JP5835700B2 - Method for manufacturing solar cell using inductively coupled plasma enhanced chemical vapor deposition - Google Patents

Description

  The present invention relates to a method for manufacturing a solar cell using inductively coupled plasma chemical vapor deposition.

Currently, the obligation to reduce greenhouse gas under the climate change agreement is accelerating, which has stimulated the carbon dioxide market, raising interest in the field of new renewable energy.
Solar cells, which are a typical new renewable energy field, are systems that produce electricity using sunlight, an infinite source of clean energy, and the core is solar cells that directly convert light into electricity. .
Currently, more than 90% of solar cells in commercial use are bulk-based silicon solar cells that are affected by the supply and demand of silicon and are complicated by high-temperature-centered processes. There is a problem that the low temperature process is not easy.

Therefore, an object of the present invention is to provide a solar cell manufacturing method using inductively coupled plasma chemical vapor deposition.
Another object of the present invention is to provide a method for forming a P layer of a solar cell.
Still another object of the present invention is to provide a method for forming a hydrogenated intrinsic layer of a solar cell.
Still another object of the present invention is to provide a method for forming a microcrystalline intrinsic layer of a solar cell.

In order to achieve the above object, according to one aspect of the present invention, in manufacturing a solar cell including a first electrode, a first type layer, an intrinsic layer, a second type layer, and a second electrode, hydrogen (H ₂ ) An intrinsic layer forming step of forming the intrinsic layer of a hydrogenated amorphous silicon thin film using an inductively coupled plasma enhanced chemical vapor deposition apparatus using a mixed gas containing a gas and a silane (SiH ₄ ) gas. However, the mixed gas is provided with a ratio of silane gas to hydrogen gas of the hydrogen gas and silane gas (H ₂ / SiH ₄ ratio) of 8 to 10. A method for manufacturing a solar cell is provided.

  The intrinsic layer forming step has a process pressure of 70 to 90 mtorr, a process power of 200 to 300 W, and a process temperature of 250 to 350 degrees.

  The manufacturing method of the solar cell includes a first-type silicon substrate preparing step of preparing a first-type silicon substrate before the intrinsic layer forming step, and forming the first electrode on the rear surface of the first-type silicon substrate. A first electrode forming step, and after the intrinsic layer forming step, a second mold forming step for forming a second mold layer on the intrinsic layer, and a second electrode on the second mold layer. Forming a second electrode to be formed.

  The first electrode is made of Ag, the second type layer is made of a hydrogenated second type amorphous silicon layer, the second electrode is made of a transparent electrode layer formed on the second type layer, and It consists of a patterned aluminum electrode formed on the transparent electrode layer.

  The solar cell manufacturing method includes a transparent substrate preparing step for preparing a transparent substrate before the intrinsic layer forming step, a first electrode forming step for forming the first electrode on the transparent substrate, Forming a second type layer on the first electrode, and forming the first type layer on the intrinsic layer after the intrinsic layer forming step. And a second electrode forming step of forming the second electrode on the first mold layer.

  A buffer layer forming step for forming a buffer layer between the second type layer forming step and the intrinsic layer forming step, wherein the first type layer forming step and the second electrode forming step; The step of forming a transparent electrode layer for forming a transparent electrode layer on the first mold layer is included.

  The first electrode is made of a TCO layer, and the second electrode is made of aluminum.

In order to achieve the above object, according to another aspect of the present invention, in manufacturing a solar cell including a first electrode, a first type layer, an intrinsic layer, a second type layer, and a second electrode, hydrogen (H ₂ ) Using an inductively coupled plasma chemical vapor deposition apparatus using a mixed gas containing gas, silane (SiH ₄ ) gas, diborane (B ₂ H ₆ ) gas and ethylene (C ₂ H ₄ ) gas. Although the second type layer forming step of forming the second type layer made of a silicon carbide thin film is included, the ethylene gas is an ethylene gas diluted with 60% hydrogen gas, and the diborane gas is 97% A diborane gas diluted with hydrogen gas, wherein the ethylene gas is included in the mixed gas in an amount of 1 to 1.2%, and the diborane gas is included in the mixed gas in an amount of 6 to 6.5%. Method of manufacturing a solar cell, wherein Rukoto is provided.

  The method for manufacturing a solar cell includes a step of preparing a first type silicon substrate for preparing a first type silicon substrate before the step of forming the second type layer, and the first electrode on the rear surface of the first type silicon substrate. Forming a first electrode for forming the first layer, and forming an intrinsic layer for forming the intrinsic layer on the front surface of the first type silicon substrate. After the step of forming the second type layer, the second type Forming a second electrode to form a second electrode on the layer;

  The first electrode is made of Ag, the intrinsic layer is made of a hydrogenated amorphous silicon layer, and the second electrode is formed on the transparent electrode layer and the transparent electrode layer formed on the second mold layer. It consists of the patterned aluminum electrode formed.

  The method for manufacturing a solar cell includes a step of preparing a transparent substrate for preparing a transparent substrate before the step of forming the second mold layer, and a step of forming a first electrode for forming the first electrode on the transparent substrate. And after the step of forming the second type layer, a step of forming an intrinsic layer on the second type layer, and a first type of forming the first type layer on the intrinsic layer A layer forming step and a second electrode forming step of forming the second electrode on the first mold layer.

  A buffer layer forming step for forming a buffer layer between the second type layer forming step and the intrinsic layer forming step, wherein the first type layer forming step and the second electrode forming step; The step of forming a transparent electrode layer for forming a transparent electrode layer on the first mold layer is included.

  The first electrode is made of a TCO layer, and the second electrode is made of aluminum.

In order to achieve the above object, according to still another aspect of the present invention, in manufacturing a solar cell including a first electrode, a first type layer, an intrinsic layer, a second type layer, and a second electrode, hydrogen (H ₂ ) Using an inductively coupled plasma chemical vapor deposition apparatus using a mixed gas containing a gas and a silane (SiH ₄ ) gas, any one of the second type layer, the intrinsic layer, and the first type layer is used. Although the layer is formed of a crystallized silicon layer, the mixed gas has a silane gas ratio (SiH ₄ / (SiH ₄ + H ₂ )) of 0.016 to 0.2. A method for manufacturing a solar cell is provided.

  The inductively coupled plasma enhanced chemical vapor deposition apparatus uses a process power of 1150 to 1250W.

Forming the first type layer with a crystallized silicon layer uses a mixed gas containing phosphine (P ₂ H ₃ ) gas, but contains 0.075 to 0.1% of phosphine gas relative to the silane gas. Use the mixed gas.

  Forming the second-type layer with a crystallized silicon layer uses a mixed gas containing 0.1 to 0.5% of diborane gas with respect to the silane gas, although a mixed gas containing diborane gas is used.

  The manufacturing method of the solar cell includes a step of preparing a first type silicon substrate for preparing a first type silicon substrate, a step of forming a first electrode for forming the first electrode on a rear surface of the first type silicon substrate, Forming an intrinsic layer on the front surface of the first type silicon substrate; forming a second type layer on the intrinsic layer; forming a second type layer on the intrinsic layer; and on the second type layer. And a second electrode forming step of forming a second electrode.

  The first electrode is made of Ag, and the second electrode is made of a transparent electrode layer formed on the second mold layer and a patterned aluminum electrode formed on the transparent electrode layer.

  The manufacturing method of the solar cell includes a step of preparing a transparent substrate for preparing a transparent substrate, a step of forming a first electrode for forming the first electrode on the transparent substrate, and the second mold on the first electrode. Forming a second type layer to form a layer; forming an intrinsic layer on the second type layer; forming a first type layer on the intrinsic layer; And a second electrode forming step of forming the second electrode on the first mold layer.

  A buffer layer forming step for forming a buffer layer between the second type layer forming step and the intrinsic layer forming step, wherein the first type layer forming step and the second electrode forming step; The step of forming a transparent electrode layer for forming a transparent electrode layer on the first mold layer is included.

  The first electrode is made of a TCO layer, and the second electrode is made of aluminum.

According to the configuration of the present invention, all the objects of the present invention described above can be achieved. Specifically, according to the present invention, there is an effect of providing a method for manufacturing a solar cell using an inductively coupled plasma chemical vapor deposition method.
Moreover, according to this invention, there exists an effect of providing the P layer formation method of a solar cell.
Moreover, according to this invention, there exists an effect of providing the method of forming the hydrogenation intrinsic layer of a solar cell.
Moreover, according to this invention, there exists an effect of providing the method of forming the microcrystallized intrinsic layer of a solar cell.

It is a conceptual diagram which shows schematic structure of the inductively coupled plasma chemical vapor deposition apparatus used in the manufacturing method of the solar cell by embodiment of this invention. It is sectional drawing which shows one Embodiment of the solar cell manufactured by the manufacturing method of the solar cell by one embodiment of this invention. It is sectional drawing which shows other embodiment of the solar cell manufactured by the manufacturing method of the solar cell by other embodiment of this invention. It is a flowchart which shows the process sequence of the manufacturing method of the solar cell by one embodiment of this invention. It is a graph which shows the thickness and surface roughness of an intrinsic layer according to the ratio of the silane gas with respect to the hydrogen gas of mixed gas. It is a graph which shows the thickness and surface roughness of an intrinsic layer according to the change of process pressure. It is a graph which shows the change of the thickness of an intrinsic layer according to process power change, and a band gap. It is a graph which shows the Fourier-transform infrared spectroscopy analysis according to a process power change. It is a graph which shows the change of the carrier lifetime in the intrinsic layer according to process temperature. It is a graph which shows the change of the vapor deposition rate and optical band gap of the hydrogenation amorphous silicon carbide thin film according to addition of ethylene gas. It is a graph which shows the change of the joint structure of the hydrogenation amorphous silicon carbide thin film according to addition of ethylene gas. It is a graph which shows the change of the optical band gap and safety | security of a hydrogenation amorphous silicon carbide layer doped to the 2nd type according to addition of diborane gas. It is a graph which shows the characteristic change of the solar cell according to the thickness of the hydrogenation amorphous silicon carbide layer doped by the 2nd type. It is a flowchart which shows the process sequence of the manufacturing method of the solar cell by other embodiment of this invention. It is a graph which shows the change of the electrical conductivity and activation energy of the hydrogenation fine crystalline silicon layer of an intrinsic layer according to the quantity of silane gas. It is a graph which shows the change of the crystallization peak according to the quantity of silane gas, and an amorphous peak. It is a graph which shows the electrical property change of the hydrogenation fine crystalline silicon layer of an intrinsic layer according to the change of process power. It is a graph which shows the change of the optical band gap and dark conductivity by a phosphine gas ratio. It is a graph which shows the change of the optical band gap and dark conductivity by the ratio of diborane gas.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a conceptual diagram showing a schematic configuration of an inductively coupled plasma chemical vapor deposition apparatus used in a method for manufacturing a solar cell according to an embodiment of the present invention.
As shown in FIG. 1, an inductively coupled plasma chemical vapor deposition (Inductively Coupled Plasma Chemical Vapor Deposition) 100 used in a method for manufacturing a solar cell according to an embodiment of the present invention includes a chamber 110, an antenna 120, and a power supply unit. 130, a shower head 140 and a susceptor 150.

The chamber 110 includes an insulating plate 112, a door 114 and an exhaust port 116.
The chamber 110 has a function of spatially separating the inside and the outside of the chamber 110 so that the inside of the chamber 110 is maintained in a vacuum state.

The insulating plate 112 is provided on the upper stage of the chamber 110.
The insulating plate 112 functions to insulate the antenna 120 from the chamber 110 and to transmit an electromagnetic field generated from the antenna 120 into the chamber 110.

  The door 114 is provided for loading or unloading the substrate 60 into the chamber 110.

  The exhaust port 116 is connected to a vacuum pump (not shown) and exhausts gas or the like from the inside of the chamber 110 to exhaust the inside of the chamber 110 to a constant vacuum state or a constant vacuum. It fulfills the function of maintaining the state.

The antenna 120 functions to generate high-density plasma in the chamber 110 with the power supplied from the power supply unit 130.
The antenna 120 is provided in a state in which a coil is helically wound, and is provided on the insulating plate 112 of the chamber 110.

The power supply unit 140 functions to supply power to the antenna 120 and the susceptor 150.
In particular, the power supply unit 140 applies RF of 13.5 MHz to the antenna 120 so that high-density plasma is generated inside the chamber 110.
The shower head 140 functions to supply gas uniformly from the gas supply unit 142 provided outside the chamber 110 and supply the gas into the chamber 110.
The shower head 140 also functions to uniformly mix different types of gases supplied to the shower head 140 to form a uniformly mixed gas.

The susceptor 160 functions to support the substrate 160.
Although not shown in detail in FIG. 1, the susceptor 160 may include a heating member that heats the substrate 160 at a constant temperature and a cooling member that can cool the substrate 160.
The susceptor 160 is provided at a position where the distance between the substrate 160 and the shower head 140 is a predetermined distance, preferably 23 cm.

FIG. 2 is a cross-sectional view showing one embodiment of a solar cell manufactured by the method for manufacturing a solar cell according to one embodiment of the present invention.
As shown in FIG. 2, a solar cell 200 manufactured by the method for manufacturing a solar cell according to an embodiment of the present invention includes a first electrode 210, a first type silicon substrate 220, an intrinsic layer 230, and a second type layer 240. And a second electrode 250.
At this time, the first type silicon substrate 220 may be an N type silicon substrate or a P type silicon substrate.

The second-type layer 240 is a P-type layer when the first-type silicon substrate 220 is an N-type silicon substrate, and when the first-type silicon substrate 220 is a P-type silicon substrate. , N-type layer.
In the present embodiment, it is assumed that the first-type silicon substrate 220 is an N-type silicon substrate and the second-type layer 240 is a P-type layer. That is, the description will be made on the assumption that the first type is an N type and the second type is a P type.

At this time, the second electrode 250 includes a transparent electrode layer 252 and a metal electrode 254.
The solar cell 200 includes the first electrode 210 on a rear surface of the first type silicon substrate 220 with the first type silicon substrate 220 as a center. The intrinsic layer 230, the second type layer 240, and the second electrode 250 are sequentially stacked.

The first electrode 210 is a rear electrode provided on the rear surface of the first-type silicon substrate 220, and is preferably made of a conductive material, preferably Ag.
The first electrode 210 has a thickness of 0.3 to 0.8 μm, preferably 0.5 μm.

The first type silicon substrate 220 is a silicon substrate doped with a first type impurity, more precisely, a first type, that is, a single crystal substrate doped with a first type impurity.
The first-type silicon substrate 220 has a thickness of 300 to 1000 μm, preferably 650 μm.

  The intrinsic layer 230 may be a hydrogenated amorphous silicon layer that is not doped with impurities, that is, an Ia-Si: H layer. In addition, the intrinsic layer 230 may be a hydrogenated fine crystalline silicon layer that is not doped with impurities, that is, an I μc-Si: H layer.

  When the intrinsic layer 230 is the Ia-Si: H layer, the thickness may be 3 to 5 μm, preferably 5 μm. When the intrinsic layer 230 is the I μc-Si: H layer, the thickness may be 0.5 to 2 μm, preferably 1 μm.

  The second type layer 230 may be a hydrogenated amorphous carbide silicon layer doped with a second type impurity, that is, a second type a-SiC: H layer. The second type layer 230 may be a hydrogenated amorphous silicon layer doped with a second type impurity, that is, a Pa-Si: H layer.

  When the second type layer 230 is formed of the second type a-SiC: H layer, the second type layer 230 may have a thickness of 10 to 20 μm, preferably 12 μm. In addition, when the second type layer 230 is formed of the second type a-Si: H layer, the thickness may be 11 to 12 μm, preferably 12 μm.

The transparent electrode layer 252 of the second electrode 250 includes TCO (Transparent Conducting Oxide), for example, ZnO (Zinc Oxide), AZO (Aluminum Zinc Oxide) which is a ZnO film doped with aluminum, ITO (Indium Tin Oxide), and ITO. It can be made of a transparent conductive oxide such as SnO ₂ : F.

The transparent electrode layer 252 of the second electrode 250 may have a thickness of 100 to 200 μm, preferably 120 μm.
The metal electrode 254 of the second electrode 250 includes a patterned metal electrode 254 provided on the transparent electrode layer 252.

The metal electrode 254 is made of a conductive material such as aluminum.
The metal electrode 254 has a thickness of 0.2 to 1 μm, preferably 0.5 μm.

FIG. 3 is a cross-sectional view showing another embodiment of a solar cell manufactured by a method for manufacturing a solar cell according to another embodiment of the present invention.
As shown in FIG. 3, a solar cell 300 manufactured by a method for manufacturing a solar cell according to another embodiment of the present invention includes a transparent substrate 310, a first electrode 320, a second mold layer 330, a buffer layer 340, an intrinsic property. A layer 350, a first mold layer 360, a transparent electrode layer 370, and a second electrode 380 are provided.

  In the solar cell 300, the first electrode 320, the second mold layer 330, the buffer layer 340, the intrinsic layer 350, the first mold layer 360, the transparent electrode layer 370, and the second electrode 380 are sequentially stacked on the transparent substrate 310. Has been.

  The transparent substrate 310 may be a substrate that transmits light and is made of an insulating material, such as a glass substrate or a plastic substrate.

The first electrode 320 may be made of a transparent conductive oxide such as TCO, such as ZnO, AZO, ITO, and SnO ₂ : F, which transmits light and is a conductive material.
The first electrode 320 may have an uneven surface formed by textured processing.

The second type layer 330 may be a hydrogenated amorphous silicon carbide layer doped with a P-type impurity, that is, a second type a-SiC: H layer. The second type layer 330 may be a hydrogenated amorphous silicon layer doped with a second type impurity, that is, a second type a-Si: H layer.
When the second type layer 330 is formed of the second type a-SiC: H layer, the second type layer 330 may have a thickness of 10 to 20 μm, preferably 12 μm. In addition, when the second type layer 330 is formed of the second type a-Si: H layer, the thickness may be 11 to 12 μm, preferably 12 μm.

The buffer layer 340 is provided as a buffer for the second-type layer 330 and the intrinsic layer 350, and includes a second-type doped hydrogenated amorphous silicon layer, that is, a second-type a-Si: H layer. ing.
The buffer layer 340 has a thickness of 2 to 5 μm, preferably 3 μm.

The intrinsic layer 350 may be a hydrogenated amorphous silicon layer that is not doped with impurities, that is, an Ia-Si: H layer. The intrinsic layer 350 may be a hydrogenated fine crystalline silicon layer that is not doped with impurities, that is, an I μc-Si: H layer.
When the intrinsic layer 350 is the Ia-Si: H layer, the thickness may be 3 to 5 μm, preferably 5 μm. When the intrinsic layer 350 is the I μc-Si: H layer, the thickness may be 0.5 to 2 μm, preferably 1 μm.

The first type layer 360 may be a hydrogenated amorphous silicon doped with a first type impurity, that is, a first type a-Si: H layer. The first type layer 360 may be made of hydrogenated microcrystalline silicon doped with a first type impurity, that is, first type μc-Si: H.
The first mold layer 360 has a thickness of 20 to 60 μm, preferably 40 μm.

The transparent electrode layer 370 may be made of a transparent conductive oxide such as TCO, for example, ZnO, AZO, ITO, and SnO ₂ : F, which transmits light and is a conductive material.
The transparent electrode layer 370 has a thickness of 100 to 200 μm, preferably 120 μm.

  The second electrode 380 is made of a conductive material such as aluminum.

FIG. 4 is a flowchart showing a process sequence of a method for manufacturing a solar cell according to an embodiment of the present invention.
As shown in FIG. 4, a method for manufacturing a solar cell according to an embodiment of the present invention includes a first-type silicon substrate preparation step (S410), a first electrode formation step (S420), and an intrinsic layer formation step ( S430), a second type layer forming step (S440) and a second electrode forming step (S450).

  At this time, a method for manufacturing a solar cell according to an embodiment of the present invention will be described based on the solar cell 200 described with reference to FIG.

The first-type silicon substrate preparation step (S410) is a step of preparing the first-type silicon substrate 220.
The first-type silicon substrate 220 may be a single crystal silicon substrate grown by a CZ method (Czochralski method) or the like.
At this time, the first-type silicon preparing step (S410) includes cleaning the first-type silicon substrate 220 and removing the oxide film.

  The first-type silicon substrate 220 is washed with a solution in which sulfuric acid and hydrogen peroxide are mixed at a ratio of 4: 1 and maintained at 120 ° C. for 10 minutes, and a cleaning process is performed for about 10 seconds in a BOE (Buffered Oxide Etchant). An oxide film removing step of removing the oxide film by dipping is performed.

  The first-type silicon substrate preparing step (S410) includes a drying step of drying the first-type silicon substrate 220. That is, the first type silicon substrate 220 is subjected to a drying process for removing moisture adsorbed on the first type silicon substrate 220 in the cleaning process and the oxide film removing process. The drying process may be a process in which the first-type silicon substrate 220 is charged into a vacuum chamber or the like and heated to 200 ° C. for about 2 hours in a state where oxygen is removed.

The step of forming the first electrode (S420) is a step of forming the first electrode 210 by depositing a conductive material, that is, Ag and a metal on the rear surface of the first-type silicon substrate 220.
The conductive material, for example, Ag may be deposited by using a physical vapor deposition method such as an evaporation method or a sputtering method.

  The intrinsic layer forming step (S430) is a step of forming an intrinsic silicon layer not containing impurities of the first type and the second type on the front surface of the first type silicon substrate 220.

  The intrinsic layer forming step (S430) may be performed using the inductively coupled plasma enhanced chemical vapor deposition apparatus 100 described with reference to FIG. 1, and may be performed using a plasma enhanced chemical vapor deposition apparatus (Plasma Enhanced Chemical Vapor). It can also be formed using a chemical vapor deposition apparatus such as Deposition).

In the present embodiment, a method for forming the intrinsic layer 230 using the inductively coupled plasma enhanced chemical vapor deposition apparatus 100 will be described as a reference.
The intrinsic layer 230 may be formed by using a mixed gas including hydrogen (H ₂ ) gas and silane (SiH ₄ ) gas using the inductively coupled plasma enhanced chemical vapor deposition apparatus 100.
As the mixed gas, a mixed gas in which a ratio of silane gas to hydrogen gas of the hydrogen gas and silane gas (H ₂ / SiH ₄ ratio) is 8 to 10 is used.

In addition, the intrinsic layer forming step (S430) for forming the intrinsic layer 230 is performed under a process condition of a process pressure of 70 to 90 mtorr, a process power of 200 to 300 W, and a process temperature of 250 to 350 degrees. Do.
Hereinafter, Experimental Example 1 to Experimental Example 3 are experiments for selecting optimal process conditions for forming the intrinsic layer 230 using the inductively coupled plasma enhanced chemical vapor deposition apparatus 100.

<Experimental example 1>
FIG. 5 is a graph showing changes in the thickness and surface roughness of the intrinsic layer according to the ratio of the silane gas to the hydrogen gas of the mixed gas.

FIG. 6 is a graph showing the thickness and surface roughness of the intrinsic layer according to changes in process pressure.
Referring to FIG. 5 and FIG. 6, the ratio of the silane gas to the hydrogen gas of the mixed gas and the process pressure are changed, and the results for the thickness and surface roughness of the intrinsic layer 230 are respectively expressed by a stylus profiler. And a scanning probe microscope (Scanning Probe Microscope).

  At this time, when selecting the optimum process condition of the ratio of silane gas to hydrogen gas, the process time, process pressure, process power and process temperature are fixed at 10 seconds, 70 mTorr, 300 W and 100 ° C., respectively, and the optimum process pressure is selected. When selecting the process conditions, the ratio of silane gas to hydrogen gas, process time, process pressure and process temperature were fixed at 10, 10 seconds, 300 W and 100 ° C., respectively.

  As shown in FIG. 5, it can be seen that as the amount of hydrogen gas increases, the thickness gradually decreases, and at the same time, the surface roughness increases again during the decrease. This suggests that the appropriate addition of hydrogen gas plays an important role in making the surface roughness uniform, and is effective in removing radicals generated from the surface and removing weakly bonded structures by etching. Tell them that there is.

Accordingly, the ratio of the silane gas to the hydrogen gas is preferably 8 to 10 in which the intrinsic layer 230 is formed thick and the surface roughness is a relatively low section.
At this time, when the ratio of the silane gas to the hydrogen gas is 10, the intrinsic layer 230 having a large thickness and excellent surface roughness can be formed.

As shown in FIG. 6, when the process pressure is performed at a process pressure of 0.1 torr or less, the best characteristics are shown at 70 to 90 mtorr.
It can be seen that the thickness of the intrinsic layer 230 is not only relatively thick compared to other process pressures, but also has a lower surface roughness than other process pressures.
At this time, it can be seen that the process pressure shows the most excellent characteristics at 90 mtorr.

<Experimental example 2>
FIG. 7 is a graph showing changes in intrinsic layer thickness and band gap in response to process power changes.
FIG. 8 is a graph showing Fourier transform infrared spectroscopic analysis according to process power change.

  7 and 8, among the process conditions, the ratio of silane gas to the hydrogen gas, the process time, the process pressure, and the process temperature are fixed at 10, 1200 seconds, 70 mTorr, and 300 ° C., respectively. As a result of investigating the optimum process power by changing the process power, it was possible to obtain the intrinsic layer 230 having excellent characteristics with a process power of 200 to 300 W.

  As the process power increases, the thickness of the intrinsic layer 230 increases linearly, suggesting that the number of radicals generated by increasing the process power increases.

In order to use the intrinsic layer 230 as an intrinsic layer of the solar cell 200, the optical band gap is 1.6 to 1.8 eV, the dark conductivity is 10 ^{9 to} 10 ¹⁰ S / cm, The conductivity is preferably 10 ^{4 to} 10 ⁵ S / cm.
Therefore, it can be seen that the graph shown in FIG. 7 shows the best results when the process power is 200 to 300 W, preferably 300 W.

At this time, as shown in the graph shown in FIG. 8, the absorption peak was observed from 2000 cm ^−1, which is an absorption peak in the Si—H stretching region with few defect factors with respect to the process power of 200 to 300 W. This suggests that even though the power is increased, the thin film is not broken by the high energy particles, and Si radicals are bonded mainly with relatively few defect factors, so that the high quality intrinsic layer 230 is formed. Indicates the possibility that can be formed.

<Experimental example 3>
FIG. 9 is a graph showing the change in carrier lifetime in the intrinsic layer according to the process temperature.
As shown in FIG. 9, among the process conditions, the ratio of the silane gas to the hydrogen gas, process time, process pressure and process power are fixed at 10, 1200 seconds, 70 mTorr and 300 W, respectively, and the process temperature is changed to optimize. As a result of investigating the process temperature, it was possible to obtain the intrinsic layer 230 having excellent characteristics at a process temperature of 250 to 350 ° C.

As shown in FIG. 9, as the process temperature increases, the carrier lifetime has a high carrier lifetime of 250 to 350 ° C., and shows a maximum carrier lifetime of about 160 ns.
At this time, the measurement / analysis of the lifetime of the carrier utilized a QSSPCD (Quasi-steady state photoconductivity decay) method.

  Therefore, it can be understood that the process temperature is preferably 250 to 350 ° C. in forming the intrinsic layer 230.

  In addition, referring to FIG. 4, the solar cell manufacturing method for manufacturing the solar cell 200 will be described. The second mold formation for forming the second mold layer after the intrinsic layer forming step (S430). Step (S440) is performed.

  The step of forming the second type layer (S440) is a step of forming the second type layer 240 on the intrinsic layer 230.

The second-type layer 240 can be formed by a chemical vapor deposition apparatus such as a plasma chemical vapor deposition apparatus, like the intrinsic layer 230.
In addition, the second type layer 240 may be formed using the inductively coupled plasma enhanced chemical vapor deposition apparatus 100.

  In the present embodiment, a method of forming the second type layer 240 by the inductively coupled plasma chemical vapor deposition apparatus 100 will be mainly described.

The second-type layer forming step (S440) is performed by adding diborane (B ₂ H ₆ ) gas to the process conditions described above in the intrinsic layer forming step (S430), thereby adding a second-type doped hydrogenation. The second type layer 240 may be formed of an amorphous silicon layer, that is, a second type a-Si: H layer.

In addition, the second-type layer forming step (S440) includes hydrogen (H ₂ ) gas, silane (SiH ₄ ) gas, diborane (B ₂ H ₆ ) gas, and mixed gas containing ethylene (C ₂ H ₄ ) gas. Can be used to form a hydrogenated amorphous carbide silicon layer doped with the second type, ie, a second type a-SiC: H layer.

  Hereinafter, Experimental Example 4 and Experimental Example 5 are mixed for forming the second type layer 230 composed of the second type a-SiC: H layer using the inductively coupled plasma enhanced chemical vapor deposition apparatus 100. This is an experiment for selecting the optimum gas mixing conditions.

<Experimental example 4>
FIG. 10 is a graph showing changes in the deposition rate and optical band gap of the hydrogenated amorphous silicon carbide thin film in response to addition of ethylene gas.
FIG. 11 is a graph showing a change in the bonding structure of the hydrogenated amorphous silicon carbide thin film according to the addition of ethylene gas.

Referring to FIGS. 10 and 11, first, the ratio of silane gas to hydrogen gas of hydrogen gas containing ethylene gas and mixed gas containing hydrogen gas (H ₂ / SiH ₄ ) is fixed at 6, and the process power Was fixed at 600 W and the process temperature was fixed at 250 ° C.
Then, ethylene gas diluted with 60% hydrogen gas was increased from 0 sccm to 8 sccm and mixed with the mixed gas. At this time, the total flow rate of the mixed gas containing the ethylene gas was fixed at 100 sccm.
The deposition rate and the optical band gap were measured using a stylus profiler and a scanning probe microscope, respectively.

It can be seen that as the mixing ratio of ethylene gas increases, the deposition rate decreases sequentially, and at the same time, the optical band gap increases to 2.9 eV. This is because the function of hydrogen contained in ethylene gas shows a low deposition rate by etching weak bonding groups present on the surface of the thin film, and carbon and hydrogen are doped into amorphous silicon. by, shows that the band gap defect factor is removed that exist within the band gap is expanded, if increased ethylene gas, Si-C (790cm ^-1) and C-H (2800~3000cm ^-1 ) Was observed, but it was found that the peak gradually increased.

In addition, a peak of Si—H 2 (2090 cm ⁻¹ ) with many defect factors is observed, and it can be seen that the intensity of the peak increases sequentially. Overall ethylene gas ratio (the amount of the amount / total inflow gas of ethylene gas) ^10-2 around, the ethylene gas to total gas mixture, it is mixed in a ratio of 1 to 1.2% Can be seen to show good characteristics.

<Experimental example 5>
FIG. 12 is a graph showing changes in the optical band gap and safety of the hydrogenated amorphous silicon carbide layer doped in the second type according to the addition of diborane gas.
FIG. 13 is a graph showing changes in characteristics of the solar cell depending on the thickness of the hydrogenated amorphous silicon carbide layer doped in the second type.

Referring to FIGS. 12 and 13, among the process conditions of Experimental Example 5, the ethylene gas is fixed at 1.2 sccm, the other process conditions are the same, and the diborane gas is increased from 0 sccm to 8 sccm. And mixed with the mixed gas.
At this time, the diborane gas is diborane gas diluted with 97% hydrogen gas. The optical band gap and electrical conductivity of the hydrogenated amorphous silicon carbide layer doped in the second type were analyzed by changing the flow rate of the diborane gas.

  As the diborane gas increases, the band gap decreases from 2.2 eV to 1.98 eV, and it can be seen that a defect factor is generated by boron atoms doped in the expanded band gap.

Moreover, it turns out that dark electrical conductivity increases to 5 * 10 < ^-6 > S / cm. It can be seen that when the diborane gas is mixed at about 6 sccm, that is, when the ratio of diborane gas (diborane gas amount / total gas flow amount) is 6 to 6.5%, the best characteristics are shown.
In addition, when the thickness is changed from 9 to 15 nm by applying the above-described process conditions as the second layer mold 240 of the solar cell, the open voltage, current density, fidelity, and conversion efficiency are compared. It was found to show a high open circuit voltage (0.81 V), current density (21.1 mA / cm ² ), fidelity (0.53) and conversion efficiency of 9.08% at 12 nm.
Referring to FIG. 4 again, the solar cell manufacturing method for manufacturing the solar cell 200 will be described. After the second mold layer forming step (S440), the second electrode forming step (S440) is performed. S450) is performed.

  The second electrode forming step (S450) is a step of forming a transparent electrode layer 252 on the second mold layer 240 and forming a patterned metal electrode 254 on the transparent electrode layer 252.

The transparent electrode layer 252 is formed by depositing a transparent conductive oxide such as TCO, for example, ZnO, AZO, ITO, and SnO ₂ : F, using a physical vapor deposition apparatus or a chemical vapor deposition apparatus. Can be done.
The metal electrode 254 may be formed by forming a conductive material such as aluminum using a physical vapor deposition apparatus and then patterning to form a patterned metal electrode 254 or using a pattern mask. A method of forming the patterned metal electrode 254 with a vapor deposition apparatus can be used.

FIG. 14 is a flowchart showing a process sequence of a method for manufacturing a solar cell according to another embodiment of the present invention.
As shown in FIG. 14, a method for manufacturing a solar cell according to another embodiment of the present invention includes a transparent substrate preparation step (S510), a first electrode formation step (S520), and a second mold layer formation step ( S530), buffer formation step (S540), intrinsic layer formation step (S550), first mold layer formation step (S560), transparent electrode layer formation step (S570), and second electrode formation step (S580). Is included.

  At this time, a method of manufacturing a solar cell according to another embodiment of the present invention will be described based on the solar cell 300 described with reference to FIG.

The transparent substrate preparation step 510 is a step of preparing a transparent substrate 310 that is transparent and insulating, such as a glass substrate or a plastic substrate.
The transparent substrate preparing step 510 includes a step of removing organic substances from the transparent substrate 310. That is, the transparent substrate preparing step 510 includes a step of removing organic substances from the transparent substrate 310 using TCE (Tri Chloro Ethylene), acetone, and methanol.
The transparent substrate preparing step 510 includes a drying process for drying the transparent substrate 310. That is, a drying process is performed to remove moisture adsorbed on the transparent substrate 310 in the process of removing organic substances from the transparent substrate 310. The drying process may be a process in which the transparent substrate 310 is charged into a vacuum chamber or the like and heated to 200 ° C. for about 2 hours in a state where oxygen is removed.

The first electrode forming step (S520) is a step of forming the first electrode 310 made of a TCO layer on the transparent substrate 310.
The TCO layer may be formed by depositing a transparent conductive oxide such as ZnO, AZO, ITO and SnO ₂ : F using a physical vapor deposition apparatus or a chemical vapor deposition apparatus.

At this time, the first electrode 310 performs a texture process by performing a wet process using diluted hydrochloric acid.
The first electrode 310 includes a plurality of protrusions, preferably a plurality of pyramidal protrusions, on the surface thereof by the texture process.

  The second type layer forming step 530 is a step of forming the second type layer 330 on the first electrode 310, and the second type forming step (S440) described with reference to FIG. Since it can be formed by the same method, detailed description thereof is omitted.

The buffer layer forming step (S540) is a process that is performed continuously with the second-type layer forming step 530, and has a concentration lower than the concentration of the second-type impurities forming the second-type layer 330. Forming the buffer layer 340 to be doped;
Therefore, the buffer layer forming step (S540) is performed under the process conditions in which the second type gas, for example, diborane (B ₂ H ₆ ) gas amount is reduced in the second type layer forming step 530. The detailed description will be omitted.

The intrinsic layer forming step (S550) can be formed by the same method as the intrinsic layer forming step (S450) described with reference to FIG.
The intrinsic layer forming step (S550) is a step of forming a hydrogenated fine crystalline silicon layer that is not doped with impurities, that is, an I μc-Si: H layer.

  Hereinafter, Experimental Example 6 uses the inductively coupled plasma enhanced chemical vapor deposition apparatus 100 to form the intrinsic layer 350 as a hydrogenated fine crystalline silicon layer that is not doped with impurities, that is, an I μc-Si: H layer. This is an experiment for selecting the optimum conditions of the mixed gas and the process pressure.

<Experimental example 6>
FIG. 15 is a graph showing changes in electrical conductivity and activation energy of the hydrogenated microcrystalline silicon layer of the intrinsic layer according to the amount of silane gas.
FIG. 16 is a graph showing changes in the crystallization peak and the amorphous peak depending on the amount of silane gas.
FIG. 17 is a graph showing changes in electrical characteristics of the intrinsic hydrogenated fine crystalline silicon layer in response to changes in process power.

15 to 17, the mixed gas in which the silane gas and the hydrogen gas are mixed increases the ratio of silane gas (SiH ₄ / (SiH ₄ + H ₂ )) from 0.016 to 0.045. The process power was changed from 800 to 1400W.
As shown in FIGS. 15 and 16, darkness, photoconductivity, and activation energy of the intrinsic layer according to the ratio of the silane gas were measured. At this time, the process power is 1200 W, the process pressure is 70 mtorr, and the process temperature is 250 ° C.

At this time, it can be seen that the ratio of the silane gas is 0.016 to 0.02 under the condition that the photoconductivity is the highest and the activation energy range is satisfied. That is, as the ratio of the silane gas decreases, that is, as the flow rate of the silane gas increases, the intensity of the crystal peak at 520 cm ⁻¹ decreases, and at the same time, the peak at 480 cm ⁻¹ increases.
At this time, when the ratio of the silane gas is 0.02, the crystallinity is about 68% or more.

As shown in FIG. 17, the process power was 1150 to 1250 W with the highest photoconductivity and satisfying the activation energy range.
At this time, the second mold layer 330 and the first mold layer 360 may also be formed of a hydrogenated fine crystalline silicon layer.

  Hereinafter, the experimental example 7 uses the inductively coupled plasma enhanced chemical vapor deposition apparatus 100 to make the second type layer 330 and the first type layer 360 doped with the second type and first type impurities, respectively. This is an experiment for selecting an optimum mixing condition of a mixed gas for forming a crystalline silicon layer, that is, a second type and a first type μc-Si: H layer.

<Experimental example 7>
FIG. 18 is a graph showing changes in optical band gap and dark conductivity depending on the ratio of phosphine gas.
FIG. 19 is a graph showing changes in optical band gap and dark conductivity depending on the ratio of diborane gas.

Referring to FIGS. 18 and 19, the method for refining and crystallizing the second mold layer 330 and the first mold layer 360 uses the mixed gas while maintaining the process conditions in Experimental Example 6. Among them, the ratio of the phosphine gas and the ratio of the diborane gas to the silane gas were changed, and the optimum ratio of the phosphine gas and the ratio of the diborane gas were selected.
The second type layer 330 uses a mixed gas containing 0.075 to 0.1% of a phosphine gas with respect to the silane gas, and the first type layer 360 has a diborane gas with respect to the silane gas of 0.1 to 0.00. It is preferable to use a mixed gas containing 5%.

  As shown in FIGS. 18 and 19, when the ratio of phosphine gas increases, both the band gap and the dark conductivity value decrease, and the band gap increases as the ratio of the diborane gas increases. It can be seen that the dark conductivity value increases and the dark conductivity value increases.

  In addition, referring to FIG. 14, the solar cell manufacturing method for manufacturing the solar cell 300 will be described. After performing the intrinsic layer forming step (S550), the second mold layer forming step (S560). )I do.

  The first type layer forming step (S560) is substantially the same as the second type layer forming step (S440) described with reference to FIG. 4 except that only the impurities are changed to the first type. Since a 1-type hydrogenated amorphous silicon layer can be formed and can be formed of a hydrogenated fine crystalline silicon layer doped with a first-type impurity as described above in Experimental Example 7, detailed description thereof is omitted.

In the transparent electrode layer forming step (S570), a TCO layer, that is, a transparent conductive oxide such as ZnO, AZO, ITO, and SnO ₂ : F is deposited on the first mold layer 360 by physical vapor deposition. Since it is a step of vapor deposition using an apparatus or a chemical vapor deposition apparatus, the method for forming the TCO layer has been described above, and a detailed description thereof will be omitted.

The second electrode forming step (S580) is a step of forming a conductive material such as aluminum on the transparent electrode layer 370 using a physical vapor deposition apparatus.
Since the second electrode forming step (S580) can be formed by a general method of forming a conductive electrode, detailed description thereof is omitted.

  The present invention has been described above by taking the embodiment as an example. However, the present invention is not limited to this. A person skilled in the art can make modifications and changes without departing from the spirit and scope of the present invention, and such modifications and changes are of course within the scope of the present invention.

210 First electrode 220 First type layer 230 Intrinsic layer 240 Second type layer 250 Second electrode

Claims (1)

In manufacturing a solar cell including a first electrode, a first type layer, an intrinsic layer, a second type layer and a second electrode,
Using an inductively coupled plasma chemical vapor deposition apparatus using a mixed gas containing hydrogen (H ₂ ) gas, silane (SiH ₄ ) gas, diborane (B ₂ H ₆ ) gas, and ethylene (C ₂ H ₄ ) gas A step of forming a second mold layer for forming the second mold layer comprising an amorphous silicon carbide thin film,
The ethylene gas is ethylene gas diluted 60% with hydrogen gas, and the diborane gas is diborane gas diluted 97% with hydrogen gas,
The ethylene gas is included in the mixed gas in an amount of 1 to 1.2%, and the diborane gas is included in the mixed gas in an amount of 6 to 6.5%.
The manufacturing method of the solar cell is as follows:
Before the step of forming the second type layer,
A first-type silicon substrate preparation step of preparing a first-type silicon substrate;
Forming a first electrode on the rear surface of the first-type silicon substrate;
Forming an intrinsic layer on the front surface of the first-type silicon substrate;
After the step of forming the second mold layer,
Look including the steps of forming the second electrode forming the second electrode on the second-type layer,
The first electrode is made of Ag,
The intrinsic layer comprises a hydrogenated amorphous silicon layer,
The method for manufacturing a solar cell, wherein the second electrode includes a transparent electrode layer formed on the second mold layer and a patterned aluminum electrode formed on the transparent electrode layer .

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