KR101729744B1 - Method for manufacturing solar cell - Google Patents

Abstract

The present invention relates to a method of manufacturing a solar cell. One example of a method of manufacturing a solar cell according to the present invention includes forming an emitter portion having a second conductivity type opposite to the first conductivity type on a semiconductor substrate of a first conductivity type; Forming a front protective portion on an incident surface of the semiconductor substrate; Forming a first electrode connected to the emitter portion; Forming a second electrode connected to the semiconductor substrate; And spraying hydrogen (H) in a plasma state to the front protective portion.

Description

[0001] METHOD FOR MANUFACTURING SOLAR CELL [0002]

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

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 the generated electron-hole pairs are separated into electrons and holes which are charged by the photovoltaic effect, 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.

An object of the present invention is to provide a method of manufacturing a solar cell that improves efficiency of a solar cell.

One example of a solar cell according to the present invention comprises: forming an emitter portion in a semiconductor substrate of a first conductivity type, the emitter portion having a second conductivity type opposite to the first conductivity type; Forming a front protective portion on an incident surface of the semiconductor substrate; Forming a first electrode connected to the emitter portion; Forming a second electrode connected to the semiconductor substrate; And spraying hydrogen (H) in a plasma state to the front protective portion.

Here, the step of injecting hydrogen may use a plasma torch that injects hydrogen gas (H ₂ ) from the outside and injects a plasma jet which has undergone a state change to hydrogen (H) in a plasma state.

In addition, in the step of spraying hydrogen, the temperature of the plasma jet containing hydrogen at the surface of the front surface protection portion may be between 250 ° C and 800 ° C.

In addition, the step of injecting hydrogen may be performed after the heat treatment process of the first electrode and the second electrode. In addition, the step of injecting hydrogen may be performed by removing the edges of the front protective portion and the emitter portion below the front protective portion, Or after the edge isolation step exposing a portion of the substrate.

The front surface protection portion may be formed of a hydrogenated silicon nitride film (SiNx: H), a silicon oxide film (SiOx: H), a silicon nitride oxide film (SiNxOy: H), a silicon oxynitride film (SiOxNy: H), an amorphous silicon (a- May be formed of a plurality of layers.

In the step of forming the front protective part, the front protective part may be formed of a hydrogenated silicon nitride film (SiNx: H), a silicon oxide film (SiOx: H), a silicon nitride oxide film (SiNxOy: H), a silicon oxynitride film (SiOxNy: (a-Si: H).

Further, in the step of forming the emitter portion, the emitter portion may be formed on the incident surface or the surface opposite to the incident surface of the semiconductor substrate.

When the emitter portion is formed on the incident surface of the semiconductor substrate, the front surface protection portion is formed on the emitter portion, the first electrode is formed on the front surface protection portion, and may be connected to the emitter portion through the front surface protection portion.

When the emitter portion is formed on the side opposite to the semiconductor substrate incident surface, the first electrode may be formed on the opposite side of the semiconductor substrate incident surface and connected to the emitter portion.

The manufacturing method of the solar cell may further include forming a rear electric field portion on the opposite side of the semiconductor substrate incident surface, prior to the step of forming the second electrode.

One example of the method for manufacturing a solar cell according to the present invention is to improve the photoelectric efficiency of a solar cell by spraying hydrogen (H) in a plasma state to the front protective part in the last heat treatment step of the solar cell manufacturing step.

FIG. 1 is a partial perspective view of a solar cell according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II of the solar cell shown in FIG.
3A to 3G illustrate an example of a method of manufacturing the solar cell shown in Figs. 1 and 2. Fig.
4 and 5 are views for explaining another example of a solar cell to which the method for manufacturing a solar cell according to the present invention can be applied.

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.

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

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

1 and 2, a solar cell 1 according to an embodiment of the present invention includes a substrate 110, an emitter region 120, a front protective portion 125, a first electrode (not shown) 140, a back surface field (BSF) 172, and a second electrode 150. Here, the rear electric section 172 may be omitted. However, since the efficiency of the solar cell 1 is further improved when the rear electric section 172 is provided, the following description will be made on the assumption that the rear electric section 172 is included do.

The semiconductor substrate 110 may have a first conductivity type, for example, a p-type conductivity type. The semiconductor substrate 110 may be formed of any one of single crystal silicon, polycrystalline silicon, and amorphous 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.

The front surface of the substrate 110 is textured to have a textured surface that is an uneven surface. For convenience, in FIG. 1, only the edge portion of the substrate 110 is shown as a textured surface, and the front protective portion 125 located thereon) also shows only the edge portion thereof as an uneven surface. However, the entire front surface of the substrate 110 substantially has a textured surface, and thus the front surface protective portion 125 located on the front surface of the substrate 110 also has a rough surface.

At this time, the textured surface is formed mainly by using an alkaline solution, and the plural irregularities have irregular width and height. At this time, the width and height of each concavity and convexity formed may be several tens of 탆.

The light incident on the front surface of the substrate 110 due to the textured surface having a plurality of irregularities is reflected by the surface of the substrate 110 and the surface of the substrate 110, (110). As a result, the amount of light reflected from the front surface of the substrate 110 decreases and the amount of light incident into the substrate 110 increases. In addition, due to the textured surface, the surface area of the substrate 110 and the front surface protective part 125 on which the light is incident increases, and the amount of light incident on the substrate 110 also increases.

The emitter section 120 is formed on the incident surface of the semiconductor substrate of the first conductivity type as shown in FIGS. 1 and 2, and is of a second conductivity type opposite to the first conductivity type, for example, an n-type Impurity of the conductive type may be doped to the substrate 110 and may be located on the surface where the light is incident, that is, inside the front surface of the substrate 110. [ Thus, the emitter portion 120 of the second conductivity type forms a p-n junction with the first conductive type portion of the substrate 110.

However, as shown in FIGS. 1 and 2, the emitter section 120 may be disposed on the rear surface opposite to the incident surface of the substrate 110, which will be described with reference to FIGS. 4 and 5. FIG.

Due to the built-in potential difference caused by the pn junction between the substrate 110 and the emitter section 120, the electron-hole pairs, which are charges generated by the light incident on the substrate 110, Electrons move to the n-type and holes move to the p-type. Accordingly, when the substrate 110 is p-type and the emitter section 120 is n-type, the separated holes move toward the back surface of the substrate 110, and the separated electrons move toward the emitter section 120.

Since the emitter section 120 forms a pn junction with the first conductive section of the substrate 110, that is, the substrate 110, unlike the present embodiment, when the substrate 110 has the n-type conductivity type, The terminal portion 120 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 emitter section 120.

When the emitter section 120 has an n-type conductivity type, the emitter section 120 can be formed by doping an impurity of a pentavalent element into the substrate 110. Conversely, when the emitter section 120 has a p-type conductivity type, May be formed by doping an impurity of the element into the substrate 110. [

1 and 2, when the emitter section 120 is located on the incident surface of the substrate 110, the front surface protective section 125 is located on the incident surface of the semiconductor substrate 110, The front protective portion 125 may be located on the upper portion of the emitter.

The front protective portion 125 may be formed of a hydrogenated silicon nitride film (SiNx: H), a silicon oxide film (SiOx: H), a silicon nitride oxide film (SiNxOy: H), a silicon oxynitride film (SiOxNy: H) Si: H). ≪ / RTI >

The front protective portion 125 may be a defect such as a dangling bond mainly present on the surface of the semiconductor substrate 110 and its vicinity due to hydrogen (H) contained in the front protective portion 125 defects in the semiconductor substrate 110 are changed into stable bonds and a passivation function is performed to reduce the disappearance of the charges moving toward the surface of the semiconductor substrate 110 due to the defects, Lt; RTI ID = 0.0 > loss < / RTI >

When the semiconductor substrate 110 has a textured surface, the front surface protection portion 125 has a textured surface having a plurality of irregularities in a manner similar to the substrate 110.

Since the defects are mainly present on the surface or near the surface of the semiconductor substrate 110 in general, the front protection portion 191 directly contacts the surface of the semiconductor substrate 110, The amount of charge loss is further reduced.

The front protective portion 125 may be formed of the hydrogenated silicon nitride film (SiNx: H), the silicon oxide film (SiOx: H), the silicon nitride oxide film (SiNxOy: H), the silicon oxynitride film (SiOxNy: And silicon (a-Si: H).

For example, the front protective portion 125 may be formed of two layers of hydrogenated silicon nitride (SiNx: H).

In the case where the hydrogenated silicon nitride film (SiNx: H) is formed of two layers, the hydrogen concentration of the first silicon nitride film (SiNx: H) located at the uppermost portion of the incident surface of the substrate 110 among the two silicon nitride films May be higher than the hydrogen concentration of the second silicon nitride film located between the first silicon nitride film and the emitter section 120.

By doing this, the passivation function of the front surface protective part 125 can be further strengthened, and the photoelectric efficiency of the solar cell 1 can be further improved.

1 and 2, the first electrode 140 may be disposed on the front surface of the semiconductor substrate 110 and may be connected to the emitter unit 120 through the front protection unit 125. However, when the emitter section 120 is located on the rear surface of the semiconductor substrate 110, the first electrode 140 may also be located on the rear surface of the semiconductor substrate 110, which will be described later with reference to FIGS. 4 and 5 Explain.

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

The plurality of finger electrodes 141 are electrically and physically connected to the emitter section 120 and are spaced apart from each other and extend in a predetermined direction. The plurality of finger electrodes 141 collect electrons, for example, electrons, which have migrated toward the emitter section 120.

A plurality of front bus bars 142 are electrically and physically connected to the emitter section 120 and extend in a direction parallel to the plurality of finger electrodes 141.

The plurality of front bus bars 142 are located on the same layer as the plurality of finger electrodes 141 and are electrically and physically connected to the corresponding finger electrodes 141 at a position intersecting the respective finger electrodes 141.

1, the plurality of finger electrodes 141 may have a stripe shape extending in the horizontal or vertical direction, and the plurality of front bus bars 142 may be formed in a stripe shape extending in the vertical or horizontal direction And the first electrode 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 portion of the contacted emitter portion 120 as well as the charge collected and moved by the plurality of finger electrodes 141.

The width of each front bus bar 142 must be greater than the width of each finger electrode 141 so that the width of each front bus bar 142 is larger than the width of each finger electrode 141. [ It can be big.

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

The plurality of finger electrodes 141 and the plurality of front bus bars 142 of the first electrode 140 are made of at least one conductive material such as silver (Ag).

In FIG. 1, the number of the finger electrodes 141 and the front-side bus bars 142 located on the substrate 110 is only an example, and may be changed depending on the case.

The rear electric field portion 172 may be located on the opposite side of the incident surface of the semiconductor substrate 110 and may include a region of the same conductivity type as that of the substrate 110 and doped more heavily than the substrate 110, Area.

A potential barrier is formed due to the difference in impurity concentration between the first conductive region and the rear conductive portion 172 of the substrate 110, thereby hindering the electron movement toward the rear conductive portion 172, which is the direction of the movement of the holes Thereby facilitating hole transport toward the rear electric field 172. Accordingly, by reducing the amount of charge lost due to the recombination of electrons and holes at the back surface and the vicinity of the substrate 110 and accelerating the movement of a desired charge (e.g., hole), the amount of charge transfer to the second electrode 150 is increased .

The second electrode 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 part 172 located on the rear side of the substrate 110 and substantially contacts the back side electrode part 172 of the substrate 110 except for the rear edge of the substrate 110 and the part where the rear bus bar 152 is located. 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.

The back electrode 151 is in contact with the rear electric field portion 172 which maintains the impurity concentration higher than that of the substrate 110 so that the contact between the substrate 110 and the rear electric field portion 172 and the rear electrode 151 The resistance is reduced 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).

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

When light is irradiated to the solar cell 1 and is incident on the emitter portion 120 and the substrate 110 through the front protective portion 125, electron-hole pairs are generated in the semiconductor portion due to light energy. At this time, the reflection loss of the light incident on the substrate 110 is reduced by the texturing surface of the substrate 110 and the front protective portion 125, 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 emitter section 120, and the electrons and the holes are separated from each other by, for example, the emitter section 120 having the n-type conductivity type and the p- Type substrate 110, respectively. Electrons migrated toward the emitter section 120 are collected by the plurality of finger electrodes 141 and the plurality of front bus bars 142 and travel along the plurality of front bus bars 142 to the substrate 110 The moved 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.

Next, FIGS. 3A to 3G illustrate an example of a method of manufacturing the solar cell 1 shown in FIGS. 1 and 2. FIG.

3A, a plurality of protrusions are formed on the entire surface of the semiconductor substrate 110 by texturing the entire surface of the semiconductor substrate 110 having the first conductivity type. Before the texturing process, there are a saw damage process that occurs during a slicing process for cutting an ingot-shaped semiconductor into a semiconductor substrate for a solar cell, and a contamination substance existing on the surface of the semiconductor substrate A cleaning process for removing the cleaning liquid may be further performed.

Such a texturing process may use a wet etching process, and may perform a cleaning process to clean the surface of the semiconductor substrate 110 after the wet etching process.

3B, the emitter layer 120 of the second conductivity type opposite to the first conductivity type is formed on the entire surface of the semiconductor substrate 110 of the first conductivity type.

3C, a hydrogenated silicon nitride film (SiNx: H), a silicon oxide film (SiOx: H), a silicon nitride oxide film (SiNxOy: H), a silicon oxynitride film (SiOxNy: H) and amorphous silicon (a-Si: H).

More specifically, when a hydrogenated silicon nitride film (SiNx: H) is used as the front protective part 125, a hydrogenated silicon nitride film (SiNx: H) may be formed on the emitter part 120 by coating.

If a hydrogenated silicon oxide film (SiOx: H) is formed on the emitter layer 120 by the front surface protecting part 125, a thermal oxide layer forming method may be used.

When the amorphous silicon (a-Si: H) layer is formed on the emitter section 120 as the front surface protection section 125, the amorphous silicon (a- Si: H) layer may be deposited.

As described above, the method of forming the front surface protecting part 125 on the emitter part 120 can be variously implemented.

3D, a first electrode 140 formed on the front protection part 125 and connected to the emitter part 120 through the front protection part 125 is formed, An impurity of the same conductivity type as that of the substrate 110 may be diffused into the opposite surface of the substrate 110 on the opposite side of the substrate 110 to form a rear electric field 172 doped at a higher concentration than the substrate 110.

In addition, the second electrode 150 including the rear electrode 151 and the rear bus bar 152 may be formed on the rear electric part 172.

Meanwhile, during the process of forming the first electrode 140 and the rear electric section 172, a heat treatment process is accompanied.

More specifically, in order to form the first electrode 140, the conductive paste is patterned on the upper surface of the front protective portion 125, and then the conductive paste passes through the front protective portion 125 through the heat treatment process, (Not shown).

When the second electrode 150 is first formed on the rear surface of the substrate 110, the rear electric conductor 172 is subjected to a heat treatment process so that impurities of the first conductivity type included in the second electrode 150 And may be diffused into the backside of the substrate 110.

As described above, the heat treatment for forming the first electrode 140 and the heat treatment for forming the second electrode 150 or the rear electric part 172 may be simultaneously performed through a single heat treatment process.

Meanwhile, during the heat treatment process, heat is also applied to the front protective portion 125 to affect the hydrogen contained in the front protective portion 125, so that the hydrogen concentration inside the front protective portion 125 can be reduced have.

If the hydrogen concentration in the front protective portion 125 is reduced as described above, the passivation function of the front protective portion 125 described above with reference to FIGS. 1 and 2 can be weakened, so that the photovoltaic efficiency of the solar cell 1 is lowered .

3E, when hydrogen (H) in a plasma state is injected on the front protective part 125, the first electrode 140 and the rear electric part 172 are formed in a heat treatment process It is possible to enhance the passivation function of the front surface protecting part 125 by supplementing the hydrogen concentration of the front surface protecting part 125 which is reduced.

3E, the step of injecting hydrogen to the front surface protective part 125 is a step of injecting hydrogen gas (H ₂ ) from the outside into the plasma jet (Plama jet, A plasma torch 300 may be used.

An inert gas such as argon (Ar) or nitrogen (N ₂ ) gas may be used as the process gas. The plasma torch 300 may include an anode and a cathode, When a high voltage is applied between the anode and the cathode in the state of being introduced into the torch 300, the plasma jet 300 is emitted.

3E, when the hydrogen gas H ₂ is injected into the plasma torch 300, the hydrogen gas H ₂ is supplied to the hydrogen H in the plasma state, So that the plasma jet 300 is injected into the front protective part 125 when the plasma jet 300 is injected.

On the other hand, a method of spraying hydrogen (H) in a plasma state may use a PECVD apparatus, as shown in FIG. 3E.

If the PECVD apparatus is used, the moving solar cell 1 in one process line is moved from the process line to the chamber of the PECVD apparatus, and then the PECVD apparatus is operated so that hydrogen (H ). In this way, hydrogen gas (H ₂ ) is injected into the PECVD apparatus together with the process gas in order to cause the PECVD apparatus to inject plasma H in the chamber.

However, as shown in FIG. 3E, when the plasma torch 300 is used, the process efficiency can be improved as compared with the PECVD apparatus.

This is because, when the plasma torch 300 is used, the plasma torch 300 can be installed above the process line of the solar cell 1 due to the lightness of the plasma torch 300, (H) in a plasma state can be injected into the plasma 125.

Accordingly, in the case of using the plasma torch 300, it is not necessary to move to a separate place in the process line in order to inject hydrogen into the solar cell 1 moving along the process line, so that the process time can be saved, The process efficiency can be improved due to the characteristics of the plasma torch 300 that can be used.

The temperature of the plasma jet 310 ejected from the plasma torch 300 is controlled by the plasma torch 300 so that the plasma torch 300 is ejected from the plasma torch 300. [ ≪ / RTI > For example, the temperature t1 of the central portion of the plasma jet 310 adjacent to the plasma torch 300 becomes approximately 1000 ° C or higher, and the temperature of the plasma jet 310 decreases as the distance from the plasma torch 300 increases. .

The distance D between the front surface protective part 125 and the plasma torch 300 may vary depending on the capacity of the plasma torch 300. However, 300 may be between 250 ° C and 800 ° C.

The reason why the temperature of the plasma jet 300 is 250 ° C. or more is to efficiently introduce the hydrogen H contained in the plasma jet 300 into the front protective part 125, To prevent the first electrode 140, the emitter 120, or the semiconductor substrate 110 from being excessively heated in the plasma jet 300.

In addition, as shown in FIG. 3E, the step of spraying hydrogen (H) in a plasma state to the front protective part 125 may be performed after the heat treatment process of the first electrode and the second electrode. This is because, as described above, since the front protective part 125 is already formed, the front protective part 125 is formed during the heat treatment process for forming the first electrode 140, the second electrode 150 or the rear electric part 172 125) can be reduced.

As described above, the solar cell manufacturing method according to the present invention is characterized in that after the front protective part 125 is formed, the first electrode 140 and the second electrode 150 are subjected to a heat treatment process, The step of spraying hydrogen (H) in a plasma state is performed once more to enhance the passivation function of the front surface protective part 125, so that the photovoltaic efficiency of the solar cell 1 can be improved.

In addition, unlike the manufacturing method of the solar cell 1 according to the present embodiment, the manufacturing method of the solar cell 1 according to the alternative example may further include the edge isolation step.

3B, when the emitter section 120 is formed on the front surface as well as the front surface of the semiconductor substrate 110, the side separating step may include a front protecting section 125 and a plurality of emitter sections 120 The first electrode 140 and the second electrode 150 for outputting different kinds of charges are formed on the side surface of the semiconductor substrate 110 by exposing the edges of the semiconductor substrate 110, Thereby preventing electrical contact with the emitter section 120 located therein. Such a side separation step can be performed using a laser.

If such a side separation step is further included, the step of injecting hydrogen may be performed after or before the side separation step.

Here, when the step of injecting hydrogen is performed after the side separation step, the passivation function of the front protective part 125 can be further strengthened as described above.

This eliminates the edges of the emitter section 120 and the front surface protection section 125 using the laser in the side separation step. At this time, the edges of the front surface protection section 125 are heated by the laser. In this case, the concentration of hydrogen may be lowered at the edge portion of the front surface protective portion 125. If the step of spraying hydrogen is performed after the side separation step as in the present invention, This makes it possible to further enhance the passivation function of the front protection part.

1, 2 and 3A to 3E, the manufacturing method of the solar cell 1 according to the present invention is different from that of the first embodiment in that the first electrode 140 and the emitter section 120 are arranged in the direction of the incident surface of the semiconductor substrate 110 The present invention is also applicable to a solar cell having a structure in which the first electrode 140 and the emitter section 120 are formed in the direction opposite to the incident surface of the semiconductor substrate 110 .

4 and 5 are diagrams for explaining another example of a solar cell to which the method of manufacturing a solar cell according to the present invention can be applied.

4 is a cross-sectional view illustrating an IBC (Back-contact) structure in which an emitter section 120 is formed on a rear surface of a semiconductor substrate 110 and a first electrode 140 is formed on an emitter section 120, ) Is an example of a solar cell (2).

In the IBC solar cell 2 shown in FIG. 4, a backside protection (not shown) having the same function as the front protection unit 125 is provided between the first electrode 140 and the second electrode 150 on the rear surface of the semiconductor substrate 110 Shaped portion 192 is formed as an example, this may be omitted.

The IBC solar cell 2 as shown in FIG. 4 may also be formed after the front protection part 125 is formed, so that impurities are removed from the semiconductor substrate 110 Or the first electrode 140 or the second electrode 150 is formed on the emitter layer 120 or the rear electric field portion 172. In the heat treatment process, Can be performed.

If the heat treatment process is performed after the front protective portion 125 is formed, the passivation function of the front protective portion 125 may be weakened as described above with reference to FIG. 3D, Likewise, after all the other heat treatment processes are performed, the step of spraying hydrogen (H) in a plasma state to the front protective portion 125 is performed once more to enhance the passivation function of the front protective portion 125 So that the photoelectric efficiency of the solar cell 2 can be improved.

The solar cell 3 shown in FIG. 5 is a solar cell having a back contact structure as described above with reference to FIG. 4. The semiconductor substrate 110 is crystalline silicon, and the emitter portion 120 and the rear surface The electric field portion 172 is a heterojunction structure formed of amorphous silicon.

In the case of the solar cell 3 having such a heterojunction structure, after the front protective part 125 is formed, the rear electric part 172, the emitter part 120, the first electrode 140 or the second electrode 150 may be formed by a heat treatment process.

However, after the heat treatment process for forming the rear electric section 172, the emitter section 120, the first electrode 140, or the second electrode 150 is performed as shown in FIG. 3E of the present invention, The step of spraying the hydrogen H in a plasma state to the protective portion 125 is performed once more to enhance the passivation function of the front surface protective portion 125, thereby improving the photoelectric efficiency of the solar cell 3 .

In addition, in the method of manufacturing a solar cell according to the present invention, after the front protecting part 125 is formed, a heat treatment process for forming another constitution of the solar cell is performed, and then, as shown in FIG. 3E of the present invention, The step of spraying the hydrogen (H) in a plasma state to the protective portion 125 is performed once more, so that it can be used in the process of manufacturing solar cells of various structures.

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.

110: substrate 120: emitter portion
125: front protection part 140: first electrode
141: finger electrode 142: front bus bar
150: second electrode 151: rear electrode
152: rear bus bar 172: rear front fascia

Claims (11)

Forming an emitter portion having a second conductivity type opposite to the first conductivity type on a semiconductor substrate of a first conductivity type;
Forming a front protective portion on an incident surface of the semiconductor substrate;
Forming a first electrode connected to the emitter by performing a heat treatment process after printing a conductive paste;
Forming a second electrode connected to the semiconductor substrate; And
And spraying hydrogen (H) in a plasma state to the front surface protection portion after the heat treatment process for forming the first electrode, thereby increasing the hydrogen concentration of the front surface protection portion reduced by the heat treatment process ,
In the step of injecting hydrogen, a plasma torch is used in which hydrogen gas (H ₂ ) is injected from the outside and a plasma jet, which is changed into hydrogen (H) in a plasma state, is injected,
Wherein the temperature of the plasma jet including the hydrogen on the surface of the front protective part in the step of spraying the hydrogen is between 250 ° C and 800 ° C. delete delete The method according to claim 1,
The forming of the second electrode includes printing a conductive paste and then performing a heat treatment process. The heat treatment process for forming the second electrode and the heat treatment process for forming the first electrode are simultaneously performed. Gt; The method according to claim 1,
Wherein the step of injecting hydrogen is performed before or after the edge isolation step of exposing a part of the semiconductor substrate by removing the edges of the front protective part and the emitter part below the front protective part. ≪ / RTI > The method according to claim 1,
Wherein the front surface protection portion includes at least one of a hydrogenated silicon nitride film, a hydrogenated silicon oxide film, a hydrogenated silicon nitride oxide film, a hydrogenated silicon oxynitride film, and a hydrogenated amorphous silicon film. The method according to claim 1,
Wherein at least one of the hydrogenated silicon nitride film, the hydrogenated silicon oxide film, the hydrogenated silicon nitride oxide film, the hydrogenated silicon oxynitride film, and the hydrogenated amorphous silicon film is formed of a plurality of layers. Way. The method according to claim 1,
Wherein the emitter portion is formed on an incident surface or an opposite surface of the semiconductor substrate. 9. The method of claim 8,
When the emitter portion is formed on the incident surface of the semiconductor substrate,
Wherein the front protective portion is formed on the emitter portion,
Wherein the first electrode is formed on an upper portion of the front protection portion and is connected to the emitter portion through the front protection portion. 9. The method of claim 8,
When the emitter portion is formed on the side opposite to the semiconductor substrate incident surface,
Wherein the first electrode is formed on an opposite surface of the semiconductor substrate and is connected to the emitter. The method according to claim 1,
The manufacturing method of the solar cell
Further comprising the step of forming a rear surface electric field portion on the opposite side of the semiconductor substrate incident surface.

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