JP2989055B2 - Solar cell manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solar cell, and more particularly to a method for diffusing incident light by stably improving the power output characteristics of the solar cell and absorbing the light absorbed by an active layer of the solar cell. The present invention relates to a method for manufacturing a solar cell that can effectively use the solar cell.

[0002]

2. Description of the Related Art At present, a solar cell is used as a driving energy source in various devices. The solar cell uses a PN junction or a PIN junction for the functional part.
Generally, silicon is used as a semiconductor constituting the N-junction. From the viewpoint of the efficiency of converting light energy into electromotive force, it is preferable to use single crystal silicon as a semiconductor material. However, from the viewpoint of increasing the area and reducing the cost, amorphous silicon is said to be advantageous.

[0003] On the other hand, in recent years, the use of polycrystalline silicon has been studied for the purpose of obtaining a low cost equivalent to that of amorphous silicon and a high energy conversion efficiency comparable to that of single crystal silicon. Conversion efficiency has not yet been obtained.

In single-crystal silicon, various high-efficiency techniques, such as the point-contact method (Richard M.
Swanson et al., IEEE, Vol.ED-31, No.5, MAY (1984) P
661) and surface passivation technology and electrode area reduction technology (T. Nammori, Research Forum of Crystalline Sola
r Cells, (1989) p77, Tokyo), optical confinement technology (T. Uematsu
et al., Conf.Recordof the 20th IEEEPVSC (1988) p79
Although studies such as 2) have been conducted, none of them are sufficient technologies in terms of cost reduction at present. That is, it is necessary to sufficiently reduce the thickness in order to reduce the cost.

In order to reduce the thickness of conventional single-crystal silicon solar cells, a flat-type substrate obtained by thinning single-crystal silicon by etching must be used. In a heat treatment step such as thermal diffusion or oxidation, distortion of the substrate or formation of electrodes occurs. There is a problem of the curvature of the substrate, and there are many difficult points such as formation of a fine structure, stabilization of a formation process, and enlargement of an area.

Also, US Pat. No. 4,816,420 discloses that
A method for manufacturing a tandem solar cell is disclosed. In this method, a mask layer is first formed on a crystal substrate, and a crystal material is deposited on an unmasked region of a substrate under the condition of providing a laterally grown crystal material on the mask layer. The lateral growth is continued until it is obtained, the sheet is separated from the substrate, and a thin-film solar cell is formed from the separated sheet. To form a tandem solar cell, the solar cell and another solar cell are bonded .

However, it is not enough to provide a solar cell having a high conversion efficiency with a relatively thin semiconductor layer, and there is still room for improvement. There is also room for improvement in the yield.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to manufacture a solar cell having a higher photoelectric conversion efficiency than a conventional solar cell formed of the same material and the same layer thickness with a high yield.

Another object of the present invention is to provide a method of manufacturing a solar cell suitable for producing a large-area solar cell panel at low cost.

[0010]

The method for manufacturing a solar cell according to the present invention for achieving the above object has an effect of confining light.
Of a solar cell with a photovoltaic element
In the manufacturing method, an uneven surface serving as a mold for forming the uneven portion
Processing the first substrate surface so as to exhibit
A concave portion serving as the photovoltaic element is formed on the uneven surface of the first substrate.
Forming a single crystal semiconductor layer having a convex portion;
Bonding a single crystal semiconductor layer having a projection to a second substrate
Forming a single crystal semiconductor layer having the uneven portion by the first step.
Peeling off from the substrate of the solar cell
It is.

Hereinafter, a preferred embodiment of the present invention will be described. However, the present invention is not limited to the embodiment, and any material, shape, and size may be used as long as the object of the present invention is achieved. , And those in which the manufacturing process is changed.

The first substrate used in the present invention is composed of Si,
A single crystal substrate made of Ge, C, SiC, SiGe, etc.,
A substrate made of GaAs, InP, CdTe, or the like is used. Further, a substrate made of a non-single-crystal material such as silicon oxide or silicon nitride may be used. Of course, a material in which SiO ₂ is formed on single-crystal Si, or a material in which the above-mentioned materials are coated on a substrate made of resin or the like may be used.

Then, using a substrate having a substantially flat surface made of a non-single-crystal material, a semiconductor layer having a plurality of single-crystal regions and an uneven surface having a plurality of crystal faces is formed. In that case, a single crystal semiconductor layer forming step described in JP-A-3-94477 may be used.

On the other hand, when a semiconductor layer having an uneven surface is formed using a single crystal substrate, it is preferable that the single crystal substrate itself has the unevenness.

As a method of forming a deposited film for forming a semiconductor layer having an uneven surface on the above-mentioned various substrates, physical vapor deposition (PVD) or chemical vapor deposition (CVD) is used. Can be In particular, in order to form a deposited film including a single crystal total region, an epitaxial growth method by a bias sputtering method or a CVD method is preferable.
Among them, the CVD method described later in detail is desirable for improving the deposition rate and forming a single crystal semiconductor layer having a high-quality uneven surface. Such a CVD method is disclosed in detail in U.S. Pat. No. 4,835,005.

One of the more preferable techniques used in the present invention is to form a V-shaped groove as a concavo-convex portion on a single-crystal silicon wafer so as to exhibit an optical confinement effect, as shown in FIG. Is formed on the V-shaped groove.

Here, the formation of a V-shaped groove which is preferable for achieving the light confinement effect will be briefly described.

As shown in FIG. 1A, a method of forming a V-shaped groove having an optical confinement effect is to use a silicon wafer having a (100) plane and form a silicon oxide film, a silicon nitride film, or the like. After forming the etching mask, the silicon wafer is etched with a solution that causes anisotropic etching such as a potassium hydroxide solution or hydrazine. In this etching, the (100) plane having a high etching rate is etched into the inside of the wafer as time passes, and a V-shaped groove surrounded by the (111) plane is finally formed. The inclination of the V-shaped groove is determined by the crystal plane orientation, and its opening angle is about 70.5 °.

The depth (etching depth) of the V-shaped groove is (10
0) It can be arbitrarily controlled by the thickness of the silicon wafer having the surface and the interval between the etching masks.

Then, the etching mask is removed with a solution capable of dissolving the etching mask, such as an aqueous solution of hydrogen fluoride, and a first groove having a V-shaped groove processed into a structure having a light confinement effect as shown in FIG. Of the substrate 103 can be formed.

Next, as shown in FIG. 1 (c), have a V-groove
A silicon oxide thin film 104 is non-uniformly deposited as an insulating layer on the surface of the first substrate 103 by a PVD method, a CVD method, a thermal oxidation method, or the like. As a result, the underlying single-crystal Si surface is exposed at a plurality of locations, causing a difference in surface energy and the like, and furthermore, crystal growth is more likely to occur due to generation of edge energy and the like. Further, the crystal growth layer can be easily separated from the first substrate having the V-shaped groove processed into a structure exhibiting the light confinement effect. Such a silicon oxide thin film 104
The thickness of the film is appropriately determined as desired.
Å-100Å, more preferably 3Å-50Å, optimally 4Å
~ 10Å. With such a thin film, even with the conventional film forming method, the film tends to be naturally non-uniform.

Another preferred technique used in the present invention is to form a deposited film on the first substrate processed into the structure having the light confinement effect shown in FIG. 1C. (A) generated by decomposing a compound containing silicon and halogen on the first substrate and a chemical interaction with the active species (A) The active species (B) generated from the film-forming chemical substance are simultaneously or separately introduced, and the first type is used as shown in FIG. Layer 201 (hereinafter referred to as a first layer) substantially composed of a single crystal of the conductivity type
Electrically referred to as conductivity-type layer) is formed, a layer 20 of the first conductivity type
This is a technique of forming a layer 202 (hereinafter, referred to as a layer of the second conductivity type) substantially composed of a single crystal of the second conductivity type above 1. The layer thicknesses of such single crystal layers 201 and 202 are appropriately determined as desired. Particularly, the layer thickness of layer 202 is preferably 3 μm to 50 μm, more preferably 4 μm to 3 μm.
Desirably, it is 0 μm, most preferably 5 μm to 20 μm.

In this method, instead of generating plasma in a film forming space for forming a deposited film, a compound containing silicon and halogen is applied with activation energy in an active space (A) different from the film forming space. In the presence of the active species (A) generated by the decomposition and the active species (B) generated from the chemical substance for film formation, a chemical interaction is caused. And adverse effects such as sputtering and electrons due to generated ions and the like. Further, according to the present invention, a more stable CVD method can be achieved by arbitrarily controlling the atmosphere temperature and the substrate temperature in the film formation space as desired.

One of the points that this method differs from the ordinary CVD method is that an active species that has been activated in a space different from the film formation space (hereinafter referred to as an activation space) is used. Thereby or extend the deposition rate dramatically by conventional CVD method, board temperature during formation of the deposited film also becomes possible to achieve further low temperature. In addition, it is a method for easily forming a single crystal layer.

In the present invention, the activation introduced into the film formation space
Active species (A) from space (A) are productivity and handling
In terms of ease, etc., the life is more preferable than 0.1 seconds.
Or more than 1 second, optimally 10 seconds or more
The active species (A) is
Constituting the components that make up the deposited film formed in the film formation space
It will be. Also, the chemicals for film formation are in the activation space.
(B) the activation energy can be applied
Is activated to become an active species (B). Active species
(B) shows that when a deposited film is formed by being introduced into the film forming space,
Of the deposited film introduced from the activation space (A) and formed
Active species (A) containing constituent elements and chemically
Interact. Silicon introduced into the activation space (A)
As the compound containing halogen, for example, a chain or ring
A part or all of the hydrogen atoms of the silane compound
A compound substituted with an atom is used. Specifically, for example,
Si_uY_{Two u + 2}(U is a positive number of 1 or more, Y is F, Cl, Br,
And at least one element selected from I and I. )
A cyclic silicon halide represented by_vY_2v(V is 3
The above positive numbers, Y, have the above-mentioned meaning. Ring)
Silicon halide, Si _uH_xY_y(U and Y are
Meaningful. x + y = 2u or 2u + 2. )
A chain or cyclic compound is exemplified.

More specifically, for example, SiF ₄ , (Si
F ₂ ) ₅ , (SiF ₂ ) ₆ , Si ₂ F ₆ , Si ₃ F ₈ , SiHF
₃ , SiH ₂ F ₂ , SiCl ₄ , (SiCl ₂ ) ₅ , SiBr
₄ , (SiBr ₂ ) ₅ , Si ₂ Cl ₆ , Si ₂ Br ₆ , SiH
Cl ₃ , SiH ₃ Cl, SiH ₂ Cl ₂ , SiHBr ₃ , S
Examples thereof include those in a gas state such as iHI ₃ and Si ₂ Cl ₃ F ₃ or those which can be easily gasified.

In order to generate the active species (A), in addition to the compound containing silicon and halogen, if necessary, simple silicon or another silicon compound, hydrogen, a halogen compound (for example, F ₂ gas, Cl ₂ Gas, gasified Br ₂ , I ₂
Etc.) can be used in combination.

As a method for generating the active species (A) in the activation space (A), electric conditions such as microwaves, RF, low frequency, DC, etc., heater heating, infrared heating are considered in consideration of each condition and apparatus. Activation energy such as heat energy and light energy is used.

In the activation space (B), the active species (B)
As the film-forming chemical substance for generating hydrogen, a hydrogen gas and / or a halogen gas (for example, F ₂ gas, Cl ₂
Gas, gasified Br ₂ , I _2, etc.) are advantageously used.
In addition to these film forming chemical substances, an inert gas such as helium, argon, or neon can be used. When a plurality of these film forming chemicals are used, they can be mixed in advance and introduced into the activation space (B) in a gas state, or these film forming chemicals can be used in a gas state. It is also possible to individually introduce into the activation space (B) from independent sources. Alternatively, they can be introduced into independent activation spaces and activated individually.

In the present invention, the ratio of the amount of the active species (A) and the amount of the active species (B) to be introduced into the film formation space is appropriately determined according to the film formation conditions, the type of the active species, and the like. Preferably, the ratio is 10: 1 to 1:10 (introduction flow ratio), and more preferably, the ratio is 8: 2 to 4: 6.

The deposited film formed by this method is
It is possible to dope with an impurity element in the semiconductor field during or after film formation. As the impurity element to be used, an element belonging to Group 3B of the periodic table, for example, B, Al, Ga, In, Tl, or the like is preferable as the p-type impurity.
Group B elements, such as P, As, Sb, Bi, etc., are preferred, but B, Ga, P, Sb, etc. are particularly preferred. The amount of the impurity to be doped is appropriately determined according to the desired electrical and optical characteristics.

The substance containing such an impurity element as a component (impurity-introducing substance) is in a gaseous state at normal temperature and normal pressure, or is a gas at least under activation conditions.
It is preferable to select a compound that can be easily vaporized by an appropriate vaporizer. Such compounds include PH ₃ , P ₂ H
_{4, PF 3, PF 5,} AsH 3, AsF 3, AsF 5, AsC
l ₃ , SbH ₃ , SbF ₅ , SiH ₃ , BF ₃ , BCl ₃ , B
_{Br 3, B 2 H 6,} B 4 H 10, B 5 H 9, B 5 H 11, B 6 H 10,
B ₆ H ₁₂ and AlCl ₃ can be exemplified. The compound containing an impurity element may be used alone or in combination of two or more.

The compound containing an impurity element as a component may be directly introduced into the film formation space in a gaseous state.
Alternatively, after activation in the activation space (A) or the activation space (B) or the third activation space (C), the film can be introduced into the film formation space.

In this CVD method, "active species" can be a raw material of a deposited film to be formed, but a precursor and a chemical which cannot or cannot form a deposited film at all under the same energy condition. It acts to cause an interaction, for example, to give energy to the precursor or to chemically react with the precursor to bring the precursor into a state where a deposited film can be formed. Therefore, the active species may include a component that constitutes a deposited film to be formed, or may not include such a component.

Next, as shown in FIG. 2B, the conductive adhesive 2
03, a support 20 for fixing the layer of the second conductivity type
Glue 4 and fix. As the conductive adhesive 203, for example, an Ag-based paste, an Ag / Cu-based paste, a Ni-based paste, or the like is used .
As the substrate 204, a conductive support is used, for example, a stainless plate, an aluminum plate, an iron plate, or the like.

The present invention in another preferred technique used, as shown in FIG. 3 (a), (b) , has a V-shaped groove was processed to a structure provides the light confinement effect in FIG. 2 (b) No.
The first substrate 103 and the first conductive type layer 201 are separated from each other.

The first substrate 103 having the V-groove where
A method of separating the first conductive type layer 201 from the first conductive type layer 201 will be briefly described.

[0038] In FIG. 2 (b), having a said V-groove
A thin silicon oxide film 104 non-uniformly deposited on the surface of the first substrate 103 by a CVD method or the like is immersed in a solution capable of dissolving the silicon oxide film, for example, a hydrogen fluoride aqueous solution or the like. The first conductive type layer 201 is peeled off from the surface of the first substrate by adding the like.

Next, as shown in FIG. 3C, a transparent electrode 301 such as SnO ₂ , In ₂ O ₃ , ITO (Indium-Tin Oxide) is formed on the surface of the peeled first conductive type layer 201. ), And then, as shown in FIG. 4, a current collecting electrode 401 is formed on the transparent electrode by, for example, Ag, Ni, Au, Ti, P
d, Al, etc. by a vacuum evaporation method, or Ag, Al, C
A solar cell is manufactured by printing a conductive paste containing a powder of u, Ni, or the like, followed by baking and the like. The first substrate 103 that has been peeled off returns to the step of depositing the silicon oxide thin film 104 unevenly again, and is reused as the first substrate .

[0040] That is, one embodiment of the present invention, prior to
A plurality of parts separated from each other on the uneven surface of the first substrate;
The step of forming the insulating layer, the first substrate was disposed in the deposition space for forming a deposited film, by decomposing a compound containing silicon and halogen on said first substrate The active species (A) to be generated and the active species (B) formed by a chemical substance for film formation that chemically interacts with the active species (A) are simultaneously or separately introduced, and forming a layer of the second conductivity type above the active species of a chemical process of forming a layer of a first conductivity type by using the action, the first conductivity type layer, the sun including capital This is a method for manufacturing a battery.

[0041]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 (V-shaped groove having an optical confinement effect and easy peeling
First Step of Forming First Substrate ) As shown in FIG.
On a surface of a (100) silicon wafer 101 having a thickness of μm, a thermal oxide film was formed as an insulating layer 102 by 2000 mm. Next, etching is performed using photolithography to prepare a substrate in which the width (a ′) of the insulating layer 102 is 1 μm and the interval (b ′) between the insulating layers 102 is 200 μm, and the substrate is placed in an aqueous KOH solution or hydrazine solution. About 70 ℃
After performing the crystal plane selective etching for about 24 hours, washing with running water was performed. Next, the structure is immersed in a 5% aqueous hydrogen fluoride solution for one hour to remove the insulating layer 102 serving as an etching mask, washed with running water, and then dried to obtain a structure having an optical confinement effect as shown in FIG. having a machined V-grooves
A first substrate 103 was formed.

Next, the first substrate 103 having the V-shaped groove is used.
, A conventional RF plasma CV having a capacitively coupled electrode
Placed in the reaction chamber in the D unit, while introducing a separate system of SiH ₄ gas and O ₂ gas at respective 20sccm and 40sccm into the reaction chamber, board temperature 270 ° C., RF power 50 W, frequency frequency 13.56 MHz, the pressure By discharging at 0.8 Torr for several minutes, a silicon oxide thin film 104 having a thickness of 8 mm was formed as shown in FIG.

[0044] (formation of the crystal layer) Using a device as shown in FIG. 5, first having the V-groove
A crystal layer was formed on the surface of one substrate 103. In FIG. 5, 501 is a gas introduction pipe for introducing a compound containing silicon and halogen, and 502 is a film-forming chemical substance that chemically reacts with an active species (A) generated by decomposing a compound containing silicon and halogen. Gas introduction pipe to be introduced, 503 is the base, 5
04 a heater is incorporated so that it can appropriately set the holder in and board temperature to hold the board 503. Gas inlet pipe
Each gas introduced from 501 and 502 is exhausted by a vacuum pump (not shown) including unreacted or reaction products.

The compound containing silicon and halogen introduced from the gas introduction pipe 501 is partially or entirely decomposed and introduced into the association space 505 under the control of the high-frequency power generator. On the other hand, active species (B) introduced from the gas introduction pipe 502
Is introduced, and the gas introduced by the high-frequency power generator is plasma-decomposed, so that a large amount of active species (B) is generated and introduced into the association space 505. In the association space 505, the active species (A), which is a decomposition product of a compound containing silicon and halogen, and the active species (B) that chemically reacts with the active species (A) are transported to the substrate 503 through a chemical reaction, and undergo a substrate surface reaction. After that, a deposited film is formed. Now, according to the production conditions of the crystalline silicon shown in Table 1, 75 sccm of SiF ₄ gas is introduced from the gas introduction tube 501, and H ₂ and Ar gas are introduced respectively by 9,75 sccm from the gas introduction tube 502 to form a film formation space. 380mTorr pressure
Adjust the exhaust valve (not shown) so that Adjust high frequency power 2.45GHz to 400W and start deposition. Based on plate 503
A Si (100) wafer (resistivity of about 1 kΩcm) was used. This is a cleaning method generally known as RCA cleaning (NH ₃ : H ₂ O ₂ : H ₂ O = 1: 1: 4 mol after organic cleaning in advance).
After boiling for 10 minutes in a ratio, further HCl: H ₂ O ₂ : H ₂ O
= 1: 1: 4 mol ratio for 10 minutes, and then dipping for 30 seconds with an etching solution (HF: H ₂ O = 1: 9 mol ratio).

[0046]

[Table 1] Crystalline silicon manufactured under the above manufacturing conditions,
The deposition rate was as high as 18 ° / s, and the reflection-type high-speed electron diffraction image shows that the Kikuchi belt is an excellent single-crystal thin film.

Next, as the base plate 503, machined V-grooves in the structure to achieve the optical confinement effect shown in FIG. 1 (c)
Using the first substrate having the above structure, deposition was performed using the apparatus shown in FIG. 5 under the above-described crystalline silicon production conditions shown in Table 1 (FIG. 2A). However, organic cleaning and RCA cleaning of the substrate, HF dipping is not performed, also before
The first conductive type layer 201 formed on the surface of the first substrate
Introduces B ₂ H ₆ / Ar gas as a substance for introducing impurities into SiF.
1 ppm with respect to ₄ gases, introduced together with H ₂ and Ar gas from the gas introduction pipe 502, and the second conductive type layer 202 is used to introduce PH ₃ / Ar gas as a substance for introducing impurities into the SiF ₄ gas. 1 ppm, together with H ₂ and Ar, were introduced from a gas introduction tube 502 to deposit a silicon crystal layer.

Next, board 50 depositing a silicon crystal layer
After cooling by natural cooling 3 from board temperature 410 ° C., board
Take out 503 from the deposition device, apply a silver paste as a conductive adhesive 203 on the surface of the second conductive type layer 202,
Next, as the support 204 for fixing the single crystal layer,
A 1.5 mm stainless steel plate was attached (FIG. 2 (b)).

[0049] (exfoliation of the crystal layer) depositing a single crystal layer shown in FIG. 2 (b), the first conductive than the first substrate 103 side of the conductive adhesive adhered to stainless steel plates through the wearing and board The layer 201 up to the mold layer 201 is immersed in a 5% hydrogen fluoride aqueous solution, and ultrasonic vibration is applied thereto .
The substrate 103 was peeled off (FIG. 3 (a)), and those remaining on the stainless steel support side shown in FIG. 3 (b) were sufficiently washed with running water.

Next, SnO ₂ / ITO was applied as a transparent electrode 301 to the sufficiently dried surface of the layer 201 by RH method.
0 ° was deposited (FIG. 3 (c)). Finally, a current collecting electrode 401 was formed on the transparent electrode 301 by a printing method in which a conductive paste containing Ag powder was printed and then fired to obtain a thin film single crystal silicon solar cell as shown in FIG.

With respect to the IV characteristics of the thin-film single-crystal silicon solar cell obtained in this manner, AM 1.5, 100 mW / cm
^The measurement was performed under the light irradiation of No. ² . As a result, the conversion efficiency of the photovoltaic power was 17%, which was excellent as a practical single-crystal silicon solar cell characteristic. The area of the solar cell at the time of measurement was 4 cm ² .

Further, a single-crystal silicon solar cell was manufactured a total of ten times using the peeled first substrate 103 again, and the IV characteristics were measured in the same manner. Was within ± 5%.

Example 2 In Example 1, a single crystal silicon film was formed by a film forming apparatus shown in a schematic diagram of FIG. 6 instead of the apparatus of FIG.

In the figure, reference numeral 601 denotes a gas introduction ring,
A compound mainly containing silicon atoms and halogen is introduced into the vacuum chamber 603. Reference numeral 602 denotes a gas introduction pipe for supplying gas mainly serving as a raw material of the active species (b) to the quartz cavity 60.
Introduce into 3. The microwave is generated from a microwave oscillator (not shown), propagates through the waveguide 605, and appropriately adjusts the aperture 606 to generate a standing wave between the aperture 606 and the mesh 604, thereby generating a standing wave in the quartz cavity 603. Can be converted into plasma. 607 is a holder in the heater built, it is possible to heat holds the base plate 608 to the desired temperature. In the present embodiment, a V fabricated to have a light confinement effect manufactured in the same manner as in the first embodiment.
It was placed a first substrate having a mold groove as the base plate 608.

25 sccm of hydrogen gas and He
A gas of 35 sccm was introduced into the quartz cavity 603. Also introduced toward the Si ₂ F ₆ gas 12sccm from the gas-introducing ring 601 on the board 608 as shown in FIG. By adjusting the power of the microwave oscillator to 300 W and adjusting the throttle 606, the hydrogen gas and the He gas in the quartz cavity 603 can be turned into plasma. Table 2 shows the conditions for producing crystalline silicon.

[0056]

[Table 2] Thus hydrogen radicals generated by the Si ₂ F ₆ and gas and chemical reaction ejected from the gas-introducing ring 601, board 608
A silicon crystal layer is deposited thereon.

Firstly, in order to deposit the first conductivity type layer 201 on the base plate 608, a BF ₃ gas to Si ₂ F ₆ gas 1.5ppm
It was performed by mixing. Thereby the silicon crystal layer of 0.5μm on the base plate 608 is deposited. Thereafter, the output of the microwave oscillator to zero, the deposition was stopped, and after stopping the supply of the gas, after completely discharging the sufficient exhaust residual gases of the vacuum chamber 609, Si ₂ F ₆ PH ₃ in the gas Gas 0.7pp
m, and the second conductive type layer 202
Was subsequently deposited in a layer thickness of 7.5 μm.

Next, based on depositing a silicon crystal layer plate 60
After cooling by natural cooling 3 from board temperature 360 ° C., board
Take out 603 from the deposition apparatus, apply a silver paste as a conductive adhesive 203 on the surface of the second conductive type layer 202,
Next, as the support 204 for fixing the single crystal layer,
A 2.0 mm stainless steel plate was attached (FIG. 2 (b)).

[0059] The up layer 201 of the first from the substrate 103 side first conductivity type having a V-groove of the board that was attached to the stainless steel plate, immersed in a 5% aqueous solution of hydrogen fluoride, applying ultrasonic vibrations As a result, the layer 201 and the first substrate 103 are separated (FIG.
(a)) The material remaining on the stainless steel support was thoroughly washed with running water.

Next, SnO ₂ / ITO was applied as a transparent electrode 301 to the sufficiently dried surface of the layer 201 as a transparent electrode 301 by RH method.
0 ° was deposited (FIG. 3 (c)). Finally, a current collecting electrode 401 was formed on the transparent electrode 301 by a printing method in which a conductive paste containing Ag powder was printed and then fired to obtain a thin film single crystal silicon solar cell as shown in FIG.

With respect to the IV characteristics of the thin-film single-crystal silicon solar cell thus obtained, AM 1.5, 100 mW / cm
^The measurement was performed under the light irradiation of No. ² . As a result, the conversion efficiency of the photovoltaic power was 16.5%, which was excellent as a practical single-crystal silicon solar cell characteristic. The measurement was performed with a solar cell area of 144 cm ² .

Further, a single-crystal silicon solar cell was manufactured a total of seven times using the separated first substrate 103 again,
Similarly, when the IV characteristics were measured, the variation in the conversion efficiency of the photovoltaic power was within ± 7%.

Example 3 In Example 1, the thickness of the non-uniform silicon oxide thin film 104 deposited on the surface of the first substrate 103 having the V-shaped groove was changed as shown in Table 3 to obtain the following. Operation Example 1
A thin-film single-crystal silicon solar cell was fabricated in the same manner as described above.

The I of the obtained thin film single crystal silicon solar cell was
The -V characteristics were measured under irradiation of light of AM 1.5 and 100 mW / cm ² . Table 3 also shows the results of the photovoltaic conversion efficiency.

From the results in Table 3, it can be seen that the first base having a V-shaped groove
It was found that the optimal thickness range of the non-uniform silicon oxide thin film 104 formed on the plate 103 was 4 to 10 °.

[0066]

[Table 3] Example 4 In Example 2, a thin-film single-crystal silicon solar cell was manufactured by changing the thickness of the silicon crystal layer, in particular, the thickness of the layer 202 of the second conductivity type as shown in Table 4.

The I of the obtained thin film single crystal silicon solar cell was
The -V characteristics were measured under irradiation of light of AM 1.5 and 100 mW / cm ² . The results of the photovoltaic conversion efficiency are also shown in Table 4.

[0068]

[Table 4] From Table 4, it was found that there was an optimum region for the thickness of the silicon crystal layer.

[0069]

As described above, according to the manufacturing method of the present invention, it is possible to manufacture a thin-film single-crystal silicon solar cell having a high conversion efficiency and having an uneven surface processed into a structure having a light confinement effect. In particular, the area of the solar cell can be easily increased. Further, since the first substrate can be used a plurality of times, high-quality thin-film solar cells can be mass-produced at lower cost.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of each step in a method for manufacturing a solar cell according to the present invention.

FIG. 2 is a schematic cross-sectional view of each step in a method for manufacturing a solar cell according to the present invention.

FIG. 3 is a schematic cross-sectional view of each step in a method for manufacturing a solar cell according to the present invention.

FIG. 4 is a schematic perspective view of a solar cell manufactured by the method of the present invention.

FIG. 5 is a schematic diagram of a film forming apparatus used in Example 1.

FIG. 6 is a schematic diagram of a film forming apparatus used in Example 2.

[Explanation of Signs] 101 Silicon wafer 102 Insulating layer 103 V-shaped groove processed into a structure having an optical confinement effect
First substrate 104 having silicon oxide thin film 201 First conductivity type layer 202 Second conductivity type layer 203 Conductive adhesive layer 204 Conductive support 301 Transparent electrode 401 Current collecting electrode 501,502 Gas inlet tube 503 plate 504 holder 505 meeting space 601 gas-introducing ring 602 gas introduction pipe 603 quartz cavity 604 mesh 605 Microwave 606 aperture 607 holder 608 groups plate 609 vacuum chamber

Claims (12)

(57) [Claims] An uneven portion having an optical confinement effect is provided.
In a method of manufacturing a solar cell including a photovoltaic element, a first uneven surface serving as a mold for forming the uneven portion is provided .
Processing the surface of the substrate, and forming the photovoltaic element on the uneven surface of the first substrate.
Forming a single crystal semiconductor layer having an uneven portion, and contacting the single crystal semiconductor layer having the uneven portion on a second substrate.
Combining the single crystal semiconductor layer having the uneven portion with the first substrate.
Peeling off from the solar cell. 2. A process for producing a solar cell of the first substrate according to claim 1 wherein is made of single-crystal semiconductor. 3. A process for producing a solar cell of the first substrate according to claim 1, wherein those having a surface made of a single crystal semiconductor. 4. The photovoltaic device according to claim 1, wherein said photovoltaic element is a PN junction or P
The method for manufacturing a solar cell according to claim 1 having an IN junction. 5. The single crystal semiconductor layer having the uneven portion,
Crystal growth of a second conductivity type layer on the first conductivity type layer
The method for manufacturing a solar cell according to claim 1, wherein the solar cell is a laminated layer. 6. The single crystal semiconductor layer having the uneven portion,
The first conductive type layer is formed by diffusing a dopant into a part of the layer.
The method for manufacturing a solar cell according to claim 1, further comprising: 7. The method according to claim 7, wherein the first substrate is provided on the uneven surface with each other.
Forming a plurality of separated insulating layers; placing the first substrate in a film forming space for forming a deposited film;
Disposing silicon and halogen on the first substrate.
Active species (A) generated by decomposing a compound
And a chemical interaction with the active species (A) for forming a film.
Simultaneously with the active species (B) formed by the chemical substance
Are introduced separately, and the chemical
Forming a layer of one conductivity type, substantially above a layer of the second conductivity type,
Forming a layer made of a crystal . 8. The method according to claim 8, further comprising the step of :
The solar cell according to claim 1, wherein the solar cell is used several times.
Manufacturing method. 9. The method according to claim 1 , wherein the processing step is performed on a surface of the first substrate.
2. The solar cell according to claim 1, wherein the step of forming a V-shaped groove is performed.
Manufacturing method. 10. The method according to claim 10, further comprising the step of:
Through a plurality of insulating layers separated from each other.
The solar cell according to claim 1, wherein the single-crystal semiconductor layer having
Pond manufacturing method. 11. The insulating layer has a thickness of 4 to 10 °.
A method for manufacturing a solar cell according to claim 7. 12. The layer of the second conductivity type having a thickness of 5 to 20.
The method for manufacturing a solar cell according to claim 5, wherein the thickness is μm.