KR20090128913A - Texturing apparatus and method for solar battery silicon board - Google Patents

Abstract

PURPOSE: A texturing apparatus and a method for a solar battery silicon board are provided to improve the efficiency of chemical dry etch by using first catalytic gas including oxygen, a nitrogen component and a second catalytic gas including nitric. CONSTITUTION: In a device, a texturing apparatus of a silicon substrate for the solar cell includes a chamber and a gas supply unit. A gas supply unit injects a reaction gas, first gas, and the second catalytic gas into the chamber. The gas supply unit includes the first feeding unit(120) injecting the reaction gas, a second feeding unit(130) injecting the first catalytic gas, and a third feeding unit(140) injecting the second catalytic gas. The reaction gas and the first catalytic gas which are plasma and provided to the chamber. The second catalytic gas which is not plasma is provided to the chamber.

Description

TEXTURING APPARATUS AND METHOD FOR SOLAR BATTERY SILICON BOARD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a texturing apparatus and method for a silicon substrate for a solar cell, and more particularly, to a texturing apparatus and method for a silicon substrate for a solar cell, which can prevent damage to a surface of a substrate generated during a texturing process and effectively reduce reflectance. It is about.

In general, a solar battery is a photovoltaic cell manufactured for converting solar energy into electrical energy. When light is irradiated on a contact surface of a metal and a semiconductor or a PN junction of a semiconductor, photovoltaic power is generated by a photoelectric effect. It is a battery using the principle. Examples of such solar cells include selenium photovoltaic cells using metal and semiconductor contacts, copper sulfite photovoltaic cells, and silicon photovoltaic cells using semiconductor PN junctions.

Among the various types of solar cells described above, a solar cell using a semiconductor PN junction has a structure in which an N-type silicon semiconductor layer is formed by diffusing phosphorus (P) on the surface of a P-type silicon semiconductor in which boron (B) is added to silicon. Is done. When light enters the structure, electrons (-) and holes (+) in the semiconductor are excited to move freely inside the semiconductor, and the freely moving electrons (-) and holes (+) are generated by PN junctions. The electrons (-) move to the N-type semiconductor, and the holes (+) move to the P-type semiconductor.

Recently, in order to increase the efficiency of solar cells, a method of maximizing light absorption by texturing the surface of a substrate has been used. Such texturing methods include plasma etching and mechanical scribing. And photolithography.

Among them, the plasma etching method is a method of applying a photoresist to form a pattern, followed by etching using a plasma and removing a mask layer, which requires a long time and requires expensive vacuum equipment, so it is less commercially available. .

In addition, the mechanical scribing method is a method of forming a groove on the surface of the substrate and texturing using chemical etching, which also takes a long time, making it difficult to commercially produce and apply to thin films. .

In addition, the method using photolithography is a method that forms a pattern by applying a photoresist on the substrate with an oxide film and texturing it through anisotropic / isotropic etching method, which is too expensive to commercially apply to the production of polycrystalline solar cells Hard.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a texturizing apparatus and method for fabricating a silicon substrate for a solar cell, which can prevent damage to the surface of a substrate generated during a texturing process and effectively reduce reflectance.

In addition, another object of the present invention is to provide a texturing apparatus and method of the silicon substrate for solar cells, which can shorten the texturing work time, reduce the manpower and cost required during the work and commercially available.

According to another aspect of the present invention, a texturing apparatus for a silicon substrate for a solar cell according to the present invention includes a chamber in which a substrate stage is provided, a first supply pipe for supplying a reaction gas containing a fluorine component to the chamber, and the first supply pipe on the first supply pipe. And a first remote plasma generator configured to convert the reaction gas into plasma. That is, dry etching is performed by exposing the surface of the substrate to a reaction gas (reaction gas containing a fluorine component) that is plasmaized through the first remote plasma generator.

The texturing apparatus of the silicon substrate for a solar cell according to the present invention having the above-described configuration may use a variety of catalysts to improve the chemical dry etching efficiency using the reaction gas.

To this end, it may further include a second supply pipe for supplying a first catalyst gas containing oxygen and nitrogen components to the chamber, and a second remote plasma generator provided on the second supply pipe for plasmalizing the first catalyst gas. have. In addition, it may further comprise a third supply means for supplying a second catalyst gas containing a nitrogen oxide component directly to the chamber.

Meanwhile, another device for improving the chemical dry etching efficiency using the reaction gas, a lower electrode provided inside the substrate stage, an upper electrode spaced upwardly from the lower electrode by a predetermined interval, and a high frequency power source is applied to the upper and lower electrodes. It may further comprise a power supply means for supplying.

Here, the reaction gas is a gas containing a fluorine component as described above, at least one of F ₂ , NF ₃ , and at least one of N ₂ , O ₂ , N ₂ O, and NO ₂ are preferably combined. The first catalyst gas may include N ₂ , O ₂ , N ₂ O, and NO ₂ as a gas including oxygen and nitrogen, and may be supplied to a chamber by being plasmaized through the second remote plasma generator. . In addition, the second catalyst gas is a gas containing a nitrogen oxide component, a gas in which one or more of N _X O _X and Ar are combined, and is preferably supplied directly to the chamber through a third supply means.

The texturing method of the silicon substrate for a solar cell according to the present invention uses a reaction gas containing a fluorine component to prevent damage to the surface of the substrate generated during the texturing process and effectively reduce the reflectance. That is, chemical dry etching is performed by exposing the surface of the substrate to the first radical generated by plasma-forming a reaction gas containing a fluorine component.

Herein, the present invention may use various types of catalysts to improve chemical dry etching efficiency, wherein the surface of the substrate is formed on the second radical generated by plasmalizing the first catalyst gas including the first radical and oxygen and nitrogen components. The dry etching may be performed by exposing the surface of the substrate to the second catalyst gas including the first radical and the nitrogen oxide component. In addition, dry etching may be performed by exposing the surface of the substrate to the first and second radicals and the second catalyst gas.

Meanwhile, high-frequency power is applied to the upper and lower portions of the substrate to further improve the texturing efficiency and speed, thereby further generating plasma inside the chamber. At this time, the plasma generation method using a high frequency power supply is a continuous method of applying a high frequency power to both the top and bottom of the substrate, a stepwise method of applying a high frequency power to only one side of the top and bottom of the substrate, and the top and bottom of the substrate There is a cyclic method of alternately applying high frequency power.

According to the present invention, an apparatus and method for texturing a silicon substrate for a solar cell is performed by dry etching by exposing the substrate to a plasmaized reaction gas (reaction gas containing a fluorine component) without immersing the substrate in a solution. It can prevent damage and reduce the reflectance effectively.

In addition, by using the first catalyst gas containing the oxygen and nitrogen components and the second catalyst gas containing the nitrogen oxide components in addition to the reaction gas containing the fluorine component, the chemical dry etching efficiency is improved, thereby reducing the texturing work time. It is highly commercially available because it saves manpower and money in the work.

With reference to the accompanying drawings will be described embodiments of the present invention;

1 is a schematic view showing a texturing apparatus for a silicon substrate for solar cell according to the present invention.

As shown in FIG. 1, the texturing apparatus for a silicon substrate for a solar cell according to the present invention includes a chamber 110 and a gas supply unit 120 to 140 for supplying a reaction gas and a catalyst gas to the chamber 110. It consists of.

Looking at the gas supply means 120 ~ 140 first, means for injecting the reaction gas, the first and second catalyst gas into the interior of the chamber 110, the first supply means 120 is injected reaction gas And a second supply means 130 into which the first catalyst gas is injected, and a third supply means 140 into which the second catalyst gas is injected. In this case, the reaction gas and the first catalyst gas are supplied to the chamber 110 in a plasma state, and the second catalyst gas is directly supplied to the chamber 110 in a non-plasma state.

Looking at the configuration of each gas supply means (120 ~ 140) for this purpose, the first supply means 120 is a first supply pipe 122 for supplying the reaction gas and the first provided on the first supply pipe 122 Remote plasma generator 124, the second supply means 130 is a second supply pipe 132 for supplying a first catalyst gas and a second remote plasma generator provided on the second supply pipe (132) 134). In addition, the third supply means 140 is a pipe for supplying the second catalyst gas.

Here, the reaction gas is a gas for chemical dry etching of a silicon substrate (hereinafter, referred to as a substrate) 150 and includes a fluorine component. In addition, the first and second catalyst gas is a gas for improving chemical dry etching efficiency, the first catalyst gas is a gas containing oxygen and nitrogen components, the second catalyst gas is a gas containing nitrogen oxide components. . In one example, the reaction gas is preferably a combination of one or more of F ₂ , NF ₃ , and one or more of N ₂ , O ₂ , N ₂ O, NO ₂ , the first catalyst gas is N ₂ , It is preferable to include O ₂ , N ₂ O, NO ₂ , and the second catalyst gas is preferably a gas in which one or more of N _X O _X and Ar are combined.

Meanwhile, the first and second remote plasma generators 124 and 134 for converting the reaction gas and the first catalyst gas into the chamber 110 remotely supply the generated first and second radicals. Therefore, the first and second remote plasma generators 124 and 134 described above do not shoot the generated first and second radicals directly on the substrate 150, thereby preventing damage to the surface of the substrate 150 generated during the texturing process. .

On the other hand, the first and second remote plasma generator (124,134) is a toroidal type (toroidal) generates an induction magnetic field in the first and second supply pipe (122,132), the secondary induction current according to the first and second The high density plasma is generated by being formed inside the second remote plasma generators 124 and 134. As such, the present invention uses a toroidal type remote plasma generator, but the present invention is not limited thereto, and various types of remote plasma generators such as microwave type and inductively coupled plasma (ICP) types may be used. Of course, can be applied.

The chamber 110, which is another component of the texturing apparatus of the silicon substrate for solar cell according to the present invention, is a portion where the texturing process of the substrate 150 is performed, and a predetermined reaction space 112 is formed therein. In addition, a substrate stage 114 on which the substrate 150 is mounted and fixed is provided in the reaction space 112, and a lower electrode 116d is provided inside the substrate stage 114. In addition, an upper electrode 116u is provided at a position spaced apart upward from the lower electrode 116d by a predetermined interval.

In this case, the upper and lower electrodes 116u and 116d are made of a conductive member and are connected to power supply means 118u and 118d for supplying high frequency power. Therefore, when high frequency power is applied to the upper and lower electrodes 116u and 116d, ion particles are accelerated in the electric field region between them 116u and 116d to ionize the injected gas to generate plasma. That is, since the plasma is further generated inside the chamber 110, texturing efficiency and speed may be improved.

The above-described method for generating plasma using the upper and lower electrodes 116u and 116d includes a continuous method, a stepped method, and a cyclic method. Among them, the continuous method is a method of applying a high frequency power to the upper and lower electrodes 116u and 116d, and the step method is a method of applying a high frequency power to only one of the upper and lower electrodes 116u and 116d. The method is a method of alternately applying high frequency power to the upper and lower electrodes 116u and 116d.

Meanwhile, a method of mounting and fixing the substrate 150 to the substrate stage 114 may include a mechanical method using a chucking tool, a method of using a vacuum force by forming a vacuum hole in the substrate stage 114, and a lower electrode. There is a method of applying power to 116d and absorbing it. Of course, any one can be applied according to the needs of the user and the structure of the device.

2 to 4 are diagrams showing a texturing method using a texturing apparatus for a silicon substrate for a solar cell according to the above configuration. Looking at the various embodiments of the texturing method of the silicon substrate for solar cells according to the present invention with reference to this.

First embodiment

A first embodiment of the method for texturing a silicon substrate for a solar cell according to the present invention performs a chemical dry etching process using a reaction gas containing a fluorine component. As such, when the silicon substrate 150 is exposed to a radical containing a fluorine component, the fluorine component and the silicon component bind to each other to weaken the bond between the silicon components, and promote the formation of SiF ₄ , which is an easy-to-remove reactant. This is because the texturing speed of 150 can be improved.

Looking at the process with reference to Figure 2, the reaction gas supplied through the first supply pipe 122 is plasmalized in the first remote plasma generator (124). The first radical generated at this time is injected into the chamber 110, and the substrate 150 provided inside the chamber 110 is exposed to the first radical to texture the surface of the substrate 150.

At this time, the reaction gas used is a combination of one or more of F ₂ , NF ₃ , and one or more of N ₂ , O ₂ , N ₂ O, NO ₂ , F ₂ / N ₂ / O ₂ , F ₂ / N ₂ O, F ₂ / NO ₂ , F ₂ / N ₂ / O ₂ / Ar, F ₂ / N ₂ O / Ar, F ₂ / NO ₂ / Ar, NF ₃ / N ₂ / O ₂ , NF ₃ / N ₂ O, NF ₃ / NO ₂ , NF ₃ / N ₂ / O ₂ / Ar, NF ₃ / N ₂ O / Ar, NF ₃ / NO ₂ / Ar. In addition, the first radical generated using the reaction gas is in a form in which a fluorine (F) radical or a fluorine radical and a nitrogen oxide (N _X O _X ) radical are mixed.

Second embodiment

A second embodiment of the method for texturing a silicon substrate for a solar cell according to the present invention performs a chemical dry etching process using a reaction gas containing a fluorine component and a first catalyst gas containing oxygen and nitrogen components. In this second embodiment, by further using a radical containing a nitric oxide component in addition to the radical including a fluorine component, it is possible to further promote the generation of the reactant SiF ₄ , thereby rapidly increasing the texturing speed of the substrate 150.

As shown in FIG. 3, the reaction gas supplied through the first supply pipe 122 is converted into plasma by the first remote plasma generator 124 to generate first radicals, and at the same time, the second supply pipe 132 is formed. Through the first catalyst gas to plasma in the second remote plasma generator 134 to generate a second radical. The first and second radicals generated in this way are injected into the chamber 110, and the substrate 150 provided inside the chamber 110 is exposed to the first and second radicals, thereby texturing the surface of the substrate 150. do.

In this case, the reaction gas used is a gas in which one or more of F ₂ and NF ₃ , and one or more of N ₂ , O ₂ , N ₂ O, and NO ₂ are combined as the first embodiment, and the first catalyst gas is used. Is a gas containing a nitrogen oxide component including N ₂ , O ₂ , N ₂ O, and NO ₂ . The first radical generated using the reaction gas is in the form of a fluorine (F) radical or a mixture of fluorine radicals and nitrogen oxides (N _X O _X ) radicals, and the second radical generated using the first catalyst gas It is a nitrogen oxide (N _X O _X ) radical.

Third embodiment

A third embodiment of the method for texturing a silicon substrate for a solar cell according to the present invention performs a chemical dry etching process using a reaction gas containing a fluorine component and a second catalyst gas containing a nitrogen oxide component. In this second embodiment, by further using a radical containing a nitric oxide component in addition to the radical including a fluorine component, it is possible to further promote the generation of the reactant SiF ₄ , thereby rapidly increasing the texturing speed of the substrate 150.

Looking at the process with reference to Figure 4, the reaction gas supplied through the first supply pipe 122 to the plasma generated in the first remote plasma generator 124 to generate a first radical. In addition, the first radical and the second catalyst gas supplied through the fourth supply means 140 are injected into the chamber 110, so that the substrate 150 provided in the chamber 110 is formed of the first radical and the first radical. The surface of the substrate 150 is textured by being exposed to two catalyst gases.

In this case, the reaction gas used is a gas in which at least one of F ₂ and NF ₃ , and at least one of N ₂ , O ₂ , N ₂ O, and NO ₂ are combined as the first embodiment, and the second catalyst gas is used. Is a gas in which at least one of N _X O _X and Ar is combined.

Fourth embodiment

A fourth embodiment of the texturing method of a silicon substrate for a solar cell according to the present invention is based on the first to third embodiments described above. That is, the plasma is additionally generated by applying high frequency power to the inside of the chamber 110 in the process of performing one selected from the first to third embodiments as needed (see FIG. 5).

At this time, a method of generating a plasma by applying a high frequency power source includes a continuous method, a step method and a cyclic method. Among them, the continuous method is a method of applying a high frequency power to the upper and lower electrodes 116u and 116d, and the step method is a method of applying a high frequency power to only one of the upper and lower electrodes 116u and 116d. The method is a method of alternately applying high frequency power to the upper and lower electrodes 116u and 116d.

As such, when the plasma is further generated inside the chamber 110, the texturing efficiency and speed of the substrate 150 may be improved by activating the first and second radicals and the second catalyst gas.

As described above, the method of texturing a silicon substrate for a solar cell according to the first to fourth embodiments includes the first and second radicals and the second and second radicals and the second catalyst gas without directly contacting the substrate. By exposing the substrate to the catalyst gas and chemically dry etching, damage to the surface of the substrate generated during the texturing process can be prevented.

In addition, the fluorine radical or the fluorine radical and the nitrogen oxide radical binds to the silicon component of the silicon substrate 150 to weaken the bond between the silicon and promote the generation of SiF ₄ , which is an easy-to-remove reactant, thus the texturing rate of the substrate 150. Can improve. In particular, when using nitric oxide radicals and nitric oxide gas as in the second and third embodiments, it is possible to further promote the generation of the reactant SiF ₄ , thereby rapidly increasing the texturing speed of the substrate 150. As described above, when the plasma is further generated in the chamber 110, the texturing efficiency and speed of the substrate 150 may be improved by activating the first and second radicals and the second catalyst gas.

Meanwhile, in the process of texturing the substrate 150 using the first to fourth embodiments described above, the temperature of the substrate 150 is preferably maintained at 25 to 300 ° C. In addition, since the first to fourth embodiments described above are independent of the direction of texturing, both single crystal and polycrystalline silicon substrates can be used.

6 is a graph showing a change in reflectivity according to the first experimental example when texturing a silicon substrate for a solar cell according to the present invention.

In the first experimental example, the change of reflectivity according to the flow rate ratio of the nitric oxide gas during texturing of the substrate (150 of FIG. 1) using the method illustrated in the first embodiment was tested. Looking at the experimental conditions at this time, the substrate 150 used is a single crystal substrate, the reaction gas and the first and second catalyst gas comprises a component such as Ar. In addition, the flow rate of the NF ₃ contained in the reaction gas and the first and second catalyst gas is 2100 ~ 2700sccm, NO flow rate is 700 ~ 900sccm, process pressure is 3Torr, process temperature is 100 ℃, texturing time is 1 minute Set.

As a result, as shown in the graph of FIG. 6, the results (substrate reflectance) can be obtained. As shown in the graph, the lowest reflectance (%) can be obtained at a flow rate of 2400 sccm for NF ₃ and 800 sccm for NO. have.

7 is a graph showing a change in reflectivity according to the second experimental example during texturing of the silicon substrate for a solar cell according to the present invention.

In the second experimental example, the reflectivity change according to the texturing time was tested under the condition of the lowest reflectance among the first experimental examples, that is, the flow rate of NF ₃ is 2400sccm and the flow rate of NO is 800sccm.

As a result of the experiment, as the texturing time increases as shown in the graph of FIG. 7, a lower reflectance (%) can be obtained.

Although the configuration of the texturing apparatus and the texturing method using the same of the silicon substrate for a solar cell according to the preferred embodiment of the present invention is shown in accordance with the above description and drawings, but this is only an example and the scope does not depart from the spirit of the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made therein.

1 is a schematic view showing a texturing apparatus for a silicon substrate for a solar cell according to the present invention.

2 is a view showing a first embodiment of the texturing method of the silicon substrate for solar cells according to the present invention.

3 is a view showing a second embodiment of the texturing method of the silicon substrate for solar cells according to the present invention.

4 is a view showing a third embodiment of the texturing method of the silicon substrate for solar cells according to the present invention.

5 is a view showing a fourth embodiment of the texturing method of the silicon substrate for solar cells according to the present invention.

Figure 6 is a graph showing the change in reflectivity according to the flow rate of nitric oxide gas during texturing of the silicon substrate for solar cells according to the present invention.

7 is a graph showing a change in reflectivity according to texturing time during texturing of a silicon substrate for a solar cell according to the present invention.

* Description of the symbols for the main parts of the drawings *

110: chamber 120: first supply means

130: second supply means 140: third supply means

150: substrate

Claims (18)

A chamber in which a substrate stage is provided; A first supply pipe supplying a reaction gas containing a fluorine component to the chamber; And And a first remote plasma generator provided on the first supply pipe to plasma the reaction gas. The method of claim 1, Texturing of a silicon substrate for a solar cell comprising a second supply pipe for supplying a first catalyst gas containing oxygen and nitrogen to the chamber, and a second remote plasma generator provided on the second supply pipe for plasmalizing the first catalyst gas. Device. The method according to claim 1 or 2, And a third supply means for supplying a second catalyst gas containing a nitrogen oxide component directly to the chamber. The method of claim 3, Texturing of a silicon substrate for a solar cell further comprises a lower electrode provided inside the substrate stage, an upper electrode spaced upward from the lower electrode by a predetermined interval, and a power supply means for supplying high frequency power to the upper and lower electrodes. Device. The method of claim 4, wherein The reaction gas is one or more of F ₂ , NF ₃ , and at least one of N ₂ , O ₂ , N ₂ O, NO _{2 It} is a gas texturing apparatus of a silicon substrate for a solar cell characterized in that combined. The method of claim 4, wherein And the first catalyst gas is a gas in which one or more of N ₂ , O ₂ , N ₂ O, and NO ₂ are combined. The method of claim 4, wherein The second catalyst gas is N _X O _X , Ar texturing apparatus for a silicon substrate for a solar cell, characterized in that the combination of at least one of Ar. The method of claim 4, wherein And the first and second remote plasma generators are any one of a toroidal type, a microwave type, and an inductively coupled plasma type. In the texturing method of the silicon substrate for solar cells, A method of texturing a silicon substrate for a solar cell, comprising etching the dry gas by exposing the surface of the substrate to a first radical generated by plasma-forming a reaction gas containing a fluorine component. The method of claim 9, A method of texturing a silicon substrate for a solar cell, wherein the first catalyst gas including oxygen and nitrogen components is plasma-generated to generate second radicals, and dry etching is performed by exposing the surfaces of the substrate to the first and second radicals. The method of claim 9 or 10, A method of texturing a silicon substrate for a solar cell, further comprising dry etching the surface of the substrate using a second catalyst gas containing a nitrogen oxide component. The method of claim 11, A method of texturing a silicon substrate for a solar cell, wherein a high frequency power is applied from at least one of the upper and lower portions of the substrate. The method of claim 12, Method for texturing a silicon substrate for a solar cell, characterized in that the high frequency power is applied alternately in the upper and lower portions of the substrate. The method of claim 13, The reaction gas is one or more of F ₂ , NF ₃ , and at least one of N ₂ , O ₂ , N ₂ O, NO _{2 It} is a combination method of texturing a silicon substrate for a solar cell. The method of claim 13, The first catalyst gas is N ₂ , O ₂ , N ₂ O, NO ₂ characterized in that the silicon substrate for a solar cell texturing method. The method of claim 13, The second catalyst gas is a method of texturing a silicon substrate for a solar cell, characterized in that the combination of one or more of N _X O _X , Ar. The method of claim 13, A method of texturing a silicon substrate for a solar cell, wherein the temperature of the substrate is maintained at 25 to 300 ° C. The method of claim 13, A method of texturing a silicon substrate for a solar cell, characterized in that the substrate comprises a monocrystalline or polycrystalline silicon substrate.

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