JP2012234950A - Silicon-based thin film production apparatus, photoelectric conversion device equipped with the same, silicon-based thin film production method and photoelectric conversion device manufacturing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon-based thin film production method and a silicon-based thin film production apparatus, which can produce a silicon-based thin film of cluster free or of a minimal cluster while inhibiting decrease in film production speed.SOLUTION: A silicon-based thin film production apparatus is an apparatus in which a material gas containing Si is supplied to the inside of a vacuum chamber in which a substrate 101 is housed and a high-frequency power is supplied to a discharge electrode 106 provided in a plasma generation part 103 to produce a silicon-based thin film on the substrate 101 by generating plasma of the material gas. The silicon-based thin film production apparatus comprises a cluster removal part 104 arranged between the substrate 101 and the discharge electrode 106. The cluster removal part 104 includes a plurality of openings in such a way that an opening ratio is 50% and over. The openings communicate the plasma generation part side and the substrate side. An opening width of the opening is not more than twice a mean free path of an Si nanocluster under a pressure in film production, and a length of the opening is not less than twice the opening width.

Description

  The present invention relates to a silicon-based thin film forming apparatus and film forming method, and a photoelectric conversion device manufacturing apparatus and manufacturing method, and more particularly to a thin-film silicon solar cell using silicon as a power generation layer.

  When forming a silicon-based thin film using plasma, Si particles (Si clusters) generated in the silane plasma with a size of about 10 nm or less may be closely related to the photodegradation of the silicon-based thin film. Has been suggested. Specifically, when Si clusters are taken into the film, Si—Hx (x ≧ 2) bonds are formed, and photodegradation of hydrogenated amorphous silicon (hereinafter a-Si: H) is induced. In order to solve this problem, a method of forming a silicon-based thin film by removing clusters with a cluster filter has been proposed (see Patent Document 1).

  FIG. 26 shows an amorphous silicon-based thin film deposition apparatus described in Patent Document 1. In the amorphous silicon-based thin film deposition apparatus, a substrate 101, a mesh-like counter electrode 141, and a mesh-like high-frequency electrode 142 are arranged to face each other. In the amorphous silicon-based thin film deposition apparatus, a silane gas is allowed to flow vertically on the surface of each electrode to generate plasma between the electrodes, thereby forming a silicon-based thin film on the substrate. A cluster removal filter 143 is installed between the substrate 101 and the counter electrode 141. Since the reflectance of the Si cluster from the filter is 0%, the Si cluster is removed from the plasma flow by colliding with the filter wall. This prevents Si large clusters 145 (diameter: 1 nm or more) generated in the plasma from being mixed into the silicon-based thin film deposited on the substrate.

  The cluster removal filter has a structure in which two or more grids (thin plates) 144 with holes are stacked. Each grid is arranged so that holes do not overlap with other adjacent grids, and the aperture ratio of each grid is 50% or less.

International Publication No. 2006/022179 (paragraphs [0025] to [0027])

  Since the cluster removal filter described in Patent Document 1 requires two or more grids to be stacked, it is difficult to increase the area.

In addition, when the cluster removal filter described in Patent Document 1 is installed, the SiH ₃ radical that is the basis of the film is reflected by the grid arranged on the substrate side and then further reflected by the grid arranged on the electrode side. Pass through the cluster removal filter. That is, SiH ₃ radicals collide with the grid at least twice in the process of passing through the filter. According to Patent Document 1, the reflectance of the SiH ₃ radical from the filter is about 70%, so that the SiH ₃ radical passing through the filter by the second collision is almost halved. Further, in order to prevent holes from overlapping other grids when two or more grids are stacked, the aperture ratio of the grids cannot be larger than 50%, so that the supply amount into the apparatus is ¼. Only the following SiH ₃ radicals are involved in the film formation, and the film formation speed is greatly reduced.

  The present invention has been made in view of such circumstances, and a method for producing a silicon-based thin film and a silicon-based thin film capable of forming a cluster-free or cluster-small silicon-based thin film while suppressing a decrease in the film-forming speed. It aims at providing the manufacturing apparatus of a thin film.

  In order to solve the above-described problems, the present invention supplies a source gas containing Si into a vacuum vessel in which a substrate is accommodated, supplies high-frequency power to a discharge electrode provided in a plasma generation unit, and plasma of the source gas A silicon-based thin film forming apparatus for forming a silicon-based thin film on the substrate, wherein a cluster removing portion is disposed between the substrate and the discharge electrode, and the cluster removing portion is opened A plurality of openings so that the rate is 50% or more, the openings communicate with the plasma generation part side and the substrate side, and the opening width of the opening part is Si nanocrystals under pressure during film formation Provided is a silicon-based thin film forming apparatus in which the average free path of the cluster is not more than twice and the length of the opening is not less than twice the opening width.

According to the said invention, it becomes a structure which comprises a side wall in the length direction of the opening part of a cluster removal part. For this reason, by setting the aperture ratio to 50% or more, the raw material gas can easily pass through the cluster removal portion, so that a decrease in film forming speed can be reduced. In the film forming apparatus of the present invention, the plasma flow of the source gas is supplied to the substrate side via the opening. The plasma flow on the plasma generation part side of the cluster removal part contains radicals and Si nanoclusters.
When the Si nanocluster passes through the opening, it directly collides with the side wall of the opening and is adsorbed. Or, it collides with radicals etc. contained in the plasma flow to change its orbit, collides with the side wall of the opening, and is adsorbed. The Si nanoclusters that have entered the opening at an angle along the length of the opening from the vicinity of the center of the opening pass through the position farthest from the side wall. Even in such a case, by making the opening width less than twice the mean free path, the Si nanoclusters that once collided with the radical collide with the side wall of the opening without colliding with other radicals etc.・ Adsorption is possible. Moreover, most Si nanoclusters can be made to collide with the side wall of an opening part by making the length of an opening part into 2 times or more of opening width. About 30% of the radicals are also adsorbed when colliding with the side wall of the opening, but with the above configuration, the number of collisions when passing through the opening can be reduced to one. As a result, the radicals can easily reach the substrate surface through the opening, and a decrease in the film forming speed can be suppressed.

In one embodiment of the present invention, the cluster removal portion may have a honeycomb-like or lattice-like structure.
According to one aspect of the present invention, it is possible to increase the aperture ratio of the cluster removal unit. For this reason, it becomes easier for radicals to pass through the opening and reach the substrate surface, thereby further suppressing a decrease in film forming speed.

  In one aspect of the invention described above, the cluster removal unit includes a plurality of plate-shaped members having an opening width and an opening on a plasma generation unit side and an opening on a substrate side when viewed from the normal direction of the substrate. And the opening width is equal to or less than the mean free path of the Si nanoclusters at the pressure during film formation, and the length of the opening is equal to the opening width. It may be twice or more.

  According to one aspect of the invention, adjacent plate-like members are arranged with an opening width, and most of the Si nanoclusters are opened by making the length of the opening more than twice the mean free path. It can be made to collide with the side wall of the part. Since the plurality of plate-like members are arranged with an interval in an inclined state with respect to the substrate, radicals included in the plasma flow will collide with the plate-like member (side wall of the opening) two or more times. Since the opening can be made larger, it is possible to further suppress a decrease in the film forming speed.

  1 aspect of the said invention WHEREIN: The said plasma generation part contains the counter electrode arrange | positioned facing the said discharge electrode, the said cluster removal part is the said counter electrode which consists of an electroconductive material, and the said opening width is at the time of film forming The size may be such that the plasma is not generated in the opening at a pressure lower than the average free path of the Si nanoclusters under a pressure of less than the lower limit in the film forming pressure range.

  Since the cluster removal unit also serves as the counter electrode, the ground potential for power feeding is directly connected, so that power feeding efficiency can be improved. At that time, by setting the opening width within the above range, it is possible to suppress discharge at the opening.

1 aspect of the said invention WHEREIN: The said discharge electrode is comprised from several rod-shaped electrode, The supply which supplies the said source gas to the space between the said discharge electrode and the said counter electrode to at least 1 clearance gap between the said rod-shaped electrodes A mechanism, and an exhaust mechanism for exhausting the gas in the space out of the vacuum vessel;
It is preferable to provide.

  The movement of the Si nanocluster is easily influenced by the flow of the source gas. According to the above invention, since the supply mechanism and the exhaust mechanism are provided on the discharge electrode side, it is possible to reduce the amount of Si nanoclusters flowing in the cluster removal unit and the substrate direction when supplying the raw material gas into the vacuum vessel. .

  In one embodiment of the above invention, the discharge electrode and the counter electrode are preferably held via an insulating material.

  The counter electrode has an aperture ratio of 50% or more, but the strength is reinforced by being connected to the discharge electrode through an insulating material. This makes it possible to prevent deformation of the counter electrode even if the counter electrode has a large area as the substrate size increases.

  In one aspect of the invention described above, a substrate holding unit that holds the substrate in the vacuum vessel may be provided, and the substrate holding unit and the discharge electrode may have a temperature adjustment mechanism that adjusts its own temperature.

  According to the said invention, the temperature distribution in a vacuum vessel can be made small. For this reason, it is possible to suppress thermal deformation of the cluster removal portion having an aperture ratio of 50% or more.

  The present invention also provides a photoelectric conversion device comprising the silicon-based thin film forming apparatus described above. According to the present invention, it is possible to form a silicon-based thin film that is cluster-free or has very few clusters, so that it is possible to suppress photodegradation of the photoelectric conversion layer.

Further, the present invention supplies a source gas containing Si into a vacuum container in which a substrate is accommodated, supplies high frequency power to a discharge electrode provided in a plasma generation unit, and generates plasma of the source gas to generate the substrate. A method for forming a silicon-based thin film on which a silicon-based thin film is formed, comprising a plurality of openings so that the aperture ratio is 50% or more, and the openings are formed on the plasma generation unit side and the substrate side. Cluster removal in which the opening width of the opening is less than twice the mean free path of Si nanoclusters under pressure during film formation, and the length of the opening is more than twice the opening width A method for forming a silicon-based thin film is provided in which a portion is disposed between the substrate and the discharge electrode, and the plasma is supplied to the substrate side through the opening of the cluster removal portion.

According to the above invention, the side wall is formed in the length direction of the opening of the cluster removal portion, and the opening ratio is 50% or more, so that the source gas can easily pass through the cluster removal portion. The decrease in speed can be reduced. In the film forming apparatus of the present invention, the plasma flow of the source gas is supplied to the substrate side via the opening. The plasma flow on the plasma generation part side of the cluster removal part contains radicals and Si nanoclusters.
When the Si nanocluster passes through the opening, it directly collides with the side wall of the opening and is adsorbed. Or, it collides with radicals etc. contained in the plasma flow to change its orbit, collides with the side wall of the opening, and is adsorbed. Si nanoclusters entering the opening at an angle along the length direction of the opening from the vicinity of the center of the opening pass through a position farthest from the side wall. Even in such a case, by making the opening width less than twice the mean free path, the Si nanoclusters that once collided with the radical collide with the side wall of the opening without colliding with other radicals etc.・ Adsorption is possible. Moreover, most Si nanoclusters can be made to collide with the side wall of an opening part by making the length of an opening part into 2 times or more of opening width. About 30% of the radicals are also adsorbed when colliding with the side wall of the opening, but with the above configuration, the number of collisions when passing through the opening can be reduced to one. As a result, the radicals can easily reach the substrate surface through the opening, and a decrease in the film forming speed can be suppressed.

In one embodiment of the present invention, the cluster removal portion may have a honeycomb-like or lattice-like structure.
According to one aspect of the present invention, it is possible to increase the aperture ratio of the cluster removal unit.

  In one aspect of the invention, when the cluster removing portion is viewed from the normal direction of the substrate with a plurality of plate-shaped members having an opening width, the opening on the plasma generation portion side and the opening on the substrate side of the opening portion The opening width is equal to or less than the mean free path of the Si nanoclusters at the pressure during film formation, and the length of the opening is twice the opening width. It is good also as above.

  According to one aspect of the invention, adjacent plate-like members are arranged with an opening width, and most of the Si nanoclusters are opened by making the length of the opening more than twice the mean free path. It can be made to collide with the side wall of the part. Since the plurality of plate-like members are arranged with an interval in an inclined state with respect to the substrate, radicals included in the plasma flow will collide with the plate-like member (side wall of the opening) two or more times. Since the opening can be made large, it is possible to further suppress a decrease in the film forming speed.

  1 aspect of the said invention WHEREIN: The said cluster removal part is made into the counter electrode which consists of an electroconductive material, The said opening width is 2 times or less of the mean free path | route of Si nanocluster under the pressure at the time of film formation, and film formation The size may be such that the plasma is not generated in the opening with the lower limit pressure in the pressure range, and the counter electrode may be disposed opposite the discharge electrode to generate plasma between the electrodes.

  Since the cluster removal unit also serves as the counter electrode, the ground potential for power feeding is directly connected, so that power feeding efficiency can be improved. At that time, by setting the opening width within the above range, it is possible to suppress discharge at the opening.

  In one aspect of the invention, the discharge electrode is composed of a plurality of rod-shaped electrodes, and the source gas is introduced into a space between the discharge electrode and the counter electrode by a supply mechanism provided in at least one gap between the rod-shaped electrodes. And a step of exhausting gas from the space by an exhaust mechanism provided in at least one gap between the rod-shaped electrodes.

  The movement of the Si nanocluster is easily influenced by the flow of the source gas. According to the above invention, since the supply mechanism and the exhaust mechanism are provided on the discharge electrode side, it is possible to reduce the amount of Si nanoclusters flowing in the cluster removal unit and the substrate direction when supplying the raw material gas into the vacuum vessel. .

In one aspect of the invention described above, a step of supplying the source gas to a space between the discharge electrode and the counter electrode by a supply mechanism, a step of exhausting the gas from the space by an exhaust mechanism,
It is preferable that the discharge electrode and the counter electrode are held via an insulating material.

  The counter electrode has an aperture ratio of 50% or more, but the strength is reinforced by being connected to the discharge electrode through an insulating material. This makes it possible to prevent deformation of the counter electrode even if the counter electrode has a large area as the substrate size increases.

  In one embodiment of the present invention, the substrate may be held by a substrate holding portion, and a temperature adjustment mechanism may be provided in each of the substrate holding portion and the discharge electrode to adjust its own temperature.

  According to the said invention, the temperature distribution in a vacuum vessel can be made small. For this reason, it is possible to suppress thermal deformation of the cluster removal portion having an aperture ratio of 50% or more.

  Moreover, this invention provides the manufacturing method of the photoelectric conversion apparatus which forms a silicon-type thin film by the film forming method as described above. According to the present invention, it is possible to form a silicon-based thin film that is cluster-free or has very few clusters, so that it is possible to suppress photodegradation of the photoelectric conversion layer.

  According to the present invention, it is possible to form a silicon-based thin film that is cluster-free or has very few clusters while suppressing a decrease in film formation speed.

It is the schematic of the film-forming apparatus of the silicon-type thin film which concerns on embodiment which concerns on 1st Embodiment. It is a perspective view of the cluster removal part which has a honeycomb-like structure concerning a 1st embodiment. It is an image figure at the time of the plasma which concerns on 1st Embodiment passes an opening part. It is sectional drawing of the cluster removal part which has the blind-like structure which concerns on 2nd Embodiment. It is a figure which illustrates the structure of the film forming apparatus which concerns on 3rd Embodiment. It is a figure which illustrates the structure of the film forming apparatus which concerns on 3rd Embodiment. It is a top view of the plasma generation part which concerns on 4th Embodiment. It is sectional drawing of the x direction of the plasma generation part shown in FIG. It is sectional drawing of the y direction of the plasma generation part shown in FIG. It is sectional drawing of the y direction of the plasma generation part as a modification. It is a figure explaining the supply mechanism and exhaust mechanism which concern on 4th Embodiment. It is a figure explaining the detail of the supply mechanism which concerns on 4th Embodiment. It is a top view of the plasma generation part which concerns on 5th Embodiment. It is sectional drawing of the x direction of the plasma generation part shown in FIG. It is sectional drawing of the y direction of the plasma generation part shown in FIG. It is sectional drawing of the y direction of the plasma generation part as a modification. It is the cross-sectional schematic of the silicon-type thin film forming apparatus which concerns on 6th Embodiment. It is the schematic which shows the structure of the photoelectric conversion apparatus which concerns on 7th Embodiment. It is the schematic which shows embodiment of the manufacturing method of the solar cell panel of 7th Embodiment. It is the schematic which shows embodiment of the manufacturing method of the solar cell panel of 7th Embodiment. It is the schematic which shows embodiment of the manufacturing method of the solar cell panel of 7th Embodiment. It is the schematic which shows embodiment of the manufacturing method of the solar cell panel of 7th Embodiment. It is the schematic which shows embodiment of the manufacturing method of the solar cell panel of 7th Embodiment. It is a figure which shows the result of the ESR measurement of the test piece 1 and the test piece 2. FIG. It is a figure which shows the result of the electric power generation test of the test piece 3 and the test piece 4. FIG. It is the schematic which shows the conventional amorphous silicon thin film deposition apparatus.

  Hereinafter, an embodiment of a silicon-based thin film deposition apparatus and method according to the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 shows a schematic view of a silicon-based thin film forming apparatus according to this embodiment. The film forming apparatus includes a film forming chamber (not shown), a substrate holding unit 102, a plasma generating unit 103, and a cluster removing unit 104.
Here, the silicon-based is a generic name including silicon (Si), silicon carbide (SiC), and silicon germanium (SiGe).

  The film forming chamber is a vacuum container and has a structure capable of withstanding a pressure difference between inside and outside the container. For example, a structure formed of stainless steel (SUS material in JIS standard), aluminum alloy steel, or general structural rolling material (SS material in JIS standard) and reinforced with a rib material or the like can be used. The film forming chamber is provided with a supply mechanism for supplying a source gas containing Si (hereinafter referred to as source gas) into the film forming chamber and an exhaust mechanism for exhausting the gas from the film forming chamber. As the exhaust mechanism, for example, a known vacuum pump, a pressure adjusting valve, a vacuum exhaust pipe, or the like can be used. The film forming chamber can be evacuated to about 0.1 kPa to 10 kPa by the exhaust mechanism.

The substrate holding unit 102 is disposed in the film forming chamber and can hold the substrate on its upper surface. The substrate holding unit 102 has a temperature adjustment mechanism that adjusts its own temperature. In the present embodiment, the temperature adjustment mechanism is such that a heat source (heater) whose temperature can be controlled from the outside is embedded in the substrate holder 102. The temperature adjustment mechanism is not limited to the above, and may be a heat medium circulation method in which a temperature-controlled heat medium is circulated inside. The heat medium is a non-conductive medium, and high heat conductive gas such as hydrogen and helium, fluorine-based inert liquid, inert oil, pure water, etc. can be used. Use of a fluorine-based inert liquid (for example, trade name: Galden, F05, etc.) is preferable because control is easy without going up.
The temperature adjustment mechanism has a function of setting the entire upper surface of the substrate holding unit 102 to a substantially uniform temperature and equalizing the temperature of the substrate held on the upper surface to a predetermined temperature.

  The plasma generation unit 103 includes a counter electrode 105, a discharge electrode 106, a high frequency power source 107, and a matching unit 108. The counter electrode 105 and the discharge electrode 106 are arranged to face each other in parallel in the film forming chamber.

The counter electrode 105 is made of a conductive flat plate and is connected to a ground member. The counter electrode 105 is disposed to face the upper surface of the substrate holding unit 102 in parallel with a gap.
For the counter electrode 105, for example, SUS304 or the like, or an aluminum-based metal having a remarkably large heat transfer coefficient can be used. The counter electrode 105 has a mesh structure and includes a plurality of vent holes. The diameter of the air hole is preferably 2 mm to 5 mm. The aperture ratio of the counter electrode 105 is preferably 60% to 80%. The thickness of the counter electrode 105 is preferably 0.5 mm or more and 3 mm or less so that the warp amount due to the temperature difference between the front and back surfaces of the electrode plate is reduced. By doing so, it becomes difficult to generate a temperature difference between the front and back surfaces of the electrode plate during film formation, so that it is possible to maintain the flatness that suppresses thermal deformation of the counter electrode 105. In order to ensure structural handling strength even though the plate thickness of the counter electrode 105 is thin, it is more preferably 1 mm or more and 2 mm or less.

The discharge electrode 106 is made of a conductive flat plate, and is disposed above the counter electrode 105 (on the side opposite to the substrate) in parallel with the counter electrode 105 with a space therebetween. A matching unit 108 and a high frequency power source 107 are connected to the discharge electrode 106 through power supply lines 109a and 109b. Plasma can be generated between the discharge electrode 106 and the counter electrode 105 by supplying high-frequency power to the discharge electrode 106 in a state where the source gas is supplied into the film forming chamber. The interval between the discharge electrode 106 and the counter electrode 105 is appropriately set according to the frequency of the high-frequency power source 107, the size of the substrate, and the like. For example, the interval between the discharge electrode 106 and the counter electrode 105 is set to a range of about 10 mm to 30 mm.
For the discharge electrode 106, for example, a nonmagnetic metal such as SUS304, or aluminum or an aluminum alloy metal that hardly deforms due to a temperature difference due to a remarkably large heat transfer coefficient can be used.

  The matching unit 108 matches the impedance on the output side and transmits the high frequency power from the high frequency power source 107 to the discharge electrode 106.

  The cluster removal unit 104 is disposed with a space between the substrate holding unit 102 and the counter electrode 105 so as to be positioned immediately above the substrate 101 during film formation. The distance between the counter electrode 105 and the cluster removal unit 104 is preferably 2 mm to 10 mm. The distance between the cluster removal unit 104 and the substrate 101 is preferably 5 mm to 20 mm.

  The cluster removal unit 104 has a function of removing Si nanoclusters from the plasma flow generated by the plasma generation unit. The cluster removal unit 104 has a size equal to or larger than that of the counter electrode 105. Although the material of the cluster removal part 104 is not specifically limited, It is preferable to consist of an electroconductive material. This makes it difficult for the cluster removal unit 104 to be charged. The cluster removing unit 104 may be made of a positively chargeable material. Thereby, negatively charged Si nanoclusters are easily adsorbed on the wall surface. The cluster removal unit 104 may be made of, for example, a nonmagnetic metal such as SUS304, or aluminum or an aluminum alloy metal that is not easily deformed due to a temperature difference due to a remarkably large heat transfer coefficient.

The cluster removal unit 104 includes a plurality of openings that communicate from the counter electrode 105 side to the substrate holding unit 102 side, and a wall surface that forms the opening. The aperture ratio of the cluster removal unit 104 is set to 50% or more. The cluster removal unit 104 may have a honeycomb or lattice structure. The shape of the opening may be set as appropriate. The cluster removing unit 104 has a honeycomb-like structure, so that it is lightweight and has high strength and can be hardly deformed. FIG. 2 illustrates a cluster removal unit 104 having a honeycomb structure. The opening width w of the opening is set to be equal to or less than twice the average free path of the Si nanoclusters at the pressure during film formation, and is equal to or more than the plate thickness of the honeycomb-shaped structural material. The “opening width” indicates the maximum length of the opening, and is the diameter of the circle when the opening shape is circular. The “opening width” is a length connecting vertices facing each other when the opening shape is a polygon. The length l of the opening is at least twice the opening width w. The “length of the opening” means the length from the end on the side of the counter electrode 105 to the end on the side of the substrate holding unit 102 of the wall surface constituting one opening.
Here, when the absolute value of the opening width w of the opening is set smaller, the absolute value of the length l of the opening that is set to be twice or more is also set short, but the opening width w is the opening length. Considering the solid angle of the opening defined by l, the number of Si nanoclusters passing through the opening without colliding with the wall surface constituting the opening is extremely small, and the cluster removal effect is sufficiently exhibited.
On the other hand, the length of the opening is desirably about twice or less the average free path of a film forming radical such as SiH ₃ radical at the film forming pressure. This is because the radical hits the wall twice, the number of radicals is reduced by half, and the film forming speed is reduced by about half, so that a practical film forming speed cannot be obtained.
In this embodiment, the cluster removing unit 104 is a punching metal in which a plurality of through holes are formed in a thin aluminum alloy plate. In that case, the opening width w is the diameter of the through hole, and the length of the opening is the thickness of the thin plate.

Next, a method for forming a silicon thin film on a substrate using the film forming apparatus will be described.
First, after the air is exhausted by the exhaust mechanism and the film forming chamber is evacuated, the substrate is placed on the upper surface of the substrate holder 102. Next, high-frequency power from the high-frequency power source 107 is supplied to the discharge electrode 106 through the matching unit 108, and a source gas is supplied into the film forming chamber by the supply mechanism. For example, SiH ₄ gas can be used as the source gas. At this time, the exhaust amount of the exhaust mechanism is controlled so that the film forming chamber is maintained in a desired vacuum state.

When high frequency power is supplied, plasma is generated between the discharge electrode 106 and the counter electrode 105. In consideration of uniform plasma formation on a large discharge electrode, the high frequency power is preferably 10 MHz to 100 MHz, for example. The plasma moves from the counter electrode 105 side to the substrate side through the opening of the cluster removal unit 104 by diffusion. The plasma contains radicals such as SiH ₃ , SiH ₂ , and SiH. The SiH ₃ radicals are diffused by a diffusion phenomenon and adsorbed on the substrate surface, so that a silicon thin film such as an amorphous silicon film or a crystalline silicon film is obtained. Is formed. The silicon thin film can be selectively formed as an amorphous silicon film or a crystalline silicon film by optimizing the flow rate ratio of SiH ₄ and H _{2 in} the film forming conditions, the pressure, and the high-frequency power to be supplied.
Note that the crystalline silicon system means an amorphous silicon system, that is, a silicon system other than the amorphous silicon system, and includes a microcrystalline silicon system and a polycrystalline silicon system.

FIG. 3 shows an image when the plasma passes through the opening of the cluster removal unit 104. In addition to SiH ₃ radicals, SiH ₄ gas molecules 110 and Si nanoclusters 111 are contained in the plasma. A part of the Si nanoclusters 111 incident on the opening at an arbitrary prospective angle collides directly with the inner wall (wall surface) of the opening and is adsorbed. Further, a part of the Si nanocluster collides with SiH ₄ gas molecules existing in the opening and is orbitally changed, and then collides with the inner wall of the opening and is adsorbed. By making the opening width w less than twice the mean free path of the Si nanocluster 111 and making the length l of the opening more than twice the opening width w, Si nano-crystals incident at an angle along the inner wall surface of the opening Even the cluster 111 can collide with the inner wall of the opening with high probability. Thereby, most of the Si nanoclusters 111 contained in the plasma flow can be adsorbed on the inner wall of the opening and removed. Further, SiH ₃ radicals also collide with the inner wall of the opening. However, by configuring the cluster removal unit 104 as described above, it is possible to reduce multiple collisions of SiH ₃ radicals with the inner wall. In addition, since the cluster removal unit 104 has a single layer configuration, the aperture ratio can be increased to 50% or more, and a decrease in film forming speed can be suppressed.
The plasma generation unit 103 in the film forming chamber shown in FIG. 1 is described in a form in which the substrate holder 102 is installed in the horizontal direction, but is not particularly limited to the horizontal direction, Needless to say, the direction may be a vertical direction or a direction inclined by 5 ° to 15 ° from the vertical direction.

[Second Embodiment]
The silicon-based thin film deposition apparatus according to the present embodiment has the same configuration as that of the first embodiment except that the cluster removal unit is in a blind shape.
The cluster removal unit has a structure in which a plurality of plate-like members are arranged in a blind shape with an opening width w. FIG. 4 illustrates a cross-sectional view of the cluster removal unit 114 having a blind structure. As shown in FIG. 4, a plurality of plate-like members 115 are arranged in parallel with each other with an opening width w in a state inclined with respect to the substrate holding portion 102 (substrate). Each plate-like member 115 is inclined so that the opening p ₁ on the counter electrode 105 side and the opening p ₂ on the substrate side of one opening do not overlap when viewed from the normal direction of the substrate 101. The opening width w of the opening is set to be equal to or less than the mean free path of the Si nanocluster 111 at the pressure during film formation. The length l of the opening is at least twice the opening width w. On the other hand, the length l of the opening is preferably about twice or less the average free path of the film-forming radicals at the pressure during film formation. The aperture ratio of the cluster removal unit 104 is set to 50% or more.

  According to this embodiment, the substrate cannot be seen directly even when viewed perpendicularly to the substrate from the electrode side. For this reason, the Si nanocluster which passes through the opening without colliding with the wall surface constituting the opening is eliminated or extremely reduced, and the cluster removal effect is sufficiently exhibited. Moreover, since an opening part can be taken large by making an opening part into the said structure, the effect of the fall suppression of the film forming speed obtained becomes large.

[Third Embodiment]
In the silicon-based thin film deposition apparatus according to the present embodiment, the cluster removal unit also serves as the counter electrode. Unless otherwise specified, the other configurations are the same as those in the first embodiment.
The cluster removal unit has a function as a counter electrode in addition to the function of removing Si nanoclusters from the plasma flow generated by the plasma generation unit. The cluster removal portion is made of a conductive material. The cluster removal unit includes a plurality of openings that communicate from the discharge electrode side to the substrate holding unit side. The aperture ratio of the cluster removal portion is set to 50% or more. The cluster removal portion may have a honeycomb-like or lattice-like structure. The shape of the opening may be set as appropriate. The opening width of the opening is less than twice the mean free path of Si nanoclusters under the pressure during film formation, and the size that does not cause plasma discharge at the opening at the lower limit pressure in the film forming pressure range It is. In order not to generate plasma discharge in the opening, it is influenced by the shape of the opening, but it is not more than several times the mean free path of electrons at the lower limit pressure in the film forming pressure range, and is substantially Is preferably 1 to 5 times the mean free path of the electrons. The length of the opening is at least twice the opening width. With the above configuration, it is possible to suppress discharge at the opening when the plasma passes through the opening, and eliminate Si nanoclusters that pass through the opening without colliding with the wall surface forming the opening. Or very little, and the cluster removal effect is sufficiently exerted.

  5 and 6 illustrate the configuration of the film forming apparatus according to this embodiment. The cluster removal unit 124 is disposed with a space between the substrate holding unit 102 and the discharge electrode 106 so as to be positioned immediately above the substrate 101 during film formation. The interval between the discharge electrode 106 and the cluster removal unit 124 is preferably 10 mm to 30 mm. The distance between the cluster removal unit 124 and the substrate 101 is preferably 5 mm to 20 mm.

  In FIG. 5, the high frequency power source 107 is connected to a matching unit via a power supply line (coaxial cable) 116. The high frequency power from the high frequency power source 107 is preferably 10 MHz to 100 MHz, for example, in consideration of uniform plasma formation on a large discharge electrode. The matching unit is connected to a current introduction terminal 118 provided in the film forming chamber 117 via a power supply line (coaxial cable) 116. The core wire 119 of the coaxial cable 116 is connected to the discharge electrode 106, and the shield wire 120 is connected to the cluster removal unit 124 that also serves as the counter electrode 105. By connecting the ground of the power feeding system directly to the cluster removal unit 124, the potential transmission between the core wire 119 and the shield wire 120 of the feeding system can be smoothly guided to the discharge electrode 106, and the power feeding efficiency can be improved.

  In addition, as shown in FIG. 6, the cluster removing unit 124 that also serves as the counter electrode may be connected to the ground of the power feeding system via the wall surface of the film forming chamber 117 instead of the shield wire 120 of the coaxial cable 116. good.

  Further, the supply of high-frequency power from the coaxial cable 116 to the discharge electrode 106 may be performed by a balun power feeding method. A balun (balanced-unbalanced converter) is installed between a coaxial cable (unbalanced mode) and a two-wire feeder (balanced mode) to convert the transmission mode between balanced and unbalanced states. It is an element. That is, the balun circuit may be set to correct the difference in transmission mode by assuming that the supply of high-frequency power from the coaxial cable to the discharge electrode is in an unbalanced and balanced state.

[Fourth Embodiment]
The silicon-based thin film deposition apparatus according to this embodiment has the same configuration as that of the third embodiment unless otherwise described, except that the plasma generation unit is different. FIG. 7 is a plan view of the plasma generation unit according to the present embodiment as viewed from the discharge electrode side. FIG. 8 shows a cross-sectional view of the plasma generating unit according to the present embodiment.

  The discharge electrode 126 has a ladder structure in which rod-shaped members are combined substantially in parallel. For the discharge electrode 126, the cross-sectional shape of the rod-shaped member can be appropriately selected according to the film forming conditions, and may be a quadrangle, a long quadrangle, a trapezoid, a polygon, a circle, an ellipse or the like, and is not specified. In the present embodiment, the discharge electrode 126 is divided into a plurality of electrode units according to the number of current introduction terminals 118. The discharge electrodes 126 are respectively connected to the corresponding current introduction terminals 118 through power supply lines. Each current introduction terminal 118 is connected to a matching unit 108 and a high-frequency power source 107.

  The counter electrode has the same configuration as that of the third embodiment, and is disposed opposite to the substrate holding part side of the discharge electrode 126. Both ends of the counter power are connected to the ground of the power feeding system. The counter electrode also serves as the cluster removal unit 124. The counter electrode 124 is physically connected to the discharge electrode 126 and held by a holding member (insulator for filter holding) 121 made of an insulating material such as ceramics. The holding member 121 is disposed at any plurality of locations of the counter electrode 124 and holds the counter electrode 124. Thereby, since it becomes easy to maintain a plane, the aperture ratio is high, and thermal deformation of the cluster removing unit 124 that also serves as a counter electrode made of a thin plate can be suppressed.

  As shown in FIG. 9, the cluster removing unit 124 that also serves as the counter electrode has a single structure having a size slightly larger than the size of the substrate. Further, the cluster removing unit 124 that also serves as the counter electrode may be divided into the same size as the divided discharge electrode 126 as shown in FIG.

FIG. 11 is a view for explaining a film forming source gas supply mechanism and a film forming residual gas exhaust mechanism according to this embodiment. In the present embodiment, the supply mechanism 122 and the exhaust mechanism 123 are alternately connected to the gaps between the rod-shaped members of the discharge electrode 126. The exhaust mechanism 123 can exhaust gas that has not contributed to film formation from the space between the discharge electrode 126 and the counter electrode 124 to the outside of the film formation chamber from the gap between the rod-shaped members. The supply mechanism 122 can supply the source gas into the space between the discharge electrode 126 and the counter electrode 124 from the gap between the rod-shaped members. FIG. 12 shows details of the supply mechanism according to the present embodiment. The supply mechanism 122 according to the present embodiment is a gas supply tube that extends along the longitudinal direction of the rod-shaped member of the discharge electrode 126. The gas supply pipe is composed of an inner pipe 127 and an outer pipe 128. The inner pipe 127 is alternately connected between the rod-shaped members. The inner tube 127 is provided with a plurality of holes 129 on the side opposite to the substrate 101. The plurality of holes 129 are arranged along the longitudinal direction of the gas supply pipe. Thereby, gas can be equally distributed and ejected. The outer tube 128 has a larger diameter than the inner tube 127, and a slit 130 extending along the longitudinal direction of the gas supply tube is formed at a position facing the substrate 101. Accordingly, it is possible to suppress the jets ejected from the plurality of holes 129 of the inner tube 127 from directly spraying on the substrate 101, and to form a uniform gas flow on the substrate 101 as much as possible.
With the above-described configuration of the supply mechanism, local film distribution due to the jet flow to the substrate 101 can be suppressed.

[Fifth Embodiment]
The silicon-based thin film deposition apparatus according to this embodiment has the same configuration as that of the third embodiment unless otherwise described, except that the plasma generation unit is different. FIG. 13 is a plan view of the plasma generation unit according to the present embodiment as viewed from the discharge electrode side. FIG. 14 shows a cross-sectional view of the plasma generating unit according to this embodiment.

The discharge electrode 126 has a ladder structure in which rod-shaped members are combined substantially in parallel. In the present embodiment, the discharge electrode 126 is divided into a plurality of electrode units according to the number of current introduction terminals 118 for the discharge electrode 126. The discharge electrodes 126 are connected to the corresponding current introduction terminals 118, respectively.
The counter electrode 124 has the same configuration as that of the third embodiment, and is disposed opposite to the substrate holding portion side of the discharge electrode. A current introducing terminal 131 for the counter electrode 124 is provided in the film forming chamber. The counter electrode 124 is connected to the corresponding current introduction terminal 131.

  The current introduction terminal 118 for the discharge electrode 126 and the current introduction terminal 131 for the counter electrode 124 are connected to one balun circuit 132 for each corresponding electrode unit. The balun circuit 132 is connected to the matching unit 108 and the high-frequency power source 107 through power supply lines.

  The counter electrode 124 also serves as a cluster removal unit. The counter electrode 124 is physically connected to and held by the discharge electrode 126 by a holding member made of an insulating material such as ceramics. The holding member 121 is disposed at any plurality of locations of the counter electrode 124 and holds the counter electrode 124. Thereby, since it becomes easy to maintain a plane, the aperture ratio is high, and thermal deformation of the cluster removing unit 124 that also serves as a counter electrode made of a thin plate can be suppressed.

  As shown in FIG. 15, the cluster removing unit 124 that also serves as a counter electrode has a single-sheet structure corresponding to the size of the substrate. Further, the cluster removing unit 124 that also serves as the counter electrode may be divided into the same size as the divided discharge electrode 126 as shown in FIG.

  In the present embodiment, the supply mechanism and the exhaust mechanism are the same as those in the fourth embodiment.

[Sixth Embodiment]
The silicon-based thin film deposition apparatus according to this embodiment has the same configuration as that of the fourth embodiment unless otherwise specified, except that the discharge electrode includes a temperature adjustment mechanism and a supply mechanism. FIG. 17 is a schematic cross-sectional view of a silicon-based thin film forming apparatus according to this embodiment.

The discharge electrode 136 is disposed so as to face the cluster removal portion 124 that also serves as a counter electrode, in parallel with the gap. The discharge electrode 136 and the counter electrode 124 are physically connected and held by a holding member (insulating material) 121. The arrangement of the holding member 121 is appropriately set.
The discharge electrode 136 has a ladder structure in which rod-shaped members are combined substantially in parallel. There is a gap between the rod-shaped members. An exhaust mechanism 123 is connected to the gap so that gas can be exhausted from the space between the discharge electrode 136 and the counter electrode 124.

Each rod-like member includes a supply mechanism 133 and a temperature adjustment mechanism 134 inside.
The supply mechanism 133 is a gas supply pipe composed of an inner pipe and an outer pipe, as in the fourth embodiment. The gas supply pipe extends along the longitudinal direction of the rod-shaped member, and is disposed on the side away from the counter electrode 124 from the center of the cross-section of the rod-shaped member. The plurality of holes in the inner tube are formed facing the opposite side of the counter electrode 124. The slit of the outer tube is formed at a position facing the counter electrode 124. A concave portion that extends along the longitudinal direction of the rod-shaped member and communicates with the slit of the outer tube is formed at the center of the cross section of the surface of the rod-shaped member facing the counter electrode 124.

  The temperature adjustment mechanism 134 provided in the rod-shaped member may be any mechanism that can adjust the temperature of the discharge electrode 136 itself. The temperature adjustment mechanism 134 is preferably a heat medium circulation method, but is not limited to this, and a heat source that can be temperature-controlled from the outside may be embedded. In the present embodiment, the temperature adjustment mechanism (temperature adjustment medium introduction hole) 134 provided in the rod-shaped member employs a heat medium circulation method in which a temperature-controlled heat medium is circulated therein. In the present embodiment, the substrate holding unit 102 is also provided with a temperature adjustment mechanism 134 of the heat medium circulation method.

  A heat medium circulation path is formed inside the rod-shaped member. The heat medium circulation path is arranged on both sides so as to sandwich the central portion of the cross section of the rod-shaped member so as to extend along the longitudinal direction of the rod-shaped member. When a temperature-controlled heat medium is supplied into the heat medium circulation path having the above configuration, the entire rod-shaped member can be brought to a substantially uniform temperature. The heat medium supplied into the heat medium circuit is a non-conductive medium, and can use a highly heat conductive gas such as hydrogen or helium, a fluorine-based inert liquid, an inert oil, or pure water. . In particular, the use of a fluorine-based inert liquid (for example, trade name: Galden, F05, etc.) is preferable because the pressure does not increase even in the range of 150 ° C. to 250 ° C. and control is easy.

  According to this embodiment, by controlling the discharge electrode 136 to a desired temperature by the temperature adjustment mechanism 134 of the discharge electrode 136, it is possible to appropriately maintain the heat balance in the film forming chamber. As a result, it is possible to suppress warpage deformation due to the temperature difference between the front and back surfaces of the substrate and the temperature difference between the front and back surfaces of the cluster removal unit 124 that also serves as the counter electrode.

[Seventh Embodiment]
In the present embodiment, a photoelectric conversion device manufactured using the silicon-based thin film forming apparatus according to the first to sixth embodiments and a manufacturing method thereof will be described.

First, the structure of the photoelectric conversion device manufactured by the method for manufacturing a photoelectric conversion device of the present invention will be described.
FIG. 18 is a schematic diagram illustrating a configuration of a photoelectric conversion device manufactured by the method for manufacturing a photoelectric conversion device of the present invention. The photoelectric conversion device 90 is a silicon solar cell, and includes a substrate 1, a transparent electrode layer 2, a solar cell photoelectric conversion layer 3, and a back electrode layer 4. Here, the silicon-based is a generic name including silicon (Si), silicon carbide (SiC), and silicon germanium (SiGe).

  Next, an embodiment of a method for manufacturing a solar cell panel according to this embodiment will be described. Here, an example in which a single-layer amorphous silicon thin film solar cell is used as the solar cell photoelectric conversion layer 3 on a glass substrate as the substrate 1 will be described. FIGS. 19-23 is schematic which shows embodiment of the manufacturing method of the solar cell panel of this invention.

(1) FIG. 19 (a)
In this embodiment, the substrate 1 is a soda float glass substrate (for example, 1.4 m × 1.1 m × plate thickness: 3.0 mm to 4.5 mm) as a large substrate having an area exceeding 1 m ² . The end face of the substrate is preferably subjected to corner chamfering or R chamfering to prevent damage due to thermal stress or impact.

(2) FIG. 19 (b)
A transparent electrode film mainly composed of a tin oxide film (SnO ₂ ) is formed as a transparent conductive layer 2 at a temperature of about 500 nm to 800 nm at about 500 ° C. using a thermal CVD apparatus. At this time, a texture with appropriate irregularities is formed on the surface of the transparent electrode film. As the transparent conductive layer 2, in addition to the transparent electrode film, an alkali barrier film (not shown) may be formed between the substrate 1 and the transparent electrode film. As the alkali barrier film, a silicon oxide film (SiO ₂ ) is formed at a temperature of about 500 ° C. in a thermal CVD apparatus at 50 nm to 150 nm.

(3) FIG. 19 (c)
Thereafter, the substrate 1 is placed on an XY table, and the first harmonic (1064 nm) of the YAG laser is irradiated from the film surface side of the transparent electrode film as indicated by an arrow in the figure. The laser power is adjusted so as to be suitable for the processing speed, and the transparent electrode film is moved relative to the direction perpendicular to the series connection direction of the power generation cells 5 to move the substrate 1 and the laser beam to form the groove 10. Thus, laser etching is performed in a strip shape having a predetermined width of about 6 mm to 15 mm.

(4) FIG. 19 (d)
A p-layer made of an amorphous silicon thin film as the photoelectric conversion layer 3 at a reduced pressure atmosphere: 30 to 1000 Pa and a substrate temperature: about 200 ° C. by the film forming apparatus including the cluster removing unit 104 of the first to sixth embodiments. A film / i-layer film / n-layer film is sequentially formed. The film forming apparatus in this embodiment is a plasma CVD apparatus. The photoelectric conversion layer 3 is formed on the transparent conductive layer 2 using SiH ₄ gas and H ₂ gas as main raw materials. A p-layer 41, an i-layer 42, and an n-layer 43 are laminated in this order from the sunlight incident side. In this embodiment, the photoelectric conversion layer 3 is composed of a p layer 41: B-doped amorphous SiC and a film thickness of 10 nm to 30 nm, an i layer 42: mainly amorphous Si, a film thickness of 200 nm to 350 nm, and an n layer 43: amorphous Si. The film thickness is 30 nm to 50 nm mainly composed of a p-doped Si layer containing microcrystalline Si. A buffer layer may be provided between the p layer film and the i layer film in order to improve the interface characteristics.

(5) FIG. 19 (e)

  The substrate 1 is placed on an XY table, and the second harmonic (532 nm) of the laser diode-pumped YAG laser is irradiated from the film surface side of the photoelectric conversion layer 3 as indicated by an arrow in the figure. Pulse oscillation: 10 to 20 kHz, the laser power is adjusted so as to be suitable for the processing speed, and laser etching is performed so that the groove 11 is formed on the lateral side of about 100 to 150 μm of the laser etching line of the transparent conductive layer 2. . Further, this laser may be irradiated from the substrate 1 side. In this case, the photoelectric conversion layer 3 can be etched by using a high vapor pressure generated by the energy absorbed by the amorphous silicon layer of the photoelectric conversion layer 3. A stable laser etching process can be performed. The position of the laser etching line is selected in consideration of positioning tolerances so as not to intersect with the etching line in the previous process.

(6) FIG. 20 (a)
As the back electrode layer 4, an Ag film / Ti film is sequentially formed by a sputtering apparatus in a reduced pressure atmosphere at about 150 to 200 ° C. In this embodiment, the back electrode layer 4 is formed by stacking an Ag film: about 150 to 500 nm and a Ti film having a high anticorrosive effect: 10 to 20 nm in this order as a protective film. Alternatively, a laminated structure of an Ag film having a thickness of about 25 nm to 100 nm and an Al film having a thickness of about 15 nm to 500 nm may be used. In addition, in the case where a long wavelength side reflected light of 600 nm or more is required, such as a tandem solar cell, a laminated structure of a Cu film having a thickness of about 100 nm to 450 nm and a Ti film having a thickness of about 5 nm to 150 nm It is also good.

  For the purpose of reducing the contact resistance between the n layer and the back electrode layer 4 and improving the light reflection, a ZnO (Ga or AL doped ZnO) film is formed between the photoelectric conversion layer 3 and the back electrode layer 4 to a thickness of 50 to 100 nm. A film may be formed by a sputtering apparatus.

(7) FIG. 20 (b)
The substrate 1 is placed on an XY table, and the second harmonic (532 nm) of the laser diode-pumped YAG laser is irradiated from the substrate 1 side as indicated by the arrow in the figure. The laser light is absorbed by the photoelectric conversion layer 3, and the back electrode layer 4 is exploded and removed using the high gas vapor pressure generated at this time. Pulse oscillation: 1 to 50 kHz, the laser power is adjusted so as to be suitable for the processing speed, and laser etching is performed on the lateral side of about 250 to 400 μm of the laser etching line of the transparent conductive layer 2 so as to form the groove 12. .

(8) FIG. 20 (c) and FIG. 21 (a)
The power generation region is divided to eliminate the influence that the serial connection portion due to laser etching is likely to be short-circuited at the film edge around the substrate edge. The substrate 1 is placed on an XY table, and the second harmonic (532 nm) of the laser diode pumped YAG laser is irradiated from the substrate 1 side. The laser light is absorbed by the transparent conductive layer 2 and the photoelectric conversion layer 3, and the back electrode layer 4 explodes using the high gas vapor pressure generated at this time, and the back electrode layer 4 / photoelectric conversion layer 3 / transparent conductive layer 2 is removed. Pulse oscillation: 1 to 50 kHz, the laser power is adjusted so as to be suitable for the processing speed, and the position of 5 to 20 mm from the end of the substrate 1 is set to the X-direction insulating groove 15 as shown in FIG. Laser etching to form In FIG. 20C, the photoelectric conversion layer 3 is a cross-sectional view in the X direction cut in the direction connected in series. Therefore, the back electrode layer 4 / photoelectric conversion is originally located at the position of the insulating groove 15. Although there should be a state corresponding to the peripheral film removal region 14 where the layer 3 / transparent conductive layer 2 has been removed by polishing (see FIG. 21A), it is convenient for the explanation of the processing to the end of the substrate 1. The insulating groove formed to represent the Y-direction cross section at this position will be described as the X-direction insulating groove 15. At this time, the Y-direction insulating groove does not need to be provided because the film surface polishing removal processing of the peripheral film removal region of the substrate 1 is performed in a later process.

The insulating groove 15 terminates the etching at a position of 5 to 15 mm from the end of the substrate 1, thereby having an effective effect in suppressing moisture intrusion from the outside into the solar cell module 6 from the end of the solar cell panel. This is preferable.
In addition, although the laser beam in the above process is made into a YAG laser, there exists what can use a YVO4 laser, a fiber laser, etc. similarly.

(9) FIG. 21 (a: view from the solar cell film side, b: view from the substrate side of the light receiving surface)
Since the laminated film around the substrate 1 (peripheral film removal region 14) has a step and is easy to peel off in order to ensure a sound adhesion / seal surface with the back sheet 24 via EVA or the like in a later process, The film is removed to form a peripheral film removal region 14. When removing the film over the entire circumference of the substrate 1 at 5 to 20 mm from the end of the substrate 1, the X direction is closer to the substrate end than the insulating groove 15 provided in the step of FIG. The back electrode layer 4 / photoelectric conversion layer 3 / transparent conductive layer 2 is removed by using grinding stone polishing, blast polishing, or the like on the substrate end side with respect to the groove 10 near the side portion.
Polishing debris and abrasive grains were removed by cleaning the substrate 1.

(10) FIG. 21 (a, b)
An attachment portion of the terminal box 23 is provided with an opening through window in the back sheet 24 to take out the current collector plate. Insulating materials are installed in a plurality of layers in the opening through window portion to suppress intrusion of moisture and the like from the outside.
The back electrode layer 4 of the solar power generation cell 5 at one end arranged in series and the back electrode layer 4 of the current collecting cell connected to the solar power generation cell 5 at the other end are collected using copper foil. Then, it is processed so that electric power can be taken out from the portion of the terminal box 23 on the back side of the solar cell panel. In order to prevent short circuit with each part, the copper foil for current collection arrange | positions an insulating sheet wider than copper foil width.

  After the current collecting copper foil or the like is disposed at a predetermined position, an adhesive filler sheet made of EVA (ethylene vinyl acetate copolymer) or the like is disposed so as to cover the entire solar cell module 6 and not protrude from the substrate 1. .

  A back sheet 24 having a high waterproofing effect is installed on the adhesive filler sheet. In this embodiment, the back sheet 24 has a three-layer structure of PET sheet / AL foil / PET sheet so that the waterproof and moisture proof effect is high.

An opening through window is provided at the attachment portion of the terminal box 23 of the back sheet 24 to take out the copper foil for current collection. In the opening through window portion, an insulating material is provided in a plurality of layers between the back sheet 24 and the back electrode layer 4 to suppress intrusion of moisture and the like from the outside.
The one with the back sheet 24 in place is degassed in a reduced pressure atmosphere with a laminator and pressed at about 150 to 160 ° C., and the adhesive filler sheet (EVA) is cross-linked and tightly sealed. Process.

  The adhesive filler sheet is not limited to EVA, and an adhesive filler having a similar function such as PVB (polyvinyl butyral) can be used. In this case, the processing is performed by optimizing the conditions such as the pressure bonding procedure, temperature and time.

(11) FIG. 22 (a)
The terminal box 23 is attached to the back side of the solar cell module 6 with an adhesive.

(12) FIG. 22 (b)
The copper foil and the output cable of the terminal box 23 are connected by solder or the like, and the inside of the terminal box 23 is filled with a sealing agent (potting agent) and sealed.

(13) FIG. 22 (c)
A power generation inspection and a predetermined performance test are performed on the solar cell panel 100 formed through the steps up to FIG. The power generation inspection is performed using a solar simulator of AM1.5 and solar radiation standard sunlight (1000 W / m ² ). The power generation inspection may be performed after the solar cell panel 100 is completely completed, or may be performed before the aluminum frame is attached, and is not particularly limited.

(14) FIG. 22 (d)
Before and after the power generation inspection (FIG. 22C), a predetermined performance inspection is performed including an appearance inspection.

(15) FIG.
Around the solar cell module 6, strength is added to the solar cell module 6 and an aluminum frame frame serving as a mounting seat is attached. It is preferable to securely hold the solar cell module 6 and the aluminum frame frames 33L and 33S through rubber gaskets or the like while maintaining elasticity.
Thus, the solar cell panel 100 is completed.

In the above embodiment, a solar cell using a single layer amorphous silicon solar cell has been described. However, the present invention is not limited to this example.
For example, crystalline silicon solar cells including microcrystalline silicon as a solar cell, silicon germanium solar cells, and amorphous silicon solar cells and crystalline silicon solar cells or silicon germanium solar cells are laminated in one to a plurality of layers. The present invention can be similarly applied to other types of thin film solar cells such as a multi-junction type (tandem type) solar cell.
Furthermore, the present invention can be similarly applied to a solar cell manufactured on a non-light-transmitting substrate such as a metal substrate or the like, on which light is incident from the side opposite to the substrate.

(Example)
An amorphous silicon-based thin film was formed on a substrate (30 cm × 40 cm × plate thickness: 2 mm) using the film forming apparatus of the first embodiment.
The cluster removal unit 104 is made of an aluminum alloy (35 cm × 45 cm × plate thickness: 10 mm). The cluster removing unit 104 has a plurality of hexagonal openings (opening width: 3 mm), and the opening ratio is 78%. The cluster removal unit 104 was disposed immediately above the substrate with an interval of 5 mm. On the cluster removal part 104, the counter electrode 105 and the discharge electrode 106 were arrange | positioned at intervals. A space of 20 mm was provided between the cluster removal unit 104 and the counter electrode 105.

A test piece 1 was obtained by forming an amorphous silicon thin film on a substrate under the following conditions.
Film forming conditions:
Reaction gas: Monosilane gas (SiH ₄ ) (100%)
Gas flow rate: 200sccm
Pressure: 5Pa
Substrate temperature: 200 ° C
Power supply frequency: 60 MHz
Electric power: 0.08 W / cm ^{2 to} 0.23 W / cm ²

As a comparative example, an amorphous silicon thin film was formed on a substrate without providing the cluster removal unit 104, and a test piece 2 was obtained. The film forming conditions were the same as those for the test piece 1.
Each test piece was irradiated with light (AM1.5, 125 mW / cm ² ) for 310 hours while maintaining at 48 ° C. as an evaluation condition for confirming the state of light degradation. The defect density was measured by the electron spin resonance (ESR) method for the test pieces at the initial stage of light irradiation and after light irradiation.

FIG. 24 shows the results of ESR measurement. In the figure, the horizontal axis represents the film forming speed and the horizontal axis represents the defect density. In both the test piece 1 and the test piece 2, the defect density increased as the film forming rate increased. The film forming speed of the test piece 1 was reduced only by about 50% as compared with the test piece 2. As a result, it was confirmed that the film forming speed due to the provision of the cluster removing unit 104 can be suppressed from being significantly lower than before, and a practical film forming speed can be obtained.
The defect density at the initial stage of light irradiation of the test piece 1 and the defect density at the initial stage of light irradiation of the test piece 2 were substantially the same. The defect density of the test piece 1 after light irradiation was 10 ¹⁶ pieces / cc level. On the other hand, the defect density after light irradiation of the test piece 2 was 10 ¹⁷ / cc level. Thereby, it was confirmed that the photodegradation of the amorphous silicon thin film can be significantly suppressed by providing the cluster removal unit 104.

  Next, the photoelectric conversion apparatus which formed the amorphous silicon thin film into a film using the film forming apparatus of 1st Embodiment was manufactured, and it was set as the test piece 3. FIG. The photoelectric conversion device includes a single-layer amorphous silicon photoelectric conversion layer. The other structure of the photoelectric conversion device was formed according to the seventh embodiment. The film thickness of the i layer of the amorphous silicon thin film was 250 nm. The film forming conditions of the amorphous silicon thin film were the same as those of the test piece 1 except that the film forming speed was 0.5 nm / s.

As a comparative example, a photoelectric conversion device was manufactured without providing the cluster removal unit 104, and a test piece 4 was obtained. The manufacturing conditions were the same as those for the test piece 3.
Each test piece was irradiated with light (AM1.5, 125 mW / cm ² ) for 310 hours while keeping each test piece at 48 ° C. The power generation inspection was performed on the test piece 3 and the test piece 4 after the initial light irradiation and after the light irradiation.

  FIG. 25 shows the result of the power generation inspection. In the figure, the bar on the left side of the paper on the horizontal axis is the test piece 4, the right side of the paper on the horizontal axis is the test piece 3, and the vertical axis is the conversion efficiency. In both the test piece 3 and the test piece 4, the conversion efficiency after the light irradiation was lower than that in the initial stage of the light irradiation. The conversion efficiencies at the initial stage of light irradiation of the test piece 3 and the test piece 4 were 10.5% and 10.7%, respectively, and both were substantially the same value. The conversion efficiency of the test piece 3 after light irradiation was 9.8%. On the other hand, the conversion efficiency after light irradiation of the test piece 4 was 7.1%. Thus, it was confirmed that the reduction in conversion efficiency due to light degradation can be significantly suppressed by providing the cluster removal unit 104.

DESCRIPTION OF SYMBOLS 1,101 Substrate 2 Transparent electrode layer 3 Photoelectric conversion layer 4 Back surface electrode layer 41 P layer 42 i layer 43 n layer 102 Substrate holding part 103 Plasma generation part 104 Cluster removal part 105 Counter electrode 106, 126, 136 Discharge electrode 107 High frequency power supply 108 Matching units 109a and 109b Power supply line 110 SiH ₄ gas molecule 111 Si nanocluster 116 Power supply line (coaxial cable)
117 Film forming chamber 118 Current introduction terminal 119 Core wire 120 Shield wire 121 Holding member (insulator for holding filter)
122 Supply Mechanism 123 Exhaust Mechanism 124 Cluster Removal Unit (Nanocluster Removal Filter / Electrode)
127 Inner tube 128 Outer tube 129 Hole 130 Slit 131 Current introduction terminal (for counter electrode)
132 Balun circuit 134 Temperature adjustment mechanism (Temperature adjustment medium introduction hole)

Claims (16)

A source gas containing Si is supplied into a vacuum container in which a substrate is housed, high-frequency power is supplied to a discharge electrode provided in a plasma generation unit, and plasma of the source gas is generated to form a silicon-based thin film on the substrate. A silicon-based thin film forming apparatus for forming a film,
A cluster removal unit is disposed between the substrate and the discharge electrode,
The cluster removal portion includes a plurality of openings so that the opening ratio is 50% or more,
The opening communicates the plasma generation unit side and the substrate side,
The opening width of the opening is not more than twice the mean free path of Si nanoclusters under pressure during film formation,
A silicon-based thin film forming apparatus in which the length of the opening is twice or more the opening width.   The silicon-based thin film forming apparatus according to claim 1, wherein the cluster removal unit has a honeycomb-like or lattice-like structure. The cluster removing unit
A structure in which a plurality of plate-shaped members have an opening width and are arranged in a blind shape so that the opening on the plasma generation portion side of one opening portion and the opening on the substrate side do not overlap when viewed from the normal direction of the substrate And
The opening width is equal to or less than the mean free path of the Si nanoclusters at the pressure during film formation;
The silicon-based thin film forming apparatus according to claim 1, wherein a length of the opening is at least twice as large as the opening width. The plasma generating unit includes a counter electrode disposed to face the discharge electrode;
The cluster removal portion is the counter electrode made of a conductive material;
The opening width is not more than twice the mean free path of Si nanoclusters under the pressure during film formation, and is a size that does not generate the plasma at the opening at a lower limit pressure in the film forming pressure range. The silicon-based thin film forming apparatus according to any one of claims 1 to 3. The discharge electrode is composed of a plurality of rod-shaped electrodes, and in at least one gap between the rod-shaped electrodes,
A supply mechanism for supplying the source gas to a space between the discharge electrode and the counter electrode;
An exhaust mechanism for exhausting the gas in the space out of the vacuum vessel;
A silicon-based thin film forming apparatus according to claim 4.   The silicon-based thin film deposition apparatus according to claim 4 or 5, wherein the discharge electrode and the counter electrode are held via an insulating material. A substrate holding unit for holding the substrate in the vacuum container;
The silicon-based thin film forming apparatus according to claim 5 or 6, wherein the substrate holding part and the discharge electrode have a temperature adjusting mechanism for adjusting their own temperatures.   An apparatus for manufacturing a photoelectric conversion device, comprising the silicon-based thin film forming apparatus according to claim 1. A source gas containing Si is supplied into a vacuum container in which a substrate is housed, high-frequency power is supplied to a discharge electrode provided in a plasma generation unit, and plasma of the source gas is generated to form a silicon-based thin film on the substrate. A method for forming a silicon-based thin film to be formed,
Provided with a plurality of openings so that the aperture ratio is 50% or more,
The opening communicates the plasma generation unit side and the substrate side;
The opening width of the opening is not more than twice the mean free path of Si nanoclusters under pressure during film formation,
A cluster removal portion having a length of the opening that is twice or more the opening width is disposed between the substrate and the discharge electrode,
A method for forming a silicon-based thin film in which the plasma is supplied to the substrate side through the opening of the cluster removal unit.   The method for forming a silicon-based thin film according to claim 9, wherein the cluster removal portion has a honeycomb-like or lattice-like structure. The cluster removal unit,
A plurality of plate-shaped members have openings that are arranged in a blind shape so that the opening on the plasma generation side of one opening and the opening on the substrate do not overlap when viewed from the normal direction of the substrate. ,
The opening width is equal to or less than the mean free path of Si nanoclusters at the pressure during film formation,
The method for forming a silicon-based thin film according to claim 9, wherein the length of the opening is at least twice the width of the opening. The cluster removal portion is a counter electrode made of a conductive material,
The opening width is not more than twice the mean free path of Si nanoclusters under the pressure at the time of film formation, and a size that does not generate the plasma at the opening at a lower limit pressure in the film forming pressure range,
The method for forming a silicon-based thin film according to any one of claims 9 to 11, wherein plasma is generated between the electrodes by disposing the counter electrode to face the discharge electrode. The discharge electrode is composed of a plurality of rod-shaped electrodes, and the source gas is supplied to a space between the discharge electrode and the counter electrode by a supply mechanism provided in at least one gap between the rod-shaped electrodes;
Exhausting gas from the space by an exhaust mechanism provided in at least one gap between the rod-shaped electrodes;
A method for forming a silicon-based thin film according to claim 12. Supplying the source gas to the space between the discharge electrode and the counter electrode by a supply mechanism;
Exhausting gas from the space by an exhaust mechanism;
With
The method for forming a silicon-based thin film according to claim 12 or 13, wherein the discharge electrode and the counter electrode are held via an insulating material. Holding the substrate by the substrate holder,
The method for forming a silicon-based thin film according to claim 12 or 13, wherein a temperature adjusting mechanism is provided for each of the substrate holding part and the discharge electrode to adjust its own temperature. The manufacturing method of the photoelectric conversion apparatus which forms a silicon-type thin film with the film-forming method of the silicon-type thin film in any one of Claim 9 thru | or 15.

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