JP2010199309A - Plasma processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing device capable of suppressing adverse effect on a substrate, and sufficiently confining plasma. <P>SOLUTION: A gas to be made into plasma is supplied between a pair of electrodes 54 and 56 across which a high frequency voltage is applied, and the substrate 2 is arranged along the surface of one electrode 54. A plasma confining portion 65 is provided on a flow channel of the gas discharged from between the electrodes 54 and 56. The plasma confining portion 65 has a pair of magnet portions 60 wherein S-poles 58S and N-poles 58N are alternately arranged in a row in the direction crossing to a gas flow A on the surface. In the pair of magnet portions 60, the S-poles 58S and the N-poles 58N are arranged opposite to each other so that the gas flows between the pair of magnet portions 60. The plasma confining portion 65 further includes a block 59 preventing circulation of gas between a boundary of the S-pole 58S and the N-pole 58N of one magnet portion 60 and a boundary of the S-pole 58S and the N-pole 58N of the other magnet portion 60. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus.

  2. Description of the Related Art Conventionally, there is known a plasma processing apparatus in which a gas to be converted into plasma is supplied between a pair of electrodes to which a high-frequency voltage is applied, and a substrate disposed along the surface of one electrode is processed by this plasma. . In such a plasma processing apparatus, a reaction product can be deposited on the substrate by using a CVD source gas as a gas, or a material on the substrate can be etched by using an etchant source gas as a gas. .

  In such a plasma processing apparatus, it is necessary to discharge the processed gas from between the electrodes to the outside. At this time, it is necessary to confine between the electrodes without discharging the plasma. As a plasma confinement part that realizes this, it is disclosed that an electrostatic slit is arranged in a gas discharge channel as in Patent Documents 1 and 2, or a punching metal or a metal mesh is used as in Patent Document 3. Has been.

JP 2008-184661 A JP 2002-066404 A JP 2001-335948 A

  However, in the above-mentioned plasma confinement part, it is often necessary to make the slit interval and the hole interval considerably small, and the powder confinement is clogged by the powder generated by the plasma treatment, and this powder is The powder may not be discharged well, and this powder may deteriorate the characteristics of the plasma-treated substrate.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a plasma processing apparatus capable of suppressing adverse effects on a substrate and sufficiently confining plasma.

  The plasma processing apparatus according to the present invention is a plasma processing apparatus in which a gas to be converted into plasma is supplied between a pair of electrodes to which a high-frequency voltage is applied, and a substrate is disposed along the surface of one of the electrodes. Thus, a plasma confining portion is provided in the flow path of the gas discharged from between the electrodes. And a plasma confinement part has a pair of magnet part by which the south pole and the north pole were alternately arrange | positioned in a line in the direction which cross | intersects the flow of gas on the surface. Here, the pair of magnet parts are arranged so that the S pole and the N pole face each other, and the gas flows between the pair of magnet parts. In addition, the plasma confinement unit further includes a block that prevents gas flow between the boundary between the S pole and the N pole of one magnet unit and the boundary between the S and N poles of the other magnet unit. Have.

  According to the present invention, the discharged gas passes between the south pole and the north pole of a pair of magnet portions facing each other, so that a magnetic field in a direction crossing the gas flow is applied to the gas, and the exhaust gas is discharged. The plasma in the gas to be trapped is confined. Further, since the S pole and the N pole are alternately arranged in each magnet portion, the magnetic flux leaking to the outside can be reduced, and abnormal discharge (micro discharge) in an unintended place is suppressed. Furthermore, between the S pole and N pole boundary part of one magnet part and the S pole and N pole boundary part of the other magnet part, the gas flow is crossed by the magnetic flux from both magnetic poles. Although the magnetic field in the direction becomes weak and it is difficult to confine the plasma, the plasma can be confined more efficiently by having a block in this part. Furthermore, since the opening width in the plasma confinement portion can be increased as compared with the conventional case where slits or nets are used as the plasma confinement portion, the accumulation of particles in the flow path of the plasma confinement portion is suppressed. . Accordingly, it is possible to stably discharge the particles to the outside for a long time, and it is possible to stably prevent the particles from being mixed into the film for a long time.

  Here, the substrate is a long flexible substrate, and is supplied in the longitudinal direction of the flexible substrate along the surface of one of the electrodes, and a magnetic shield is provided between the flexible substrate and the magnet portion. It is preferable to further provide.

  Thereby, the magnetic field applied to a board | substrate can be reduced and the pinhole formed in a board | substrate etc. by abnormal discharge can be reduced more.

  The gas is a CVD source gas, and it is preferable that the reaction product is deposited on the substrate.

  ADVANTAGE OF THE INVENTION According to this invention, the plasma processing apparatus which can suppress the bad influence with respect to a board | substrate and can fully confine | separate plasma can be provided.

FIG. 1 is a schematic diagram showing an overall configuration of a film forming system according to the present invention. FIG. 2 is a schematic sectional view (corresponding to Example 1) of the N chamber, the I chamber, and the P chamber of FIG. 3 is a view taken in the direction of arrows III-III in FIG. FIG. 4 is a modification of FIG. 3 (corresponding to Example 2). FIG. 5 is a schematic cross-sectional view showing one embodiment of a solar cell. FIG. 6 is a distribution of magnetic flux density along line III-III in FIG. 2 for the plasma confinement portion of the first embodiment. FIG. 7 shows the distribution of magnetic flux density immediately above the substrate 2 as seen from V in FIG. 8 is a view taken along the line III-III of FIG. 2 with respect to the plasma confinement portion of Comparative Example 1. FIG. FIG. 9 is a distribution of magnetic flux density along the line III-III in FIG. 2 for the plasma confinement portion of Comparative Example 1. FIG. 10 is a magnetic flux density distribution immediately above the substrate 2 as viewed from V in FIG. 2 for the plasma confinement portion of the comparative example. FIG. 11 is a schematic cross-sectional view of the N chamber, I chamber, and P chamber of Comparative Example 2. FIG. 12 is a schematic cross-sectional view of the N chamber, I chamber, and P chamber of Comparative Example 3. FIG. 13 is a graph showing the open circuit voltage of the solar cell sampled at each film formation distance for Example 1 and Comparative Examples 1 to 3.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a film forming system 100 including an N chamber 50a, an I chamber 50b, and a P chamber 50c as a plasma CVD apparatus (plasma processing apparatus). The film forming system 100 in the present embodiment is used for forming an amorphous silicon film on a flexible substrate 2 by a so-called roll-to-roll method in manufacturing a so-called amorphous silicon thin film solar cell.

  The film forming system 100 mainly includes a feeding chamber 10, a pretreatment chamber 12, an N chamber 50 a, an I chamber 50 b, a P chamber 50 c, a post treatment chamber 13, and a winding chamber 20.

  In the feeding chamber 10, the flexible substrate 2 that has been previously wound in a roll shape around the bobbin 1 is fed out. The flexible substrate 2 fed from the feeding chamber 10 is supplied to the winding chamber 20 after passing through the pretreatment chamber 12, the N chamber 50a, the I chamber 50b, the P chamber 50c, and the posttreatment chamber 13, and is wound up. The bobbin 1 in the chamber 20 is wound up in a roll shape.

  In the pretreatment chamber 12, an electrode 14 and an electrode 16 connected to a high frequency power source 18 are disposed, and a discharge cleaning process is performed on the flexible substrate.

  The N chamber 50a, the I chamber 50b, and the P chamber 50c are respectively a plasma CVD apparatus (plasma processing apparatus) for forming an n-type amorphous silicon thin film, an i-type amorphous silicon thin film, and a p-type amorphous silicon thin film on the flexible substrate 2. ), And a grounded electrode 54 and an electrode 56 to which the high-frequency power source 19 is connected are disposed. The flexible substrate 2 is configured to pass between the electrode 54 and the electrode 56 in the longitudinal direction of the flexible substrate 2. In particular, the flexible substrate 2 is disposed on the surface of one electrode 54. It is supposed to move along.

  A buffer chamber is provided between the pretreatment chamber 12 and the N chamber 50a, between the N chamber 50a and the I chamber 50b, between the I chamber 50b and the P chamber 50c, and between the P chamber 50c and the posttreatment chamber 13. 30 are arranged respectively. The buffer chamber 30 is a chamber for suppressing gas mixing between the chambers, and a small amount of inert gas is supplied from the inert gas source IN so that gas from each chamber does not flow. It is also possible to suppress gas mixing between the respective chambers by supplying high vacuum evacuation of the gas in the buffer chamber 30 without supplying the inert gas to the buffer chamber 30. The space from the feeding chamber 10 to the winding chamber 20 is maintained in a reduced pressure state by the pump 15.

As the raw material gas for CVD reaction is N chamber 50a, for example, a gas containing a SiH ₄ and dopant example phosphine (PH ₃₎ is, in the I chamber 50b is gas including SiH _4, SiH the P chamber 50c ₄ and a gas containing diborane (B ₂ H ₆ ) serving as a dopant are supplied from each gas source GI. Further, the gas after reaction in the N chamber 50a, the I chamber 50b, and the P chamber 50c is discharged out of the system from each chamber by the gas recovery device GO.

  In the post-processing chamber 13, an electrode 14 and an electrode 16 connected to a high-frequency power source 18 are disposed, and a discharge process is performed on the film formation surface.

  Next, details of the N chamber 50a, the I chamber 50b, and the P chamber 50c, which are plasma CVD apparatuses, will be described in detail with reference to FIGS. Here, the N chamber 50a will be described as an example, but the I chamber 50b and the P chamber 50c are the same as the N chamber 50a.

  The N chamber 50a includes a grounded electrode 54 functioning as an anode side, an electrode 56 functioning as a cathode side and connected to the high frequency power source 19, a supply pipe 52 for supplying a source gas, and a reaction in the decompression vessel 51. It mainly includes a discharge pipe 53 for discharging the subsequent gas.

  The electrode 54 and the electrode 56 each have a flat plate shape and are disposed horizontally so as to face each other. As described above, the flexible substrate 2 is transported in the longitudinal direction along the electrode 54 that is one of the electrodes. That is, the flexible substrate 2 passes through a position close to the electrode 54 between the electrode 54 and the electrode 56.

  Although the distance of the electrode 54 and the flexible substrate 2 is not specifically limited, For example, it can be set as about 1 mm-5 mm.

  The supply pipe 52 is disposed on the upstream side in the conveyance direction of the flexible substrate 2 (from left to right in FIG. 2), and gas from the gas source GI is passed between the electrode 54 and the electrode 56 and is flexible. The substrate 2 is fed in the transport direction.

A gas dispersion plate 57 is provided at the gas outlet of the supply pipe 52. The gas dispersion plate 57 has a plurality of slits 57b for horizontally dispersing the source gas from the supply pipe 52 to the plasma formation region P between the electrodes. The width of the slit 57b is not particularly limited. However, in order to prevent the plasma from leaking from the plasma forming region P into the supply pipe 52, the width is set to be equal to or smaller than the Debye length λ _{D of} the plasma existing in the vicinity of the gas outlet 57d of the slit 57b. It is preferable. The gas dispersion plate 57 may be formed with a large number of holes.

  Further, as shown in FIG. 2, the discharge pipe 53 is arranged in the conveyance direction of the flexible substrate 2 and discharges the gas between the electrode 54 and the electrode 56 to the outside, that is, outside the decompression vessel 51. A particle collection device GO for collecting particles is connected to the downstream side of the discharge pipe 53.

  The exhaust pipe 53 is formed so as to collect gas that has passed through a plasma confining portion 65 (to be described later), guide the gas in the horizontal direction for a while, and then guide the gas downward.

  As shown in FIGS. 2 and 3, the plasma confining portion 65 mainly includes a pair of magnet portions 60, a block 59, and a magnetic shield 62.

  As shown in FIG. 3, each magnet unit 60 has a plurality of magnets 58. In each magnet part 60, a plurality of magnets 58 are arranged on the surface of the magnet part 60 in a direction in which the S pole 58 S and the N pole 58 N of each magnet 58 intersect the gas flow direction (Z direction) (here, further with the substrate 2. (Horizontal direction) are alternately arranged in a line. The pair of magnet parts 60 are disposed so that the S pole 58S and the N pole 58N face each other, and a flow path FP through which a gas flows is formed between the pair of magnet parts 60.

  The magnet 58 is not particularly limited. For example, a ferrite magnet, a samarium-cobalt (SmCo) -based magnet, a neodymium (Nd) -based magnet, or the like can be used. Here, the magnetic flux density formed between the magnet parts 60 does not have to be such a strength Bz that the fully magnetized plasma condition, that is, the condition in which the electrons do not collide with the neutral gas while making a round of the magnetic field lines. . The magnetic flux density is preferably 1/10 or more of the magnetic flux density Bz that is a fully magnetized plasma condition. For example, when the pressure is 133 Pa, the magnetic flux density Bz that is a fully magnetized plasma condition is about 10 kG.

  The form of each magnet 58 is not particularly limited, but it is preferable to use a plate-like magnet magnetized in the thickness direction (Y direction) as shown in FIG.

  The size of the magnet 58 is not particularly limited. The length of the magnet 58 in FIG. 2 in the gas flow direction (Z direction) may be adjusted to a length that can sufficiently confine the plasma, for example, 40 mm at a pressure of 100 to 200 Pa. The length of the magnet 58 in the X direction (film width direction) and the interval between the magnet parts 60 (Y direction) are intended to prevent the flow path FP from being blocked due to accumulation of particles generated by plasma formation for a long time. The length can be set to, for example, 8 mm or more, preferably 20 mm.

  Returning to FIG. 3, the block 59 is provided between the boundary portion between the S pole 58S and the N pole 58N of one magnet portion 60 and the boundary portion between the S pole 58S and the N pole 58N of the other magnet portion 60. The flow of gas between the boundaries. The material of the block 59 is not particularly limited as long as it is a nonmagnetic material, and may have sufficient rigidity. Specifically, nonmagnetic stainless steel is mentioned.

  The size of the block 59 is not particularly limited, but covers a portion that is less than 1/10 of the magnetic flux density Bz, which is a fully magnetized plasma condition. For example, if the pressure is 133 Pa, the portion where the magnetic flux density is less than 750 G is covered. It is preferable to make it. For example, at a pressure of 100 to 200 Pa, the length of the block 59 in the X direction (film width direction) can be set to 13 mm, for example. The height of the block 59 in the Y direction is preferably the same as the interval between the magnet parts 60. Also, the length of the block 59 in FIG. 2 in the gas flow direction (Z direction) is preferably equal to or longer than the length of the magnet 58.

  The magnetic shield 62 is provided so as to surround the magnet portion 60 and the block 59 around the Z-axis direction, and leakage of magnetic flux from the magnet portion 60 to the outside, in particular, magnetic flux from the magnet portion toward the substrate 2. This suppresses the leakage. The material of the magnetic shield may be a soft magnetic material, for example, pure iron. Although the thickness of the magnetic shield 62 is not particularly limited, it is preferable that the magnetic flux leakage on the substrate is 40 G or less, more preferably 30 G or less.

  The material of the gas dispersion plate 57 is not particularly limited. For example, a ceramic material such as alumina, a resin material such as quartz, a glass material, and a fluororesin can be used. Fluoropolymers include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), fluorinated ethylene propylene copolymer (FEP), tetrafluoroethylene perfluoroalkyl And vinyl ether copolymer (PFA).

  Next, the operation of the film forming system 100 including such a plasma CVD apparatus will be described.

  First, as shown in FIG. 1, a flexible substrate 2 in which a lower reflective electrode such as aluminum is formed in advance on a resin base material such as PEN from a bobbin 1 is transferred from a feeding chamber 10 to a winding chamber 20. It is conveyed to the bobbin 1 in the longitudinal direction. At this time, in the N chamber 50a, the I chamber 50b, and the P chamber 50c, an n-type amorphous silicon thin film, an i-type amorphous silicon thin film, and a p-type amorphous silicon thin film are respectively formed on the flexible substrate 2 by plasma CVD. Form a film.

  Specifically, in FIG. 2, a CVD source gas is supplied from the supply pipe 52 between the electrode 54 and the electrode 56, and a predetermined high frequency, for example, a high frequency of 13.56 MHz is provided between the electrode 54 and the electrode 56. Apply voltage. Then, plasma of the CVD source gas is generated in the plasma forming region P between the electrode 54 and the electrode 56, and an amorphous silicon thin film is formed on the flexible substrate 2. This film forming process is normally performed continuously while the flexible substrate 2 is conveyed at a predetermined speed.

  Then, the gas after the reaction flows in the conveyance direction of the flexible substrate 2 and is discharged to the outside through the discharge pipe 53.

  By the way, in the plasma formation region P, particles are inevitably generated as the source gas plasma is formed. Such particles have a small particle size of about 0.01 to several μm, for example, and are usually discharged from the plasma formation region P through the discharge pipe 53 along the gas flow.

  Here, in the present embodiment, a plasma confining portion 65 is provided at the inlet of the discharge pipe 53, and the gas discharged in a direction (Y direction) intersecting the gas flow direction by the pair of magnet portions 60. Is applied with a magnetic field. Therefore, the charged particles in the plasma are wound around the magnetic field lines, so that the plasma is confined and the plasma formed in the plasma formation region P is prevented from leaking to the discharge pipe 53. Accordingly, generation of extra particles in the discharge pipe 53 and film formation in the discharge pipe 53 are suppressed, and the cause of waste of raw material gas, fluctuation of injected power during long-time operation, and waste of power are reduced.

  Further, since the S poles 58S and the N poles 58N are alternately arranged on the back surface (shield 62 side) of each magnet portion 60, the magnetic flux leaking to the outside can be extremely reduced, and an unintended location, particularly, Abnormal discharge (micro discharge) in the vicinity of the substrate 2 is suppressed. Thereby, generation | occurrence | production of the pinhole to the film | membrane to precipitate is suppressed and the characteristic of a deposit film improves.

  Further, the boundary between the S pole 58S and the N pole 58N on the surface (flow path FP side) of one magnet portion 60 and the boundary between the S pole 58S and the N pole 58N on the surface of the other magnet portion (flow path FP side). The magnetic field in the direction intersecting the gas flow (Y direction) is weakened by the magnetic flux from the magnetic poles on both sides, making it difficult to confine the plasma. Can be performed more efficiently.

  In addition, since the opening width in the plasma confinement portion 65 can be increased as compared with the conventional case where slits or nets are used as the plasma confinement portion, particle deposition in the flow path FP of the plasma confinement portion 65 is prevented. It is suppressed. Therefore, it is possible to stably discharge particles from the plasma forming region P to the outside for a long time. Therefore, it is possible to stably suppress the mixing of particles into the film formed on the flexible substrate 2 for a long time.

  And by these synergistic effects, the film formation with few defects by plasma CVD can be performed continuously for a very long time at low cost.

  In addition, this invention is not restricted to the said embodiment, A various deformation | transformation aspect is possible.

  For example, in the above-described embodiment, the electrodes 54 and 56 are arranged to face each other in the vertical direction. However, for example, the present invention can be implemented even if the electrodes 54 and 56 are arranged to face each other in the horizontal direction.

  Further, in the above embodiment, the plasma confining portion 65 is disposed on the upstream side of the discharge pipe 53, but may be provided inside the discharge pipe 53. It is preferable from the viewpoint of suppressing plasma leakage to be disposed inside the discharge pipe 53 also on the inlet side (electrode side). Further, the form of the discharge pipe 53 is not particularly limited.

  Moreover, in the said embodiment, although the magnetic shield 62 is provided in order to suppress the leakage of the magnetic flux from the magnet part 60, the shape of the magnetic shield 62 is not specifically limited, It can implement even without the magnetic shield 62. is there.

  Moreover, in the said embodiment, although the plate-shaped magnet 58 magnetized by the thickness direction (Y direction) is used, even if it arrange | positions the magnet magnetized by the X direction in the X direction, for example, it is possible.

  In the above embodiment, the flexible substrate 2 is transported along the electrode 54, but may be transported along the electrode 56. Further, the present invention can be implemented even if the substrate is not a flexible substrate 2 but may be a hard substrate, and a continuous film is not formed on a long substrate but is formed in a batch manner on a short substrate.

  In the above embodiment, the gas flow direction is the same direction as the substrate transport direction, but it may be the opposite direction to the substrate transport direction.

  Moreover, in the said embodiment, although the NIP type photoelectric conversion film is manufactured, you may manufacture the photoelectric conversion film of other forms, such as PIN type and a tandem type, by plasma CVD as mentioned above. Needless to say.

  The plasma CVD apparatus described above can be used not only for the production of amorphous silicon thin films for solar cells but also for other plasma CVD applications such as TFTs (thin film transistors).

Furthermore, the present invention is not limited to a plasma CVD apparatus, and any apparatus that forms a plasma of a supplied gas and processes a substrate may be used. For example, the source gas is an etchant source gas (for example, NF ₃ or the like). Thus, even an apparatus that performs plasma etching can be implemented.

  Furthermore, as shown in FIG. 4, the plasma confining portion 65 may include an auxiliary magnet 158 that reinforces the magnetic field strength of a portion where the magnetic field is relatively weak in the flow path FP. The auxiliary magnets 158 are plate-shaped magnets that are respectively disposed at both ends in the X direction on the surface of the magnet 58 on the flow path FP side, are magnetized in the Y direction, and face each other across the flow path FP. Yes. The polarity of the surface on the flow path FP side of the auxiliary magnet 158 is made to be the same as the polarity of the surface on the flow path FP side of the magnet 58 provided with the auxiliary magnet 158, thereby increasing the magnetic field strength. Providing the auxiliary magnet 158 can reduce the portion with weak magnetic field strength in the vicinity of both ends of the magnet 58, and can further reduce the width of the block 59 in the X direction, thereby reducing the ventilation resistance. And particles are discharged more smoothly. The auxiliary magnet 158 is preferably made of a material having a higher magnetic flux density than the magnet 58. The auxiliary magnet 158 may be embedded at both ends of the magnet 58.

  Then, an example of the solar cell manufactured with the above-mentioned apparatus is demonstrated easily. As shown in FIG. 5, the flexible substrate 2 is obtained by forming a lower reflective electrode 2g on a base material 2f. Examples of the material of the substrate 2f include resin films such as PEN (polyethylene naphthalate) and PI (polyimide).

  Examples of the material of the lower reflective electrode 2g include metals such as aluminum, titanium, and silver.

  An n-type amorphous silicon thin film 3n, an i-type amorphous silicon thin film 3i, and a p-type amorphous silicon thin film 3p are formed in this order on the lower reflective electrode 2g, and these three constitute the photoelectric conversion layer 3. This photoelectric conversion layer 3 can be formed by the above-described film formation system.

  On the photoelectric conversion layer 3, a transparent upper electrode film 4 such as ITO is formed. The photoelectric conversion layer 3 and the lower reflective electrode 2g are divided into a plurality of regions in a direction orthogonal to the stacking direction by an insulating material layer 6 such as an epoxy resin. Correspondingly, the upper electrode film 4 is also divided into a plurality of regions by the openings 7, and each region is formed so as to straddle the two photoelectric conversion layers 3. Furthermore, a conductive portion 8 made of silver paste or the like that conducts the upper electrode film 4 and the lower reflective electrode 2g is provided in each region, and the photoelectric conversion layers 3 are connected in series.

  For example, the insulating material layer 6 can be formed by applying a resin by printing after drilling with a laser, the opening 7 can also be formed by laser, and the conductive portion 8 is irradiated with a laser after applying a conductive material by a printing method or the like. Therefore, it can be formed by roll-to-roll, batch type or the like. These processes are also called integration processes.

Example 1
As a long flexible substrate, an aluminum film having a thickness of 300 nm as a base electrode was formed on a PEN film by a DC sputtering method. On the base electrode of the flexible substrate, a photoelectric conversion layer made of an NIP bonding film made of amorphous silicon was formed to a thickness of about 700 nm using the plasma CVD apparatus described above.

The film formation conditions were SiH ₄ : H ₂ = 100 sccm: 1000 sccm, pressure 133 Pa, and input power 140 W. The thickness of each layer was N / I / P = 20 nm / 700 nm / 15 nm. At this time, the magnet portion 58 of the plasma confining portion 65 has a height of 5 mm in the Y direction, a width of 56 mm in the direction orthogonal to the gas flow (X direction in FIG. 2), and the gas flow direction (Z direction in FIGS. 1 and 2). A magnet having a rectangular parallelepiped shape with a width of 40 mm and magnets (ferrite magnets) magnetized in the Y direction, in which six S poles and N poles are arranged alternately in the X direction, this magnet portion 60 is formed with a gap of 18 mm. Opposed. Further, a SUS304 block 59 having a width in the X direction of 11 mm, a height in the Y direction of 18 mm, and a length in the Z direction of 40 mm was disposed between the boundary portions between the S pole and the N pole. Further, as the magnetic shield 62, a pure iron plate having a thickness of 5 mm was used.

  FIG. 6 shows the intensity distribution of the magnetic field at the entrance when the plasma confining portion 65 is viewed from the direction V in FIG. Further, FIG. 7 shows a distribution of the magnetic field intensity distribution in the substrate 2 immediately above the plasma confining portion 65 viewed from the VI direction of FIG. These results are simulation results.

  After the photoelectric conversion layer is continuously formed by such a plasma CVD apparatus, an ITO layer as a transparent upper electrode is formed on the photoelectric conversion layer to a thickness of 60 nm, and then drilling by laser processing and printing application of a conductive resin are performed. The solar cells were electrically connected in series with each other, and finally sealed with an insulating resin.

  The solar cell was sampled at regular intervals from the starting point of continuous film formation, and the open circuit voltage Voc was measured.

(Example 2)
As shown in FIG. 4, plasma confinement in which auxiliary magnets (samarium / cobalt magnets (REC32 (manufactured by TDK), length in the X direction is 12 mm, thickness is 2 mm)) 158 are provided at both ends of the magnet 58. In addition, by adopting the auxiliary magnet, the width in the X direction that gives a magnetic flux density Bz of less than 750 G is changed from 11 mm to 6 mm, so the width in the X direction of the block 59 is set to 6 mm. Same as Example 1.

(Comparative Example 1)
The plasma confining portion 65 is as shown in FIG. 8, that is, the same as the embodiment except that one magnet portion 58 and the other magnet portion 58 are each a single magnet.

  FIG. 9 shows the intensity distribution of the magnetic field at the entrance when the plasma confining portion 65 is viewed from the direction V in FIG. FIG. 10 shows a distribution of the magnetic field intensity distribution in the substrate 2 immediately above the plasma confining portion 65 as viewed from the VI direction of FIG. These results are simulation results.

(Comparative Example 2)
As shown in FIG. 11, the same procedure as in Example 1 was used except that a plasma confining member 58 that confined plasma by a slit 58b was used instead of a magnet. Here, a plurality of slits 58b extending in the lateral direction (X direction) are formed by providing a plurality of horizontally extending plates 58a apart from each other in the vertical direction (Y direction). The plate 58a is made of PTFE, the slit width D58 is 5 mm, the inclination angle θ of the straight line 58d connecting the upstream end 58c of the gas flow direction of the plate 58a is 20 °, and the slit flow path The length L58 was 30 mm.

(Comparative Example 3)
As shown in FIG. 12, the plates 58a arranged in the vertical direction (Y direction) are arranged apart from each other in the horizontal direction (X direction), and a plurality of slits extending in the vertical direction (Y direction) are formed. Same as Example 2. The slit width (in the X direction) was the same as in Comparative Example 2. Further, the gas flow upstream side of each plate 58a is formed by two inclined surfaces 58c and is pointed toward the upstream side, and the angle formed by the two inclined surfaces 58c in the XZ plane cross section is 40 °. is there. Further, the inclination angle θ formed by the gas flow direction of the slope formed by the front end portion 58d of the plate 58a when viewed from the horizontal direction (X direction) is 20 °.

(Evaluation)
Implemented a graph in which the distance from the start point of continuous film formation (hereinafter referred to as film formation distance) is made dimensionless by a predetermined distance and the horizontal axis is plotted, and the value obtained by dimensioning the open circuit voltage Voc by a predetermined voltage is plotted by the vertical axis. Example 1 and Comparative Examples 1, 2, and 3 are shown in FIG. The open-circuit voltage Voc on the vertical axis is required to be 0.95 or more. In addition, about the comparative example 2 and the comparative example 3, it is abbreviate | omitting about the data before an open circuit voltage falls.

  In Comparative Example 1, the open-circuit voltage decreased immediately compared to Example 1 at the time when the film formation distance slightly advanced (film formation length to 0.1). In Comparative Example 1, since single magnets are opposed to each other, the leakage magnetic field becomes large, and the leakage flux captures free electrons existing between the substrate and the magnetic shield by Lorentz force. Increases, and local micro discharge, that is, abnormal discharge occurs. As a result, it is considered that Voc immediately decreases because a pinhole is formed in the a-Si film on the negatively charged substrate surface.

  In addition, the open circuit voltage deteriorated to about 90% at the film formation distance of about 2.1 in Comparative Example 2 and about 2.2 in Comparative Example 3, whereas it was about 3.3% in Example 1. The open circuit voltage maintained 90% or more of the initial value until the membrane distance was reached. It is considered that the open-circuit voltage deteriorates with time mainly due to the incorporation of particles into the amorphous silicon film. That is, silicon particles are generated between the electrodes by plasma CVD, and most of the silicon particles are discharged to the gas recovery device GO side. When it becomes larger, it is considered that clogging occurs and particles are easily taken into the film. In Example 1 in which the plasma is confined by the magnet, the opening can be made wider than in Comparative Examples 2 and 3 in which the plasma is confined by the slit, so that the plasma confining member is not easily clogged. It is thought that clogging is difficult compared to 3.

  In Example 2, it was confirmed that the open circuit voltage was 0.95 or more until the film formation distance exceeded 3.5.

  2 ... Flexible substrate (substrate), 50a ... N chamber (plasma processing apparatus), 50b ... I chamber (plasma processing apparatus), 50c ... P chamber (plasma processing apparatus), 53 ... Discharge pipe, 54 ... Electrode, 56 ... Electrode, 58 ... Magnet, 58S ... S pole, 58N ... N pole, 59 ... Block, 60 ... Magnet part, 62 ... Magnetic shield, 65 ... Plasma confinement part.

Claims (3)

A plasma processing apparatus in which a gas to be converted into plasma is supplied between a pair of electrodes to which a high-frequency voltage is applied, and a substrate is disposed along the surface of one of the electrodes,
A plasma confining portion is provided in the flow path of the gas discharged from between the electrodes,
The plasma confining portion has a pair of magnet portions on the surface of which S poles and N poles are alternately arranged in a line in a direction intersecting the gas flow, and the pair of magnet portions are the S pole and the N pole. The poles are opposed to each other, and are arranged so that the gas flows between the pair of magnet parts,
The plasma confinement part further includes gas between a boundary part of the S pole and the N pole of one of the magnet parts and a boundary part of the S and N poles of the other magnet part. A plasma processing apparatus having a block that hinders distribution.   The substrate is a long flexible substrate, and is supplied in the longitudinal direction of the flexible substrate along the surface of one of the electrodes, and a magnetic shield is provided between the flexible substrate and the magnet unit. The plasma processing apparatus according to claim 1, further comprising:   The plasma processing apparatus according to claim 1, wherein the gas is a CVD source gas, and a reaction product is deposited on the substrate.