JP4870615B2 - Plasma CVD film forming apparatus and plasma CVD film forming method - Google Patents

Description

The present invention relates to a plasma CVD film forming apparatus and a plasma CVD film forming method.

  Conventionally, there has been known a plasma CVD apparatus that decomposes a film forming material gas using plasma to form a thin film on a substrate. In this plasma CVD apparatus, in order to generate plasma, a pair of discharge electrodes are provided, and it is common to apply a voltage using the substrate side as a ground electrode and the film forming material gas supply side as a counter electrode. there were.

Conventionally, it has been common to form a thin film on a glass substrate, but in recent years, taking into account weight reduction, mass productivity, etc., a resin film is used as the substrate, and the thin film is formed on this film-like substrate. How to do is known. As described above, Patent Document 1 describes a roll-type manufacturing apparatus as a manufacturing apparatus that forms a thin film on a film-like substrate. The roll-type manufacturing apparatus described in Patent Document 1 includes a reaction chamber including a part of a drum roll, a high-frequency electrode, and a ground shield in a vacuum chamber, another part of the drum roll, and a film substrate transport unit. It is divided into a non-reaction chamber, a sealing means is provided between the reaction chamber and the non-reaction chamber, between the drum roll and the inner wall of the vacuum chamber, for suppressing the flow of the reaction gas, and the gas supply Means and gas exhaust means are provided in communication with the reaction chamber, and the non-reaction chamber is provided with auxiliary gas supply means for preventing the reaction gas from flowing into the non-reaction chamber by pressurization. It is.
JP 2002-221744 A

  By the way, in a film forming apparatus using a conventional plasma CVD method such as the manufacturing apparatus of Patent Document 1 described above, it is common to use a high-frequency power source that normally has an oscillation frequency of 13.56 MHz. Further, in order to obtain a film formation rate that can be used for mass production with a plasma CVD apparatus, the pressure in the film formation space is often set to 100 Pa to 300 Pa. Under this pressure condition, the counter electrode to which a voltage is applied and the ground electrode The distance between the electrodes is generally about 15 to 25 mm. However, in the roll-type film forming apparatus, it is difficult to maintain a constant distance between the counter electrode and the ground electrode at a short distance of 15 to 25 mm, and as a result, there is a problem that uneven film formation occurs.

  Accordingly, the present invention has been made in view of the above-described circumstances, and provides a film forming apparatus and a film forming method capable of forming a film uniformly without causing uneven film formation in a roll-type film forming apparatus. To do.

According to the first aspect of the present invention, a chamber into which a film forming material gas can be introduced, and the sheet-like substrate is disposed on the outer peripheral surface so as to be rotatable around the central axis. In a film forming apparatus comprising: a cylindrical substrate arrangement electrode; and a counter electrode arranged opposite to the outer peripheral surface of the substrate arrangement electrode, the counter electrode is grounded, and the substrate arrangement electrode By applying a low frequency AC voltage of 100 kHz or more and 2 MHz or less to the substrate, the plasma is unevenly distributed on the substrate arrangement electrode side between the substrate arrangement electrode and the counter electrode. The distance from the substrate placement electrode is greater than 25 mm .

  In this way, by applying a low frequency AC voltage of 100 kHz or more and 2 MHz or less to the cylindrical substrate placement electrode and using the counter electrode as a ground electrode, a phenomenon in which plasma discharge sticks in the vicinity of the substrate placement electrode is surely seen. There is an effect that plasma that is a decomposition source of the film forming material gas is generated only in the vicinity of the substrate, and the film can be efficiently formed on the substrate surface.

  Further, since plasma is generated only in the vicinity of the substrate arrangement electrode, the film forming material is positively formed on the substrate surface. That is, the amount of deposition material deposited on the counter electrode and the inner wall of the chamber can be reduced as compared with the conventional case where plasma is generated in substantially the entire region between the substrate arrangement electrode and the counter electrode. Therefore, since the maintenance frequency can be reduced, the production efficiency of the substrate can be improved.

  In addition, since the frequency of the voltage applied to the substrate arrangement electrode is 100 kHz or more and 2 MHz or less, the problem of plasma non-uniformity due to voltage distribution in the electrode surface due to standing waves is eliminated, and the plasma is transferred to the substrate. It can be generated only in the vicinity of the arrangement electrode, and the distance between the substrate arrangement electrode and the counter electrode can be increased. Therefore, the tolerance for physical distortion and deflection due to aging of the substrate arrangement electrode and the counter electrode is increased, and even if the distance between the substrate arrangement electrode and the counter electrode is slightly shifted, the influence on the film formation is reduced. As a result, there is an effect that the film can be uniformly formed without uneven film formation on the substrate.

  Further, since the sheet-like substrate is used and arranged so as to be along the surface of the cylindrical substrate arrangement electrode, there is an effect that film formation can be simultaneously performed while moving the sheet-like substrate. A method of alternately repeating the movement of the substrate and the film formation on the substrate can also be selected.

  And since the board | substrate arrangement | positioning electrode was comprised by the cylindrical shape so that rotation was possible, a board | substrate surface can be reliably made to contact | abut to the outer peripheral surface of a board | substrate arrangement | positioning electrode by giving appropriate tension | tensile_strength with respect to a sheet-like board | substrate. Therefore, the film can be uniformly formed on the sheet-like substrate without causing uneven film formation.

The invention described in claim 2 guides the substrate from the outside of the chamber to the outer peripheral surface of the substrate placement electrode, and guides the substrate from the outer peripheral surface of the substrate placement electrode to the outside of the chamber. A guide mechanism is provided.
With this configuration, there is no need to provide a sheet-like substrate supply unit and a film-winding unit after film formation in the chamber, and the chamber can be downsized. In addition, it is possible to provide a sheet-like substrate supply unit and a film-winding unit after film formation outside the chamber, so that even a long substrate can be formed.

According to a third aspect of the present invention, there is provided a rotation driving means for rotating the substrate arrangement electrode at a predetermined speed.
With such a configuration, the sheet-like substrate can be reliably moved along the outer peripheral surface of the substrate placement electrode, so that there is an effect that the film can be uniformly formed on the entire substrate.

The invention described in claim 4 is characterized in that a heater for heating the substrate is provided inside the substrate arrangement electrode.
By comprising in this way, the board | substrate arrange | positioned on the outer peripheral surface of a board | substrate arrangement | positioning electrode can be heated uniformly.

The invention described in claim 5 is characterized in that the counter electrode is constituted by a shower plate capable of ejecting the film forming material gas toward the substrate.
With such a configuration, since the film forming material gas can be uniformly ejected toward the substrate surface, there is an effect that the film can be uniformly formed on the substrate. In addition, since the deposition material can be prevented from adhering to a region other than the substrate surface, the maintenance frequency can be reduced.

The invention described in claim 6 is characterized in that the chamber includes a reaction chamber in which a film is formed on the substrate including at least a part of the substrate arrangement electrode and the counter electrode, and a non-reaction chamber in which the substrate flows. And the pressure in the non-reaction chamber is maintained higher than the pressure in the reaction chamber.
With such a configuration, it is possible to prevent the film forming material gas from entering the non-reaction chamber, and thus it is possible to prevent the film formation on the substrate positioned in the non-reaction chamber. Therefore, since only the substrate located in the reaction chamber can be formed, there is an effect that the film can be formed uniformly over the entire surface of the sheet-like substrate.

According to the seventh aspect of the present invention, a chamber into which the film forming material gas can be introduced, and the sheet-like substrate is disposed on the outer peripheral surface so as to be rotatable around the central axis. The counter electrode is grounded by using a film forming apparatus including a cylindrical substrate arrangement electrode and a counter electrode arranged to be opposed to each other with a predetermined distance from the outer peripheral surface of the substrate arrangement electrode, and the substrate By applying a low frequency AC voltage of 100 kHz or more and 2 MHz or less to the arrangement electrode, plasma is unevenly distributed on the substrate arrangement electrode side between the substrate arrangement electrode and the counter electrode, and the counter electrode and the substrate The substrate is deposited on the substrate while moving the substrate at a predetermined speed while rotating the substrate placement electrode in a state where the distance from the placement electrode is larger than 25 mm .

  With this configuration, the substrate can be moved without causing scratches due to friction between the cylindrical substrate placement electrode and the substrate. Therefore, there is an effect that film formation can be performed at the same time while constantly moving the substrate. In addition, since an appropriate tension can be applied to the substrate, the substrate can be reliably brought into contact with the surface of the cylindrical substrate placement electrode, so that the film can be uniformly formed without uneven film formation. is there.

  According to the present invention, by applying a low frequency AC voltage of 100 kHz to 2 MHz to a cylindrical substrate arrangement electrode and using the counter electrode as a ground electrode, a phenomenon in which plasma discharge sticks in the vicinity of the substrate arrangement electrode is observed. Therefore, plasma that is a decomposition source of the film forming material gas can be generated only in the vicinity of the substrate, and the film can be efficiently formed on the substrate surface.

  In addition, since the frequency of the voltage applied to the substrate arrangement electrode is 100 kHz or more and 2 MHz or less, the problem of plasma non-uniformity due to voltage distribution in the electrode surface due to standing waves is eliminated, and the plasma is transferred to the substrate. It can be generated only in the vicinity of the arrangement electrode, and the distance between the substrate arrangement electrode and the counter electrode can be increased. Therefore, the tolerance for physical distortion and deflection due to aging of the substrate arrangement electrode and the counter electrode is increased, and even if the distance between the substrate arrangement electrode and the counter electrode is slightly shifted, the influence on the film formation is reduced. As a result, there is an effect that the film can be uniformly formed without uneven film formation on the substrate.

  Furthermore, since the substrate arrangement electrode is configured to be cylindrical and rotatable, the substrate surface can be reliably brought into contact with the outer peripheral surface of the substrate arrangement electrode by applying an appropriate tension to the sheet-like substrate. Therefore, the film can be uniformly formed on the sheet-like substrate without causing uneven film formation.

  Next, an embodiment of the present invention will be described with reference to FIGS. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

(Deposition system)
FIG. 1 is a front sectional view of a film forming apparatus in the present embodiment, and FIG. 2 is a side sectional view of the film forming apparatus.
As shown in FIGS. 1 and 2, a film forming apparatus 10 that performs a plasma CVD method has a vacuum chamber 11 made of a conductive material such as aluminum. The vacuum chamber 11 includes a reaction chamber 15 for forming a film on a sheet-like substrate 13 and a non-reaction chamber 17 provided with a guide mechanism 16 for the substrate 13 and the like.

In the reaction chamber 15, approximately half of the circumferential direction of the rotating drum 21 for placing and moving the substrate 13 is disposed. The rotating drum 21 is formed in a substantially cylindrical shape. That is, the hollow portion 51 is formed inside the rotary drum 21. The rotating drum 21 is made of a conductive material such as aluminum.
The rotating drum 21 is held so as to be rotatable with respect to the vacuum chamber 11. That is, the rotary drive device 43 such as a motor is connected to the rotary drum 21 via the power transmission means 44 such as a belt, and is configured to be able to rotate the rotary drum 21 at a predetermined speed.

  An RF power source (low frequency power source) 41 provided outside the vacuum chamber 11 is electrically connected to the rotating drum 21 by a metal brush (not shown). With this configuration, the voltage from the RF power source 41 can always be applied to the rotating drum 21 even when the rotating drum 21 rotates. That is, the substrate arrangement electrode is constituted by the rotary drum 21.

  It should be noted that a means for preventing relative movement between the rotating drum 21 and the substrate 13 may be provided so that the substrate 13 disposed on the outer peripheral surface 55 can reliably move at a predetermined speed as the rotating drum 21 rotates. . Specifically, a sprocket is formed on the outer peripheral surface 55 of the rotating drum 21, and an engagement hole that engages with the sprocket is formed in the substrate 13, so that the substrate 13 can move together with the rotating drum 21. You may comprise.

  The hollow portion 51 of the rotating drum 21 is provided with a substantially cylindrical heater 52. The central axis of the heater 52 is arranged coaxially with the central axis of the rotary drum 21. The heater 52 is fixed to the vacuum chamber 11, and a gap is formed between the outer peripheral surface 53 of the heater 52 and the inner peripheral surface 54 of the rotating drum 21. In other words, the rotating drum 21 is heated by the radiant heat from the heater 52, and the substrate 13 can be heated by transferring heat from the rotating drum 21.

  The heater 52 is formed of a conductive material such as an aluminum alloy. Further, the heater 52 is held at the ground potential similarly to the vacuum chamber 11. The heater 52 includes a heater cable 57 therein, and the heater cable 57 is connected to a power source (not shown) outside the vacuum chamber 11 so that the temperature is adjusted.

  A counter electrode is arranged at a predetermined distance from the outer peripheral surface 55 of the rotating drum 21. Here, the counter electrode is configured as a shower plate 22. The shower plate 22 is made of a conductive material such as aluminum. The inner wall of the wall portion 23 of the vacuum chamber 11 in the reaction chamber 15 is formed so as to leave a predetermined distance from the shower plate 22. That is, a space 25 is formed between the wall 23 of the vacuum chamber 11 and the shower plate 22. A connecting member 24 made of a conductive material is provided between the wall 23 of the vacuum chamber 11 and the shower plate 22. That is, the wall portion 23 of the vacuum chamber 11 and the shower plate 22 are electrically connected via the connection member 24.

A gas introduction pipe 31 is connected to the space portion 25 of the vacuum chamber 11, and a film forming gas (for example, SiH ₄ ) is supplied from the film forming material gas supply portion 32 provided outside the vacuum chamber 11 to the space portion 25. It is configured to supply.

  The shower plate 22 is provided with a number of gas jets 26 so that the film forming material gas introduced into the space 25 is jetted from the gas jets 26 into the reaction chamber 15 of the vacuum chamber 11. It is configured. Further, the shape of the gas outlet 26 and the space portion 25 is configured so that the film forming gas can be uniformly ejected onto the surface of the substrate 13.

  Further, an exhaust pipe 33 is connected to the reaction chamber 15 of the vacuum chamber 11, and a vacuum pump 34 is provided at the tip thereof, so that the inside of the reaction chamber 15 of the vacuum chamber 11 can be in a reduced pressure state. It is configured as follows.

  Further, a cleaning gas introduction pipe 37 is connected to the reaction chamber 15 of the vacuum chamber 11. The gas introduction pipe 37 is provided with a fluorine gas supply unit 38 and a radical source 39, the fluorine gas supplied from the fluorine gas supply unit 38 is decomposed by the radical source 39, and the fluorine radicals thereby are converted into the vacuum chamber 11. It is configured to be supplied to the film formation space in the reaction chamber 15.

  The substrate 13 is disposed so as to be in close contact with the outer peripheral surface 55 of the rotary drum 21 in the reaction chamber 15. If the board | substrate 13 is arrange | positioned on the outer peripheral surface 55 of the rotating drum 21, the board | substrate 13 and the shower plate 22 are comprised so that it may mutually adjoin and may be located in parallel.

  Next, the non-reaction chamber 17 is provided with a guide mechanism 16 composed of a roller for transferring the sheet-like substrate 13. The guide mechanism 16 includes a first guide roller 16a for guiding the substrate 13 transferred from a roll chamber (not shown) to the reaction chamber 15, and a first guide roller 16 for feeding the substrate formed in the reaction chamber 15 to the roll chamber. It consists of two guide rollers 16b. The configuration of the guide mechanism 16 is not limited to the case where two guide rollers are used, and any configuration that can transfer the substrate 13 may be used.

  A gas introduction pipe 61 is connected to the non-reaction chamber 17. The gas introduction pipe 61 is provided with a gas supply unit 62 composed of argon gas or the like, and the gas supplied from the gas supply unit 62 is supplied into the non-reaction chamber 17, so that the non-reacting chamber 17 can be used during the film forming process. The pressure in the reaction chamber 17 is configured to be higher than the pressure in the reaction chamber 15. That is, since the film forming material gas can be prevented from entering the non-reaction chamber 17, it is possible to prevent the film formation on the substrate 13 located in the non-reaction chamber 17.

  An insulating portion 65 made of an insulating material such as ceramic is provided at the boundary between the non-reaction chamber 17 and the reaction chamber 15. The insulating portion 65 is configured to block between the reaction chamber 15 and the non-reaction chamber 17 except for the portion through which the substrate 13 passes. In other words, by covering the non-reaction chamber 17 side of the rotary drum 21 to which the AC voltage is applied with the insulating portion 65, it is possible to prevent the occurrence of abnormal discharge in the non-reaction chamber 17.

(Function)
Next, the operation of forming a film on the sheet-like substrate 13 using the film forming apparatus 10 will be described.
First, the substrate 13 is pulled out from the roll of the sheet-like substrate 13 prepared in a roll chamber (not shown). The substrate 13 is pulled out of the film forming apparatus 10 via the first guide roller 16a of the guide mechanism 16 in the film forming apparatus 10, the rotary drum 21 and the second guide roller 16b of the guide mechanism 16, and is used for winding the roll chamber. Wind around the roll and fix. At this time, the tension is adjusted so that the substrate 13 is in close contact with the outer peripheral surface 55 of the rotary drum 21.

  A roll driving device (not shown) is provided on the roll for winding the roll chamber, and the substrate 13 is conveyed at a predetermined speed by rotating at the same rotational speed as the rotational driving device 43 of the rotary drum 21.

  After setting the substrate 13 in the vacuum chamber 11, the inside of the vacuum chamber 11 is evacuated by the vacuum pump 34, and the inside of the vacuum chamber 11 is kept in a reduced pressure state. Thereafter, the film forming material gas is introduced into the gas introduction pipe 31 from the film forming material gas supply unit 32, and the film forming material gas is supplied to the space 25. The film forming material gas supplied to the space 25 is ejected from the gas ejection port 26 of the shower plate 22 to the substrate 13 in the reaction chamber 15 of the vacuum chamber 11.

  Here, in a state where the vacuum chamber 11 is connected to the ground potential, that is, in a state where the shower plate 22 electrically connected to the vacuum chamber 11 is also held at the ground potential, the RF power source 41 is activated and the rotary drum 21 is turned on. Apply low frequency AC voltage.

  With this configuration, the rotary drum 21 functions as a substrate arrangement electrode, and the shower plate 22 functions as a counter electrode (ground electrode). The voltage applied to the rotating drum 21 is 100 kHz or more and 2 MHz or less. When the frequency of the applied voltage is smaller than 100 kHz, it is difficult to generate glow discharge between the discharge electrodes. On the other hand, if the frequency of the applied voltage is higher than 2 MHz, a phenomenon in which plasma discharge sticks in the vicinity of the rotating drum (substrate-arranged electrode) 21 hardly occurs, which is not preferable.

  FIG. 3 is an explanatory view showing the principle of the present invention. FIG. 3A shows a case where a high frequency voltage of 13.56 MHz is applied to the applied voltage (conventional method), and FIG. This shows a case where a low frequency voltage of 100 kHz to 2 MHz is applied to the applied voltage (the present invention).

  As shown in FIG. 3A, when the applied voltage to the shower plate 22 as the application electrode is a high frequency, the glow occurs in substantially the entire region between the rotary drum 21 as the substrate arrangement electrode and the shower plate 22 as the counter electrode. A discharge is generated.

  That is, by applying such a high-frequency AC voltage to the shower plate 22, the film forming material gas ejected from the gas ejection port 26 of the shower plate 22 uses the shower plate 22 as a cathode and the rotating drum 21 as an anode. A glow discharge phenomenon of a capacitive coupling method (CCP method) occurs, and as a result, the film forming material gas is activated in almost the entire region between the rotary drum 21 and the shower plate 22 in the reaction chamber 15 of the vacuum chamber 11. For this reason, the radical species 40a decomposed by the glow discharge is deposited on the surface of the substrate 13 and the surface of the shower plate 22 at approximately the same amount of about 50%.

On the other hand, as shown in FIG. 3B, when the applied voltage to the rotary drum 21 as the application electrode is set to a low frequency , the rotary drum 21 side, that is, the rotation between the rotary drum 21 and the shower plate 22 is rotated. plasma is unevenly distributed by glow discharge in the vicinity of the drum 21, thereby, radical species 40b near the rotary drum 21 is bonded Ri attached phenomena observed.

  That is, by applying such a low-frequency AC voltage to the rotating drum 21, the film forming material gas ejected from the gas outlet 26 of the shower plate 22 uses the rotating drum (substrate arrangement electrode) 21 as a cathode and the shower. A capacitive coupling type (CCP type) glow discharge phenomenon in which the plate (counter electrode) 22 is used as an anode occurs, whereby a film forming material is formed in the space between the rotating drum 21 and the shower plate 22 in the reaction chamber 15 of the vacuum chamber 11. The gas is activated.

  The substrate 13 is heated in advance to a predetermined temperature (200 to 450 ° C.) by the heater 52 in the vacuum chamber 11. When the activated film forming material gas reaches the surface of the substrate 13, the film forming material gas is heated. React to deposit reaction products on the surface of the substrate 13. In consideration of the discharge stability and the deposition rate, it is preferable to set the pressure in the vacuum chamber 11 to 10 Pa to 500 Pa with the deposition material gas introduced.

  Thus, when the voltage applied to the rotating drum (substrate placement electrode) 21 that is the application electrode is a low-frequency AC voltage, plasma due to glow discharge is unevenly distributed near the rotating drum 21 toward the rotating drum 21. The substrate 13 can be formed.

  Here, in this embodiment, since the sheet-like substrate 13 is transferred by the guide mechanism 16 including the rotary drum 21 and the roller, film formation can be performed while the substrate 13 is being transferred. In addition, since the outer shape of the rotating drum 21 that contacts the substrate 13 is circular, no gap is formed at the contact portion between the substrate 13 and the rotating drum 21, and the substrate 13 is surely attached to the outer peripheral surface of the rotating drum 21. 55 abuts. On the other hand, for example, when a film is formed while the substrate is transferred onto a substrate arrangement electrode made of a flat plate, a gap is formed between the substrate arrangement electrode and the substrate, and the substrate and the substrate arrangement electrode are arranged at the peripheral portion of the substrate arrangement electrode. May rub against each other and scratches may be formed on the substrate. Therefore, when film formation is performed simultaneously with the substrate 13 being transferred, the rotating drum 21 may be used as in the present embodiment.

  In addition, after the surface of the substrate 13 on which the film 13 is not formed is positioned in the reaction chamber 15 and the conveyance of the substrate 13 is stopped, film formation is performed on the substrate 13. It is also possible to adopt a method of carrying out film formation by transporting the substrate 13 to the side and positioning the surface of the substrate 13 on which no film is formed in the reaction chamber 15.

  Further, the transport driving force for transporting the substrate 13 is not limited to the configuration of the above-described embodiment, but when a power source is provided in the guide mechanism 16 or when only a rotary drum 21 is provided, only a roll chamber (not shown) is used. However, in any case, any configuration may be used as long as the substrate 13 can be reliably transported.

  Further, when film formation is performed on the substrate 13 in the reaction chamber 15, the non-reaction chamber 17 is held at a positive pressure with respect to the reaction chamber 15 so that the film forming material gas does not flow into the non-reaction chamber 17. . In order to maintain the non-reaction chamber 17 in a positive pressure state, a gas such as argon is supplied from the gas supply unit 62 connected to the non-reaction chamber 17 into the non-reaction chamber 17 through the gas introduction pipe 61. With this configuration, no film is formed on the substrate 13 located in the non-reaction chamber 17, and the film is formed only on the substrate 13 in the reaction chamber 15.

  When the film formation on the substrate 13 is repeated several times, the film forming material adheres to the inner wall surface of the vacuum chamber 11 and the like, so that the inside of the vacuum chamber 11 is periodically cleaned. For cleaning the inside of the vacuum chamber 11, fluorine gas is supplied to the radical source 39 from a fluorine gas supply unit 38 provided in the cleaning gas introduction pipe 37. Fluorine gas is decomposed by the radical source 39, and the resulting fluorine radicals are supplied to the film formation space in the vacuum chamber 11 to cause a chemical reaction, thereby removing deposits.

Example 1
A case where an amorphous silicon film is formed on a sheet-like substrate by the film forming apparatus 10 will be described.
The RF applied voltage to the substrate placement electrode was 4800W. Further, as the film forming gas, SiH ₄ (monosilane) was used at a flow rate of 30 slm. The distance between the discharge electrodes was 50 mm.
Furthermore, the film forming temperature was 200 to 300 ° C., and the frequency of the applied voltage was 100 kHz to 2 MHz.

In this example, when the source gas is discharged using only SiH ₄ , if the frequency of the applied voltage exceeds 2 MHz, a phenomenon of plasma sticking to the substrate arrangement electrode side which is an applied electrode, which is a feature of the present invention, is observed. I can't. For this reason, it seems that the frequency needs to be 2 MHz or less.
On the other hand, when the frequency of the applied voltage is lower than 100 kHz, it becomes difficult to match the power source power and the discharge load, and the discharge phenomenon is not observed.
When discharging was performed in the frequency range of 100 kHz to 2 MHz, the ratio between the conductivity during light irradiation and the conductivity during non-light irradiation, which is a measure of amorphous silicon performance, showed a substantially constant value. This value is substantially equivalent to the case where the frequency of the applied voltage is 13.56 MHz, which is a high frequency, and the effect of the present invention could be confirmed by this example.

When the film formation temperature was lower than 200 ° C., the amorphous silicon became a non-uniform film and could not be evaluated.
On the other hand, when the film forming temperature was 200 ° C. or higher, it was confirmed that the performance was improved as the temperature was increased, but due to the performance limitation of the substrate heating function, performance evaluation at higher temperatures could not be performed.

(Example 2)
Next, a PIN type solar cell was prepared by the following procedure.
The substrate surface temperature was controlled at 200 ° C.
On this substrate, an ITO film was formed as a transparent conductive film using another film forming apparatus. In addition to the ITO film, another transparent oxide conductive film such as a ZnO film may be formed.

According to the method of the present invention, a p-layer is formed on the above-described substrate using monosilane and diborane (B ₂ H ₆ ), and then an i-layer is formed using monosilane. Further, monosilane and phosphine (PH ₃ ) To form an n layer.
In this case, the film thickness was 20 nm for the p layer, 300 nm for the i layer, and 50 nm for the n layer.
After this film formation, a pattern electrode made of aluminum was formed using another film forming apparatus for electrode formation.
When the PIN solar cell device manufactured in this way was irradiated with light, a voltage was generated between the electrodes, and it was confirmed that it functions as a solar cell.

  According to the present embodiment, the vacuum chamber 11 into which the film forming material gas can be introduced, and the sheet-like substrate 13 is disposed on the outer peripheral surface 55 so as to be rotatable around the central axis. In a film forming apparatus 10 including a formed cylindrical rotating drum (substrate arrangement electrode) 21 and a shower plate (counter electrode) 22 arranged to face each other at a predetermined distance from the outer peripheral surface 55 of the rotation drum 21. The shower plate 22 is grounded, and a low frequency AC voltage of 100 kHz to 2 MHz can be applied to the rotating drum 21.

  Thus, by applying a low-frequency AC voltage of 100 kHz or more and 2 MHz or less to the cylindrical rotating drum (substrate placement electrode) 21 and using the shower plate (counter electrode) 22 as the ground electrode, the vicinity of the rotating drum 21 is ensured. Therefore, plasma that is a decomposition source of the film forming material gas can be generated only in the vicinity of the substrate 13 and can be efficiently formed on the substrate surface.

  In addition, since the plasma is generated only in the vicinity of the rotary drum 21, the film forming material is positively formed on the surface of the substrate 13. That is, the amount of deposition material deposited on the counter electrode and the inner wall of the chamber can be reduced as compared with the conventional case where plasma is generated in substantially the entire region between the substrate arrangement electrode and the counter electrode. Therefore, since the maintenance frequency can be reduced, the production efficiency of the substrate 13 can be improved.

  In addition, since the frequency of the voltage applied to the rotating drum 21 is lower than the conventional frequency of 100 kHz to 2 MHz, the problem of plasma non-uniformity due to the voltage distribution in the electrode surface due to the standing wave is eliminated, and the plasma is rotated. It can be generated only in the vicinity of the drum 21 and the distance between the rotating drum 21 and the shower plate 22 can be increased. Therefore, tolerances for physical distortion and deflection due to aging of the rotating drum 21 and the shower plate 22 are also increased, and even if the distance between the rotating drum 21 and the shower plate 22 is slightly deviated, the influence on the film formation is small. Become. As a result, it is possible to form a film uniformly on the substrate 13 without causing uneven film formation.

  Furthermore, since the sheet-like substrate 13 is used and arranged along the outer peripheral surface 55 of the cylindrical rotating drum 21, film formation can be performed simultaneously while moving the sheet-like substrate 13. Here, when the substrate arrangement electrode is configured by the rotary drum 21 as in the present embodiment, it is caused by rubbing the substrate arrangement electrode against the substrate 13 when simultaneously forming a film while conveying the sheet-like substrate 13. The generation of scratches can be prevented, and no gap is formed between the substrate 13 and the substrate placement electrode, so that the substrate 13 can be uniformly formed. It is more preferable to take measures for preventing relative movement between the substrate 13 and the substrate placement electrode. A method of alternately repeating the movement of the substrate 13 and the film formation on the substrate 13 can also be selected.

  And since the board | substrate arrangement | positioning electrode was comprised with the rotating drum 21 which can be rotated cylindrically, the board | substrate 13 is made to contact | abut to the outer peripheral surface 55 of the rotating drum 21 reliably by giving appropriate tension | tensile_strength with respect to the sheet-like board | substrate 13. be able to. Therefore, the film can be uniformly formed on the sheet-like substrate 13 without causing uneven film formation.

A guide mechanism 16 that guides the substrate 13 from the outside of the vacuum chamber 11 to the outer peripheral surface 55 of the rotary drum 21 and guides the substrate 13 from the outer peripheral surface 55 of the rotary drum 21 to the outside of the vacuum chamber 11. Prepared.
Since it comprised in this way, it becomes unnecessary to provide the supply part of the sheet-like board | substrate 13, and the winding-up part after film-forming in the vacuum chamber 11, and the vacuum chamber 11 can be reduced in size. Further, it is possible to provide a sheet-like substrate 13 supply unit and a film-winding unit outside the vacuum chamber 11, and even a long substrate 13 can be formed.

Moreover, the rotary drive device 43 which rotationally drives the rotary drum 21 at a predetermined speed is provided.
Since it comprised in this way, the sheet-like board | substrate 13 can be reliably moved along the outer peripheral surface 55 of the rotating drum 21, and it can form into a film uniformly on the whole board | substrate 13. FIG.

Further, a heater 52 for heating the substrate 13 is provided inside the rotary drum 21.
Since it comprised in this way, the board | substrate 13 arrange | positioned on the outer peripheral surface 55 of the rotating drum 21 can be heated uniformly.

Further, the counter electrode was constituted by a shower plate 22 capable of ejecting a film forming material gas toward the substrate 13.
Since it comprised in this way, the film-forming material gas can be ejected uniformly toward the substrate 13 surface, and it can form into a film uniformly on the board | substrate 13. FIG. Further, since the deposition material can be prevented from adhering to a region other than the surface of the substrate 13, the maintenance frequency can be reduced.

Furthermore, the non-reaction chamber in which the vacuum chamber 11 is provided with a reaction chamber 15 that includes a substantially half of the circumferential direction of the rotary drum 21 and the shower plate 22 and forms a film on the substrate 13 and a guide mechanism 16 that guides the substrate 13. 17 so that the pressure in the non-reaction chamber 17 is kept higher than the pressure in the reaction chamber 15.
Since it comprised in this way, it can prevent that the film-forming material gas enters into the non-reaction chamber 17, and it can prevent that film-forming is made | formed on the board | substrate 13 located in the non-reaction chamber 17. FIG. Therefore, since only the substrate 13 positioned in the reaction chamber 15 can be formed, the film can be uniformly formed over the entire surface of the sheet-like substrate 13.

  It should be noted that the technical scope of the present invention is not limited to the above-described embodiment, and includes those in which various modifications are made to the above-described embodiment without departing from the spirit of the present invention. That is, the specific materials, configurations, and the like given in the embodiment are merely examples, and can be changed as appropriate.

  For example, in the present embodiment, the case where the heater and the vacuum chamber are electrically connected to function as the ground electrode has been described. However, the heater and the vacuum chamber are separately grounded and function as the ground electrode. You may make it do.

It is a schematic block diagram (front sectional drawing) of the film-forming apparatus in embodiment of this invention. It is a schematic block diagram (side sectional drawing) of the film-forming apparatus in embodiment of this invention. It is explanatory drawing which shows this invention and the conventional film-forming principle, (a) is a prior art example, (b) is explanatory drawing of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Film-forming apparatus 11 ... Vacuum chamber (chamber) 13 ... Substrate 15 ... Reaction chamber 16 ... Transfer mechanism 17 ... Non-reaction chamber 21 ... Rotating drum (substrate arrangement electrode) 22 ... Shower plate (counter electrode) 52 ... Heater

Claims (7)

A chamber capable of introducing a film forming material gas;
A cylindrical substrate placement electrode disposed in the chamber and having a sheet-like substrate disposed on the outer peripheral surface so as to be rotatable about the central axis, and a predetermined distance from the outer peripheral surface of the substrate placement electrode. And a counter electrode disposed opposite to each other,
The counter electrode is grounded, and a low frequency AC voltage of 100 kHz to 2 MHz is applied to the substrate placement electrode ,
Plasma is unevenly distributed on the substrate arrangement electrode side between the substrate arrangement electrode and the counter electrode ,
A plasma CVD film-forming apparatus , wherein a distance between the counter electrode and the substrate arrangement electrode is greater than 25 mm . A guide mechanism for guiding the substrate from the outside of the chamber to the outer peripheral surface of the substrate placement electrode and guiding the substrate from the outer peripheral surface of the substrate placement electrode to the outside of the chamber; The plasma CVD film forming apparatus according to claim 1. The plasma CVD film forming apparatus according to claim 1, further comprising a rotation driving unit that rotates the substrate arrangement electrode at a predetermined speed. The plasma CVD film forming apparatus according to any one of claims 1 to 3, further comprising a heater for heating the substrate inside the substrate arrangement electrode. 5. The plasma CVD film forming apparatus according to claim 1, wherein the counter electrode is configured by a shower plate capable of ejecting the film forming material gas toward the substrate. The chamber includes a reaction chamber that includes at least a part of the substrate arrangement electrode and the counter electrode to form a film on the substrate, and a non-reaction chamber in which the substrate flows.
6. The plasma CVD film forming apparatus according to claim 1, wherein the pressure in the non-reaction chamber is maintained at a pressure higher than the pressure in the reaction chamber. A chamber capable of introducing a film forming material gas;
A cylindrical substrate placement electrode disposed in the chamber and having a sheet-like substrate disposed on the outer peripheral surface so as to be rotatable about the central axis, and a predetermined distance from the outer peripheral surface of the substrate placement electrode. And a counter electrode disposed opposite to each other,
By grounding the counter electrode and applying a low frequency AC voltage of 100 kHz to 2 MHz to the substrate placement electrode,
Plasma is unevenly distributed on the substrate arrangement electrode side between the substrate arrangement electrode and the counter electrode,
In a state where the distance between the counter electrode and the substrate arrangement electrode is larger than 25 mm,
A plasma CVD film forming method comprising forming a film on a substrate while rotating the substrate arrangement electrode while moving the substrate at a predetermined speed.

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