electrodes 55-1 and 55-2 of the electrode units 27-1 and 27-2 are opposed to the upper surface of the base material 16, and the plasma 28 is generated toward the upper surface of the base material 16 to form a film. Done.
In general, the electrode units (for example, the electrode units 27-1 and 27-2) and the electrodes that are used as a set preferably have the same size and the same structure in order to make the balance electrically equivalent.

  The power supply line 59 is connected to the power source 29, and when power is supplied from the power source 29, plasma 28 is generated from the electrode 55. The temperature adjusting medium flows inside the temperature adjusting medium pipe 57, and the electrode 55 and the electrode unit 27 can be cooled or heated. For example, the electrode 55 and the electrode unit 27 are cooled by circulating a refrigerant such as an ethylene glycol aqueous solution through the temperature control medium pipe 57.

The electrode units 27-1 to 27-4 preferably have a structure including a magnet 85 as shown in FIGS. 5, 6, and 7 in addition to those shown in FIGS. 2, 3, and 4. .
5 is a side view of the electrodes 27-3 and 27-4, FIG. 6 is a view taken in the direction of the arrow B in FIG. 5, and FIG. 7 is a cross-sectional view taken along the line CC in FIG.
The electrode units 27-1 and 27-2 have a structure in which the electrode units 27-3 and 27-4 are turned upside down, and are basically the same as the structures of the electrode units 27-3 and 27-4.

The electrode 55 has a magnetron structure. As shown in FIGS. 5, 6, and 7, an insulating spacer 84 and a base plate 83 are provided in the magnet case 81, and a magnet 85 is provided on the base plate 83. An insulating shield plate 87 is provided on the magnet case 81, and an electrode 89 is attached to the insulating shield plate 87. Therefore, the magnet case 81 and the electrode 89 are electrically insulated, and even if the magnet case 81 is installed and fixed in the chamber 3, the electrode 89 can be brought to an electrically floating level. Inside the electrode 89, a temperature control medium pipe 91 for cooling the electrode and the magnet is provided.
Also in this case, for example, the electrode 89 and the magnet are cooled by circulating an ethylene glycol aqueous solution or the like through the temperature control medium pipe 91 as a cooling medium.

  The magnet 85 is provided so that the plasma from the electrode 89 is concentrated on the substrate 16. By providing the magnet 85, the reactivity in the vicinity of the surface of the substrate 16 is increased, and a high-quality film can be formed at a high speed.

  The magnet 85 has a horizontal magnetic flux density of 10 gauss to 10000 gauss at the surface position of the substrate 16. If the horizontal magnetic flux density on the surface of the base material 16 is 10 gauss or more, the reactivity in the vicinity of the surface of the base material 16 can be sufficiently increased, and a high-quality film can be formed at high speed. On the other hand, an expensive magnet or a magnetic field generating mechanism is required to make the horizontal magnetic flux density on the surface of the base material 16 higher than 10,000 Gauss.

  The arrangement structure of the electrode 89 and the magnet 85 is a magnetron structure. By adopting a magnetron structure, ions and electrons formed during plasma CVD film formation move according to this magnetron structure. For this reason, for example, when plasma CVD film formation is performed on a large-area substrate 16 having a size of 300 mm × 300 mm or more, the above-described electrons, ions, and decomposition products of the film formation material are uniformly diffused over the entire surface of the electrode 89. In addition, even when the substrate 16 has a large area, uniform and stable film formation is possible.

  In addition, there is no accumulation of thermionic electrons and ions locally on the electrode unit consisting of electrodes and magnets, and the heat resistance of the structural members can be reduced. It is possible to suppress the occurrence of problems such as hole punching and cracking.

The electrode 89 is conductive for supplying electric power, has excellent plasma resistance, has heat resistance, has high cooling efficiency with cooling water (high thermal conductivity), is a non-magnetic material, and has excellent workability It is preferable to use a material. Specifically, aluminum, copper, and stainless steel are preferably used.
The insulating shield plate 87 is preferably made of an insulating material having excellent plasma resistance, heat resistance, and workability. Specifically, a fluororesin and a polyimide resin are preferably used.
In general, it is preferable to use the same size and the same structure since the electrode units and the electrodes used in pairs are electrically balanced.

The power supply 29 has a frequency of 10 Hz to 27.12 MHz. Stable film-forming discharge can be performed at a frequency of 10 Hz or higher, and the power supply and its matching circuit are expensive at a frequency higher than 27.12 MHz, resulting in an increase in apparatus cost.
More preferably, 10 kHz to 500 kHz, 13.56 MHz, and 27.12 MHz are preferable.
When a power source for film formation of 10 kHz to 500 kHz is used, the film formation material is high in efficiency because it causes decomposition necessary for film formation, and the film formation material has a high effect on the base material 16, so that the quality is high. A membrane is obtained. In addition, 13.56 MHz and 27.12 MHz further increase the decomposition efficiency for causing the decomposition necessary for the film formation of the film forming material, increase the gas reactivity, and enable high-quality film formation with high density and high adhesion. . Since these power supplies have frequencies that are allowed to be industrially used even in a high frequency band, there are advantages that a large number of such power supplies are commercially available and are inexpensive.

  As a control method of the power source 29, there is an impedance control method of controlling the input impedance control or the discharge impedance indicating the difficulty of the flow of electricity obtained by dividing the discharge voltage value by the discharge current value. In the input power control, film formation can be performed stably, simply, and inexpensively by a method of performing film formation while stabilizing plasma discharge so that the film formation input power of the power source 29 is constant.

  In the impedance control, when the responsiveness is fast and the impedance change occurs during the film formation for a long time, the composition of the CVD film forming gas is influenced by the influence of moisture that starts to be released when the inner wall of the chamber 3 is warmed by discharge, for example. If the impedance changes as a result, there is an effect of maintaining this constant.

  Further, as a control method for stable film formation of the power supply 41, an optical method may be used. For example, a plasma emission monitor may be installed, the emission intensity of a specific element in the plasma may be monitored, and process control for making the emission intensity constant may be performed. As a process control method in this case, the amount of supply gas such as film forming source gas, decomposable gas, oxidizing gas, discharge gas, ionized gas, etc. is controlled, and film forming conditions such as film forming pressure and substrate temperature are controlled. May be.

In order to stably convey the substrate 16, the second substrate conveyance chamber 19 includes guide rollers 43-2, 43-3, 43-4 and a tension pickup roll 44 in addition to the take-up roller 47. It has been.
Here, the guide roller 43-2 is the first contact with the base material 16 after film formation. The guide roller 43-2 is provided with a pipe similar to the temperature control medium pipe 57 provided in the electrode unit 27, and a base material cooling mechanism that allows the base material 16 to be cooled by circulating the temperature control medium. May be installed.
By providing the substrate cooling mechanism, it is possible to efficiently remove the heat generated during film formation. The temperature control range is from −20 ° C. to + 20 ° C., and the temperature is desirably controlled with an accuracy of ± 2 ° C.

Further, by setting the guide roller 43-2 to the ground level electrically, it is possible to efficiently remove the electric charges charged during the film formation.
Further, the guide roller 43-2 may be provided with a base material charge removing mechanism. As a result, it is possible to carry out static elimination simply and stably with a DC power source.

On the other hand, the guide roller 43-2 may be set electrically to a floating level. Thereby, it becomes possible to convey the base material 16 stably.
Then, a charging removal mechanism may be provided in the guide roller 43-2 at the floating level. By adopting such a configuration, it is possible to perform static elimination by applying a simple and inexpensive DC voltage or by applying an AC voltage that can be stably discharged.

  Further, in FIG. 1, a post-processing device 49 as a base material neutralization mechanism provided at the front stage of the guide roller 43-2 may be provided at the rear stage of the guide roller 43-2. With such a structure, it is possible to perform static elimination efficiently and stably.

  Next, an outline of the operation of the film forming apparatus 1 will be described. A film-forming gas is supplied from the gas storage units 25-1 to 25-6 to the gas supply units 21-1 to 21-6, and is formed from the gas supply units 21-1 to 21-6 toward the base material 16. Gas is injected.

  In addition, power is supplied from the power source 29-1 and the power source 29-2 to the electrode 55-1 and the electrode 55-2, the electrode 55-3 and the electrode 55-4, respectively. Plasma 28 is emitted from the electrodes 55-3 and 55-4 to the lower surface of the base material 16 on the upper surface of the material 16, and a thin film is formed on the base material 16.

At this time, different types of films can be formed by independently controlling the gas supply units 21-1 to 21-6 and the electrode units 21-1 to 21-6.
Further, gas supply units 21-1 to 21-3 and electrode units 21-1 and 21-2 for forming a film on the upper surface of the base material 16, and a film for forming a film on the lower surface of the base material 16 By making the control of the film formation time of the gas supply units 21-4 to 21-6 and the electrode units 21-3 and 21-4 the same, it is possible to perform film formation on the lower surface of the upper surface of the substrate 16 at the same time. In addition, by independently controlling the film formation time, it is possible to perform film formation on the upper and lower surfaces of the substrate 16 at different times.

Next, an experimental result when film formation is performed using the film formation apparatus 1 illustrated in FIG. 1 and the film formation apparatus 201 as a comparative example illustrated in FIG. 8 will be described.
In the film forming apparatus 1 of the present embodiment shown in FIG. 1, the electrodes 55-1, 55-2, 55-3, 55-4 have a magnetron structure as shown in FIGS. 5, 6, and 7 described above. The magnet 85 was set and set so that the average horizontal magnetic flux density on the surface of the substrate 16 was 1000 gauss. The chamber 3 is at the ground level, and the electrodes 55-1 to 55-4 and the guide roll 43-2 with which the substrate 16 after film formation first contacts in the second substrate transport chamber 19 are electrically floating. It was.

  An ethylene glycol aqueous solution with a concentration of 30% is supplied as a refrigerant so as to circulate individually to the temperature control medium pipe 91 of the electrode units 27-1 to 27-4, and the temperature of the electrodes 55-1 to 55-4 is set to 0 ° C. Cooled down. At this time, the resistance between each electrode 55-1 to 55-4, the chamber 3, and each electrode was 1 MΩ.

A 0.6 m wide PET film (Toyobo Co., Ltd., A4100, thickness 100 μm) was prepared as the substrate 16 and set in the substrate conveyance system of the first substrate conveyance chamber 15 and the second substrate conveyance chamber 19. .
The inside of the chamber 3 including the second exhaust chamber 11, the film formation chamber 8, and the first exhaust chamber 9 was evacuated to 1 × 10 ⁻⁴ Pa by the vacuum pumps 33-1, 33-2, and 33-3.
As a film-forming gas, TEOS (tetraethoxysilane Si (OC ₂ H ₅ ) ₄ ) was vaporized at a heating temperature of 120 ° C. and supplied. Then, TEOS, oxygen, and argon were supplied at 20 sccm, 500 sccm, and 200 sccm, respectively, and mixed uniformly, and then the same gas was supplied onto the substrate 16 in a shower shape.

Next, the vacuum pumps 33-1 to 33-5 are adjusted so that the pressure in the film forming chamber 8 is 10 Pa, the first and second base material transfer chambers 15 and 19, and the first and second exhaust chambers 9, respectively. The pressure of 11 was adjusted to be a constant pressure of 0.5 Pa.
A power supply with a frequency of 40 kHz (Advanced Energy
Industries, Inc., PEII, 10 kW), 3 kW power was applied to the electrodes 55-1 and 55-2, and 3 kW power was applied to the electrodes 55-3 and 55-4. These powers were controlled by impedance control. A 1200 m film was formed at a substrate line speed of 5 m / min. In addition, after the start of film formation, the average discharge voltage for 1 minute before and after the film formation distance was determined every 200 m. In addition, the number of discharge arcing (abnormal discharge) occurrence was visually counted.

After the film formation, the residual gas in the chamber 3 is evacuated, the base material 16 is taken out, the surface of the base material is visually observed, and the center portion in the width direction of the base material 16 is sampled every 200 m. Film thickness measurement, film density measurement, and substrate warpage evaluation were performed. The film thickness was determined by performing cross-sectional observation using a scanning electron microscope (SEM; manufactured by Hitachi, Ltd., S-5000H). The film density was calculated using an X-ray reflectivity measuring apparatus (manufactured by Rigaku Corporation, ATX-E) and attached software. The warpage evaluation of the base material is performed by cutting the base material 16 into a size of 20 mm × 20 mm, placing the surface on an upper (positive side) flat surface, and the maximum warp height from the flat surface due to the warpage of the base material. Was measured with a laser displacement meter.
FIG. 9 is a diagram showing a film formation result.

  In contrast, a film forming apparatus 201 shown in FIG. 8 was prepared as a comparative example. This film forming apparatus 201 is different from the film forming apparatus 1 shown in FIG. 1 in that the film forming process is performed while the base material 16 is wound around the drum 9 provided in the chamber 3 and conveyed.

  The chamber 3 is divided into a base material transfer chamber 15, a film forming chamber 8 and an exhaust chamber 9 by a partition wall 5 and a partition wall 7, and a drum 9 is provided so as to be sandwiched between the partition walls 5. The drum 9 winds the base material 16. Gas supply units 21-1 and 21-3 are installed so as to be sandwiched between the partition walls 7, and a gas supply unit 21-2 is provided along the outer periphery of the drum 9. The gas supply units 21-1, 21-2, and 21-3 are respectively connected to the gas storage units 25-1, 25-2, and 25-3 via the flow rate controllers 23-1, 23-2, and 23-3. The film forming gas is connected and supplied. The gas injection ports of the gas supply units 21-1, 21-2, and 21-3 are directed toward the surface of the substrate 16 wound around the drum 9, and gas is injected toward the substrate surface.

An electrode unit 27-1 is provided between the gas supply units 21-1 and 21-2, and an electrode unit 27-2 is provided between the gas supply units 21-2 and 21-3. The structure of the electrode units 27-1 and 27-2 is the same as that of the film forming apparatus 1.
In addition to the unwinding roller 41 and the winding roller 47, the base material transport chamber 15 is provided with guide rollers 43-1 to 43-5 and a tension pickup roll 44, and the base material 16 is fed from the unwinding roller 41. Then, it reaches the drum 9 through the guide rolls 43-1 and 43-2, enters the film forming chamber 8, and the film forming process is performed.

  Further, in the base material transfer chamber 15, a charge removing device 49 similar to the post-processing device 49 provided in the second base material transfer chamber 19 of the film forming apparatus 1 of the present embodiment is provided. The base material 19 after film formation is discharged by the charge removing device 49 and then collected by the take-up roller 47 through the guide roll 43-3, the tension pickup roll 44, and the guide rolls 43-4 and 43-5. .

The electrodes 55-1 and 55-2 of the film forming apparatus 201 were electrically connected to the same potential, and the resistance between both electrodes was 0.1Ω. The film forming pressure was 0.5 Pa at all locations in the chamber 3. Other conditions were set according to the same setting and procedure as the film forming apparatus 1 of the present embodiment. Since this film forming apparatus 201 can only perform film formation on one side, after the film formation on one side is completed, the chamber 3 is opened to the atmosphere, the substrate 16 is reversed and set on the unwinding roller 41 again, and the opposite side The film was formed again on the surface with the same setting and procedure. The evaluation method of the formed film was also performed in the same manner as the experiment of this example.
FIG. 10 shows an experimental result of the film forming apparatus 201.

9 and 10, in the film forming apparatus 1 according to the present invention shown in FIG. 1, the number of occurrences of arcing (abnormal discharge) of discharge is zero, and stable film formation is possible without abnormal discharge. It has been found. For this reason, in the film forming apparatus 1 according to the present invention, arcing during discharge hardly occurs, so that a high-quality and uniform film can be formed.
Further, the discharge voltage is reduced, and the discharge is easily stabilized. Since the input electric power is effectively used for film formation, the film formation speed is improved, and a high-quality film with high film density, that is, high density can be formed. Furthermore, according to the measurement result of the substrate warp, a uniform film can be formed on both surfaces, and a film without the substrate warp (curl) was formed.

  The preferred embodiments of the film forming apparatus 1 according to the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea disclosed in the present application, and these naturally belong to the technical scope of the present invention. Understood.

The figure which shows the film-forming apparatus 1 concerning embodiment of this invention Cross section of electrode unit 27-3 A direction arrow view of FIG. CC sectional view of FIG. Cross section of electrode unit 27-3 (magnet installation) B direction arrow view of FIG. CC sectional view of FIG. The figure which shows the film-forming apparatus 201 used as a comparative example The figure which shows the film-forming result by the film-forming apparatus 1 The figure which shows the film-forming result by the film-forming apparatus 201

Explanation of symbols

3 ......... Chambers 5, 7 ......... Partition walls 8 ......... Deposition chamber 9 ......... First exhaust chamber 11 ......... Second exhaust chamber 15 ......... First base material transfer chamber 16 ......... Base Material 19 ......... Second base material transfer chamber 21 ......... Gas supply part 23 ......... Flow controller 25 ......... Gas storage part 27 ......... Electrode unit 31 ......... Pressure adjustment valve 33 ......... Vacuum Exhaust pump 41... Unwinding roller 43... Guide roller 44... Tension pick-up roller 45 ... Pre-treatment device 47 ... Take-up roller 49 ... Post-treatment device 55.

Claims (30)

A film forming apparatus for forming a thin film on a substrate under reduced pressure by a plasma CVD method,
A chamber;
A transport mechanism for transporting the substrate;
A gas supply unit for supplying gas into the chamber;
A set of electrodes disposed in the chamber and electrically floating level;
A power source for supplying power between the two electrodes;
Comprising
The substrate is held in the chamber to have a straight free span,
The film forming apparatus is characterized in that film formation is performed in the free span portion of the base material.   The film forming apparatus according to claim 1, wherein film formation on the base material is performed at least at two or more locations on the surface of the base material on one side.   The film formation method according to claim 2, wherein the same seed film is formed by the film formation at the two or more locations.   The film forming method according to claim 2, wherein the different kind of film is formed by the film formation at the two or more places.   The film forming apparatus according to claim 1, wherein there are a plurality of the set of electrodes, and the plurality of sets of electrodes are arranged on both sides of the base material.   6. The film forming apparatus according to claim 5, wherein the film formation on the base material is performed simultaneously on both surfaces of the base material.   The film forming apparatus according to claim 5, wherein the film formation on the base material is performed when different from both surfaces of the base material.   The film forming apparatus according to claim 1, wherein the electrode includes a magnet that concentrates and forms plasma in the vicinity of the substrate.   9. The film forming apparatus according to claim 8, wherein the magnet has a horizontal magnetic flux density on the surface of the substrate of 10 to 10,000 gauss.   The film forming apparatus according to claim 8, wherein the magnet has a magnetron structure.   The film forming apparatus according to claim 1, wherein the power source has a frequency of 10 Hz to 27.12 MHz.   The film forming apparatus according to claim 1, wherein the power source is input power controlled.   The film forming apparatus according to claim 1, wherein the power source is impedance-controlled.   The film forming apparatus according to claim 1, wherein the gas supply unit is attached to the electrode side of the substrate and supplies gas toward the surface of the substrate.   The film forming apparatus according to claim 1, wherein the gas supply unit is electrically at a floating level.   The film forming apparatus according to claim 1, wherein the chamber includes a film forming chamber and an exhaust chamber.   The transport mechanism includes a first base material transport chamber for feeding the base material into the chamber, and a second base material transport chamber for collecting the base material after film formation in the chamber. Item 2. The film forming apparatus according to Item 1.   The film forming apparatus according to claim 16, wherein a film forming pressure in the film forming chamber is between 0.1 Pa and 100 Pa.   The film forming apparatus according to claim 16, wherein a vacuum degree of the exhaust chamber is 10 to 10,000 times higher than a vacuum degree of the film forming chamber.   The degree of vacuum of the first base material transfer chamber and the second base material transfer chamber is 10 times to 10,000 times higher than the vacuum degree of the film forming chamber. Membrane device.   18. The film forming apparatus according to claim 17, further comprising a roller for transporting the base material after film formation in the second base material transport chamber.   The film forming apparatus according to claim 21, wherein the roller includes a cooling mechanism.   The film forming apparatus according to claim 21, wherein the roller is electrically at a ground level.   The film forming apparatus according to claim 21, wherein the roller is electrically in a floating level.   25. The film forming apparatus according to claim 23, wherein the roller includes a base material charge removing unit that removes base material charge generated during film formation.   26. The film forming apparatus according to claim 17, wherein the base material charge removing unit is provided upstream of the roller in the second base material transport chamber.   The film forming apparatus according to claim 17, wherein the base material charge removing unit is provided in a stage subsequent to the roller in the second base material transport chamber.   The film forming apparatus according to claim 17 or 25, wherein the first base material transfer chamber includes the base material charge removing unit.   The film forming apparatus according to any one of claims 25 to 28, wherein the base material charge removing unit is a plasma discharge apparatus. A film forming method for forming a thin film on a substrate under reduced pressure by a plasma CVD method,
Transport the base material to a straight free span provided in the chamber,
Supplying gas into the chamber;
Within the chamber, disposed on the same surface side of the substrate, and supplies power between a pair of electrodes at an electrically floating level,
Generate plasma,
A film forming method comprising forming a thin film on the base material at the free span portion.

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