KR101690333B1 - Solar cell and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a solar cell. Wherein the solar cell comprises a substrate of a first conductivity type, an emitter portion located on the substrate and doped with an impurity of a second conductivity type opposite to the first conductivity type, and an emitter portion connected to the emitter portion, A plurality of semiconductor electrodes extending apart from each other in a direction intersecting the plurality of first electrodes and having an impurity doping concentration higher than that of the emitter portion and projecting from the surface of the emitter portion; And a second electrode connected to the substrate. This increases the amount of charge collected by the plurality of semiconductor electrodes having a smaller sheet resistance value than that of the emitter portion, thereby improving the efficiency of the solar cell.

Description

SOLAR CELL AND METHOD FOR MANUFACTURING THE SAME

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

Recently, as energy resources such as oil and coal are expected to be depleted, interest in alternative energy to replace them is increasing, and solar cells that produce electric energy from solar energy are attracting attention.

Typical solar cells have a semiconductor portion that forms a p-n junction by different conductive types, such as p-type and n-type, and electrodes connected to semiconductor portions of different conductivity types, respectively.

When light is incident on such a solar cell, a plurality of electron-hole pairs are generated in the semiconductor portion, and electrons and holes of the generated electron-hole pairs are moved in the corresponding direction, that is, electrons move toward the n- And the holes move toward the p-type semiconductor portion. The transferred electrons and holes are collected by different electrodes connected to the n-type semiconductor portion and the p-type semiconductor portion, respectively, and electric power is obtained by connecting these electrodes with electric wires.

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

A solar cell according to one aspect of the present invention includes a substrate of a first conductivity type, an emitter portion located on the substrate and doped with an impurity of a second conductivity type opposite to the first conductivity type, and an emitter portion connected to the emitter portion A plurality of first electrodes spaced apart from each other and extending in parallel to each other, a plurality of second electrodes protruding from the surface of the emitter section, And a second electrode connected to the substrate.

The number of the plurality of semiconductor electrodes may be 200 to 245.

The plurality of semiconductor electrodes may have a width of 30 占 퐉 to 50 占 퐉, respectively.

The distance between two adjacent semiconductor electrodes may be 0.6 mm to 0.7 mm.

The formation ratio of the plurality of semiconductor electrodes to the entire front surface of the substrate is preferably 4% to 8%.

The plurality of semiconductor electrodes preferably contact a plurality of first electrodes at a plurality of contact portions intersecting with the plurality of first electrodes.

The plurality of contact portions may be 23,500 to 40,000.

The emitter portion may have a larger sheet resistance value than each of the plurality of semiconductor electrodes.

The emitter portion has a resistance of 90? / Sq. To 140 Ω / sq., And each semiconductor electrode has a resistance of 10 Ω / sq. Lt; RTI ID = 0.0 > ohm / sq. ≪ / RTI >

The emitter section has an impurity doping concentration of 4 x 10 ¹⁹ / cm 3 to 6 x 10 ¹⁹ / cm 3, and each semiconductor electrode can have an impurity doping concentration of 9 x 10 ¹⁹ / cm 3 to 4 x 10 ²⁰ / cm 3 . The emitter portion has an impurity doping thickness of 0.5 to 0.7 mu m, and the plurality of semiconductor electrodes may each have an impurity doping thickness of 0.6 to 0.8 mu m.

The solar cell according to the above feature may further include a bus bar connected to the emitter portion and the plurality of first electrodes.

The plurality of semiconductor electrodes may extend in the same direction as the bus bar.

The solar cell according to the above feature may further include an antireflection unit positioned on the emitter and on the plurality of semiconductor electrodes.

The anti-reflection portion may further be positioned between the emitter portion and the bus bar.

The anti-reflection portion may be made of silicon nitride (SiNx).

The anti-reflection portion may have a refractive index of 2.0 to 2.1.

The anti-reflection portion may further be positioned between the emitter portion and the plurality of first electrodes.

The solar cell according to the above feature may further include a rear surface electric field portion located on the substrate in contact with the second electrode.

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 first surface of a substrate having a first conductivity type, Forming a plurality of semiconductor electrodes and an emitter portion having different impurity doping thicknesses from each other, a plurality of first electrodes extending in a direction crossing the semiconductor electrodes and connected to the emitter portion, And forming a second electrode, wherein the emitter portion is a portion where the etching is performed in the emitter layer, and the plurality of semiconductor electrodes are portions where the etching is not performed in the emitter layer.

The emitter layer has a resistivity of 10? / Sq. Lt; RTI ID = 0.0 > ohm / sq. ≪ / RTI >

The method may further include forming an antireflection portion on the emitter portion and the plurality of semiconductor electrodes, wherein the plurality of first electrodes and the plurality of second electrodes are formed on the plurality of semiconductor electrodes, Forming a first electrode pattern on the first electrode pattern by heat treating the first electrode pattern so that the first electrode pattern passes through the anti-reflection portion to connect the emitter portion and the plurality of semiconductor electrodes; and a

The plurality of first electrodes and the second electrodes may further include a bus bar which intersects the plurality of first electrodes and is connected to the emitter portion. The bus bar penetrates the antireflection portion, Lt; / RTI >

According to this aspect, the plurality of semiconductor electrodes having different impurity doping concentrations and sheet resistance values in the emitter section increase the amount of charge collected, thereby improving the efficiency of the solar cell.

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.
3 is a partial perspective view of an emitter portion according to an embodiment of the present invention.
4 is a plan view illustrating a front electrode unit and an emitter unit disposed at a lower portion thereof according to an embodiment of the present invention.
FIGS. 5A to 5E are views sequentially illustrating a method of manufacturing a solar cell according to an embodiment of the present invention.
6 is a partial perspective view of a solar cell according to another embodiment of the present invention.
7 is a cross-sectional view taken along the line VII-VII of the solar cell shown in FIG.
FIGS. 8A and 8B and FIGS. 9A and 9B are views showing a part of a manufacturing method of a solar cell according to another embodiment of the present invention, respectively.

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. 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. Further, when a certain portion is formed as "whole" on another portion, it means not only that it is formed on the entire surface of the other portion but also that it is not formed on the edge portion.

A solar cell according to an embodiment of the present invention will now be described with reference to FIGS. 1 and 2. FIG.

1 and 2, a solar cell 11 according to an embodiment of the present invention includes a substrate 110, an incident surface (hereinafter referred to as a front surface) that is a surface of the substrate 110 on which light is incident, An antireflection portion 130 located on the impurity doping portion 121 and a front electrode portion 140 connected to the impurity doping portion 121. The impurity doped region 121 is formed on the impurity doped region 121, A back surface field (BSF) region 172 located on a surface of a substrate 110 (hereinafter referred to as a 'back surface') opposite to the front surface of the substrate 110, And a rear electrode unit 150 positioned on the rear surface of the substrate 110.

The substrate 110 is a semiconductor substrate of a first conductivity type, for example, a p-type conductivity type and made of monocrystalline silicon. Impurities such as boron (B), gallium, indium, and the like are doped to the substrate 110 when the substrate 110 has a p-type conductivity type. Alternatively, however, the substrate 110 may be of the n-type conductivity type. Impurities of pentavalent elements such as phosphorus (P), arsenic (As), and antimony (Sb) may be doped to the substrate 110 when the substrate 110 has an n-type conductivity type.

1 and 2, in an alternate example, the front side of the substrate 110 may be textured to have a textured surface that is an uneven surface. In this case, the impurity doping portion 121 and the antireflection portion 130 located on the front surface of the substrate 110 also have an uneven surface.

When the front surface of the substrate 110 is textured, the incident area of the substrate 110 increases and the light reflectivity decreases due to a plurality of reflection operations due to the irregularities, so that the amount of light incident on the substrate 110 The efficiency of the solar cell 11 is improved because the impurity doping portion 121 is doped with impurities of a second conductivity type opposite to the conductivity type of the substrate 110, for example, n- ), That is, a surface on which light is incident, that is, a front surface of the substrate 110. [ Thus, the second conductive type impurity doping portion 121 forms a p-n junction with the first conductive type portion of the substrate 110.

The impurity doping portion 121 includes a first impurity doping portion 1211 having a different impurity doping thickness and a plurality of second impurity doping portions 1212.

In this embodiment, the impurity doping thickness of the first impurity doping portion 1211 is smaller than the impurity doping thickness of the second impurity doping portion 1212. Since the impurity doping thicknesses of the first and second impurity doping portions 1211 and 1212 are different from each other, the impurity doping concentrations of the first and second impurity doping portions 1211 and 1212 are also different. Therefore, the impurity doping concentration of the first impurity doping portion 1211 is smaller than the impurity doping concentration of the second impurity doping portion 1212.

Accordingly, the impurity doping thickness of the first impurity doping portion 1211 may be about 0.5 mu m to about 0.7 mu m, and the impurity doping thickness of each second impurity doping portion 1212 may be about 0.6 mu m to about 0.8 mu m. The impurity doping concentration of the first impurity doping portion 1211 may be 4 × 10 ¹⁹ / cm 3 to 6 × 10 ¹⁹ / cm 3 and the impurity doping concentration of the second impurity doping portion 1212 may be 9 × 10 ¹⁹ / Lt; ²⁰ > / cm < 3 >.

Since the impurity doping thicknesses of the first and second impurity doping portions 1211 and 1212 are different from each other, the pn junction surface between the first impurity doping portion 1211 and the substrate 110 from the surface of the substrate 110 (That is, the thickness) from the surface of the substrate 110 to the pn junction surface (second junction surface) of the second impurity doping portion 1212 and the substrate 110 (the first junction surface) The distances (i.e., thickness) are different from each other. For example, as shown in FIGS. 1 and 2, the first shortest distance d1 (thickness) from the surface of the substrate 110 to the first bonding surface is the distance from the surface of the substrate 110 to the second bonding surface Is shorter than the second shortest distance d2 (thickness).

In the substrate 110, the first bonding surface and the second bonding surface are located on the same line, and the first shortest distance from the rear surface of the substrate 110 to the first bonding surface and the first shortest distance from the rear surface of the substrate 110 The second shortest distance to the joining surface is the same. At this time, when the front surface of the substrate 110 has a textured surface, the first shortest distance d1 and the second shortest distance d2 are considered to be the same within an error range due to the height difference of the irregularities of the textured surface.

Also, the sheet resistance of the first and second impurity doping portions 1211 and 1212 is also different due to the difference in the dopant doping thickness of the first and second impurity doping portions 1211 and 1212. Since the sheet resistance value is generally inversely proportional to the thickness of the impurity doping, the sheet resistance value of the first impurity doping portion 1211 having a thin impurity doping thickness is larger than the sheet resistance value of the second impurity doping portion 1212. For example, the sheet resistance value of the first impurity doping portion 1211 is about 90? / Sq. To about 140? / Sq. And the sheet resistance value of each second impurity doping portion 1212 is about 10? / Sq. To about 30? / Sq. Lt; / RTI >

As shown in FIGS. 1 and 3, a plurality of second impurity doping portions 1212 having a high impurity doping concentration are extended apart along a predetermined direction of the substrate 110 side by side. Therefore, each second impurity doping portion 1212 has a stripe shape.

The width W1 of each second impurity doping portion 1212 is about 30 占 퐉 to about 50 占 퐉 and the interval W2 between two adjacent second impurity doping portions 1212 is about 0.6 mm to about 0.7 mm. The number of the second impurity doping portions 1212 may be about 200 to about 245. At this time, the width of the substrate 110 may be about 156 mm x 156 mm. A plurality of second impurity doping portions 1212 are disposed at about 4% to 8% of the entire front surface of the substrate 110. This allows the pn junction between the substrate 110 and the impurity doping portion 121 Due to the built-in potential difference caused by the incident light, electrons and holes, which are charges generated by light incident on the substrate 110, move in the corresponding directions, that is, electrons move toward the n-type and holes move toward the p- do. Therefore, when the substrate 110 is p-type and the impurity doping portion 121 is n-type, the separated holes move toward the back surface of the substrate 110, and the separated electrons move toward the impurity doping portion 121.

Since the impurity doping portion 121 forms a pn junction with the first conductive portion of the substrate 110, that is, the substrate 110, unlike the present embodiment, when the substrate 110 has the n-type conductivity type, The impurity doping portion 121 has a p-type conductivity type. In this case, the separated electrons move toward the back surface of the substrate 110, and the separated holes move toward the impurity doping portion 121.

When the impurity doping portion 121 has an n-type conductivity type, the impurity doping portion 121 can be formed by doping an impurity of a pentavalent element into the substrate 110, and when the impurity doping portion 121 has a p-type conductivity type And doping the substrate 110 with an impurity of a trivalent element.

As described above, when electrons and holes are moved by the pn junction between the first conductive type portion of the substrate 110 and the impurity doping portion 121, the sheet resistance value and the impurity doping concentration The first and second impurity doping portions 1211 and 1212 differ in the direction of movement of the charge and the loss amount of the charge due to the impurity.

That is, in general, the charges are more easily moved when moving through the portion where the sheet resistance value is lower than when the sheet resistance value of the impurity doping portion 121 moves through a portion having a high sheet resistance value. Further, As the doping concentration increases, the conductivity of the part increases.

Therefore, when the charge (for example, electrons) moves to the impurity doping portion 121 as in the present example, the charge located in the first impurity doping portion 1211 having a high sheet resistance value has a lower sheet resistance value than itself, The second dopant doping portion 1212 is located closer to the second impurity doping portion 1212 than the second dopant doping portion 1212. At this time, since the impurity doping concentration of the first impurity doping portion 1211 is smaller than that of the second impurity doping portion 1212, the impurity concentration of the impurity doped in the first impurity doping portion 1211 during the movement from the first impurity doping portion 1211 to the second impurity doping portion 1212 The amount of charge lost by the second impurity doping portion 1212 is greatly reduced.

When the charges located in the first impurity doping portion 1211 move to the second impurity doping portion 1212, the conductivity of the second impurity doping portion 1212 is larger than that of the first impurity doping portion 1211, The charge moving to the second impurity doping portion 1212 moves along the second impurity doping portion 1212 extending in the corresponding direction. Therefore, the second impurity doping portion 1212 acts as a semiconductor electrode for transferring electric charges.

The first and second impurity doping portions 1211 and 1212 form a pn junction with the substrate 110. The first impurity doping portion 1211 of the impurity doping portions 1211 and 1212 forms a charge And the second impurity doping portion 1212 functions as an emitter because it is connected to the electrode portion 140 or the second impurity doping portion 1212 and is connected to the front electrode portion 140 for outputting charges, And functions as a semiconductor electrode as described above.

A portion of the first impurity doping portion 1211 is in contact with the front electrode portion 140. Since the front electrode portion 140 contains a metal, the conductivity of the front electrode portion 140 is higher than that of the first impurity doping Is much larger than the second impurity doping portion 1212 as well as the second impurity doping portion 1212. Therefore, the charge located adjacent to the front electrode unit 140 located at the first impurity doping unit 1211, which is in contact with the front electrode unit 140, moves toward the front electrode unit 140.

As described above, due to the formation of the second impurity doping portion 1212, the charge is transferred to the adjacent first impurity doping portion 1212 as well as the adjacent first impurity doping portion 1211 in contact with the front electrode portion 140 , Thereby reducing the travel distance of the charge. Therefore, the amount of charges lost during the movement to the doping portions 1211 and 1212 decreases, and the amount of charges transferred to the front electrode portion 140 increases.

When the sheet resistance value of the first impurity doping portion 1211 is about 140? / Sq. The front electrode part 140 positioned on the front electrode part penetrates the first impurity doped part 1211 and contacts the substrate 110 when the impurity doping thickness of the first impurity doping part 1211 is about 0.5 μm or more, the shunt defect is prevented, and the sheet resistance value of the first impurity doping portion 1211 is about 90? / sq. The amount of light absorbed by the first impurity doping portion 1211 itself is further reduced and the amount of light incident on the substrate 110 is increased by reducing the amount of light absorbed by the second impurity doping portion 1211 itself or when the impurity doping thickness of the first impurity doping portion 1211 is about 0.7 μm or less, And the charge loss due to impurities is further reduced.

Also, the second impurity doping portion 1212 has a sheet resistance value of about 30? / Sq. Or the impurity doping thickness of the second impurity doping portion 1212 is about 0.6 mu m or more, the conductivity of the second impurity doping portion 1212 can be more stably secured and the amount of charge transfer can be further increased, The sheet resistance value of the doping portion 1212 is about 10? / Sq. The amount of light absorbed by the second impurity doping portion 1212 per se is reduced and the amount of light incident on the substrate 110 is reduced by the amount of light incident on the second impurity doping portion 1212 itself when the impurity doping thickness of the second impurity doping portion 1212 is about 0.8 mu m or less. Is increased.

When the number of the second impurity doping portions 1212 is 200 or more, the improvement of the charge transfer rate due to the use of the plurality of second impurity doping portions 1212 functioning as semiconductor electrodes can be more stably obtained, When the number of the second impurity doping portions 1212 is 245 or less, the charge transfer efficiency using the semiconductor electrode can be stably obtained without greatly increasing the recombination rate of charges due to the increase of the high concentration doping region of the impurity doping portion 121.

When the ratio of the formation area of the plurality of second impurity doping portions 1212 to the entire front surface of the substrate 110 is about 4% or more, a plurality of second impurity doping portions 1212 are used as semiconductor electrodes When the ratio of the formation area of the second impurity doping portions 1212 to the entire front surface of the substrate 110 is about 8% or less, the impurity doping portion 121 The charge transfer efficiency using the semiconductor electrode can be stably obtained without greatly increasing the charge recombination ratio due to the increase of the high concentration doping region.

The antireflective portion 130 located on the dopant doping portion 121 reduces the reflectivity of light incident on the solar cell 11 and increases the selectivity of a specific wavelength region to increase the efficiency of the solar cell 11.

The antireflective portion 130 may be made of transparent and hydrogenated silicon nitride (SiNx), has a thickness of about 70 nm to about 80 nm, and may have a refractive index of about 2.0 to 2.1.

When the refractive index of the antireflection unit 130 is 2.0 or more, the amount of light absorbed by the antireflection unit 130 itself is further reduced while the reflectivity of light is reduced. When the refractive index of the antireflection unit 130 is 2.1 or less, The reflectivity of the antireflection portion 130 is further reduced.

In this example, the refractive index (2.0 to 2.1) of the antireflection portion 130 has a value between the refractive index (about 1) of air and the refractive index (about 3.5) of the substrate 110. Accordingly, since the change in the refractive index from the air toward the substrate 110 sequentially increases, the reflectivity of light is further reduced by the change in the refractive index, and the amount of light incident on the substrate 110 is further increased.

Further, when the thickness of the antireflecting portion 130 is about 70 nm or more, a more effective effect of preventing reflection of light is obtained. When the thickness of the antireflective portion 130 is about 80 nm or less, the amount of light absorbed by the antireflective portion 130 itself is reduced to increase the amount of light incident on the substrate 110, The front electrode part 140 is more stably and easily penetrated through the reflection preventing part 130 and the front electrode part 140 and the impurity doping part 121 are more stably connected.

The antireflective portion 130 also uses a contained hydrogen (H) to change a defect such as a dangling bond existing on the surface of the substrate 110 and its vicinity to a stable bond, And performs a passivation function to reduce the disappearance of the charges that have moved toward the surface of the substrate 110 due to the defects. Therefore, the amount of charge lost due to the defect is reduced by the passivation function of the antireflecting portion 130.

1 and 2, the antireflection portion 130 has a single-layer structure, but may have a multilayer structure such as a double-layer structure and may be omitted as necessary.

Further, as already described, the impurity doping section 121 of this embodiment has the first and second impurity doping sections 1211 and 1212 having different sheet resistance values.

In order to obtain such a structure, in this embodiment, first and second impurity doping portions 1211 and 1212 having different impurity doping concentrations and impurity doping thicknesses are formed by using an etching process. For example, after an emitter layer is formed by diffusing an n-type or p-type impurity such as phosphorus (P) or boron (B) into the substrate 110 into the substrate 110, The first impurity doping portion 1211 and the second impurity doping portion 1212 having different sheet resistance values (impurity doping thickness) may be formed depending on the positions.

In this case, since the impurity doping concentration increases from the p-n junction surface toward the surface of the substrate 110, the concentration of the inactive impurity also increases toward the surface of the substrate 110. Thus, these inactive impurities are gathered at and near the surface of the substrate 110, and these inactive impurities form a dead layer at and near the surface of the substrate 110. Charge loss occurs due to the inactive impurities present in the dead region. In this example, an impurity diffused into the substrate 110 and not capable of normally bonding (not dissolving) with the materials of the substrate 110, for example, silicon (Si) or the like, is referred to as an inert impurity.

However, in this embodiment, since the first and second impurity doping portions 1211 and 1212 are formed by using the etching method, the emitter layer is removed as much as desired from the surface of the substrate 110, At least a part of the dead region existing in the surface portion of the semiconductor substrate 110 is removed during the etching process. As the dead region is removed, the recombination rate of the charge due to the impurity in the dead region is greatly reduced, so that the amount of loss of the charge is greatly reduced. Also, at least a part of the dead region is removed and the first impurity doping The anti-reflection part 130 is positioned on the part 1211, so that the passivation effect is further improved by the anti-reflection part 130.

The front electrode unit 140 includes a plurality of front electrodes 141 and a plurality of front bus bars 142 connected to the plurality of front electrodes 141.

The plurality of front electrodes 141 are located on the first impurity doping portion 1211 and electrically and physically connected directly to the first impurity doping portion 1211 and are spaced apart from each other and extend in a predetermined direction. Therefore, the reflection prevention part 130 does not exist under the plurality of front electrodes 141.

The plurality of front electrodes 141 are made of at least one conductive material such as silver (Ag).

In this example, the line width W3 of the front electrode 141 may be about 50 占 퐉 to about 120 占 퐉, and the interval W4 between the adjacent two front electrodes 141 may be about 1.8 mm to about 2.5 mm .

When the line width W3 of each front electrode 141 is about 50 mu m or more, the wiring resistance of each front electrode 141 is further reduced and the conductivity is more stably secured, so that the charge is more stably moved, 141 can be more easily performed. When the line width W3 of each front electrode 141 is about 120 mu m or less, the incident area is more stably secured, and the reduction of the charge generation amount due to the reduction of the incident area is further prevented.

When the gap W4 between the adjacent two front electrodes 141 is about 1.8 mm or more, the incident area of the light due to the front electrodes 141 is not greatly reduced. Therefore, charges are stably collected, When the interval W4 is about 2.5 mm or less, the charge can not move to the adjacent front electrode 141 due to the interval W4 that is wider than the movement distance of the charge, and prevents the generation of the lost charge.

At this time, the plurality of front electrodes 141 extend in a direction intersecting the plurality of second impurity doping portions 1212 which are semiconductor electrodes. 4, each front electrode 141 is connected to a plurality of second impurity doping portions 1212 in a portion CT (hereinafter referred to as a "contact portion") which overlaps with the plurality of second impurity doping portions 1212. Therefore, Lt; RTI ID = 0.0 > 1212 < / RTI >

Therefore, except for a portion overlapping the plurality of second impurity doping portions 1212, each front electrode 141 directly contacts the first impurity doping portion 1211.

The plurality of front electrodes 141 collects charge (for example, electrons) traveling through the first dopant doping portion 1211 in contact with each other. Since the plurality of front electrodes 141 are connected to the plurality of second impurity doping portions 1212 at the respective contact portions CT of the plurality of second impurity doping portions 1212, ) Is collected by the corresponding front electrode 141 connected to each contact portion CT.

As described above, since the plurality of second impurity doping portions 1212, which are semiconductor electrodes, are formed in a direction crossing the plurality of front electrodes 141 at the portion where the plurality of front electrodes 141 are not formed, (The first impurity doped region 141 or the second impurity doped region 1212). Therefore, the amount of charge lost due to impurities, defects, and the like when moving to the adjacent front electrode 141 or the adjacent second impurity doping portion 1212 is reduced by the reduced moving distance.

In addition, only the transparent antireflection portion 130 is present on the plurality of second impurity doping portions 1212, and the front electrode 141 containing a metal material (for example, Ag) for reducing the incidence area of light is not located . Therefore, the incident area of the plurality of second impurity doping portions 1212 does not decrease, but instead of decreasing the travel distance of the charges and reducing the amount of charge loss as described above, The amount of charge moving to each front electrode 141 greatly increases.

At this time, when the width W1 of each second impurity doping portion 1212 is about 30 占 퐉 to 40 占 퐉 as described above and the width W1 of each second impurity doping portion 1212 is about 30 占 퐉 or more, The second impurity doping portion 1212 having the desired width W1 is designed more easily and stably. Also, as the doping concentration of the impurity increases, the amount of charge loss due to the impurity increases. Therefore, when the width W1 of each second impurity doping portion 1212 is about 40 mu m or less, the amount of charge loss due to the impurity is further reduced due to the increase in the second impurity doping portion 1212, which is the high concentration impurity doping region . Accordingly, when the width W1 of each second impurity doping portion 1212 is about 40 mu m or less, the charge collected by the second impurity doping portion 1212 is more stably moved to the plurality of front electrodes 141 Is improved.

The amount of charge lost due to the high concentration impurity concentration of the second impurity doping portion 1212 can be reduced and the amount of charges lost due to the second impurity doping portion 1212 adjacent to the second impurity doping portion 1212 can be reduced when the interval W2 between the two adjacent second impurity doping portions 1212 is 0.6 mm or more ) Is 0.7 mm or less, the amount of charge transferred to the second impurity doping portion 1212 is reduced by more stably compensating the movement distance of the charge.

Also, in this example, the number of contact portions CT in which the plurality of second dopant doping portions 1212 and the plurality of first electrodes 141 are in contact with each other may be about 23,500 to about 40,000.

When the number of the contact portions CT is about 23,500 or more, the amount of charges transferred from the plurality of second impurity doping portions 1212 to the plurality of front electrodes 141 is more stably secured and the number of contact portions CT Is less than about 40,000, the amount of charge loss due to impurities is further reduced due to an increase in the formation area of the second impurity doping portion 1212, which is a high concentration impurity doping region.

The plurality of front bus bars 142 are electrically and physically connected to the first impurity doping portions 1211 and are electrically connected to the plurality of second impurity doping portions 1212 in a direction crossing the plurality of front electrodes 141, In the same direction. Therefore, unlike the plurality of front electrodes 141, the plurality of front bus bars 142 are in contact with the first impurity doping portion 1211 only.

At this time, the plurality of front bus bars 142 are electrically and physically connected to the front electrodes 141 at the intersections of the front electrodes 141.

1, the plurality of front electrodes 141 has a stripe shape extending in the horizontal or vertical direction, and the plurality of front bus bars 142 have stripe shapes extending in the vertical or horizontal direction And the front electrode unit 140 is disposed on the front surface of the substrate 110 in a lattice form.

The plurality of front bus bars 142 collect the charge moving from the contacted first impurity doping portion 1211 as well as the charges collected and moved by the plurality of front electrodes 141.

The plurality of front bus bars 142 are connected to an external device to output the collected electric charges (e.g., electrons) to an external device.

The width of the front bus bar 142 must be equal to or greater than the width of each front electrode 141. In this case, Lt; / RTI >

Each front bus bar 142 has a width W5 of about 1.5 mm to 2 mm.

Since the front electrode unit 140 is connected to the first impurity doping unit 1211 having a low impurity doping concentration at a portion where charge transfer to the adjacent front electrode unit 140 is mainly performed, The portion of each front electrode 141 connected to the plurality of second impurity doping portions 1212 has a second impurity doping portion 1212 having a high impurity doping concentration, The conduction from the connected second impurity doping portion 1212 to the corresponding front electrode 141 is improved and the amount of charge transferred from the second impurity doping portion 1212 to the front electrode 141 increases . Therefore, the efficiency of the solar cell 11 increases.

In this example, since the antireflective portion 130 is made of silicon nitride (SiNx) having positive positive charge characteristics, when the substrate 110 has the p-type conductivity type, The charge transfer efficiency from the substrate 110 to the front electrode portion 140 is improved. That is, since the antireflective portion 130 has a characteristic of positive electric charge, it hinders the movement of positive electric charges.

That is, when the substrate 110 has a p-type conductivity type, electrons, which are negative charges moving toward the antireflection portion 130 when the antireflection portion 130 has a characteristic of positive electric charge, The polarity of the anti-reflection part 130 is pulled toward the anti-reflection part 130 because the polarity of the anti-reflection part 130 is opposite to that of the anti-reflection part 130. On the other hand, And is pushed to the opposite side of the anti-reflection portion 130 by the polarity of the portion 130.

Therefore, the movement amount of electrons moving from the substrate 110 to the front electrode portion 140 is further increased by the silicon nitride (SiNx) of both polarities, and the movement of charges (e.g., holes) So that the recombination amount of charges on the entire surface of the substrate 110 is further lowered.

In this example, the plurality of front bus bars 142 are made of the same material as the plurality of front electrodes 141.

The rear electric field 172 is a region in which impurities of the same conductivity type as the substrate 110 are doped at a higher concentration than the substrate 110, for example, a p + region.

A potential barrier is formed due to the difference in impurity concentration between the first conductive region (for example, p-type) of the substrate 110 and the rear electric field 172, and thus the electric field is directed toward the rear electric field 172 The electron transport is disturbed while the hole transport toward the rear electric field 172 becomes easier. Accordingly, the rear electric field 172 reduces the amount of electric charge lost due to the recombination of electrons and holes at the back surface of the substrate 110 and the vicinity thereof, and accelerates the movement of a desired electric charge (e.g., a hole) ) In the direction of the arrow.

The rear electrode unit 150 includes a plurality of rear bus bars 152 connected to the rear electrode 151 and the rear electrode 151.

The rear electrode 151 is in contact with the rear electric field 172 located on the rear surface of the substrate 110 and substantially entirely on the rear surface of the substrate 110 except for the portion where the rear bus bar 152 is located. In an alternative example, the back electrode 151 may not be located at the edge portion of the back surface of the substrate 110. [

The rear electrode 151 contains a conductive material such as aluminum (Al).

This rear electrode 151 collects charge, for example, holes, moving from the rear electric field 172 side.

In this case, since the rear electrode 151 is in contact with the rear electric field portion 172 having a higher impurity concentration than the substrate 110, the contact resistance between the substrate 110, i.e., the rear electric field portion 172 and the rear electrode 151 And the charge transfer efficiency from the substrate 110 to the rear electrode 151 is improved.

The plurality of rear bus bars 152 are located on the rear surface of the substrate 110 where the rear electrodes 151 are not located and are connected to the adjacent rear electrodes 151.

In addition, the plurality of rear bus bars 152 are opposed to the plurality of front bus bars 142 in correspondence with the substrate 110 as a center.

A plurality of rear bus bars 152 collects charge transferred from the rear electrode 151, similar to a plurality of front bus bars 142.

A plurality of rear bus bars 152 are also connected to external devices so that the charges (e.g., holes) collected by the plurality of rear bus bars 152 are output to an external device.

These plurality of rear bus bars 152 may be made of a material having a better conductivity than the back electrode 151 and contain at least one conductive material such as, for example, silver (Ag).

In this example, the emitter layer 120 having a conductive type opposite to the conductive type of the substrate 110 is provided on the rear surface of the substrate 110 located under the rear bus bar 152, but the present invention is not limited thereto.

The backside electrode 151 may also be located on the backside portion of the substrate 110 where the backside bus bar 152 is located, Facing the plurality of front bus bars 142 and on the rear electrode 151. [ At this time, the rear electrode 151 may be positioned substantially on the entire rear surface excluding the edge portion of the rear surface.

The operation of the solar cell 11 according to this embodiment having such a structure is as follows.

When light is irradiated to the solar cell 11 and is incident on the substrate 110 and the impurity doping portion 121 which is a semiconductor part through the reflection preventing part 130, electron-hole pairs are generated in the semiconductor part due to light energy. 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 substrate 110 is increased.

These electron-hole pairs are separated from each other by the pn junction of the substrate 110 and the impurity doping portion 121, so that the electrons and the holes are separated from the impurity doping portion 121 having the n-type conductivity type, for example, To the substrate 110 having the conductive type. The electrons moved toward the dopant doping portion 121 are collected by the plurality of front electrodes 141 and the plurality of front bus bars 142 and travel along the plurality of front bus bars 142, Holes are collected by the adjacent rear electrode 151 and the plurality of rear bus bars 152 and move along the plurality of rear bus bars 152. [ When the front bus bar 142 and the rear bus bar 152 are connected to each other by a wire, a current flows and is used as electric power from the outside.

Further, since a plurality of second impurity doping portions 1212, that is, semiconductor electrodes having a high impurity concentration in the direction crossing the plurality of front electrodes 141 are formed, the electric charges traveling through the impurity doping portions 121 are adjacent to each other But also to the second impurity doping portion 1212 which is the adjacent semiconductor electrode as well as the front electrode 141 and the adjacent front bus bar 142. Accordingly, the movement distance of the charges moving to the adjacent electrodes 141 and 1212 and the bus bar 142 is reduced, so that the amount of charges moving to the front electrode portion 140 and the second impurity doping portion 1212 increases. Since the second impurity doping portion 1212 in contact with the front electrode 141 has a high concentration impurity doping concentration with high conductivity, the conductivity from the second impurity doping portion 1212 to the front electrode 141, The contact resistance between the second impurity doping portion 1212 and the front electrode 141 is reduced and the charge transfer rate from the second second impurity doping portion 1212 to the front electrode 141 is improved. As a result, the amount of charges transferred from the impurity doping portion 121 to the front bus bar 142 increases, and the efficiency of the solar cell 11 is improved.

Next, a method of manufacturing the solar cell 11 according to one embodiment of the present invention will be described with reference to FIGS. 5A to 5E. FIG.

First, as shown in FIG. 5A, a substrate 110 is doped with a material containing an impurity of a pentavalent or trivalent element in a crystalline semiconductor substrate 110 made of single crystal, polycrystalline silicon, or the like by a thermal diffusion method, An emitter layer 120, which is an impurity doping layer, is formed. When the substrate 110 is n-type, a material including phosphorus (P) or the like (for example, POCl ₃ or H ₃ PO ₄ ) is used. When the substrate 110 is p-type, boron using the materials (for example, B ₂ H _6), comprising forming the emitter layer 120 to the substrate 110. When the emitter layer 120 is formed by the thermal diffusion method, the emitter layer 120 is formed on the front surface, the back surface, and the side surface of the substrate 11.

At this time, the emitter layer 120 to be formed is about 10 Ω / sq. To 30 < RTI ID = 0.0 > OMEGA / sq. ≪ / RTI >

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 >

If necessary, the front surface of the substrate 110 may be tested before forming the emitter layer 120 to form a textured surface that is an uneven surface. When the substrate 110 is made of monocrystalline silicon, the surface of the substrate 110 may be textured using a base solution such as KOH or NaOH. When the substrate 110 is made of polycrystalline silicon, HF or HNO ₃ May be used to texture the surface of the substrate 110.

5B, a first etch stop layer 61 is selectively positioned on the emitter layer 120 located on the front surface of the substrate 110 to expose a portion of the emitter layer 120, The second etching preventive film 62 is placed on the entire rear surface of the wafer W. At this time, the plurality of first etching preventive films 61 are spaced apart from each other on the emitter layer 120 and extend in parallel with each other in one direction. The first and second etching preventive films 61 and 62 may be formed using a screen printing method, a photolithography method, or the like.

Then, the entire substrate 110 is deposited in an etchant to remove a portion of the emitter layer 120 exposed to the etchant, thereby forming a first second impurity doping portion 1211 having a different impurity doping concentration and an impurity doping thickness, Doped portion 121 having the second second impurity doping portion 1212 of the second impurity doping portion 1212 is formed. The first and second etching preventive films 61 and 62 are then removed from the substrate 110. A desired portion of the emitter layer 120 is removed to form a first second impurity doped region 1211 And portions of the substrate 110 which are protected by the etch stopping layer 61 and are not etched, that is, the portions extending along one direction of the substrate 110 in parallel to each other, form a plurality of second impurity doping portions 1212 , The impurity portion 121 is completed. At this time, the first impurity doping portion 1211 and the second impurity doping portion 1212 are alternately disposed on the substrate 110.

Since the etched portions are formed by the first impurity doping portion 1211, the thickness of the first impurity doping portion 1211 is smaller than that of the second impurity doping portion 1212, Doped region 1212 has a larger sheet resistance value than the second impurity doped region 1212.

This causes charges present in the impurity doping portion 121 to move toward the second impurity doping portion 1212 having lower resistance than the first impurity doping portion 1211 which is a high surface resistance portion and the first impurity doping portion 1211 The second impurity doping portion 1212 has higher conductivity than the first impurity doping portion 1211 because the impurity doping concentration of the second impurity doping portion 1212 is higher than that of the first impurity doping portion 1211. [ Therefore, the charge transferred to the adjacent second impurity doping portion 1212 in the first impurity doping portion 1211 is transferred to the second impurity doping portion 1212 having a conductivity higher than that through the first impurity doping portion 1211, (E. G., Electrons) of the second impurity doping portion 1212 are moved mainly along the second impurity doping portion 1212. In this case,

A part of the emitter layer 120 located on the front surface of the substrate 110 is removed by dry etching or only the front surface of the substrate 110 is exposed to the etching solution to form a plurality of first and second impurity doping portions 1211 And 1212 may be formed on the substrate 110. In this case, a separate etch stop layer may not be formed on the back surface of the substrate 110 that is not exposed to the etchant or etchant.

Next, as shown in FIG. 5D, the antireflection portion 130 is formed on the impurity doping portion 121 formed on the entire surface of the substrate 110 by using plasma enhanced chemical vapor deposition (PECVD) or the like .

5E, a front electrode pattern 40 is formed on a corresponding portion of the antireflective portion 130 and a rear electrode pattern 51 is formed on the emitter layer 120 formed on the rear surface of the substrate 110. Next, And a rear bus bar pattern 52 are formed to complete the rear electrode pattern 50. FIG.

At this time, the front electrode pattern 40 is formed by selectively printing a paste for front electrode part including silver (Ag) on the antireflection part 130 by screen printing and then drying the paste, (41) and a front bus bar portion (42).

The rear electrode pattern 51 is formed by selectively printing a rear electrode paste containing aluminum (Al) on the rear surface of the substrate 110 by screen printing and drying the rear electrode pattern 51. The rear bus bar pattern 52 is formed by silver Ag is selectively printed on the rear surface of the substrate 110 on which the rear electrode pattern 51 is not formed by a screen printing method and then dried.

At this time, the drying temperature of these patterns 40, 51, and 52 may be about 120 ° C to about 200 ° C, and the order of forming the patterns 40, 51, and 52 may be changed.

The substrate 110 on which the front electrode pattern 40 and the rear electrode pattern 50 are formed is subjected to a heat treatment process at a temperature of about 750 ° C. to about 800 ° C. to form the first dopant doping portion 1211 A front electrode unit 140 having a plurality of front electrodes 141 and a plurality of front bus bars 142 and a rear electrode 151 and a rear bus bar 152 electrically connected to the substrate 110, The rear electrode unit 150 and the backside electrode 172 are formed in the substrate 110 in contact with the backside electrode 151.

In other words, the front electrode pattern 40 penetrates through the antireflection portion 130 at the contact portion by the lead (Pb) contained in the front electrode pattern 40 by the heat treatment process, A plurality of front electrodes 141 and a plurality of front electrode bus bars 142 are formed in contact with the first impurity doping portions 1211 of the first insulating layer 121 to complete the front electrode portions 140.

At this time, the front electrode pattern 41 of the front electrode pattern 40 becomes a plurality of front electrodes 141, and the front bus bar pattern 42 becomes a plurality of front electrode bus bars 142.

A plurality of front electrodes 141 extend in a direction intersecting the plurality of second impurity doping portions 1212. A plurality of front bus bars 142 extend in the same direction as the plurality of second impurity doping portions 1212, The second dopant doping portion 1212 of FIG. Therefore, each of the front electrodes 141 is in contact with the plurality of second impurity doping portions 1212 at portions intersecting with the plurality of second impurity doping portions 1212 as well as the first impurity doping portions 1211, The front bus bar 142 is in contact only with the first impurity doping portion 1211.

Accordingly, each front electrode 141 collects the charges transmitted through the plurality of second impurity doping portions 1212 that are in contact with the first impurity doping portions 1211 located below and the contact portions CT, And then to the adjacent front side bus bar 142.

The rear electrode pattern 51 and the rear bus bar pattern 52 of the rear electrode pattern 50 are formed by the rear electrode 151 and the plurality of rear bus bars 152 by the heat treatment process, Aluminum included in the rear electrode pattern 51 of the electrode pattern 50 is diffused into the substrate 110 as well as the emitter layer 120 formed on the rear surface of the substrate 110, A rear electric field portion 172 is formed in which an impurity portion having an impurity concentration higher than that of the substrate 110 is formed. Thus, the rear electrode 151 is electrically connected to the substrate 110 in contact with the rear electric part 172. Therefore, although the emitter layer 120 existing on the rear surface of the substrate 110 on which the rear electrode pattern 51 is not present is present, it is not limited thereto.

During the heat treatment process, the contact resistance decreases due to the chemical bonding with the layers 121 and 110 which are in contact with the metal components contained in the patterns 40 and 50, thereby improving the transfer efficiency of the electric charge, thereby increasing the current flow.

Then, the solar cell 11 is completed by performing an edge isolation process of diffusing to the side surface of the substrate 110 using a laser beam or an etching process to remove the doped emitter layer 120 on the side surface . However, the timing of the side-separating process can be changed as needed and can be omitted.

In this embodiment, the emitter layer 120 formed on the backside of the substrate 110 is not separately removed, but in an alternative example, the backside electrode pattern 50 is formed on the backside of the substrate 110, A separate process for removing the emitter layer 120 may be performed.

Next, a solar cell 12 according to another embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG. 1 and 2, the same reference numerals are assigned to the same constituent elements, and a detailed description thereof will be omitted.

The solar cell 12 shown in Figs. 6 and 7 has a structure similar to that of the solar cell 11 shown in Figs. 1 and 2.

That is, the solar cell 12 according to the present embodiment includes an impurity doping unit 121 located on the front surface of the substrate 110 and having a first impurity doping unit 1211 and a plurality of second impurity doping units 1212, A front electrode part 130a connected to the antireflection part 130a and the impurity doping part 121 located on the impurity doping part 121 and having a plurality of front electrodes 141a and a plurality of front side bus bars 142a A rear electric part 172 positioned on the rear surface of the substrate 110 and a rear electrode part 150 positioned on the rear surface of the substrate 110. [

However, as compared with the solar cell 11 of Figs. 1 and 2, the position of the solar cell 12 is different from that of the antireflection portion 130.

1 and 2, the antireflection unit 130 does not exist under the plurality of front electrodes 141 and the plurality of front bus bars 142, but includes the front electrode unit 140, And is located on the remaining portion of the impurity doping portion 121 except for the portion of the impurity doping portion 121 connected to the impurity doping portion 121.

However, in the solar cell 12 of the present embodiment, the antireflective portion 130a is formed on the portion of the impurity doping portion 121 excluding the portion where the plurality of second impurity doping portions 1212 and the plurality of front electrodes 141 are in contact with each other Located. Therefore, the antireflection portion 130a is located on the first impurity doping portion 121 and on the second impurity doping portion 1212 that does not intersect with the plurality of front electrodes 141. [

Therefore, the front electrode portion 140a differs from the front electrode portion 140 of the solar cell 11 of FIGS. 1 and 2 in the position in which it contacts the impurity doping portion 121.

That is, the plurality of front bus bars 142a of the front electrode part 140a are positioned on the antireflection part 130a instead of contacting the first impurity doping part 1211 of the impurity doping part 121, The first impurity doping portion 141a is also located on the antireflection portion 130a except for a portion intersecting the plurality of second impurity doping portions 1212. [ As a result, among the front electrode portions 140a, only a plurality of front electrode 141a portions overlapping the plurality of second dopant doping portions 1212 make contact with the impurity doping portions 121. [ Except for these differences, the front electrode part 140a is the same as the front electrode part 140 shown in FIGS. 1 and 2.

Since the antireflection portion 130a is present on all the surfaces of the impurity doping portion 121 except for the second impurity doping portion 1212 which intersects with the plurality of front electrodes 141, The area where the passivation function is performed is increased by the passivation layer 130a. Therefore, the passivation function of the antireflective portion 130a greatly reduces the amount of charge lost due to defects on the surface of the impurity doping portion 121 and the vicinity thereof, and as a result, the efficiency of the solar cell 12 becomes And further improved.

5A to 5E, and referring to Figs. 8A and 8B and Figs. 9A and 9B as well as Figs. 5A to 5E, the method of manufacturing the solar cell 12 is similar to that of the solar cell 12 The manufacturing method will be described.

5A to 5D, an impurity doping portion 121 having a first impurity doping portion 1211 and a plurality of second impurity doping portions 1212 is formed on a substrate 110, The anti-reflection part 130 is formed on the doping part 121.

Then, as shown in FIG. 8B, an anti-etching film 64 is formed on the antireflection portion 130. The etching prevention film 64 has a plurality of openings 181 for exposing a part of the antireflection portion 130. At this time, the size of each opening 181 may be equal to or smaller than the size of overlapping each second impurity doping portion and each front electrode. The anti-etching film 64 can be selectively formed on a desired portion of the anti-reflection portion 130 through screen printing or photolithography.

Next, the entire surface of the substrate 110 is etched to remove the antireflection portion 130 exposed through the plurality of openings 181 without being protected by the etch stopping layer 64, thereby forming the second impurity doping portion 1212. [ Reflection portion 130a that exposes a part of the reflection preventing portion 130a.

5E, a front electrode pattern 40 having a front electrode pattern 41 and a front bus bar pattern 42 is formed on a second impurity doping portion (not shown) selectively exposed on the antireflection portion 130a 1212 and a rear electrode pattern 50 having a rear electrode pattern 51 and a rear bus bar pattern 52 is formed on the rear surface of the substrate 110. [

Then, the substrate 110 having the patterns 40 and 50 is subjected to heat treatment to form a plurality of front electrodes 141a and a plurality of front electrodes 141a and 142b, which are partially in contact with the second impurity doped region 1212, A front electrode part 140a connected to the plurality of front electrodes 142a and having a plurality of front bus bars 142a positioned on the reflection preventing part 130a, a rear electrode 151 connected to the substrate 110, A rear electrode unit 150 having a rear electrode 151 and a rear bus bar 152 connected to the substrate 110 and a rear electrode unit 150 disposed on the substrate 110 in contact with the rear electrode 151. [ (172).

In this case, since the front electrode pattern 41 is located on the exposed portion of the second impurity doping portion 1212, the front electrode pattern 41 is electrically connected to the plurality of front electrodes 141a The heat treatment temperature for forming the front electrode part 140a and the rear electrode part 150 may be low and the second dopant doping part 1212 may not penetrate the anti-reflection part 130a. So that deterioration of the substrate 110 due to the heat and the components located thereon or deterioration of the physical characteristics of the substrate 110 is reduced or prevented.

Alternatively, only the second impurity doping portion 1212 is directly in contact with the second impurity doping portion 1212 using the two kinds of different pastes, and the remaining portion forms the front electrode portion 140 positioned on the antireflection portion 130.

That is, as described above, after the impurity doping portion 121 having the first and second impurity doping portions 1211 and 1212 and the antireflection portion 130 are formed on the substrate 110, As shown in the figure, a first paste is partially applied on the antireflection portion 130 and then dried to form a contact portion pattern 41a. At this time, the position where the first paste is applied corresponds to a position where the plurality of second impurity doping portions 1212 and the plurality of front electrodes 141 overlap.

Then, a second paste is applied onto the portion of the antireflective portion 130 to which the first paste is not applied and then dried to form a front electrode pattern (not shown) and a rear bus bar pattern 42a, Complete the pattern. At this time, the front electrode pattern contacts the contact portion pattern 41a.

At this time, the content of the glass frit is different between the first paste and the second paste, and for example, the glass paste contains a larger amount of the first paste than the second paste.

Unlike the present embodiment, when the front electrode pattern is formed by using the second paste, it can also be placed on the contact pattern 41a.

Then, as described above, after the rear electrode pattern and the rear bus bar pattern are formed on the rear surface of the substrate 110, the substrate 110 is heat-treated at a temperature of about 750 ° C to about 800 ° C.

At this time, the contact portion pattern 41a made of the first paste passes through the antireflective portion 130 located below by the amount of the glass frit and comes into contact with a part of the second impurity doping portion 1212, as described above. On the other hand, due to the amount of the glass frit, the portion of the second paste is chemically coupled to the anti-reflection portion 130 without passing through the lower anti-reflection portion 130. A backside bus bar 152 and a backside electrical part 172 are connected to the substrate 110. The backside electrode 151 is connected to the substrate 110. The backside bus bar 152 and the backside electrical part 172 are connected to the substrate 110 and the backside electrode 51, .

Each of the front electrodes 141 is positioned on the antireflection portion 130 and passes through the antireflection portion 130 only at a portion overlapping the second impurity doping portion 1212 to form the second impurity doping portion 1212 Partially contacted.

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, It belongs to the scope of right.

11, 12: solar cell 40: front electrode part pattern
41: front electrode pattern 42: front bus bar pattern
50: rear electrode part pattern 51: rear electrode pattern
52: rear bus bar pattern 61, 62, 64: etching barrier film
110: substrate 120: emitter layer
121: Impurity doping section 130, 130a:
140, 140a: front electrode part 141, 141a: front electrode part
142, 142a: front bus bar 150: rear electrode part
151: Rear electrode 152: Rear bus bar
172: rear electric field portion 1211: first impurity doping portion
1212: second impurity doping portion

Claims (26)

A substrate of a first conductivity type,
An emitter portion located on the substrate and doped with an impurity of a second conductivity type opposite to the first conductivity type and formed on a front surface of the substrate,
A plurality of first electrodes connected to the emitter section and extending in a first direction and spaced apart from each other,
A plurality of second semiconductor layers having a second thickness that is greater than the first thickness and protrudes from the surface of the emitter layer and has a higher impurity doping concentration than the emitter layer and extends in a second direction crossing the first direction, A semiconductor electrode of
And a second electrode
/ RTI >
Wherein the plurality of semiconductor electrodes are in contact with a plurality of first electrodes at a plurality of contact portions intersecting with the plurality of first electrodes. The method of claim 1,
Wherein the number of the plurality of semiconductor electrodes is 200 to 245 in one substrate. The method of claim 1,
Wherein each of the plurality of semiconductor electrodes has a width of 30 占 퐉 to 50 占 퐉. The method of claim 1,
And a distance between two adjacent semiconductor electrodes is 0.6 mm to 0.7 mm. The method of claim 1,
Wherein a ratio of formation of the plurality of semiconductor electrodes to an entire front surface of the substrate is 4% to 8%. delete The method of claim 1,
Wherein the plurality of contact portions are 23,500 to 40,000 in one substrate. The method of claim 1,
Wherein the emitter portion has a larger sheet resistance value than each of the plurality of semiconductor electrodes. 9. The method of claim 8,
The emitter portion has a resistance of 90? / Sq. To 140 Ω / sq., And each semiconductor electrode has a resistance of 10 Ω / sq. To 30 < RTI ID = 0.0 > ohm / sq. ≪ / RTI > 9. The method according to claim 1 or 8,
Wherein the emitter section has an impurity doping concentration of 4 x 10 ¹⁹ / cm 3 to 6 x 10 ¹⁹ / cm 3, and each semiconductor electrode is a solar cell having an impurity doping concentration of 9 x 10 ¹⁹ / cm 3 to 4 x 10 ²⁰ / . 11. The method of claim 10,
Wherein the emitter section has an impurity doping thickness of 0.5 to 0.7 mu m, and the plurality of semiconductor electrodes each have an impurity doping thickness of 0.6 to 0.8 mu m. The method of claim 1,
And a bus bar connected to the emitter section and the plurality of first electrodes. The method of claim 12,
Wherein the plurality of semiconductor electrodes extend in the same direction as the bus bar. The method of claim 12,
And an antireflective portion disposed on the emitter portion and the plurality of semiconductor electrodes. The method of claim 14,
Wherein the reflection preventing portion is further located between the emitter portion and the bus bar. 15. The method according to claim 14 or 15,
Wherein the reflection preventing portion is made of silicon nitride. 15. The method according to claim 14 or 15,
Wherein the antireflective portion has a refractive index of 2.0 to 2.1. The method of claim 1,
And an antireflective portion disposed on the emitter portion and the plurality of semiconductor electrodes. The method of claim 18,
Wherein the reflection preventing portion is further located between the emitter portion and the plurality of first electrodes. 20. The method according to claim 18 or 19,
Wherein the reflection preventing portion is made of silicon nitride. 20. The method according to claim 18 or 19,
Wherein the antireflective portion has a refractive index of 2.0 to 2.1. The method of claim 1,
And a rear surface electric field portion located on the substrate in contact with the second electrode. Forming an emitter layer of a second conductivity type opposite to the first conductivity type on a first side of a substrate having a first conductivity type,
Forming an emitter layer having a first thickness and a plurality of semiconductor electrodes protruding from a surface of the emitter layer and having a second thickness larger than the first thickness by selectively etching the emitter layer;
A plurality of first electrodes extending in a direction intersecting with the semiconductor electrode and connected to the emitter section are formed on a first surface of the substrate, and a second electrode connected to the substrate is formed on the first surface opposite to the first surface, Forming on the second surface
Lt; / RTI >
Wherein the emitter layer is a portion where the etching is performed in the emitter layer and the plurality of semiconductor electrodes are portions where the etching is not performed in the emitter layer,
Wherein the plurality of semiconductor electrodes are in contact with a plurality of first electrodes at a plurality of contact portions intersecting with the plurality of first electrodes,
A method of manufacturing a solar cell. 24. The method of claim 23,
The emitter layer has a resistivity of 10? / Sq. To 30 < RTI ID = 0.0 > ohm / sq. ≪ / RTI > 24. The method of claim 23,
Further comprising forming an antireflection portion on the emitter portion and the plurality of semiconductor electrodes,
The forming of the plurality of first electrodes and the forming of the second electrodes may include forming a first electrode pattern on the anti-
Forming a plurality of first electrodes through which the first electrode pattern penetrates the antireflection portion and is connected to the emitter portion and the plurality of semiconductor electrodes by heat treating the first electrode pattern;
Wherein the method comprises the steps of: 26. The method of claim 25,
The plurality of first electrodes and the second electrode forming step may further include a bus bar crossing the plurality of first electrodes and connected to the emitter part,
Wherein the bus bar passes through the antireflection portion and is connected to the emitter portion.

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