JP3556483B2 - Method for manufacturing silicon-based thin film photoelectric conversion device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a thin-film photoelectric conversion device, and more particularly, to a cost reduction and performance improvement of a silicon-based thin-film photoelectric conversion device. Note that in this specification, the terms “crystalline” and “microcrystal” also mean those partially including an amorphous state.
[0002]
[Prior art]
A typical example of the thin film photoelectric conversion device is an amorphous silicon-based solar cell. Since an amorphous photoelectric conversion material is usually formed by a plasma CVD method at a low film formation temperature of about 200 ° C., glass, It can be formed on inexpensive substrates such as stainless steel and organic films, and is expected as a leading material for low-cost photoelectric conversion devices. Further, since amorphous silicon has a large absorption coefficient in the visible light region, a short-circuit current of 15 mA / cm ² or more is realized in a solar cell using an amorphous photoelectric conversion layer having a small thickness of 500 nm or less. I have.
[0003]
However, amorphous silicon-based materials have a problem that the photoelectric conversion characteristics are deteriorated by long-term light irradiation, as called the Stebler-Wronskey effect, and the effective sensitivity wavelength region is up to about 800 nm. is there. Therefore, in a photoelectric conversion device using an amorphous silicon-based material, its reliability and high performance are limited, and the original advantages that the flexibility of substrate selection and the use of a low-cost process are sufficient. Has not been utilized.
[0004]
On the other hand, in recent years, photoelectric conversion devices using a thin film containing crystalline silicon such as polycrystalline silicon or microcrystalline silicon have been energetically developed. These developments attempt to achieve both low-cost and high-performance photoelectric conversion devices by forming high-quality crystalline silicon thin films on low-cost processes on inexpensive substrates. It is expected to be applied to various photoelectric conversion devices.
[0005]
These crystalline silicon thin films can be formed, for example, by directly depositing them on a substrate by a CVD method or a sputtering method, or by performing thermal annealing or laser annealing after depositing an amorphous film once by a similar process. In any case, in order to use an inexpensive substrate as described above, it is necessary to perform the process at 550 ° C. or lower.
[0006]
Among such processes, the method of directly depositing a crystalline silicon thin film by the plasma CVD method is the easiest to lower the temperature of the process and increase the area of the thin film, and a high-quality film can be obtained by a relatively simple process. It is expected to be obtained. When a polycrystalline silicon thin film is obtained by such a method, a high-quality silicon thin film containing a crystalline material is once formed on a substrate by some process, and then formed as a seed layer or a crystallization control layer on the substrate. Thereby, a high-quality polycrystalline silicon thin film can be formed even at a relatively low temperature.
[0007]
On the other hand, a microcrystalline silicon thin film is often obtained by diluting a silane-based source gas with hydrogen by a factor of 10 or more and setting the plasma reaction chamber pressure in a range of 10 mTorr to 1 Torr by plasma CVD. It is known that in this case, a silicon thin film can be easily microcrystallized even at a temperature of about 200 ° C. For example, a photoelectric conversion device including a photoelectric conversion unit including a pin junction of microcrystalline silicon is disclosed in Appl, Phys, Lett. Vol 65, 1994, p. 860. This photoelectric conversion unit is composed of a p-type semiconductor layer, an i-type semiconductor layer and an n-type semiconductor layer, which are simply stacked sequentially by a plasma CVD method, and all of these semiconductor layers are microcrystalline silicon. It is characterized by. However, in order to obtain a high-quality crystalline silicon film and a high-performance silicon-based thin-film photoelectric conversion device, the film forming rate is set to 0.6 μm / hr in the thickness direction under the conventional manufacturing method and conditions. It is slower than this, and it is only as low as or less than that of the amorphous silicon film.
[0008]
On the other hand, an example in which a silicon film is formed under a relatively high pressure of 5 Torr by a low-temperature plasma CVD method is described in JP-A-4-137725. However, in this case, a silicon thin film is directly deposited on a substrate such as glass, and this is a comparative example with respect to the invention disclosed in JP-A-4-137725. It is not applicable.
[0009]
In general, when the pressure condition of the plasma CVD method is increased, a large amount of powdery products and dust are generated in the plasma reaction chamber. In that case, there is a high risk that the dust or the like will fly to the surface of the film being deposited and be taken into the deposited film, which may cause pinholes in the film. In order to reduce such deterioration of the film quality, the inside of the reaction chamber must be frequently cleaned. In particular, when the film is formed under a low temperature condition such as 550 ° C. or lower, these problems when the pressure in the reaction chamber is increased become remarkable. Moreover, in the manufacture of a photoelectric conversion device such as a solar cell, it is necessary to deposit a large-area thin film, which causes problems such as a reduction in product yield and an increase in labor and cost for maintaining and managing the film formation device.
[0010]
Therefore, when a thin film photoelectric conversion device is manufactured by using the plasma CVD method, a pressure condition of 1 Torr or less has been conventionally conventionally used as described above.
[0011]
[Problems to be solved by the invention]
The photoelectric conversion device including the crystalline silicon-based thin film photoelectric conversion layer as described above has the following problems. That is, regardless of whether it is polycrystalline silicon or microcrystalline silicon partially containing an amorphous phase, when used as a photoelectric conversion layer of a solar cell, sunlight is sufficiently absorbed in consideration of the absorption coefficient of crystalline silicon. In order to absorb light, a film thickness of at least several μm to several tens μm is required. This means that the thickness is slightly less than one digit to two digits thicker than the case of the amorphous silicon photoelectric conversion layer.
[0012]
However, according to the conventional techniques, in order to obtain a high-quality crystalline silicon-based thin film at a low temperature by a plasma CVD method, various film forming conditions such as temperature, pressure in a reaction chamber, high-frequency power, and gas flow rate are required. Even when the parameters were examined, the film formation rate was about the same as or less than that of the amorphous silicon film, for example, only about 0.6 μm / hr. In other words, the crystalline silicon thin film photoelectric conversion layer requires several times to tens of times the film formation time of the amorphous silicon photoelectric conversion layer, and it is difficult to improve the throughput of the photoelectric conversion device manufacturing process. This hinders cost reduction.
[0013]
In view of the above-mentioned problems in the prior art, an object of the present invention is to increase the film formation rate of a crystalline silicon-based photoelectric conversion layer formed by a low-temperature plasma CVD method, thereby improving the throughput of a manufacturing process, and It is to improve the performance of.
[0014]
[Means for Solving the Problems]
In a method for manufacturing a silicon-based thin-film photoelectric conversion device according to the present invention, the photoelectric conversion device includes at least one photoelectric conversion unit formed on a substrate, and the photoelectric conversion unit includes one conductive film sequentially stacked by a plasma CVD method. A semiconductor layer, a crystalline silicon-based thin film photoelectric conversion layer, and a semiconductor layer of the opposite conductivity type, and the photoelectric conversion layer is deposited by a plasma CVD method on the first electrode in a plasma reaction chamber. A second electrode is disposed opposite to the substrate; the second electrode is hollow and has a plurality of gas blowing openings on a surface facing the substrate to deposit a photoelectric conversion layer; At least some of the reaction gases are introduced into the plasma reaction chamber through their gas outlets; the distance between the first and second electrodes is set to within 1.5 cm; The pressure in the Zuma reaction chamber is set to 5 Toor or more; the reaction gas contains silane-based gas and hydrogen gas as main components, and the flow rate ratio of hydrogen gas to silane-based gas contained in all reaction gases introduced into the reaction chamber is 100. Plasma discharge power density is set to 100 mW / cm ² or more; the deposition rate of the photoelectric conversion layer is 1 μm / h or more; and the reaction gas introduced from the second electrode is It is characterized in that the ratio of the silane-based gas to hydrogen in the reaction gas blown from a predetermined unit area of the second electrode is increased toward the downstream side flowing between the two electrodes.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic perspective view illustrating a silicon-based thin-film photoelectric conversion device manufactured according to an embodiment of the present invention. A metal such as stainless steel, an organic film, a low-melting-point inexpensive glass, or the like can be used for the substrate 101 of the photoelectric conversion device.
[0016]
The back electrode 110 on the substrate 101 includes one or more of the following thin films (A) and (B), and can be formed by, for example, an evaporation method or a sputtering method.
(A) A metal thin film including a layer made of at least one metal selected from Ti, Cr, Al, Ag, Au, Cu and Pt or an alloy thereof.
(B) A transparent conductive thin film including a layer made of at least one oxide selected from ITO, SnO ₂ and ZnO.
[0017]
One conductivity type semiconductor layer 104 in photoelectric conversion unit 111 is deposited on back electrode 110 by a plasma CVD method. The one conductivity type semiconductor layer 104 is, for example, an n-type silicon layer doped with 0.01% by atom or more of phosphorus which is a conductivity type determining impurity atom, or a p-type silicon layer doped with 0.01% by atom or more of boron Etc. can be used. However, these conditions for the one conductivity type semiconductor layer 104 are not limited. For example, the impurity atoms may be aluminum or the like in a p-type silicon layer, or may be an alloy material such as silicon carbide or silicon germanium. Good. The one-conductivity-type silicon-based thin film 104 may be polycrystalline, microcrystalline, or amorphous, and its thickness is set in the range of 1 to 100 nm, more preferably in the range of 2 to 30 nm. You.
[0018]
As the photoelectric conversion layer 105 of a crystalline silicon-based thin film, a non-doped i-type polycrystalline silicon thin film, an i-type microcrystalline silicon thin film having a volume crystallization fraction of 80% or more, or a weak p-type or A silicon-based thin film material that is weak n-type and has sufficient photoelectric conversion efficiency can be used. The material of the photoelectric conversion layer 105 is not limited to these materials, and an alloy material such as silicon carbide or silicon germanium may be used. The thickness of the photoelectric conversion layer 105 is in the range of 0.5 to 10 μm, and has a necessary and sufficient thickness as a crystalline silicon thin film photoelectric conversion layer.
[0019]
The film formation of the crystalline silicon-based photoelectric conversion layer 105 is performed by a parallel plate electrode type plasma CVD method widely used in general, and a high frequency power supply having a frequency of 150 MHz or less and an RF band to a VHF band can be used. Note that the film formation temperature of the crystalline silicon-based photoelectric conversion layer 105 in these plasma CVD methods is 550 ° C. or lower at which the above-described inexpensive substrate can be used.
[0020]
At the time of deposition of the crystalline silicon-based thin film photoelectric conversion layer 105, the distance between the electrode on which the substrate is placed and the electrode facing the substrate in the plasma CVD reaction chamber is set within 1.5 cm, and the pressure in the reaction chamber is 5 Torr. This is set as above. Further, the high frequency power density at that time is preferably 100 mW / cm ² or more. Further, the gas introduced into the reaction chamber contains a silane-based gas and a hydrogen gas as main components, and the flow rate ratio of the hydrogen gas to the silane-based gas is preferably 50 times or more, more preferably 100 times or more. Is more preferred. As the silane-based gas, monosilane, disilane and the like are preferable, and in addition, silicon halide gas such as silicon tetrafluoride, silicon tetrachloride and dichlorosilane may be used. In addition, an inert gas such as a rare gas, preferably helium, neon, or argon may be used. Under the conditions for forming the crystalline silicon-based photoelectric conversion layer 105 as described above, the film formation rate can be set to 1 μm / hour or more.
[0021]
Most of the crystal grains contained in the crystalline silicon-based thin-film photoelectric conversion layer 105 extend upward from the base layer 104 in a columnar shape and grow. Many of these crystal grains have a preferential crystal orientation plane of (110) parallel to the film plane, and the intensity ratio of the (111) diffraction peak to the (220) diffraction peak determined by X-ray diffraction is 1/5 or less. And more preferably 1/10 or less. Note that even when the surface shape of the one-conductivity-type layer 104, which is the underlayer, is substantially flat, the surface after the formation of the photoelectric conversion layer 105 has minute gaps of about one digit smaller than the film thickness. A surface texture structure having irregularities is formed. Further, the obtained crystalline silicon-based thin film 105 preferably has a hydrogen content determined by secondary ion mass spectrometry in the range of 0.1 atomic% or more and 20 atomic% or less.
[0022]
In the method of forming the crystalline silicon-based thin film photoelectric conversion layer 105 according to the present invention, a high pressure is used as compared with the conventional pressure condition of 1 Torr or less, so that ion damage in the film can be reduced as much as possible. Therefore, even if the high-frequency power is increased or the gas flow rate is increased in order to increase the deposition rate, ion damage on the surface of the deposited film is small, and a high-quality film can be formed at a high speed. Also, if film formation is performed under high pressure conditions, there is a concern that contamination due to powder generation in the reaction chamber may occur.However, such a problem also occurs because the source gas is diluted in large quantities with a high heat conductive gas such as hydrogen. Hateful.
[0023]
Further, for the following reasons, in the present invention, a crystalline silicon-based thin film 105 having higher quality than that of the conventional method can be obtained. First, since the film formation rate is high, the rate at which impurity atoms such as oxygen and nitrogen remaining in the reaction chamber are taken into the film decreases. Further, since the crystal nucleus generation time in the early stage of film growth is short, the nucleus generation density is relatively reduced, and crystal grains having a large grain size and strong crystal orientation are easily formed. Further, when a film is formed at a high pressure, the crystal grain boundaries and defects in the grains are easily passivated by hydrogen, and the defect density thereof is reduced.
[0024]
In FIG. 2, an example of a plasma CVD apparatus that can be preferably used for forming the crystalline silicon-based thin film photoelectric conversion layer 105 as described above is illustrated in a schematic cross-sectional view. In this plasma CVD apparatus, a lower discharge electrode 222 and an upper electrode 223 are provided to generate plasma 228 in the reaction chamber 221. At least one of the two electrodes 222 and 223 vertically opposed to each other is movable in the vertical direction, the horizontal direction and / or the inclined direction, and the distance between the electrodes can be reduced to 1.5 cm or less and 1.5 cm. The above can be expanded.
[0025]
The substrate 101 can be introduced into the reaction chamber 221 via an inlet / outlet 225 provided with a valve (not shown), and can be mounted on the upper electrode 223. At this time, in order to make it easier to mount the substrate on the electrode 223, the interval between the two electrodes 222, 223 is enlarged to 1.5 cm or more. The lower electrode 222 is hollow so as to guide the reaction gas 226, and the upper surface thereof has a plurality of gas blowing openings. When the substrate 101 is mounted on the upper electrode 223, the distance between the electrodes 222 and 223 is reduced to 1.5 cm or less. The inside of the reaction chamber 221 is evacuated through the exhaust passage 227, and at the same time, a reaction gas is supplied from a plurality of gas blowing openings of the lower electrode 222, so that a predetermined pressure can be maintained.
[0026]
By the way, in the conventional film forming method used for forming the amorphous silicon film, the distance between the discharge electrodes was relatively large and the electrode area was small, so that the gas blown out from the central part of the gas blowing electrode and the peripheral part Even when the composition ratio with the gas blown out of the amorphous silicon film was the same, there was no locational nonuniformity in the properties of the resulting amorphous silicon film. However, in order to form a high-quality crystalline silicon film, the distance between the discharge electrodes is reduced as described above, and the deposition rate is high, so that the reaction gas containing a silane-based gas and hydrogen 100 times or more than that of the silane-based gas is used. Since the total flow rate is very large, the relationship between the flow of the reaction gas introduced from the gas blowing electrode and the consumption of the gas by the plasma reaction becomes a problem. In particular, if the substrate size exceeds 10 cm, the influence of the relationship between the flow of the reaction gas and its consumption on the spatial non-uniformity of the characteristics of the crystalline silicon film cannot be ignored.
[0027]
More specifically, while the crystalline silicon film is deposited, the silane-based gas is consumed as a source gas for the film in the flow of the reaction gas. However, even if the hydrogen in the reaction gas is taken into the film, it is small and hardly consumed, so that it is exhausted from between the discharge electrodes to the outside of the reaction chamber. Therefore, when the reaction gas introduced from the gas blowing electrode flows in the direction from the center to the periphery of the electrode, the ratio of hydrogen contained in the reaction gas is high at the electrode periphery downstream of the gas flow. Become. In addition, since the hydrogen blown out from the center of the electrode is exposed to the plasma for a long time before reaching the electrode periphery, the ratio of active species such as radicals becomes high, and the ratio of hydrogen that reacts easily in the electrode periphery becomes high. It will rise further. Under such a situation, a large characteristic difference occurs between the central portion and the peripheral portion of the formed crystalline silicon film, and the characteristic difference becomes more remarkable as the substrate area increases.
[0028]
Therefore, in the present invention, in order to prevent such a problem, as the reaction gas introduced from the gas blowing electrode proceeds to the downstream side flowing between the discharge electrodes, the reaction gas introduced per predetermined unit area of the gas blowing electrode is reduced. The ratio of the silane-based gas to hydrogen in the gas is increased. By doing so, the ratio of silane-based gas and hydrogen that actually participates in the reaction on the substrate is kept constant regardless of the upstream and downstream of the reaction gas flow, and there is no variation in the characteristics locally, and the ratio is uniform and high. A quality crystalline silicon film may be formed.
[0029]
As a specific example of the method of adjusting the ratio of the silane-based gas and the hydrogen that actually participate in the reaction as described above, of the plurality of openings of the gas blowing electrode, compared to the opening arranged on the upstream side of the reaction gas, What is necessary is just to increase the ratio of the silane-based gas in the reaction gas blown out from the opening arranged on the downstream side.
[0030]
In addition, a plurality of openings for blowing a reaction gas containing a silane-based gas and a hydrogen gas at a constant ratio at a gas discharge electrode are provided at a substantially uniform density, and a reaction containing a silane-based gas at a higher ratio than the fixed ratio is provided. A plurality of openings for blowing gas may be provided more downstream than upstream of the reaction gas.
[0031]
FIG. 3 is a schematic plan view showing a part of an example of a gas blowing electrode that can be used in the case of a CVD method in which a reaction gas flows from a central portion to a peripheral portion of a discharge electrode pair. In the gas blowing electrode 310, a plurality of openings 311 of the first type represented by white circles are arranged at a substantially uniform density, and a plurality of openings 312 of the second type represented by black circles are formed of the electrode 310. Are provided more near the periphery than near the center. That is, the first type opening 311 blows out a reaction gas containing a silane-based gas and a hydrogen gas at a fixed ratio, and the second type opening 312 blows a reaction gas containing a silane-based gas at a higher ratio than the fixed ratio. Used to get out.
[0032]
FIG. 4 is a schematic cross-sectional view illustrating an example of a CVD apparatus in which a reaction gas flows from one end side to the other end side of the discharge electrode pair. In such a CVD apparatus, the substrate 101 is mounted on the substrate holding electrode 420 including a heater in the reaction chamber 400. A gas blowing electrode 410 is arranged to face the substrate holding electrode 420. From the gas blowing electrode 410, a reaction gas is introduced as indicated by an arrow 411. At the same time, as indicated by an arrow 430, a reaction gas containing a hydrogen gas or a silane-based gas in addition thereto is introduced into the reaction chamber 400 from the right side. The gas pressure in the reaction chamber 400 is maintained at a predetermined value by exhausting to the left side by an exhaust pump (not shown) as indicated by an arrow 440. That is, both the reaction gas 411 introduced from the gas blowing electrode 410 and the hydrogen or the reaction gas introduced from the right side of the reaction chamber 400 flow in the direction from the right edge to the left edge of the electrode pair.
[0033]
Therefore, in such a case, in the gas blowing electrode 410, the ratio of the silane-based gas in the reaction gas blown out from the opening closer to the left edge side as compared with the opening closer to the right edge side may be increased. Alternatively, a plurality of openings for blowing out a reaction gas containing a silane-based gas and a hydrogen gas at a fixed ratio are provided at the gas blowing electrode 410 at a substantially uniform density, and the silane-based gas is supplied at a higher ratio than the fixed ratio. A plurality of openings for blowing out a reaction gas containing a gas may be provided in a region closer to the left edge of the gas blowing electrode 410 than in a region closer to the right edge.
[0034]
On the photoelectric conversion layer 105, a silicon-based thin film as a conductive semiconductor layer 106 of a type opposite to that of the base layer 104 is deposited by a plasma CVD method. The reverse conductivity type silicon-based thin film 106 is, for example, a p-type silicon thin film doped with boron, which is a conductivity type determining impurity atom, in an amount of 0.01 atomic% or more, or an n-type silicon film doped with phosphorus, in an amount of 0.01 atomic% or more. A thin film or the like can be used. However, these conditions for the opposite conductivity type semiconductor layer 106 are not limited. For example, aluminum may be used as impurity atoms in p-type silicon, or a film of an alloy material such as silicon carbide or silicon germanium may be used. You may. The reverse conductivity type silicon-based thin film 106 may be any of polycrystalline, microcrystalline, or amorphous, and its thickness is set in the range of 3 to 100 nm, more preferably in the range of 5 to 50 nm. Is done.
[0035]
On the photoelectric conversion unit 111, a transparent conductive oxide film 107 made of at least one layer selected from ITO, SnO ₂ , ZnO or the like is formed, and further thereon Al, Ag, Au, Cu as a grid electrode. , Pt, and the like, a comb-shaped metal electrode 108 including a layer of at least one metal or an alloy thereof is formed by a sputtering method or a vapor deposition method, thereby forming a photoelectric conversion device as shown in FIG. Is completed.
[0036]
FIG. 1 illustrates only one of the silicon-based thin-film photoelectric conversion devices to which the manufacturing method and the plasma CVD device according to the present invention can be applied. In addition to at least one crystalline thin film photoelectric conversion unit including a crystalline photoelectric conversion layer, at least one other amorphous thin film photoelectric conversion unit including an amorphous photoelectric conversion layer formed by a known method is also included. Needless to say, the present invention can be applied to a tandem photoelectric conversion device.
[0037]
Among the series of manufacturing steps of the silicon-based thin-film photoelectric conversion device described above, the biggest problem in the past for improving the throughput is the manufacturing of the crystalline photoelectric conversion layer 105 requiring a large film thickness. Needless to say, it was a process. However, according to the present invention, the film formation rate of the crystalline photoelectric conversion layer is greatly improved, and a higher quality film can be obtained. Can greatly contribute to
[0038]
【The invention's effect】
As described above, according to the present invention, when a silicon-based thin film photoelectric conversion layer containing a crystalline material is formed on an inexpensive substrate at a low temperature by a plasma CVD method, the film formation speed is greatly improved as compared with the related art. And a good film quality can be obtained, which can greatly contribute to both high performance and low cost of the silicon-based thin film photoelectric conversion device.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing an example of a crystalline silicon-based thin film photoelectric conversion device obtained by a manufacturing method according to an embodiment of the present invention.
FIG. 2 is a schematic sectional view showing a plasma CVD apparatus that can be used in the manufacturing method according to the embodiment of the present invention.
FIG. 3 is a plan view schematically showing a part of an example of a gas blowing electrode that can be used in the manufacturing method according to the embodiment of the present invention.
FIG. 4 is a schematic cross-sectional view showing a part of a CVD apparatus that can be used in the manufacturing method according to the embodiment of the present invention.
[Explanation of symbols]
101: a substrate made of glass or the like 102: a film made of Ag or the like 103: a film made of ZnO or the like 104: an n-type microcrystalline silicon layer of the first conductivity type 105: a crystalline silicon-based photoelectric conversion layer 106: a p-type opposite conductivity type, for example Polycrystalline silicon layer 107: Transparent conductive film 108 of ITO or the like: Comb electrode 109 of Ag or the like 109: Irradiation light 110: Backside electrode 111: Crystalline silicon-based photoelectric conversion unit 221: Plasma reaction chamber 222: Reaction gas blowing electrode 223: Substrate Mounting electrode 225: Substrate entrance / exit 226: Reactive gas 228: Plasma 227: Exhaust 310: Gas blowing electrode 311: Opening 312 for blowing out a reactive gas containing silane-based gas and hydrogen at a fixed ratio 312: Silane-based compared to opening 311 Opening 400 for blowing out a reaction gas containing a large amount of gas: plasma reaction chamber 410: gas blowing electrode 411: reaction gas 420: base Holding electrode 430: a hydrogen gas or a reactive gas 440: exhaust

Claims (6)

A method for manufacturing a silicon-based thin-film photoelectric conversion device,
The photoelectric conversion device includes at least one photoelectric conversion unit formed on a substrate, the photoelectric conversion unit includes a one-conductivity-type semiconductor layer sequentially stacked by a plasma CVD method, a crystalline silicon-based thin-film photoelectric conversion layer, And a reverse conductivity type semiconductor layer,
Conditions for depositing the photoelectric conversion layer by the plasma CVD method include:
The substrate is disposed on a first electrode in a plasma reaction chamber;
A second electrode is disposed facing the substrate,
The second electrode is hollow and has a plurality of gas outlets on a surface facing the substrate, and at least a part of a reaction gas for depositing the photoelectric conversion layer passes through the gas outlets to the plasma reaction chamber. Was introduced to
A distance between the first and second electrodes is set within 1.5 cm;
The pressure in the plasma reaction chamber is set to 5 Torr or more,
The reaction gas contains a silane-based gas and a hydrogen gas as main components, and a flow ratio of the hydrogen gas to the silane-based gas contained in all the reaction gases introduced into the reaction chamber is 100 times or more,
Plasma discharge power density is set to 100 mW / cm ² or more;
The deposition rate of the photoelectric conversion layer is 1 μm / h or more;
Then, as the reaction gas introduced from the second electrode flows to the downstream side flowing between the first electrode and the second electrode, the reaction gas blown out from a predetermined unit area of the second electrode. A method for manufacturing a silicon-based thin-film photoelectric conversion device, wherein a ratio of a silane-based gas to hydrogen is increased. In the second electrode, a plurality of openings for blowing a reaction gas containing a silane-based gas and a hydrogen gas at a constant ratio are provided at a substantially uniform density, and a reaction containing a silane-based gas at a higher ratio than the fixed ratio is provided. The method for manufacturing a silicon-based thin-film photoelectric conversion device according to claim 1, wherein a plurality of openings for blowing gas are provided more downstream than upstream of the reaction gas. The reaction gas blown from the second electrode flows toward the other end together with a reaction gas or hydrogen gas additionally supplied from one end side of the second electrode. 3. The method for manufacturing a silicon-based thin-film photoelectric conversion device according to item 2. The photoelectric conversion layer is a polycrystalline silicon film or a microcrystalline silicon film having a volume crystallization fraction of 80% or more, which can be formed under a base temperature in the range of 100 to 400 ° C. The silicon-based thin-film photoelectric conversion device according to any one of claims 1 to 3, wherein the silicon-based thin-film photoelectric conversion device contains hydrogen of at most atomic% and has a film thickness in a range of 0.5 to 10 µm. Manufacturing method. The photoelectric conversion layer has a preferential crystal orientation plane of (110) parallel to the film plane, and the intensity ratio of the (111) diffraction peak to the (220) diffraction peak in X-ray diffraction is 1/5 or less. The method for manufacturing a silicon-based thin-film photoelectric conversion device according to claim 1, wherein: The silicon according to any one of claims 1 to 5, wherein a tandem-type photoelectric conversion device is formed by stacking at least one amorphous silicon-based photoelectric conversion unit in addition to the photoelectric conversion unit. Of manufacturing a thin film photoelectric conversion device.

Images