KR20100136640A - Solar cell and mehtod for manufacturing the same - Google Patents

Abstract

PURPOSE: A solar battery and a manufacturing method thereof are provided to reduce the manufacturing process and time of a solar battery by forming a protective layer into a single layer structure of a silicide material having superior contact efficiency. CONSTITUTION: An emitter part(120) is located on a substrate(110). The emitter part has a second conductive type opposite to a first conductive type. A first electrode is electrically connected to the emitter part. A protective layer(191) is located on the substrate.

Description

SOLAR CELL AND MEHTOD FOR MANUFACTURING THE SAME

The present invention relates to a solar cell and a method of manufacturing the same.

Recently, as the prediction of depletion of existing energy sources such as oil and coal is increasing, interest in alternative energy to replace them is increasing. Among them, solar cells are producing electric energy from solar energy, and are attracting attention because they are rich in energy resources and have no problems with environmental pollution.

A typical solar cell includes a substrate and an emitter layer made of semiconductors of different conductive types, such as p-type and n-type, and electrodes connected to the substrate and the emitter, respectively. At this time, p-n junction is formed in the interface of a board | substrate and an emitter part.

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 charged by the photovoltaic effect, respectively, and the electrons and holes are n-type. Move toward the semiconductor and the p-type semiconductor, for example toward the emitter portion and the substrate, collected by electrodes electrically connected to the substrate and the emitter portion, and connected to the wires to obtain power.

The technical problem to be achieved by the present invention is to reduce the manufacturing time and manufacturing process of the solar cell.

According to one aspect of the present invention, a solar cell includes a substrate of a first conductivity type, an emitter portion disposed on the substrate and having a second conductivity type opposite to the first conductivity type, and a first electrode electrically connected to the emitter portion. And a passivation layer on the substrate, and a conductive layer for a second electrode on the passivation layer and having a second electrode electrically connected to the substrate, wherein the passivation layer contains a silicide-based material.

The silicide-based material may be positioned near an interface between the passivation layer and the substrate.

The protective film may include a metal film part formed of a metal component contained in a silicide-based material.

The silicide-based material may be TiSi ₂ , CoiSi ₂ , NiSi ₂ , WSi ₂ , ZrSi ₂ , PtSi ₂ , IrSi _2, or TaSi ₂ .

The passivation layer may have a thickness of about 100 nm to about 500 nm.

The protective layer and the first electrode may be located opposite to each other.

According to another aspect of the present invention, a solar cell includes a substrate of a first conductivity type, an emitter portion disposed on the substrate and having a second conductivity type opposite to the first conductivity type, and a first electrode electrically connected to the emitter portion. And a conductive layer for the second electrode having a silicide-based material portion disposed on the substrate, a metal film portion positioned on the substrate, and a second electrode disposed on the metal film portion and electrically connected to the substrate.

The silicide-based material portion may be positioned at an interface between the substrate and the metal film portion.

According to still another aspect of the present invention, there is provided a solar cell including forming an emitter part of a second conductivity type opposite to the first conductivity type on a substrate having a first conductivity type, and removing a part of the emitter part to form a part of the substrate. Exposing a metal layer on the exposed substrate; forming a first electrode pattern using a screen printing method on the emitter unit; forming a second electrode conductive layer pattern on the metal layer. And a plurality of first electrodes electrically connected to the emitter unit by heating the substrate including the first electrode pattern and the second electrode conductive layer pattern, and a plurality of first electrodes electrically connected to the substrate. Forming a conductive layer for a second electrode having a second electrode, and converting at least a portion of the metal film into a silicide-based material to form a protective film.

The metal layer may include titanium (Ti), cobalt (Co), nickel (Ni), tungsten (W), zirconium (Zr), platinum (Pt), iridium (Ir), or tantalum (Ta).

The metal film may be laminated by sputtering or E-beam evaporation.

The metal film may have a thickness of about 100 nm to about 500 nm.

In the forming of the conductive layer pattern for the second electrode, forming a conductive layer pattern for the second electrode by applying a paste on the metal film by screen printing, and irradiating a portion of the conductive layer pattern for the second electrode with a laser beam. And forming a plurality of second electrode portions in which the components of the second electrode conductive layer pattern, the metal film, and the substrate are mixed, and by heat treatment of the conductive layer pattern for the second electrode, The second electrode portion may be the plurality of second electrodes, and the second electrode conductive layer pattern may be a second electrode conductive layer having a plurality of second electrodes.

The forming of the conductive layer pattern for the second electrode may include forming a plurality of exposed portions exposing a portion of the substrate by irradiating a laser beam to a portion of the metal layer, and on the exposed portion of the metal layer and the exposed portion. The method may include forming a pattern for the second electrode by applying a paste by a screen printing method, and by heat treatment of the conductive layer pattern for the second electrode, the second electrode conductive layer pattern may be formed through the exposed portion. It is good to become a 2nd electrode conductive layer provided with the some 2nd electrode electrically connected with the board | substrate.

According to this feature, since the protective film has a single film structure of silicide-based material having good contact efficiency, the manufacturing process and manufacturing time of the solar cell are reduced, and the thickness of the solar cell is thin.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement 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 the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by 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. On the contrary, when a part is "just above" another part, there is no other part in the middle. In addition, when a part is formed "overall" on another part, it means that not only is formed on the entire surface (or front) of the other part but also is not formed on the edge part.

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

First, a solar cell according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

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

Referring to FIG. 1, a solar cell 1 according to an exemplary embodiment of the present invention is an incident surface (hereinafter, referred to as a “front surface”) that is a surface of a substrate 110 and a substrate 110 to which light is incident. ] Emitter unit 120, an anti-reflection film 130 positioned on the emitter unit 120, a protective film 191 and an emitter unit 120 disposed on a rear surface of the substrate 110 facing the front surface of the substrate 110. A plurality of front electrodes 141 electrically connected to the plurality of front electrodes 141 and a plurality of front electrodes 141 connected to the plurality of front electrodes 141 and extending in a direction crossing the plurality of front electrodes 141. Located on the protective layer 191 and the conductive layer 155 for the rear electrode having a plurality of rear electrodes 151 disposed on the whole 142 and the protective film 191 and electrically connected to the substrate 110. And a plurality of rear electrode current collectors 162 and a plurality of rear electrodes 151 electrically connected to the rear electrode conductive layer 155. A plurality of back surface field (BSF) portions 170 disposed between the substrates 110 are provided.

The substrate 110 is a semiconductor substrate made of silicon of a first conductivity type, for example a p-type conductivity type. In this case, the silicon may be monocrystalline silicon, a polycrystalline silicon substrate, or amorphous silicon. When the substrate 110 has a p-type conductivity type, it contains impurities of trivalent elements such as boron (B), gallium, indium, and the like. Alternatively, the substrate 110 may be of an n-type conductivity type or may be made of a semiconductor material other than silicon. When the substrate 110 has an n-type conductivity type, the substrate 110 may contain impurities of pentavalent elements such as phosphorus (P), arsenic (As), and antimony (Sb).

Unlike FIGS. 1 and 2, in alternative embodiments, substrate 110 may be textured to have a texturing surface that is an uneven surface.

The emitter portion 120 is an impurity portion having a second conductivity type, for example, an n-type conductivity type, which is opposite to the conductivity type of the substrate 110, and forms a p-n junction with the semiconductor substrate 110.

Due to this built-in potential difference due to the pn junction, electron-hole pairs, which are charges generated by light incident on the substrate 110, are separated into electrons and holes, and the electrons move toward the n-type and the holes Moves toward p-type. Therefore, when the substrate 110 is p-type and the emitter portion 120 is n-type, the separated holes move toward the substrate 110 and the separated electrons move toward the emitter portion 120, whereby holes in the substrate 110 are formed. Is the majority carrier, and the electron in the emitter unit 120 becomes the majority carrier.

Since the emitter portion 120 forms a pn junction with the substrate 110, unlike the present embodiment, when the substrate 110 has an n-type conductivity type, the emitter portion 120 has a p-type conductivity type. . In this case, the separated electrons move toward the substrate 110 and the separated holes move toward the emitter part 120.

When the emitter unit 120 has an n-type conductivity type, the emitter unit 120 may be doped with impurities of a pentavalent element such as phosphorus (P), arsenic (As), antimony (Sb), etc. on the substrate 110. On the contrary, when having a p-type conductivity type, it may be formed by doping the substrate 110 with impurities of trivalent elements such as boron (B), gallium, indium, and the like.

An antireflection film 130 made of a silicon nitride film (SiNx), a silicon oxide film (SiOx), or the like is formed on the emitter portion 120. The anti-reflection film 130 reduces the reflectivity of light incident on the solar cell 1 and increases the selectivity of a specific wavelength region, thereby increasing the efficiency of the solar cell 1. The anti-reflection film 130 may be omitted as necessary.

The passivation layer 191 is located at the rear side of the substrate 110, reduces the recombination rate of the charge near the surface of the substrate 110, and improves the internal reflectance of the light passing through the substrate 110. Increase the re-incidence rate of light passing through 110).

The passivation layer 191 has a single layer structure including a silicide-based material part 192 and a metal film 193 made of a silicide-based material. In the present embodiment, the thickness of the passivation layer 191 may be about 100 nm to about 500 nm.

The silicide-based material is a compound of silicon (Si) and metal atoms, and has a lattice mismatch that indicates a degree of mismatch between atoms in the interface 110 due to a different crystal structure or different interatomic spacing between silicon contained in the substrate 110. (lattice mismatch) rate is very low. Therefore, since the silicide-based material has a good bonding property with silicon, that is, the substrate 110, the silicide-based material is a metal that is unstable, such as dangling bonds, present on the surface of the substrate Si. Easily bonds to atoms and converts into stabilized bonds. Therefore, the phenomenon of dissipation of charges (eg, holes) transferred to the substrate 110 due to unstable coupling is reduced.

In the present embodiment, the silicide-based material portion 192 is made of TiSi ₂ , CoiSi ₂ , NiSi ₂ , WSi ₂ , ZrSi ₂ , PtSi ₂ , IrSi ₂ , TaSi ₂ , and the like, and the metal film portion 193 is formed of Ti, Co, etc. And metal components such as Ni, W, Zr, Pt, Ir or Ta.

In addition, since the light passing through the substrate 110 is reflected by the protective film 191 and re-incident to the substrate 110, the light reflectance is improved.

The plurality of front electrodes 141 are positioned on the emitter part 120 to be electrically connected to the emitter part 120 and extend in a predetermined direction to be spaced apart from each other. The plurality of front electrodes 141 collect charges, for example, electrons, which are moved toward the emitter unit 120.

The plurality of front electrode current collectors 142 are positioned on the same layer as the plurality of front electrodes 141 on the emitter unit 120 and extend in a direction crossing the plurality of front electrodes 141. The plurality of front electrode current collectors 142 collects and moves charges collected by the plurality of front electrodes 141 and outputs them to an external device.

The front electrode 141 and the front electrode current collector 142 are made of at least one conductive material. Examples of the conductive material include nickel (Ni), copper (Cu), silver (Ag), and aluminum (Al). ), Tin (Sn), zinc (Zn), indium (In), titanium (Ti), gold (Au) and at least one selected from the group consisting of, but may be made of other conductive metal materials other than have.

The conductive layer 155 for the rear electrode is substantially disposed on the passivation layer 191 except for the plurality of rear electrode current collectors 162. The conductive layer 155 for the rear electrode is made of a conductive material such as aluminum (Al), but is not limited thereto.

The conductive layer 155 for the rear electrode includes a plurality of rear electrodes 151 electrically connected to a portion of the substrate 110 through the passivation layer 191.

As illustrated in FIG. 1, the plurality of rear electrodes 151 may be electrically connected to the substrate 110 in various shapes such as circular, elliptical, or polygonal at regular intervals, for example, about 0.5 mm to about 1 mm. have. However, in an alternative embodiment, each rear electrode 151 may have a stripe shape extending in one direction while being electrically connected to the substrate 110, such as the front electrode 141. In this case, the number of back electrodes is much smaller than the number of back electrodes having a circular, elliptical or polygonal shape.

The rear electrode 151 collects charges, for example, holes moving from the side of the substrate 110 and transfers them to the conductive layer 155 for the rear electrode.

In an alternative embodiment, the conductive layer 155 for the back electrode is nickel (Ni), copper (Cu), silver (Ag), tin (Sn), zinc (Zn), indium (In), titanium (Ti), At least one selected from the group consisting of gold (Au) and combinations thereof, or may be made of another conductive material.

In the present embodiment, the portion of the plurality of rear electrodes 151 in contact with the substrate 110 contains only the components of the conductive layer 155 for the rear electrode or the protective layer 191 as well as the components of the conductive layer 155 for the rear electrode. ) And the substrate 110 are mixed.

The plurality of rear electrode current collectors 162 extending in the same direction as the front electrode current collector 142 is disposed on the passivation layer 191. In this case, the plurality of rear electrode current collectors 162 may be positioned at positions facing the front electrode current collector 142. In an alternative embodiment, the current collector for the rear electrode 162 may be formed of a plurality of conductors of circular or polygonal shape arranged at regular intervals.

The plurality of back electrode current collectors 162 collects charges, for example, holes, which are transferred from the back electrode 151 through the back electrode conductive layer 155, and outputs them to an external device.

The plurality of rear electrode current collectors 162 are made of at least one conductive material, and examples of the conductive material include nickel (Ni), copper (Cu), silver (Ag), aluminum (Al), tin (Sn), At least one selected from the group consisting of zinc (Zn), indium (In), titanium (Ti), gold (Au), and combinations thereof may be formed of other conductive materials.

A plurality of rear electric field units 170 are positioned between the plurality of rear electrodes 151 and the substrate 110. The plurality of backside electric fields 170 are regions in which impurities of the same conductivity type as the substrate 110 are doped at a higher concentration than the substrate 110, for example, P + regions.

Due to the impurity concentration difference between the substrate 110 and the backside electric field 170, a potential barrier is formed, which prevents electrons from moving toward the backside of the substrate 110, thereby recombining electrons and holes in the backside of the substrate 110. To reduce extinction.

In the solar cell 1 according to the present exemplary embodiment having such a structure, a protective film 191 is formed on the rear surface of the substrate 110 to reduce recombination of charges due to unstable coupling present on the surface of the substrate 110. The operation of the battery 1 is as follows.

When light is irradiated onto the solar cell 1 and incident on the semiconductor substrate 110 through the anti-reflection film 130 and the emitter unit 120, electron-hole pairs are generated in the substrate 110 of the semiconductor by light energy. . At this time, the reflection loss of the light incident on the substrate 110 by the anti-reflection film 130 is reduced to increase the amount of light incident on the substrate 110.

These electron-hole pairs are separated from each other by the pn junction of the substrate 110 and the emitter portion 120 so that the electrons and holes are, for example, the emitter portion 120 having the n-type conductivity type and the p-type conductivity. Each moves toward a substrate 110 having a type. As such, the electrons moved toward the emitter unit 120 are collected by the front electrode 141 and transferred to the front electrode current collector 142, and the holes moved toward the substrate 110 are adjacent to the rear electrode 151. After the transfer to the collector for the back electrode 162 is collected. When the front electrode current collector 161 and the rear electrode current collector 162 are connected with a conductive wire, a current flows, which is used as power from the outside.

Since the passivation layer 191 having a single layer structure is positioned between the substrate 110 and the conductive layer 155 for the rear electrode, the re-defect rate of charge due to unstable coupling of the surface of the substrate 110 is greatly reduced, thereby increasing the efficiency of the solar cell. This is improved.

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

3A to 3H are views sequentially showing an example of a method of manufacturing a solar cell according to an embodiment of the present invention.

First, as shown in FIG. 3A, a material containing impurities of pentavalent elements such as phosphorus (P), arsenic (As), antimony (Sb), etc., on a substrate 110 made of p-type single crystal or polycrystalline silicon, for example For example, POCl ₃ or H ₃ PO ₄ may be heat-treated at high temperature to diffuse impurities of the pentavalent element onto the substrate 110 so that the emitter portion 120 may be disposed on the entire surface of the substrate 110, that is, the front, rear, and side surfaces thereof. Form. Unlike the present embodiment, when the conductivity type of the substrate 110 is n-type, a material containing an impurity of a trivalent element, for example, B ₂ H ₆ , is heat-treated or laminated at a high temperature to p on the entire surface of the substrate 110. The emitter portion of the mold can be formed. Then, an etching process is performed to etch an oxide containing phosphorous (PSG) or an oxide containing boron (boron silicate glass, BSG) generated as the p-type impurity or the n-type impurity diffuses into the substrate 110. Remove through.

If necessary, before forming the emitter portion 120, the front surface of the substrate 110 may be tested to form a textured surface that is an uneven surface. In this case, when the substrate 110 is made of single crystal silicon, the surface of the substrate 110 is textured using a base solution such as KOH or NaOH, and when the substrate 110 is made of polycrystalline silicon, such as HF or HNO _3. The acid solution is used to texture the surface of the substrate 110.

Next, as shown in FIG. 3B, an anti-reflection film 130 is formed on the substrate 110 by using chemical vapor deposition (CVD), such as plasma enhanced chemical vapor deposition (PECVD). .

Next, as shown in FIG. 3C, a portion of the rear surface of the substrate 110 is removed by wet etching or dry etching, and the emitter unit 120 formed on the rear surface of the substrate 110 is removed.

As shown in FIG. 3D, the metal film 190 is formed on the rear surface of the substrate 110 by the sputtering method or the E-beam evaporation method. At this time, the thickness of the metal film 190 is sufficiently high that no agglomeration occurs due to the coupling between the silicon (Si) of the substrate 110 and the metal component of the metal film 190 during the heat treatment process, which is a subsequent process. It is good to have a thick thickness. For example, the thickness of the metal layer 190 may be about 100 nm to about 500 nm.

In the present embodiment, the metal film 190 is made of titanium (Ti), cobalt (Co), nickel (Ni), tungsten (W), zirconium (Zr), platinum (Pt), iridium (Ir), or tantalum (Ta). ) May be contained.

Then, as shown in FIG. 3E, by using a screen printing method, a paste containing silver (Ag) is applied to the corresponding portion of the anti-reflection film 130 and dried at about 120 ° C. to about 200 ° C., The front electrode and the current collector pattern 140 for the front electrode are formed. The front electrode and the front electrode current collector part pattern 140 include a front electrode pattern part and a front electrode current collector part pattern part extending in a direction crossing each other. That is, at each intersection, the front electrode pattern portion and the front electrode current collector portion portion extend in different directions. In the present embodiment, the width of the front electrode current collector pattern portion is wider than the width of the front electrode pattern portion, but is not limited thereto.

Next, as illustrated in FIG. 3F, a paste including aluminum (Al) is applied to a corresponding portion of the metal film 190 using screen printing, followed by drying to form a conductive layer pattern 150 for a rear electrode. .

Next, as shown in FIG. 3G, a paste containing silver (Ag) is applied onto the metal film 190 and dried by using a screen printing method to form a plurality of current collector patterns 160 for rear electrodes. In the present embodiment, the plurality of rear electrode current collector patterns 160 are spaced apart from each other and extend in one direction, but patterns of a circular or polygonal shape may be arranged at regular intervals in one direction.

In this case, the order of forming the front electrode current collector pattern 140, the rear rear electrode conductive layer pattern 150, and the plurality of rear electrode current collector patterns 160 may be changed.

For example, after the conductive layer pattern 150 for the rear back electrode 150 and the plurality of rear electrode current collector patterns 160 are sequentially formed, the front electrode current collector pattern 140 may be formed, or the plurality of rear electrodes may be formed. After forming the current collector pattern 160, the conductive layer pattern 150 for the rear electrode may be formed, and then the front electrode and the current collector pattern 140 for the front electrode may be formed.

Next, as shown in FIG. 3H, when the laser beam is irradiated to a predetermined portion of the conductive layer pattern 150 for the rear electrode, the conductive layer pattern 150 for the rear electrode, the protective film 191 below the substrate 110 and the substrate 110 are exposed. The rear electrode portion 153 which is a molten mixture is formed. In an alternative embodiment, when the plurality of rear electrodes 151 have a stripe shape, the irradiation area of the laser beam also has a stripe shape extending in a predetermined direction.

In this case, the wavelength and intensity of the laser beam are determined according to the material, thickness, and the like of the conductive layer pattern 150 for the rear electrode and the protective film 191 below.

Subsequently, the substrate 110 having the conductive layer pattern 150 for the rear electrode, the plurality of rear electrode current collector patterns 160, and the front electrode and the front electrode current collector pattern 140 are formed at about 750 ° C. to about Firing at a temperature of 800 ° C., the protective layer 191, a conductive layer for a rear electrode including a plurality of front electrodes 141, a plurality of front electrode current collectors 142, and a plurality of rear electrodes 151. 155, a plurality of rear electrode current collectors 162, and a plurality of rear electric field units 170 are formed to complete the solar cell 1 (FIGS. 1 and 2).

That is, when the heat treatment is performed, a plurality of front surfaces through which the anti-reflection film 130 of the contact portion penetrates through the contact portion by lead (Pb) contained in the front electrode and the front electrode current collector pattern 140. The electrode 141 and the front electrode current collector 142 are formed, and the rear electrode 153 is a plurality of rear electrodes 151 in contact with the substrate 110. In addition, the contact resistance is reduced by chemical coupling between the metal components contained in each of the patterns 140, 150, and 160, and the layers 120, 110, and 190 in contact with each other, thereby improving current flow.

At this time, since the metal atoms contained in the metal film 190 are easily bonded to the silicon of the substrate 110, which is a lower film, due to the heat treatment process, at least a portion of the metal film 190, for example, at least the substrate 110. And a silicide-based material is formed on the interface between the metal layer 190 and the passivation layer 191. That is, due to the heat treatment process of the metal film 190, the metal atoms are easily combined with unstable bonds present near the surface of the substrate 110 to be changed into silicide-based materials, thereby converting the unstable bonds into stabilized bonds. The surface portion of 110 is inactive. Accordingly, in the passivation layer 191, the silicide-based material portion 192 is formed near the interface between the substrate 110 and the metal layer 190, and the metal film portion 193 is formed in other portions.

The silicide-based material of the protective film 191 formed by the heat treatment process may be TiSi ₂ , CoSi ₂ , NiSi ₂ , WSi ₂ , ZrSi ₂ , PtSi ₂ , IrSi _2, or TaSi ₂ , but is not limited thereto. As described above, since the metal film 190 has a thick thickness of about 100 nm to about 500 nm, the islanding of the silicide-based material does not occur even during the firing process of the substrate 110. The silicide-based material portion 192 is formed on all of the contact surfaces to perform a stable and efficient passivation role.

At this time, when the thickness of the metal film 190 is thinner than about 100 nm, due to the islanding phenomenon of the silicide-based material, all the portions where the metal film 190 and the substrate 110 contact each other do not form a silicide-based material. If a problem occurs that a portion of the 110 is exposed, and the thickness of the metal film 190 is thicker than about 500 nm, it takes a long time to form the metal film 190 and the reaction time is slow, so that a desired thickness is desired for a desired time. The silicide based material of may not be obtained.

As a result, charges (eg, holes) that move to the rear electrode 151 through the substrate 110 are safely moved to the rear electrode 151 without recombination with unstable bonds.

In addition, in the heat treatment process, aluminum (Al), which is a content of the rear electrode 151, is diffused toward the substrate 110 in contact with the rear electrode 151, and thus a plurality of rear surfaces are disposed between the rear electrode 151 and the substrate 110. The electric field unit 170 is formed. In this case, the plurality of rear electric field parts 170 have a p-type conductivity type, which is the same conductivity type as the substrate 110, and the impurity concentration of the rear electric field part 170 is higher than the substrate 110 and has a p + conductivity type. .

Next, another example of a method of manufacturing a solar cell according to an embodiment of the present invention will be described with reference to FIGS. 3A to 3E as well as FIGS. 4A to 4D. In this example, the description of the same content is omitted in comparison with FIGS. 3A to 3H.

4A to 4D are some views sequentially showing another example of a method of manufacturing a solar cell according to an embodiment of the present invention.

As shown in FIGS. 3A to 3E, after the emitter part 120 and the anti-reflection film 130 are sequentially formed on the substrate 110, the emitter part 120 formed on the rear surface of the substrate 110 is removed. Afterwards, the metal film 190 is formed, and the front electrode and the front electrode current collector pattern 140 are formed on the anti-reflection film 130.

Then, as shown in FIG. 4A, the laser beam is irradiated to the corresponding portion of the metal film 190 to form a plurality of exposed portions 181 exposing a portion of the substrate 110 in the metal film 190. In this case, the intensity and the wavelength of the laser beam are determined according to the material or thickness of the metal film 190.

In an alternative embodiment, when the plurality of rear electrodes 151 have a stripe shape, the exposed portion 181 has a stripe shape extending in a predetermined direction. In addition, the plurality of exposed portions 181 may be formed in various ways instead of the laser beam.

Next, as shown in FIG. 4B, a paste containing aluminum (Al) is applied by screen printing to form a conductive layer pattern for a back electrode on the substrate 110 exposed through the metal film 190 and the exposed portion 181. 150 is formed and dried, and the paste containing silver (Ag) is formed on the entire surface of the metal film 190 except for the portion where the conductive layer pattern 150 for the rear electrode is formed by screen printing. After printing, the current collector pattern 160 for the rear electrode is formed and dried.

At this time, the formation order of these patterns 140, 150, 160 can be changed.

Subsequently, the substrate 110 having the patterns 140, 150, and 160 formed thereon is fired to form the metal layer 190 as the passivation layer 191 containing a silicide-based material. A plurality of front electrode current collectors 142, a rear electrode conductive layer 155 including a plurality of rear electrodes 151, a plurality of rear electrode current collectors 162, and a plurality of rear electric field units 170. To form the solar cell 1 (FIGS. 1 and 2).

In an alternative embodiment, the emitter portion 120 and the anti-reflection film 130 are sequentially formed on the substrate 110, and the emitter portion 120 on the rear surface of the substrate 110 is removed to form the metal layer 190. After the plurality of exposed portions 181 are formed on the metal layer 190, the front electrode and front electrode current collector pattern 140, the rear electrode conductive layer pattern 150, and the rear electrode current collector pattern 160 ) May be formed in an appropriate order, and the substrate 110 may be heat treated to complete the solar cell 1. As described above, the order of forming the patterns 140, 150, and 160 may be changed.

In addition, in the present embodiment, when the substrate 110 is heat-treated without performing a separate process, the rear electric field unit 170 is formed in the contact region between the rear electrode 151 and the substrate 110, but the alternative embodiment For example, using a separate process, a plurality of impurity layers of the same conductivity type as the substrate 110 may be formed on the rear surface of the substrate 110 to have a higher concentration than the substrate 110. In this case, the impurity layer functions as a backside electric field part. Such separate plurality of impurity layers may be formed through the following process. For example, as shown in FIG. 4A, after forming a plurality of exposed portions 181 in the metal film 190, the same conductive type as that of the substrate 110, for example, using the metal film 190 as a mask. P-type impurities are implanted into the back surface of the substrate 110 by CVD or the like to form a plurality of impurity layers. In this case, the impurity concentration of the plurality of impurity layers is P + higher than that of the substrate 110. Then, after forming the front electrode and the current collector pattern for the front electrode, the conductive layer pattern for the back electrode, and the current collector pattern for the back electrode and the like, a firing process is performed to complete the solar cell.

According to the present exemplary embodiment, since the protective film 191 having a single film structure is formed using a silicide-based material having a high contact efficiency with silicon and a low contact resistance with the substrate 110, the manufacturing process and manufacturing time are reduced. The thickness of the solar cell becomes thinner.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

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 illustrated in FIG. 1 taken along the line II-II.

3A to 3H are views sequentially showing an example of a method of manufacturing a solar cell according to an embodiment of the present invention.

4A to 4C are some views sequentially showing another example of a method of manufacturing a solar cell according to an embodiment of the present invention.

* Brief description of the main parts of the drawing *

110: substrate 120 emitter part

130: antireflection film 141: front electrode

142: current collector for the front electrode 155: conductive layer for the rear electrode

162: current collector for the rear electrode 170: rear electric field

191: shield

Claims (14)

A substrate of a first conductivity type, An emitter portion disposed on the substrate and having a second conductivity type opposite to the first conductivity type, A first electrode electrically connected to the emitter unit, A protective film on the substrate, and A conductive layer for a second electrode, which is disposed on the protective film and has a second electrode electrically connected to the substrate. Including, The protective film contains a silicide-based material Solar cells. In claim 1, The silicide-based material is located near the interface between the protective film and the substrate. In claim 2, The protective film includes a metal film part made of a metal component contained in the silicide-based material. 4. The method of claim 3, The silicide based material is TiSi ₂ , CoiSi ₂ , NiSi ₂ , WSi ₂ , ZrSi ₂ , PtSi ₂ , IrSi ₂ or TaSi ₂ . In claim 1, The protective film has a thickness of about 100 nm to about 500 nm. In claim 1, The protective layer and the first electrode are located opposite to each other. A substrate of a first conductivity type, An emitter portion disposed on the substrate and having a second conductivity type opposite to the first conductivity type, A first electrode electrically connected to the emitter unit, A silicide-based material portion disposed on the substrate, A metal film part disposed on the substrate, and A conductive layer for a second electrode, which is disposed on the metal film part and has a second electrode electrically connected to the substrate. Solar cell comprising a. In claim 7, And the silicide-based material portion is located at an interface between the substrate and the metal film portion. Forming an emitter portion of a second conductivity type opposite to the first conductivity on a substrate having a first conductivity type, Removing a portion of the emitter to expose a portion of the substrate, Stacking a metal film on the exposed substrate; Forming a pattern for a first electrode on the emitter using screen printing; Forming a conductive layer pattern for a second electrode on the metal film, and Heat treating the substrate including the first electrode pattern and the second conductive layer pattern to form a plurality of first electrodes electrically connected to the emitter unit, and a plurality of second electrodes electrically connected to the substrate. Forming a conductive layer for the second electrode, and converting at least a portion of the metal film into a silicide-based material to form a protective film Method for manufacturing a solar cell comprising a. The method of claim 9, The metal film is manufactured of a solar cell including titanium (Ti), cobalt (Co), nickel (Ni), tungsten (W), zirconium (Zr), platinum (Pt), iridium (Ir) or tantalum (Ta). Way. The method of claim 9, The metal film is a method of manufacturing a solar cell is laminated by a sputtering method (E-beam evaporation) method. The method of claim 9, And the metal film has a thickness of about 100 nm to about 500 nm. The method of claim 9, The conductive layer pattern forming step for the second electrode, Applying a paste onto the metal film by screen printing to form a conductive layer pattern for a second electrode, and Irradiating a portion of the conductive layer pattern for the second electrode with a laser beam to form a plurality of second electrode portions in which the components of the second electrode conductive layer pattern, the metal film, and the substrate are mixed; Including, By the heat treatment of the conductive layer pattern for the second electrode, the second electrode portion becomes the plurality of second electrodes, and the second electrode conductive layer pattern is a second electrode conductive layer including the plurality of second electrodes. felled Method for manufacturing a solar cell. The method of claim 9, The conductive layer pattern forming step for the second electrode, Irradiating a portion of the metal film with a laser beam to form a plurality of exposed portions exposing a portion of the substrate; and Forming a pattern for a second electrode by applying a paste on a portion of the metal film and the substrate exposed through the exposed part by screen printing; Including, By heat treatment of the conductive layer pattern for the second electrode, the conductive layer pattern for the second electrode becomes a conductive layer for the second electrode having a plurality of second electrodes electrically connected to the substrate through the exposed portion. Method for manufacturing a solar cell.

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