KR100965397B1 - Apparatus and method for manufacturing tandem type solar cell - Google Patents

Abstract

PURPOSE: An apparatus and a method for manufacturing a laminated thin film solar cell are provided to reduce a manufacturing process of a laminated film solar battery by depositing an i- microcrystalline silicon and i- amorphous silicon on one same chamber. CONSTITUTION: Plasma is generated through power of a first frequency and an amorphous semiconductor layer(214) is deposited. Plasma is generated through power of a second frequency and an amorphous semiconductor layer(224) is deposited. The deposition of the amorphous semiconductor layer and microcrystalline semiconductor film are performed in the same chamber. The secondary frequency is higher than the first frequency.

Description

Stacking thin film solar cell manufacturing apparatus and method thereof {APPARATUS AND METHOD FOR MANUFACTURING TANDEM TYPE SOLAR CELL}

The present invention relates to a solar cell, and more particularly, to a laminated thin film solar cell manufacturing apparatus and method thereof.

In general, a solar cell refers to a device that generates electricity by converting solar light energy into electrical energy. Solar cells have recently attracted attention as the next generation of clean energy sources due to the development of single crystal silicon growth technology, depletion of fossil fuels, global warming by carbon dioxide, and international regulation of carbon dioxide generation.

Such solar cells may be classified into silicon solar cells and compound semiconductor solar cells according to the semiconductor material used. Silicon solar cells include single crystal or poly crystalline bulk silicon solar cells, and single crystalline, poly crystalline or amorphous thin film silicon solar cells. In compound semiconductor solar cells, the compounds are group III-V compounds such as gallium arsenide (GaAs), indium phosphorus (InP), aluminum gallium arsenide (AlGaAs), copper sulfide (Cu ₂ S), cadmium sulfide (CdS), cadmium tellurium It may be a group II-IV compound, such as a ride (CdTe).

Recently, the development of solar cells is progressing from the viewpoint of improving the photoelectric conversion efficiency, reducing the manufacturing cost and large area.Bulk type silicon solar cells have high manufacturing cost and large area of the silicon substrate in spite of high photoelectric conversion efficiency. There is a disadvantage in that. On the other hand, thin-film silicon solar cells have problems such as lower efficiency than bulk silicon solar cells, but they are likely to lead the solar cell market in the future due to the low cost of materials and low manufacturing cost and easy large area. .

In addition, since the thin-film silicon solar cell has a structure of depositing a material centered on amorphous silicon in plate-like glass or metal in multiple layers, it is possible to improve the photoelectric conversion efficiency in view of the diversification of the deposited material and the multilayer cell structure. There is also a lot of room.

Thin-film silicon solar cells, unlike crystalline silicon solar cells in which charges are diffused and collected and diffused into depletion regions, are generally due to short diffusion of charge carriers due to recombination or trapping. It has a pin structure including an intrinsic layer (i-layer) for light absorption purposes and a p layer and an n layer for forming an internal electric field for separation of generated charges.

 Since the thin-film silicon solar cell was manufactured in 1976 by Carlson et al. For the first pin structure, research to improve photoelectric conversion efficiency has been continued. As a method of increasing the photoelectric conversion efficiency of a thin-film silicon solar cell, a method of uniformly doping a small amount of boron (B) in the i layer, a method of forming a buffer layer at the interface to reduce the optical loss, a method of reducing the reflection of the substrate electrode, And a method of increasing spectral reactivity by joining a plurality of single junction cells.

Conventionally, a tandem thin film silicon solar cell called a double junction cell includes a first pin structure semiconductor layer containing i-type amorphous silicon (a-Si: H) and i-type microcrystalline silicon (μc-). The second pin structure semiconductor layer containing Si) is laminated. The first pin structure semiconductor layer has a bandgap energy of about 1.7 eV and absorbs about 400 to 500 nm of solar wavelengths well, and the second pin structure semiconductor layer has a bandgap energy of about 1.1 eV and about 600 to 700 nm of It is known to absorb sunlight wavelengths well. The thin-film solar cell having a double junction cell structure can improve photoelectric conversion efficiency because the thin film solar cell having a single junction cell has a structure that can absorb and absorb sunlight, which is hardly absorbed.

On the other hand, i-type microcrystalline silicon has a problem that the productivity is lowered when the conventional frequency power is applied because the deposition rate is very low. In order to improve the deposition rate of the i-type microcrystalline silicon by applying a high frequency power supply higher than a conventional applied frequency power supply. However, in order to increase productivity in manufacturing a multilayer thin-film silicon solar cell, when different frequency power is applied to i-type microcrystalline silicon and i-type amorphous silicon, a separate chamber and an additional process are required, so that equipment costs and processes are increased. It is disadvantageous in terms of efficiency.

Therefore, when manufacturing a stacked thin film silicon solar cell, it is required to develop a new technology capable of depositing an i-type microcrystalline silicon layer and an i-type amorphous silicon layer in one same chamber.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides an apparatus and a method for manufacturing a stacked thin film solar cell, which enable deposition of i-type microcrystalline silicon and i-type amorphous silicon having different deposition rates in one same chamber. Its purpose is to.

In order to achieve the above object, the multilayer thin film solar cell manufacturing apparatus of the present invention discharges a first pin structure semiconductor layer including an i-type amorphous semiconductor layer and a second pin structure semiconductor layer including an i-type microcrystalline semiconductor layer. A laminated thin film solar cell manufacturing apparatus sequentially formed in the same chamber using plasma, comprising: a power supply unit supplying a first frequency power source and a second frequency power source; An electrode positioned in the chamber to generate the plasma in the chamber; A matching network connected between the power supply and the electrode to match an impedance; A control unit for controlling the switching element to select the first frequency power source when depositing the i-type amorphous semiconductor layer and to select the second frequency power source when depositing the i-type microcrystalline semiconductor layer; And a switching element connected to the matching network and configured to supply a frequency power selected from among the first frequency power and the second frequency power according to the control of the controller to the electrode, wherein the second frequency is greater than the first frequency. It is desirable to be large.

In the method for manufacturing a stacked thin film solar cell of the present invention, a method for manufacturing a thin film solar cell in which a first pin structure semiconductor layer including a first i-type semiconductor layer and a second pin structure semiconductor layer including a second i-type semiconductor layer are stacked. And depositing the first i-type semiconductor layer by applying a power of a first frequency to generate a discharge plasma; And depositing the second i-type semiconductor layer by generating a discharge plasma by applying a power of a second frequency, wherein the second frequency is greater than the first frequency.

Here, the first i-type semiconductor layer is an amorphous semiconductor layer, the second i-type semiconductor layer may be a microcrystalline semiconductor layer, depositing the first i-type semiconductor layer and depositing the second i-type semiconductor layer Preferably, the step is performed in the same chamber.

In addition, the first first frequency is 13.56MHz, the second frequency is preferably a frequency selected in the Very High Frequency (VHF) frequency band.

According to the present invention, since i-type microcrystalline silicon and i-type amorphous silicon having different deposition rates can be deposited in one same chamber, a separate chamber is not required and the manufacturing process of the stacked thin film solar cell can be shortened. It works.

DETAILED DESCRIPTION In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the accompanying drawings.

In describing the present invention, in order to facilitate understanding, the same reference numerals are used for the same means regardless of the reference numerals. Numerals used in the description of the present specification, for example, first and second, are merely identification symbols for distinguishing the same or similar entities.

1 is a view showing a laminated thin film solar cell manufacturing apparatus according to an embodiment of the present invention. Referring to FIG. 1, the stacked thin film solar cell manufacturing apparatus 100 according to an exemplary embodiment may include a chamber 110, a power supply unit 140, a first electrode 120, and a second electrode 122. A Plasma Enhanced Chemical Vapor Deposition (PECVD) device including a matching network 160, a power supply 140, a switching element 150, and a controller 170.

The stacked thin film solar cell may include a first pin structure semiconductor layer including an i-type amorphous silicon (a-Si: H) layer and a second pin structure semiconductor layer including an i-type microcrystalline silicon (μc-Si) layer. This is a laminated silicon thin film solar cell.

The chamber 110 provides a reaction space in which an i-type amorphous silicon layer and an i-type microcrystalline silicon layer are deposited on the substrate 130, and includes a housing in which sidewalls, top walls, and bottom walls are sealed. The substrate 130 may be a glass substrate, a stainless steel substrate, or a plastic substrate on which a p-type or n-type amorphous silicon layer is deposited to form a first pin structure semiconductor layer and a second pin structure semiconductor layer. . In one region of the bottom wall edge of the chamber 110 is formed an outlet 114 which is connected to a vacuum pump (not shown).

The first electrode 120 has a gas inlet 112 connected to a gas supply unit (not shown), and a shower head for supplying a reaction gas introduced through the gas inlet 112 into the chamber 110. Head). Reaction gases include silane (SiH ₄ ) containing silicon (Si), diborane (B ₂ H ₆ ) containing boron (B), phosphine (PH ₃ ) containing phosphorus (P), and silane (SiH). _It may be at least one gas of hydrogen (H ₂ ) to dilute the concentration of ₄ ). The second electrode 122 may be a susceptor on which the substrate 130 is placed. The second electrode 122 includes a heater coil (not shown) that heats the substrate 130, and is preferably electrically grounded.

The first electrode 120 is positioned in the center area of the upper wall of the chamber 110, and the second electrode 122 is located in the center area of the lower wall of the chamber 110 opposite to the first electrode 120. The first electrode 120 and the second electrode 122 may be electrically connected to the switching element 150 to form a circuit for generating a plasma. The first electrode 120 and the second electrode 122 are supplied with the frequency power selected by the switching element 150 among the first frequency power source and the second frequency power source supplied from the power supply unit 140, and thus the gas inlet 112. Reaction gas flowing into the chamber 110 through the discharge in the chamber 110 to form a plasma (180). Here, the first frequency is 13.56 MHz, the second frequency is a frequency selected in the Very High Frequency (VHF) frequency band. The second frequency is preferably one frequency selected from the 27MHz to 100MHz frequency band.

The power supply 140 is electrically connected to the matching network 160, and supplies the first frequency power or the second frequency power to the first electrode 120 and the second electrode 122 through the matching network 160. It is a generator.

The switching element 150 is electrically connected to the first electrode 120, the second electrode 122, and the matching network 160. The switching element 150 performs a switching operation under the control of the controller 170 to perform a switching operation. The frequency power selected from the second frequency power is applied to the first electrode 120 and the second electrode 122. The switching element 150 may be a vacuum array.

The matching network 160 includes an inductor and a capacitor, and is located between the power supply 140 and the switching element 150. The matching network 160 matches the internal impedance of the power supply unit 140 with the impedances of the switching element 150, the first electrode 120, and the second electrode 122 to supply the first frequency supplied from the power supply unit 140. The power source and the second frequency power source may be applied to the first electrode 120 and the second electrode 122 without reflection loss.

The controller 170 controls the gas supply unit (not shown), the vacuum pump (not shown), the switching element 150 and the power supply unit 140 so that the stacked thin film solar cell may be manufactured in the chamber 110. do. The control unit 140 will be described in more detail with reference to the method of manufacturing a laminated thin film solar cell of FIG. 2 below.

In this embodiment, the frequency of the power applied to the first electrode 120 and the second electrode 122 has been described by way of example in which the switching element 150 is controlled by the controller 170. Frequency selection is not limited to this. For example, the control unit 170 directly controls the power supply unit 140 without passing through the switching element 150 to select one frequency power source of the first frequency power source and the second frequency power source and the first electrode 120. It may be applied to the second electrode 122.

In addition, in this embodiment, the power supply unit 140 has been described as an example of the case of one generator capable of selectively supplying one of the first frequency power source and the second frequency power source, the power supply unit 140 is It is not limited. For example, the power supply unit 140 may supply frequency power equal to or greater than the third frequency power supply. In addition, the power supply unit 140 may be composed of two generators for separately supplying the first frequency power and the second frequency power.

The multilayer thin film solar cell manufacturing apparatus 100 according to an exemplary embodiment of the present invention described above includes an inline method in which a plurality of chambers are connected in a linear shape, or an intermediate chamber in the center and a plurality of chambers around the same. It can be employed in a multi-chamber (Multi Chamber) arrangement.

2 is a flowchart illustrating a method of manufacturing a stacked thin film solar cell according to an embodiment of the present invention. Referring to FIG. 2, in the method of manufacturing a stacked thin film solar cell according to an embodiment of the present disclosure, a first pin structure semiconductor layer forming step S100 and a second pin structure semiconductor layer forming step controlled by the controller of FIG. 1 are performed. (S200).

The first pin structure semiconductor layer forming step (S100) is a step of forming a p-type amorphous silicon layer, an i-type amorphous silicon layer, and n-type amorphous silicon. First, the controller 170 controls the gas supply unit to introduce the silane (SiH ₄ ) and the diborane (B ₂ H ₆ ) into the chamber 110, and simultaneously control the switching element 150 to control the first frequency power supply. It is applied to the first electrode 120 and the second electrode 122. At this time, the first electrode 120 and the second electrode 122 to which the first frequency power is applied discharge the silane (SiH ₄ ) and the diborane (B ₂ H ₆ ) to generate a plasma in the chamber 110. . The decomposed silane (SiH ₄ ) and the diborane (B ₂ H ₆ ) are stacked on the substrate 130 to form a p-type amorphous silicon layer. The substrate 130 is preferably a glass substrate on which a patterned transparent electrode is already formed.

Next, the controller 170 controls the gas supply unit to introduce silane (SiH ₄ ) into the chamber 110, and simultaneously controls the switching element 150 to supply the first frequency power to the first electrode 120. To be applied to the second electrode 122. In this case, the first electrode 120 and the second electrode 122 to which the first frequency power is applied discharge the silane SiH ₄ to generate plasma in the chamber 110. The decomposed silane (SiH ₄ ) is stacked on the substrate 130 to form an i-type amorphous silicon layer.

Next, the controller 170 controls the gas supply unit to introduce the silane (SiH ₄ ) and the phosphine (PH ₃ ) into the chamber 110, and simultaneously control the switching element 150 to supply the first frequency power. It is applied to the first electrode 120 and the second electrode 122. In this case, the first electrode 120 and the second electrode 122 to which the first frequency power is applied discharge the silane (SiH ₄ ) and the phosphine (PH ₃ ) to generate a plasma in the chamber 110. The decomposed silane (SiH ₄ ) and phosphine (PH ₃ ) are stacked on the substrate 130 to form an n-type amorphous silicon layer.

In the first pin structure semiconductor layer forming step (S100), forming a buffer layer to reduce optical loss between the p-type amorphous silicon layer and the i-type amorphous silicon layer, and the first pin structure semiconductor layer and the second pin The method may further include at least one step of forming an intermediate layer between the structural semiconductor layers.

The second pin structure semiconductor layer forming step (S200) is a step of forming a p-type amorphous silicon layer, an i-type microcrystalline silicon layer, and an n-type amorphous silicon. The control unit 170 controls the gas supply unit to introduce silane (SiH ₄ ) and hydrogen (H ₂ ) into the chamber 110, and simultaneously control the switching element 150 so that the second frequency power source is the first electrode ( 120 and the second electrode 122. At this time, the first electrode 120 and the second electrode 122 to which the second frequency power is applied discharge the silane (SiH ₄ ) and the hydrogen (H ₂ ) to generate plasma in the chamber 110. The decomposed silane (SiH ₄ ) and hydrogen (H ₂ ) are stacked on the substrate 130 to form an i-type microcrystalline silicon layer. The second frequency is a frequency selected from a very high frequency (VHF) frequency band larger than the first frequency of 13.56 MHz.

In general, the plasma chemical vapor deposition (PECVD) method uses a plasma in which high-energy electrons generated through a discharge collide with a reaction gas to dissociate the reaction gas. When the frequency of the power source increases, the energy of electrons generated through the discharge is increased. Increases and the degree of dissociation of the reaction gas increases. Therefore, when the frequency power of the ultrashort plate frequency band is applied when depositing the i-type microcrystalline silicon layer, the deposition rate of the i-type microcrystalline silicon layer, which is slower than the i-type amorphous silicon layer, can be improved (preferably i-type amorphous Improved at the same rate as the silicon layer deposition rate), the i-type amorphous silicon layer and the i-type microcrystalline silicon layer can be formed in the same one chamber (110).

On the other hand, in the case of diluting the concentration of the silane (SiH ₄₎ into hydrogen (H _2), with increasing amounts of hydrogen (H ₂₎ to increase the crystallinity. This is because the activated hydrogen atoms are etched in an unstable silicon atom to be deposited in a quasi-equilibrium state of deposition and etching, or the surface movement of the adsorbed species by the hydrogen group (Hydrogen) is promoted. Therefore, the i-type microcrystalline silicon layer required in this embodiment can be formed by adjusting the amount of hydrogen (H ₂ ) diluting the concentration of silane (SiH ₄ ). In addition, when the second electrode 122 includes a heater coil, an i-type microcrystalline silicon layer may also be formed by hot-wire chemical vapor deposition (HWCVD) for decomposing silane (SiH ₄ ).

The other p-type amorphous silicon layer and the n-type amorphous silicon layer forming step are similar to the first pin structure semiconductor layer forming step, so a person skilled in the art can easily perform the first pin structure semiconductor forming step (S100), so the detailed description is omitted. do.

In the present embodiment, the formation of the i-type amorphous silicon layer and the i-type microcrystalline silicon layer, which are homogeneous materials of different phases in the same chamber, has been described by way of example, but the present invention is not limited thereto. For example, the same type of i-type amorphous silicon layer and the i-type amorphous silicon layer may be deposited at different rates in the same chamber.

3 is a diagram illustrating a laminated structure of a stacked thin film solar cell manufactured using the stacked thin film solar cell manufacturing apparatus of FIG. 1. Referring to FIG. 3, the multilayer thin film solar cell 200 manufactured according to an exemplary embodiment of the present invention includes a p-type amorphous silicon layer 212 and an i-type amorphous silicon on a glass substrate 202 on which a transparent electrode 204 is formed. The first pin structure semiconductor layer 210 on which the layer 214 and the n-type silicon layer 216 are deposited is stacked, and the p-type amorphous silicon layer 222 and the i-type microcrystalline are formed on the first pin structure semiconductor layer 210. The second pin structure semiconductor layer 220 on which the silicon layer 224 and the n type silicon layer 224 are deposited is stacked, and the n type silicon layer 226 of the second pin structure semiconductor layer 220 is disposed on the back reflection layer. 206 and the rear electrode 208 are stacked in this order.

In the stacked thin film solar cell 200 manufactured according to the present exemplary embodiment, the i-type microcrystalline silicon layer 224 of the second pin structure semiconductor layer 220 is first pin structure semiconductor to widen the absorption wavelength range while varying the band gap energy. Although formed thicker than the i-type amorphous silicon layer 214 of the layer 210, the power source frequency applied when the i-type microcrystalline silicon layer 224 is formed is higher than the power source frequency applied when the i-type amorphous silicon layer 214 is formed. Microwave frequency was used to improve the deposition rate.

In the above, the multilayer thin film solar cell manufacturing apparatus and method thereof of the present invention have been described by illustrating a tandem thin film solar cell in which two pin structure semiconductor layers are stacked, but the multilayer thin film solar cell manufacturing apparatus and method of the present invention are It may be applied to a thin film solar cell in which three or more pin structure semiconductor layers are stacked. At this time, it is preferable that the power supply unit supply two or more frequency powers selected from a reference frequency (13.56 MHz) power source and a high frequency band (VHF) higher than the reference frequency (13.56 MHz).

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art that various modifications of the present invention without departing from the spirit and scope of the invention described in the claims below And can be changed.

1 is a view showing a laminated thin film solar cell manufacturing apparatus according to an embodiment of the present invention.

2 is a flowchart illustrating a method of manufacturing a stacked thin film solar cell according to an embodiment of the present invention.

3 is a diagram illustrating a laminated structure of a stacked thin film solar cell manufactured using the stacked thin film solar cell manufacturing apparatus of FIG. 1.

<Description of Symbols for Main Parts of Drawings>

110: chamber 120: first electrode

122: second electrode 130: substrate

140: power supply unit 150: switching element

160: matching network 170: control unit

180: plasma

Claims (5)

A method of manufacturing a thin film solar cell in which a first pin structure semiconductor layer including a first i-type semiconductor layer and a second pin structure semiconductor layer including a second i-type semiconductor layer are stacked. Depositing the first i-type semiconductor layer by generating a plasma by applying a power of a first frequency; And depositing the second i-type semiconductor layer by generating a plasma by applying a power of a second frequency, The depositing of the first i-type semiconductor layer and the depositing of the second i-type semiconductor layer are performed in the same chamber, and wherein the second frequency is greater than the first frequency. The method of claim 1, And the first i-type semiconductor layer is an amorphous semiconductor layer, and the second i-type semiconductor layer is a microcrystalline semiconductor layer. The method according to claim 1 or 2, The first first frequency is 13.56MHz, the second frequency is a very high frequency (VHF: Very High Frequency) frequency band selected in the thin film solar cell manufacturing method. delete An apparatus for manufacturing a stacked thin film solar cell, wherein a first pin structure semiconductor layer including an i-type amorphous semiconductor layer and a second pin structure semiconductor layer including an i-type microcrystalline semiconductor layer are sequentially formed in the same chamber by using a discharge plasma. A power supply unit supplying a first frequency power source and a second frequency power source; An electrode positioned in the chamber to generate the plasma in the chamber; A matching network connected between the power supply and the electrode to match an impedance; A control unit for controlling the switching element to select the first frequency power source when depositing the i-type amorphous semiconductor layer and to select the second frequency power source when depositing the i-type microcrystalline semiconductor layer; And a switching element connected to the matching network and supplying a frequency power selected from among the first frequency power and the second frequency power according to the control of the controller to the electrode. And said second frequency is greater than said first frequency.

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