KR101612959B1 - Solar cell and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a solar cell. Said solar cell comprising: a substrate having an impurity portion of a first conductivity type; an emitter portion having a second conductivity type opposite to said first conductivity type and forming a pn junction with said impurity portion; Type impurity, an antireflection film disposed on the passivation part, a plurality of first electrodes electrically connected to the emitter part, at least one current collector part connected to the plurality of first electrodes, And a second electrode electrically connected to the substrate. Accordingly, since the passivation film is located on the surface of the emitter portion, defects existing near the surface of the emitter portion are reduced, thereby improving the efficiency of the solar cell.

Solar cells, passivation, passivation, dangling bonds, defects, silicon nitride oxide,

Description

SOLAR CELL AND METHOD FOR MANUFACTURING THE SAME

The present invention relates to a solar cell and a manufacturing method thereof

With the recent depletion of existing energy resources such as oil and coal, interest in alternative energy to replace them is increasing. Among them, solar cells produce electric energy from solar energy, and they are attracting attention because they have abundant energy resources and there is no problem about environmental pollution.

Typical solar cells have a substrate made of different conductivity type semiconductors, such as p-type and n-type, an emitter layer, and electrodes connected to the substrate and the emitter, respectively. At this time, a p-n junction is formed at the interface between the substrate and the emitter.

When light is incident on the solar cell, a plurality of electron-hole pairs are generated in the semiconductor, and the generated electron-hole pairs are separated into electrons and holes which are charged by the photovoltaic effect, For example, toward the emitter portion and the substrate, and is collected by an electrode electrically connected to the substrate and the emitter portion, and these electrodes are connected by a wire to obtain electric power.

The technical problem to be solved by the present invention is to improve the efficiency of a solar cell.

Another technical problem to be solved by the present invention is to reduce manufacturing cost and manufacturing time of a solar cell.

A solar cell according to one aspect of the present invention includes a substrate having an impurity portion of a first conductivity type, an emitter portion having a second conductivity type opposite to the first conductivity type and forming a pn junction with the impurity portion, And a plurality of first electrodes electrically connected to the emitter section, wherein the plurality of first electrodes are connected to the plurality of first electrodes, At least one collector, and a second electrode electrically connected to the substrate.

The passivating portion may have a uniform thickness on the emitter portion.

The passivation layer may have a thickness of about 30 A to 50 A.

It is preferable that the impurity portion, the emitter portion and the passivation portion are located in the substrate.

The passivation part may be formed of a silicon nitride oxide film.

The emitter portion and the passivation portion may have a textured surface.

The emitter portion may include a first portion and a second portion, the impurity concentrations of which are different from each other.

And the impurity concentration of the first portion is higher than the impurity concentration of the second portion.

The thickness of the first portion may be greater than the thickness of the second portion.

The plurality of first electrodes may be electrically connected to the first portion.

A solar cell according to another aspect of the present invention includes a substrate having an impurity portion of a first conductivity type, an emitter portion having a second conductivity type opposite to the first conductivity type and forming a pn junction with the impurity portion, A passivation layer formed of a silicon nitride oxide film and formed by processing a surface portion of the tab, a plurality of first electrodes electrically connected to the emitter portion, and a plurality of first electrodes connected to the plurality of first electrodes, And at least one collector, and a second electrode electrically connected to the substrate.

A method of manufacturing a solar cell according to another aspect of the present invention includes the steps of forming an emitter layer of a second conductivity type opposite to the first conductivity type on a part of a substrate of a first conductivity type, Forming a part of the surface of the layer as a passivation part, forming an antireflection film on the passivation part, forming a first electrode pattern on the antireflection film, and forming a second electrode pattern on the substrate do.

The passivation part may be formed of a silicon nitride oxide film. The passivation layer may be formed to a thickness of about 30 Å to 50 Å.

The passivation part forming step includes injecting nitrous oxide (N ₂ O) into the chamber in which the substrate is placed, and converting the nitrite (N ₂ O) into a plasma state so that a part of the surface of the impurity layer is immobilized To form a partially-formed portion.

The portion of the substrate other than the impurity layer may form a p-n junction with the emitter.

The emitter forming step may include forming a first impurity portion and a second impurity portion having different impurity concentrations from each other.

The first and second impurity region forming steps may include forming an etching mask on the impurity layer, etching the impurity layer to remove the impurity layer where the etching mask is not located, And forming a second impurity portion having a second height lower than the first height to form the impurity portion, and removing the etching mask.

And the first electrode pattern is located on the first impurity region.

The etch mask may be formed by a screen printing method. The method of manufacturing a solar cell according to the above feature may further include the step of heat treating the substrate including the first electrode pattern and the second electrode pattern to form a plurality of first electrodes electrically connected to the emitter section and a second electrode electrically connected to the substrate Two electrodes may be formed.

According to the features of the present invention, since the passivation part is formed on the surface of the emitter part located in the substrate, defects existing near the surface of the emitter part are reduced and the efficiency of the solar cell is improved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. Like parts are designated with like reference numerals throughout the specification. When a layer, film, region, plate, or the like is referred to as being "on" another portion, it includes not only the case directly above another portion but also the case where there is another portion in between. Conversely, when a part is "directly over" another part, it means that there is no other part in the middle. Also, when a part is formed as "whole" on the other part, it means not only that it is formed on the entire surface (or the front surface) of the other part but also not on the edge part.

Hereinafter, a solar cell according to an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a partial perspective view of a solar cell according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II of the solar cell shown in FIG.

1 and 2, a solar cell 1 according to an embodiment of the present invention includes a substrate 110 having a first impurity region 100, an emitter region 120 disposed on the substrate 110, A passivation portion 125 located on the emitter portion 120 of the surface of the substrate 110 on which the light is incident (hereinafter referred to as a 'front surface'), and a passivation portion 125 located on the passivation portion 125 A front electrode part 140 positioned on the emitter part 120 and a surface of a substrate 110 positioned on the opposite side of the front surface without light incident thereto (hereinafter referred to as a 'rear surface') And a back surface field (BSF) portion 171 disposed between the rear electrode 151 and the first impurity region 100. The back electrode 151 is formed on the rear surface of the first impurity region 100,

The substrate 110 is a semiconductor substrate of a first conductivity type, for example, silicon of p-type conductivity type. Here, the silicon is crystalline silicon such as single crystal silicon or polycrystalline silicon or amorphous silicon. The substrate 110 may contain an impurity of a trivalent element such as boron (B), gallium (Ga), indium (In), or the like.

Alternatively, however, the substrate 110 may be of the n-type conductivity type and in this case the substrate 110 may contain impurities of pentavalent elements such as phosphorus (P), arsenic (As), antimony (Sb) And the substrate 110 may be made of a semiconductor material other than silicon.

Such a substrate 110 is textured to have a textured surface that is an uneven surface. Therefore, the amount of light incident on the substrate 110 due to the textured surface increases, thereby improving the efficiency of the solar cell 1.

The emitter portion 120 formed on the substrate 110 is a second impurity portion having a second conductivity type opposite to the conductivity type of the substrate 110, for example, an n-type conductivity type. Therefore, substantially the region of the substrate 110 excluding the emitter section 120 becomes the first impurity region 100.

Accordingly, the substrate 110 has the n-type impurity portion 120 and the p-type impurity portion 100, and these impurity portions 100 and 120 form a p-n junction.

Due to the built-in potential difference due to the pn junction, the electron-hole pairs generated by the light incident on the substrate 110 are separated into electrons and holes, electrons move toward the n-type, Moves toward the p-type. Therefore, when the first impurity 100 is a p-type and the second impurity is an n-type emitter, the separated holes migrate toward the first impurity region 100 and the separated electrons migrate toward the emitter region 120 As a result, the holes in the substrate 100 become majority carriers, and the electrons in the emitter section 120 become the majority carriers.

The emitter section 120 forms a pn junction with the first impurity section 100. Thus, unlike the present embodiment, when the substrate 110 has an n-type conductivity type, the emitter section 120 has a p-type conductivity Type. In this case, the separated electrons move toward the first impurity region 100 and the separated holes move toward the emitter region 120.

When the emitter section 120 has an n-type conductivity type, the emitter section 120 dopes impurities of pentavalent elements such as phosphorus (P), arsenic (As), antimony (Sb) A dopant of a trivalent element such as boron (B), gallium (Ga), or indium (In) may be doped into the substrate 110 when the emitter section 120 has a p-type conductivity type .

The passivation part 125 is formed on the textured surface of the front surface of the substrate 110 and is made of a silicon nitride oxide film (SiOxNy), that is, the passivation part 125 forms the emitter part 120 on the front surface of the substrate 110 A portion of the surface of the impurity doped with the impurity impurity is a portion converted into a silicon nitride oxide film (SiOxNy). As a result, the substrate 110 for substantially manufacturing the solar cell 1 is formed in the passivation portion 125 ), an n-type emitter section 120 and a p-type impurity section 100,

The passivation part 125 is located near the textured surface of the substrate 110 from the front electrode part 140. Therefore, the passivation layer 125 contains impurities, for example, n-type impurities contained in the emitter layer 120. In addition, the passivation layer 125 has a substantially uniform thickness over the textured surface of the substrate 110. In this embodiment, the passivation layer 125 has a thickness of about 30 ANGSTROM to 50 ANGSTROM and a refractive index of about 1.5.

Generally, when the emitter layer 120 is formed by doping an impurity into the substrate 110, the surface of the substrate 110 is doped with impurities in a more than solid solubility in the substrate 110, There is a dead layer that generates light and hinders the absorption of light into the substrate 110 and hinders the collection of charge (e.g., minority carriers) generated by light, and also a dangling bond There is a defect such as a bond.

However, in this embodiment, since the surface portion of the substrate 110 is formed of the passivation portion 125 at a thickness of about 30 Å to 50 Å from the incident surface, the passivation portion 125 reduces the dead layer portion do. Nitrogen (N) contained in the passivation layer 125 can trap a dangling bond and a trap site existing at the interface between the emitter layer 120 and the antireflection film 130, The passivation effect for stabilizing the coupling is exhibited, and the amount of charge that moves toward the emitter part 120 is recombined with the unstable coupling and is lost.

This increases the amount of charge moving from the emitter section 120 to the front electrode section 140 and increases the amount of light absorbed into the substrate 110, thereby improving the efficiency of the solar cell 1.

The antireflection film 130 formed on the passivation layer 125 is formed of a silicon nitride film (SiNx), a silicon oxide film (SiOx), or the like. The antireflection film 130 reduces the reflectivity of light incident on the solar cell 1 and increases the selectivity of a specific wavelength region to increase the efficiency of the solar cell 1. The anti-reflection film 130 may have a multi-layer structure such as a single film structure or a double film structure.

The front electrode unit 140 includes a plurality of front electrodes 141 and a plurality of front electrode current collectors 142, as shown in Figs.

A plurality of front electrodes 141 are electrically and physically connected to the emitter section 120 and extend in a predetermined direction in a substantially parallel manner.

The plurality of front electrodes 141 collect electrons, for example electrons, which have migrated toward the emitter section 120.

The plurality of front electrode current collectors 142 extend substantially parallel to the plurality of front electrodes 141 on the emitter section 120 and include not only the emitter section 120 but also a plurality of first electrodes 141, And are electrically connected to each other.

The plurality of front electrode current collectors 142 are located on the same layer as the plurality of front electrodes 141 and the plurality of front electrode current collectors 142 intersect the front electrode layers 141, (Not shown). Accordingly, the plurality of front electrode current collectors 142 collects the charges transmitted through the plurality of front electrodes 141 and outputs them to the external device.

Alternatively, the front electrode unit 140 may include a conductive material such as silver (Ag). Alternatively, the front electrode unit 140 may include at least one selected from the group consisting of Ni, Cu, Al, Sn, Zn, (In), titanium (Ti), gold (Au), and combinations thereof, or may contain other conductive metal materials.

The passivation layer 125 and the antireflection layer 130 located on the passivation layer 125 are electrically connected to the emitter layer 130 where the front electrode part 140 is not formed 120).

The rear electrode 151 located on the rear surface of the substrate 110 is located on substantially the entire rear surface of the substrate 110.

The plurality of rear electrodes 151 collects charges, for example, holes, which move toward the first impurity region 100.

Although the back electrode 151 contains at least one conductive material such as aluminum (A), in an alternate embodiment, the back electrode 151 may be formed of a metal such as nickel (Ni), copper (Cu), silver (Ag), tin Zn), indium (In), titanium (Ti), gold (Au), and combinations thereof, or may contain other conductive materials.

The rear electric field portion 171 located between the rear electrode 151 and the first impurity region 100 is a region where impurities of the same conductivity type as that of the first impurity region 100 are doped at a higher concentration than the first impurity region 100 , For example, a p + region.

A potential barrier is formed due to the difference in the impurity concentration between the first impurity region 100 and the rear field region 171 and the electrons are prevented from moving toward the rear surface of the first impurity region 100, Thereby reducing the recombination of electrons and holes in the vicinity and disappearing.

In addition to this structure, the solar cell 1 may further include a plurality of rear electrode current collectors positioned on the rear surface of the substrate 110.

Similar to the plurality of front electrode current collectors 142, the plurality of back electrode current collectors are electrically connected to the back electrode 151 to collect the charges transferred from the back electrode 151 and output the collected charges to the external device . This rear electrode current collector contains at least one conductive material such as silver (Ag), and may be made of the same material as the back electrode 151. [

The operation of the solar cell 1 according to this embodiment having such a structure is as follows.

When light is irradiated to the solar cell 1 and is mainly incident on the first impurity region 100 of the semiconductor through the emitter portion 120 which is the second impurity region, light is emitted from the first impurity region 100 of the semiconductor by the light energy, Hole pairs are generated.

At this time, the reflection loss of the light incident on the substrate 110 is reduced by the anti-reflection unit 130, and the amount of light incident on the first impurity region 100 increases.

These electron-hole pairs are separated from each other by the pn junction of the first impurity region 100 and the emitter region 120, which is the second impurity region, so that the electrons are directed toward the emitter region 120, which is the second impurity region having the n- And the holes move toward the first impurity region 100 having the p-type conductivity type. Electrons migrated toward the emitter section 120 are collected mainly by a plurality of front electrodes 141 and move to a plurality of front electrode current collectors 142. Holes moved to the first impurity section 100 And is collected by the rear electrode 151 through the rear electric portion 171. When a plurality of the front electrode current collectors 142 and the rear electrodes 151 are connected by a conductor, a current flows and the external power is utilized.

At this time, since the surface of the substrate 110 on the emitter section 120 is treated with a thin silicon nitride oxide film having a thickness of about 30 ANGSTROM to 50 ANGSTROM, the recombination rate of charges due to defects existing near the surface of the emitter section 120 And the amount of charges output to the outside increases. Thus, the efficiency of the solar cell 1 is improved. Particularly, since the passivation part 125 is formed between the emitter part 120 and the surface of the substrate 110, the output efficiency of electric charges generated by the short wavelength light incident on the emitter part 120 is improved.

Since the passivation part 125 for the passivation effect is located inside the substrate 110 instead of being located on the substrate 110, it is not necessary to deposit or form a separate film on the substrate 110, And the thickness of the entire solar cell 1 also decreases.

Next, a method of manufacturing the solar cell 1 according to an embodiment of the present invention will be described with reference to FIGS. 3A to 3E.

3A and 3E are sectional views sequentially illustrating a method of manufacturing a solar cell according to an embodiment of the present invention.

First, as shown in FIG. 3A, a front surface of a substrate 110 made of p-type single crystal or polycrystalline silicon is tested to form a textured surface which is an uneven surface. At this time, the substrate 110 is in this case formed of a single crystal silicon, KOH, using a base solution, such as NaOH, and texturing the surface of the substrate 110, a substrate 110 in this case made of a polycrystalline silicon, such as HF and HNO ₃ An acid solution is used to texture the surface of the substrate 110.

Next, as shown in FIG. 3B, a substance including an impurity of a pentavalent element such as phosphorus (P), arsenic (As), antimony (Sb) or the like, for example, POCl ₃ or H ₃ PO by heating at high temperatures, such as ₄ and 5 is formed an impurity layer 20 of n-type on the entire surface, that is, front, rear and lateral diffusing an impurity element of the substrate 110, the substrate 110. Therefore, the portion of the substrate 110 where the impurity is not implanted for the impurity layer 20 becomes the first impurity portion 100 containing the impurity of the trivalent element.

When the conductive type of the substrate 110 is n-type, unlike the present embodiment, a material including an impurity of a trivalent element, for example, B ₂ H ₆ , is heat-treated at a high temperature to form a p- An impurity layer can be formed.

Then, a phosphorus silicate glass (PSG) or a boron silicate glass (BSG) containing phosphorus, which is generated as the p-type impurity or n-type impurity diffuses into the substrate 110, Lt; / RTI >

In an alternative embodiment, the impurity layer 20 may be formed on the substrate 110 and then a textured surface may be formed.

Next, as shown in FIG. 3C, the substrate 110 on which the impurity layer 20 is formed is moved to a chamber (not shown) to inject nitrous oxide (N ₂ O) gas. Subsequently, A passivation layer 125 is formed by changing a portion of the surface of the impurity layer 20 to a silicon nitride oxide film (SiO x N y). At this time, the portion of the impurity layer 20 on the entire surface of the substrate 110 which is not changed to the silicon nitride oxide film (SiOxNy) becomes the emitter portion 120 which is the second impurity portion. At this time, the silicon nitride oxide film (SiO x N y) formed has a thickness of about 30 Å to 50 Å.

As described above, the passivation layer 125 is a film formed by subjecting the surface of the impurity layer 20 located on the front surface of the substrate 110 to plasma treatment.

That is, when a plasma is generated using nitrous oxide (N ₂ O) by applying RF power of a corresponding size in a nitrous oxide (N ₂ O) atmosphere, (Si) contained in the impurity layer 20 to be converted into a silicon nitride oxide film (SiO x N y), and the passivation part 125 is completed. At this time, the thickness of the silicon nitride oxide film (SiO x N y) produced by the surface treatment operation of the impurity layer 20 is substantially uniform at the textured surface of the substrate 110, as shown in Fig. 3C. That is, the thickness of the silicon nitride oxide film (SiO x N y) formed on the concave and convex portions of the textured surface is almost constant.

At this time, the thickness of the silicon nitride oxide film (SiO x N y) is based on the amount of silicon existing near the surface of the impurity layer 20, that is, the greater the amount of silicon capable of bonding with nitrogen and oxygen, Is increased.

Such a plasma forming process is performed at a low temperature of about 200 캜 to 450 캜.

When the thickness of the passivation layer 125 is less than about 30 ANGSTROM, the thickness of the film is too thin, so that an efficient passivation effect can not be obtained.

Also, if it exceeds about 10 minutes, there is a problem that the surface of the emitter part 120 is damaged by the generated plasma. Therefore, the plasma generation time is preferably as short as possible, and preferably less than 5 minutes.

3D, a chemical vapor deposition (CVD) process such as plasma enhanced chemical vapor deposition (PECVD) is performed in a chamber used for forming the passivation layer 125 After the hydrogenated silicon nitride film (SiNx) is deposited on the passivation layer 125 to form the antireflection film 130, the substrate 110 is discharged from the chamber. The thickness of the antireflection film 130 is about 60 nm to 100 nm, and it may have a refractive index of about 2.0 to 2.2.

Next, as shown in FIG. 3E, a front electrode part paste containing silver (Ag) is applied to a desired part by screen printing and then dried at about 170 ° C. to form a front electrode part pattern 40 are formed. At this time, the front electrode pattern 40 includes a front electrode pattern 40a and a current collector pattern 40b.

At this time, the front electrode paste may be formed of a material selected from the group consisting of Ni, Cu, Al, Sn, Zn, In, Ti, ), And a combination thereof.

3F, a rear electrode paste containing aluminum (Al) is applied to a corresponding portion of the rear surface of the substrate 110 by using a screen printing method and then dried to form the rear electrode pattern 50 .

At this time, the rear electrode paste may contain at least one selected from the group consisting of Ni, Cu, Ag, Sn, Zn, In, Ti, Au, And a combination of these.

At this time, the formation order of the front electrode pattern 40 and the rear electrode pattern 50 can be changed.

Then, the substrate 110 having the front electrode pattern 40 and the rear electrode pattern 50 is fired at a temperature of about 750 ° C. to about 800 ° C. to form a plurality of front electrodes 141 and a plurality of The front electrode 142 for the front electrode, the rear electrode 151, and the rear electrode portion 171 are formed.

That is, when the heat treatment is performed, the front surface electrode pattern 40 penetrates through the antireflection film 130 and the passivation layer 125 in contact with each other in turn by lead (Pb) contained in the front electrode pattern 40 A plurality of front electrodes 141 and a plurality of front electrode current collectors 142 are formed in contact with the emitter section 120 to complete the front electrode section 140. At this time, the front electrode pattern 40a of the front electrode pattern 40 becomes a plurality of front electrodes 141, and the current collector pattern 40b becomes a plurality of front electrode current collectors 142. [

A rear electrode 151 electrically connected to the rear surface of the substrate 110, that is, the rear surface of the first impurity 100 is formed by the heat treatment process, and aluminum (Al) contained in the rear electrode 151 A rear electric field section 171 is formed between the rear electrode 151 and the first impurity section 100. The rear electric field section 171 is formed between the rear electrode 151 and the first impurity section 100. [ At this time, the impurity layer 20 located on the rear surface of the substrate 110 becomes the rear electric section 171 by the diffusion operation of the aluminum (A1).

The plurality of rear electric sections 171 has a p-type conductivity type which is the same conductivity type as that of the first impurity section 100. The impurity concentration of the rear electric section 171 is higher than that of the first impurity section 100, Type. In addition, in the heat treatment process, a passivation effect of converting the nitrogen (N) of the passivation part 125 into a stabilized bond by bonding with a defect part located near the surface of the emitter part 120 occurs, The hydrogen (H) contained in the silicon oxide film also moves toward the emitter part 120 and bonds with the defect part, so that the passivation effect is more efficiently performed.

Then, an edge isolation (not shown) for removing the emitter section 120 formed on the side surface of the substrate 110 is performed using a laser beam to form an emitter section (not shown) formed on the front surface of the substrate 110 120 and the emitter portion 120 formed on the rear surface of the substrate 110 are electrically separated to complete the solar cell 1 (FIGS. 1 and 2).

As described above, according to the present embodiment, the surface treatment of the emitter layer 120 before the formation of the antireflection film 130 provides a passivation effect on the defect. Therefore, since it is not necessary to form a separate film for the passivation effect, the manufacturing time and manufacturing cost of the solar cell are reduced, and a separate chamber for the surface treatment is not required, so that the cost for the surface treatment hardly occurs. Also, since the passivation effect is generated not only by the passivation part 125 but also by the antireflection film 130, the passivation effect on the defective part is greatly improved and the efficiency of the solar cell is increased.

The effects of this embodiment will be described in more detail with reference to the prior art.

Conventionally, a separate film is formed on the substrate 110 to obtain a passivation effect.

That is, conventionally, a silane (SiH ₄ ) gas and an ammonia (NH ₃ ) gas are injected into a chamber, and then a passivation film is deposited on the substrate using a deposition method such as PECVD.

Thus, conventionally, silane (SiH ₄ ) gas and ammonia (NH ₃ ) gas must be injected into the chamber for silicon (Si) and nitrogen (N) implantation for deposition of a passivation film such as a silicon nitride oxide film. Since the embodiment forms a silicon oxynitride film by using silicon (Si) contained in the substrate 110, it is only necessary to supply nitrogen nitrate (N ₂ O) gas.

In addition, conventionally, a separate film must be deposited on the substrate, whereas the present embodiment requires only the surface treatment, so that the processing time is much shorter than the conventional one.

Further, conventionally, when a passivation film is deposited and a separate antireflection film is formed thereon, a chamber for depositing a passivating film and a chamber for depositing an antireflection film are respectively required. However, in this embodiment, since the surface treatment of the indigo layer 20 and the deposition process of the antireflection film 130 are performed in one chamber, the number of chambers required is reduced. Thus, the manufacturing cost is greatly reduced.

In the conventional case, when the passivation film is deposited after the surface of the substrate is textured, the thickness of the passivation film deposited varies depending on the position of the texturing surface, as shown in FIG.

That is, when the passivation film is deposited using PECVD, the deposition is performed from the texturing surface of the substrate 110 to the outside, and the deposition material is further accumulated in the concave portion than the convex portion of the texturing surface. Therefore, as shown in Fig. 4, the passivation film 25 deposited on the texturing surface of the emitter portion 120 had a recessed portion thicker than the convex portion. Therefore, as the thickness of the passivation film 25 varies with the position of the textured surface, there is a problem that the property of the passivation film 25 changes at the position.

3C, since the passivation film 125 is formed from the surface of the substrate 110 toward the inside of the substrate 110, the passivation film 125 according to the present embodiment is not a deposition process, Unlike the conventional passivation film 25, the passivation film 125 maintains a substantially constant thickness irrespective of the position of the substrate 110 because the passivation film 125 is formed through the process. Therefore, the property of the passivating film 125 is kept constant regardless of the position, as compared with the conventional passivating film 25, so that a passivating effect that is more efficient than the conventional one can be obtained.

4, the deposition is carried out from the surface of the substrate 110 so that the surface of the substrate 110 has a higher level of flatness than the surface of the passivation film 25. That is, While the surface of the substrate 110 is almost flat.

2, a passivation film 125 is formed from the surface of the substrate 110 toward the inside of the substrate 110, and the surface of the passivation film 125 (that is, the surface of the substrate 110) Is higher than the interface between the passivation film 125 and the emitter section 120. [ That is, the interface between the passivation film 125 and the emitter section 120 is an uneven surface, while the surface of the passivation film 125 is substantially flat.

Since the passivation film 125 of the present embodiment is located inside the substrate 110 instead of the passivation film 25 deposited on the substrate 110 as described above, the total thickness of the solar cell 1 after the fabrication is completed The modularization process of the solar cell 1 becomes easier.

Next, a solar cell and a manufacturing method thereof according to another embodiment of the present invention will be described with reference to FIGS. 5 to 8H. In this embodiment, the same reference numerals are given to the same parts as the solar cell 1 and its manufacturing method described with reference to Figs. 1 to 3F, and detailed description thereof will be omitted.

FIG. 5 is a partial perspective view of a solar cell according to another embodiment of the present invention, and FIG. 6 is a cross-sectional view of the solar cell shown in FIG. 5 cut along the line VI-VI. FIG. 7 is a graph showing quantum efficiency according to a wavelength change of light measured in a solar cell manufactured according to another embodiment of the present invention and a conventional solar cell. 8A to 8H are sectional views sequentially illustrating a method of manufacturing a solar cell according to an embodiment of the present invention.

First, a solar cell 10 according to another embodiment of the present invention will be described with reference to FIGS. 5 and 6. FIG. The solar cell 10 shown in Figs. 5 and 6 has a structure substantially similar to that of the solar cell 1 shown in Figs. 1 and 2.

That is, the solar cell 10 according to the present embodiment includes a substrate 110 having a first impurity region 100, an emitter region 120a, and a passivation region 125; The front electrode part 140 connected to the emitter part 120a, the rear electrode 151 connected to the substrate 110, and the rear electrode 151 and the first impurity part 100 And a rear electric field portion 171 positioned therein.

However, unlike the solar cell 1 shown in FIGS. 1 and 2, in the solar cell 10 of the present embodiment, the emitter portion 120a located on the front surface of the substrate 110 has a thickness, that is, And has a first portion 121 and a second portion 122 that are different in thickness. At this time, the first portion 121 is positioned substantially below the front electrode portion 140, and the second portion 122 is located at the remaining portion. At this time, since the thickness of the first portion 121 is thicker than the thickness of the second portion 122, the surface resistance of the first portion 121 is lower than the surface resistance of the second portion 122. In this embodiment, the surface resistance to the first portion 121 is about 40 < RTI ID = 0.0 > ohm / sq. And 60 ohm / sq., And the surface resistance to the second portion 122 is about 90 ohm / sq. To 120 [Omega] / sq.

1 and 2, the plurality of front electrodes 141 and the plurality of front electrode current collectors 142 are in contact with the first portion 121 of the emitter portion 120a having low surface resistance, do. The contact resistance is lowered when the front electrode part 140 contacts the first part 121 than when the front electrode part 140 contacts the second part 122 and the first part 121 having a higher impurity concentration than the second part 122 The efficiency of the solar cell 10 is improved because the amount of charge output through the front electrode unit 140 is increased when the charge moves to the front electrode 140 through the electrode unit 121.

As described above, the passivation layer 125 is formed by changing a part of the impurity formed when the impurity is implanted into the substrate 110 for the formation of the emitter layer 120a into the silicon nitride oxide film (SiOxNy), and has a thickness of about 30 Å to 50 Å And a refractive index of about 1.5.

Such a passivation part 125 reduces the effect that the passivation effect is exerted near the surface of the emitter part 120a and the electric charge moving toward the first impurity part 100 is recombined with the unstable bond and disappears.

Next, with reference to the graph shown in FIG. 7, the quantum efficiency of the solar cell 10 according to the present embodiment and the solar cell according to the prior art will be described, respectively. At this time, the quantum efficiency is an internal quantum efficiency (IQE).

In the solar cell outputting the graph of FIG. 7, the surface resistance to the first portion of the emitter portion is about 45? / Sq. And the surface resistance for the second portion is about 90? / Sq. .

As shown in FIG. 7, the quantum efficiency graph (A) of the solar cell according to the present embodiment and the quantum efficiency graph (B) of the solar cell according to the prior art are as follows. The quantum efficiency of the solar cell according to the present embodiment is maintained at about 90%, while the quantum efficiency of the conventional solar cell is about 75%. Since the passive portion 125 is located near the surface of the emitter portion 120a as described above, the light absorbed by the emitter portion 120a is transmitted to the passive portion 125 by the passivating portion 125 It was found that the loss of charge generated mainly by short wavelength light is reduced and the quantum efficiency for short wavelength light is greatly improved.

As described above, based on the measurement graphs (A and B) shown in FIG. 7, the passivation effect is greatly improved by the passivation part 125 and the open-circuit voltage Voc of the solar cell is increased, .

Next, a method of manufacturing the solar cell 10 according to another embodiment of the present invention will be described with reference to FIGS. 8A to 8H.

First, as shown in FIG. 8A, after the surface of the substrate 110 is textured, an n-type impurity is implanted into the p-type semiconductor substrate 110 using a thermal diffusion method or the like to form n Type impurity layer 20 is formed.

Next, as shown in FIG. 8C, paste is applied on the impurity layer 20 located on the front surface of the substrate 110 by screen printing and then dried to form an etching mask 30 .

Next, as shown in FIGS. 8D and 8E, a part of the impurity layer 20 where the etching mask 30 is not located is removed using an etching method such as wet etching, A first impurity region 21 and a second impurity region 22 which are different from each other are formed to complete the impurity region. At this time, at least a part of the dead layer in which the n-type impurity is excessively doped is removed together with the removal of a part of the impurity layer 20 to form the second impurity portion 22, Loss of incident light is reduced.

Next, the vicinity of the surface of the first and second impurity portions 21 and 22 is converted into a silicon nitride oxide film (SiOxNy) in the same manner as shown in FIG. 3C to form the surface of the first and second impurity portions 21 and 22 And the remaining portions of the first and second impurity portions 21 and 22 are respectively connected to the first portion 121 and the second portion 122 of the emitter portion 120a, (Fig. 8 (f)).

3D, an antireflection film 130 is formed on the passivation layer 125 (FIG. 8F). Then, as shown in FIGS. 3E and 3F, a front electrode pattern 40 and a rear electrode pattern 150 are formed (Figs. 8G and 8H). At this time, the front electrode part pattern 40 is located above the first part 121 of the emitter part 120a.

A plurality of front electrodes 141 electrically connected to the first part 121 of the emitter part 120a through the antireflection film 130 and the passivation part 125 in order and electrically connected to the first part 121, A front electrode part 140 having a front electrode current collector 142, a back electrode 151 electrically connected to the substrate 110 physically and a back electrode 151 electrically connected to the first impurity part 100 and the back electrode 151 (Not shown) to complete the solar cell 10 (FIGS. 5 and 6) after the solar cell 10 is completed, after the rear electric field portion 171 is formed.

The defective portion in the vicinity of the surface of the emitter portion 120a is converted into the stabilized coupling by the passivation portion 125 in the same way as the effect exerted by the solar cell 1 according to the previously described embodiment, Damaged portions of the first and second portions 121 and 122 generated in the etching process for forming the two portions 121 and 122 are converted into the passivation portions 125 to reduce the amount of charge loss. As described above, since a separate film for the passivation effect is not required, the manufacturing time and manufacturing cost of the solar cell are reduced, and the antireflection film 130 located on the passivation part 125 further enhances the passivation effect, The efficiency is improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

1 is a partial perspective view of a solar cell according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the solar cell shown in FIG. 1 taken along line II-II.

3A and 3F are sectional views sequentially illustrating a method of manufacturing a solar cell according to an embodiment of the present invention.

4 is a view showing a part of a passivation film formed on a substrate according to a conventional technique.

5 is a partial perspective view of a solar cell according to another embodiment of the present invention.

FIG. 6 is a cross-sectional view of the solar cell shown in FIG. 5 taken along line VI-VI.

FIG. 7 is a graph showing quantum efficiency according to a wavelength change of light measured in a solar cell manufactured according to another embodiment of the present invention and a conventional solar cell.

8A to 8H are sectional views sequentially illustrating a method of manufacturing a solar cell according to an embodiment of the present invention.

[Description of Drawings]

1, 10: solar cell 20: impurity layer

30: etching mask 40: front electrode part pattern

40a: Front electrode pattern 40b: Current collecting pattern

100: impurity section 110: substrate

120, 120a: Emitter part 125: Passivation part

130: antireflection film 140: front electrode part

141: front electrode 142: front electrode current collector

151: rear electrode 171:

Claims (21)

A substrate having an impurity portion of the first conductivity type, An emitter portion having a second conductivity type opposite to the first conductivity type and forming a p-n junction with the impurity portion, A passivating portion located above the emitter portion and containing an impurity of the second conductivity type, An antireflection film disposed on the passivation layer, A plurality of first electrodes electrically connected to the emitter section, At least one current collector connected to the plurality of first electrodes, and And a second electrode electrically connected to the substrate / RTI > Wherein the passivation layer is made of a silicon nitride oxide film and has a thickness of about 30 to 50 Angstroms. The method of claim 1, Wherein the passivation portion has a uniform thickness on the emitter portion. delete The method of claim 1, Wherein the impurity portion, the emitter portion, and the passivation portion are located in the substrate. delete The method according to any one of claims 1, 2, and 4, Wherein the emitter portion and the passivation portion have a textured surface. The method according to any one of claims 1, 2, and 4, Wherein the emitter portion includes a first portion and a second portion having different impurity concentrations from each other. 8. The method of claim 7, And the impurity concentration of the first portion is higher than the impurity concentration of the second portion. 9. The method of claim 8, Wherein a thickness of the first portion is thicker than a thickness of the second portion. The method of claim 9, And the plurality of first electrodes are electrically connected to the first portion. A substrate having an impurity portion of the first conductivity type, An emitter portion having a second conductivity type opposite to the first conductivity type and forming a p-n junction with the impurity portion, A passivation portion formed by processing a surface portion of the emitter portion and made of a silicon nitride oxide film, An antireflection film disposed on the passivation layer, A plurality of first electrodes electrically connected to the emitter section, At least one current collector connected to the plurality of first electrodes, and And a second electrode electrically connected to the substrate / RTI > Wherein the passivation layer is made of a silicon nitride oxide film and has a thickness of about 30 to 50 Angstroms. Forming a second conductivity type impurity layer in a portion of the substrate of the first conductivity type opposite to the first conductivity type to form an emitter portion; Forming a part of the surface of the impurity layer into a passivation part, Forming an antireflection film on the passivation layer, Forming a first electrode pattern on the anti-reflection film, and Forming a second electrode pattern on the substrate Lt; / RTI > Wherein the passivation layer is formed of a silicon nitride oxide film and is formed to a thickness of about 30 to 50 Angstroms. delete delete The method of claim 12, The passivation part forming step may include: Injecting nitrous oxide (N ₂ O) into the chamber in which the substrate is located, and Converting the nitrite nitrogen (N ₂ O) into a plasma state and forming a part of the surface of the impurity layer into the passivating part Wherein the method comprises the steps of: 16. The method of claim 15, Wherein a portion of the substrate excluding the impurity layer forms a p-n junction with the emitter portion. 17. The method of claim 16, Wherein the emitter forming step includes forming a first impurity portion and a second impurity portion having different impurity concentrations from each other. The method of claim 17, Wherein the first and second impurity region forming steps comprise: Forming an etching mask on the impurity layer, The impurity layer is etched to remove the impurity layer in which the etching mask is not located to form a first impurity portion having a first height and a second impurity portion having a second height lower than the first height to form an impurity portion And Removing the etch mask Wherein the method comprises the steps of: The method of claim 18, Wherein the first electrode pattern is located on the first impurity region. The method of claim 18, Wherein the etching mask is formed by a screen printing method. The method of claim 12, Further comprising the step of heat treating the substrate having the first electrode pattern and the second electrode pattern to form a plurality of first electrodes electrically connected to the emitter section and a second electrode electrically connected to the substrate Gt;

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