KR101573044B1 - A process of making micro-sized pores on surface - Google Patents

A process of making micro-sized pores on surface Download PDF

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KR101573044B1
KR101573044B1 KR1020130154525A KR20130154525A KR101573044B1 KR 101573044 B1 KR101573044 B1 KR 101573044B1 KR 1020130154525 A KR1020130154525 A KR 1020130154525A KR 20130154525 A KR20130154525 A KR 20130154525A KR 101573044 B1 KR101573044 B1 KR 101573044B1
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light
present
light source
laser
medium
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KR20150068640A (en
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노도영
손준곤
최정원
강현철
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광주과학기술원
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E10/50—Photovoltaic [PV] energy

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Abstract

The present invention relates to a method of fabricating a microstructure using a laser, and more particularly, to a method of manufacturing a microstructure by using a capillary wave in which a thermal energy generated in a target material by a laser is generated by a convection phenomenon, To a method of forming a pattern having a three-dimensional structure.
It is still another object of the present invention to provide a method of increasing the energy conversion efficiency by increasing the absorption ratio of incident light by increasing the area of optically junction by forming a micrometer-sized fine porous structure on the surface of a solar cell using a laser. Specifically, a microwave-sized porous bend is formed by utilizing a capillary wave and a phase explosion which are formed on a target material by using a laser to transmit the optical energy, To improve the light conversion efficiency.

Figure 112013113772481-pat00001

Description

[0001] The present invention relates to a micro-sized porous surface structure,

The present invention relates to a method of manufacturing a microstructure using a laser, and more particularly, to a micrometer-sized porous structure using a capillary wave generated by a convection phenomenon of thermal energy generated in a target material using a laser Dimensional structure having a repeating three-dimensional structure.

Recent developments in solar cell technology have generally played a role in the conversion of electrical energy based on the composition of semiconductor materials and have attempted to improve the functioning of additional structures in addition to that. At the time of initial solar cell development, the power generation efficiency was 4%. However, in the case of PV power plants currently in operation in Korea, the power generation efficiency is about 17%.

In FIG. 8, the structure of the double-layer p-n junction type silicon solar cell is shown, and an aniti-reflection layer is disposed on the uppermost layer to absorb a maximum amount of light energy incident on the sunlight. The improvement of the light absorptivity using the antireflection layer can be approached as a structural aspect having a material aspect using the characteristics of constituent elements and a shape capable of increasing the optical absorption rate. In the case of FIG. 9, the silicon layer of the solar cell is surface-treated in a concave cone shape to improve the energy conversion efficiency of the solar cell in terms of structure.

For this type of machining, the machining techniques of solid materials such as metal or semiconductor wafers are generally followed, and in most cases chemical methods and optical methods or a combination of both methods are used. As a method for forming the microstructure, a photoresist (PR), a photoresist and a photomask are used as in the general photolithography process of FIG. 6, It is necessary to make mask, align, exposure step and develop step, and the layer structure for one material is completed through additional baking process at each step.

In order to make the cone-shaped concave structure, at the exposing step of the above-described process, the target solid material is tilted sideways and rotated by the motion controller. In this method, an additional motor driving system There is a hassle.

A commonly used method is a method of forming a porous surface structure using the template of FIG. 7, wherein a template material such as polystyrene (PS) is applied and etched as shown above, Or a method in which a porous surface is formed by first removing the applied template material after deposition. In this case, the processing in the depth direction is limited and complicated processes such as preparation, application and removal of the template, and conventional general chemical processing methods are performed.

The above-described conventional processing techniques have many items to be controlled under the respective process conditions, there is a complication of the processing step, and equipment costs are increased due to the necessity of various equipments. This causes problems in the management of each process step with the increase in production costs, and the use of various chemical agents may cause fatal problems such as human and environmental pollution that often occur in the semiconductor workplace recently.

Accordingly, it is an object of the present invention to provide an improved manufacturing method that can simplify the process of manufacturing such complicated components and reduce production and process management costs.

It is another object of the present invention to provide a method for achieving a non-hazardous environmentally friendly process according to the selection of an intermediate material that is a component between a laser and a material to be processed.

Another object of the present invention is to provide a method of increasing the energy conversion efficiency by increasing the absorption ratio of incident light by increasing the area of optically junction by forming a micrometer-sized fine porous structure on the surface of a solar cell using a laser.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

According to the present invention, there is provided a solution to the above problem, characterized in that it comprises a light source and an intermediate material through which light irradiated from the light source is transmitted to mediate energy to the object, and a material to be processed.

Here, the intermediate material is disposed between the light source and the object to be processed so that light irradiated from the light source can be transmitted and transmitted. At this time, the irradiation direction of the light source does not have restrictions on the vertical, horizontal, and arbitrary angles on the basis of the material to be processed. At this time, the interface between the medium and the material to be processed is limited to the machined surface on which the porous structure is produced.

As a means for solving the problem of the present invention, the object to be processed may be placed in an intermediate material, and an auxiliary water tank capable of containing the intermediate material and the object to be processed may be required.

It is preferable that such a water tank is made of a material having good light transmittance for light energy transfer. However, the constituent material of the water tank is not limited thereto, and it is necessary to have a simple structure and auxiliary optical conversion The shape of the water tank and the like are not limited and a specific form is not required.

In addition, the term "tank" means only a container capable of holding water. In the present invention, the medium contained in the tank should not necessarily be understood as "water."

In the practice of the present invention, it is preferable to arrange the mediating substance on the surface of the material to be processed. In this case, a second type of water bath may be required to limit the position of the mediating substance. It does not have to be limited to the water tank in the means.

Hereinafter, the present invention will be described with reference to the following examples. The details of other embodiments are included in the detailed description and drawings. However, it is to be understood that the scope of the present invention is not limited by these embodiments.

Therefore, according to the solution of the above-mentioned problem, the light irradiated from the light source transmits the mediating substance and irradiates the processing target substance with the light. Therefore, under the surface of the object to be processed in contact with the medium, the movement of molecules is generated by Rayleigh-Benard convection, and the movement of these molecules on the surface generates a capillary wave, The surface morphology changes. As shown in FIGS. 4 and 5, the change of the surface shape forms a porous structure having a cone shape in the depth direction in the form of dense polygons having a diameter of several tens of micro-sized.

Accordingly, the porous surface structure of the present invention can be realized, and the manufacturing process of complex components can be simplified to reduce production and process control costs.

In addition, in FIG. 4, it can be understood that the porous silicon surface produced by using water as an intermediate material can be processed in such an environment by an environmentally friendly process in which the harmfulness is removed through the method proposed by the present invention.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the claims.

1 is a conceptual view showing a manufacturing method according to an embodiment of the present invention.
2 is a conceptual diagram showing a manufacturing method according to another embodiment of the present invention.
3 is a conceptual diagram showing a manufacturing method according to another embodiment of the present invention.
FIG. 4 is a photograph of a surface of a silicon wafer prepared by a manufacturing method according to an embodiment of the present invention and observed with an electron microscope. FIG.
FIG. 5 is a photograph of a surface of a silicon nitride wafer prepared by a manufacturing method according to an embodiment of the present invention and observed with an electron microscope. FIG.
6 is a schematic diagram of a conventional general photolithography process.
7 is a schematic view of a porous surface structure forming process using a conventional template material.
8 is a schematic view showing the structure of a general double-layer pn junction type silicon solar cell.
9 is a schematic view showing a structure of a silicon solar cell having a concave porous structure as a surface layer.

One aspect of the present invention relates to a method of processing a surface texture, characterized by comprising irradiating a surface of an object to be irradiated in contact with a medium with light passing through the medium. In the present invention, surface texturing includes forming patterned fine grooves in an object to be examined.

According to one embodiment, the light source of light may be impregnated in the medium, or may be located outside the medium.

According to another embodiment, light may be incident directly onto the medium and then reach the surface of the object to be irradiated, or may enter the medium after passing through the intermediate, and then reach the surface of the object to be irradiated. At this time, the intermediate material may be a water tank wall containing the medium.

According to another embodiment, the medium can be selected from water, ethanol, methanol and mixtures of two or more thereof.

According to another embodiment, the object to be irradiated may be at least one selected from a metal, a metal oxide, a metal nitride, a metalloid, a metalloid oxide, a metalloid nitride, and a metalloid carbide.

According to another embodiment, the object to be irradiated is silicon (Si) or silicon nitride (SiN x ) or silicon carbide (SiC), wherein x is from 0.2 to 2, preferably from 0.7 to 1.7, 1.5.

According to another embodiment, examples of light sources of light include, but are not limited to, laser diodes, lasers, and the like having a linearity.

According to another embodiment, the light may have a wavelength of 300 nm to 600 nm, the output of light may be 0.5 W to 5 W, the step of irradiating light may be performed for 1 minute to 2 hours, The light irradiation interval may be 10 Hz to 40 Hz, and the pulse duration time of the light irradiation may be 7 ns to 15 ns.

In the present invention, the meaning that the used light has a certain range of wavelength does not mean that the light having the wavelength range outside the specific range physically is not generated at all from the used light source. Means that a substantial amount of light irradiated from a light source is present in the corresponding wavelength range, for example, 60%, 70%, 80%, 90%, or 95% Is present in the corresponding wavelength range.

Or that the wavelength exhibiting the maximum intensity of the light used is within the wavelength range. For example, if the laser used has a wavelength of 532 nm, it means that the light with a wavelength of 532 nm shows the strongest intensity in the wavelength versus intensity graph.

According to another embodiment, when the object to be irradiated is in particular silicon or silicon nitride or silicon carbide, (i) the medium is selected from water, ethanol, methanol and a mixture of two or more thereof, (ii) It is confirmed that the groove shape and arrangement are regularly formed and that the depth of the groove can be formed to be closest to the groove radius. If any of the following conditions is not satisfied, this effect is not exhibited Respectively.

The light source of light is a laser with a wavelength of 500 to 550 nm

② The output of the light source is 0.5 W to 1.5 W

③ Light irradiation step is performed for 10 minutes to 50 minutes

④ Light irradiation interval is 15 Hz to 25 Hz

⑤ Pulse duration of light irradiation is 7 ns to 15 ns

At this time, the surface microstructure formed by the surface texturing as described above has a structure in which a plurality of grooves having a diameter of 10 占 퐉 to 20 占 퐉 are adjacent to each other.

Another aspect of the invention relates to an irradiated object textured to a surface according to various embodiments above.

Another aspect of the present invention relates to a solar cell element including the object to be irradiated.

Another aspect of the present invention relates to a catalyst comprising the object to be irradiated as described above.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, as well as the structure and method of achieving them, will become apparent by reference to various embodiments described in detail below with reference to the accompanying drawings.

However, it is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It is intended that the disclosure of the present invention be limited only by the terms of the appended claims.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Prior to the description, the preferred embodiments of the present invention are divided into first, second, and third embodiments. In order to clearly distinguish the first, second, and third embodiments, In advance.

FIG. 1 is a schematic side view showing a manufacturing method according to a first preferred embodiment of the present invention, and FIG. 2 is a schematic side view showing a manufacturing method according to a second preferred embodiment of the present invention.

1 and 2, a manufacturing process according to a preferred embodiment of the present invention includes a light source 110, a light energy transfer medium 120, a material to be processed 130 and a first type of water tank 140 ).

1, the light source 110 is positioned in the vertical direction of the object to be processed 130 as shown in FIG. 1, and the emitted light is transmitted through the light energy transfer medium 120 to be processed And transferred to the surface of the object material 130.

FIG. 2 is a second embodiment of the present invention. As shown in FIG. 2, unlike the first embodiment, the light source 110 is positioned horizontally with the object to be processed 130, Type water tank 140 and the light energy transfer medium 120 and is transferred to the surface of the object to be processed 130.

FIG. 3 is a third embodiment of the present invention. As shown in FIG. 3, the light source 110 is located in the vertical direction of the object to be processed 130 as shown in the drawing. Unlike the first and second embodiments, Is located at a position defined by the water tank 150 of the second type on the surface of the object to be processed 130 and the light emitted from the vertical direction is transmitted through the light energy transfer medium 120, .

The difference between the first embodiment and the second embodiment of the present invention is that the light energy is transmitted between the incident position of the light source 110 and the light energy transfer medium 120 firstly between the light source 110 and the workpiece material 130 Whether or not the water is transmitted through the water tank 140 of the first embodiment.

The difference between the first, second and third embodiments of the present invention lies in the fact that the light-energy transfer medium 120 is impregnated with the material 130 to be processed. In the case of the first and second embodiments, the object to be processed 130 is a structure in which the light source 110 is irradiated on the contact surface impregnated with the light energy transfer medium 120 in whole or in part, In the embodiment, the light energy transfer medium 120 has a structure in which a contact surface is formed at a limited position with the object to be processed 130 by the water tank 150 of the second type, and the light source is irradiated on the contact surface.

The present invention is advantageous in that it does not require any additional optical processing or conversion other than the components of the above-mentioned process, and does not require a chemical process or treatment method.

The light source 110 may be incident on one side in a horizontal plane, a vertical plane, or an arbitrary angle with respect to the object to be processed 130, But the angle is not limited in the present invention. The position of the light source 110 may be disposed outside the first type of water tank as shown in FIGS. 1 and 2, or may be irradiated to one side in a form impregnated with the light energy transfer medium 120. The light source 110 may be a known device such as a laser diode or a laser having a directivity, and the use of a light source of 300 to 600 nm as the wavelength of the light source 110 may achieve the desired effect of the present invention. . The output of the light source 110 is preferably 0.5 to 2 W, and an output that is too small can not form a capillary wave at the surface of the object to be processed 130, And it does not proceed to the process of forming a porous surface structure. The irradiation time of the light source 110 is affected by the output, but it is preferably 1 minute to 1 hour. In a too short time, the surface does not change, and when the irradiation time is too long, the formed porous surface is collapsed again do.

The light energy transfer medium 120 is preferably a liquid type material and is preferably made of water (H 2 O), ethanol (C 2 H 5 OH), methanol (CH 3 OH) or the like But is not limited thereto. However, it is advantageous to use water (H 2 O) in view of achieving a non-hazardous environmentally friendly process, which is one of the secondary objects of the present invention.

In the present invention, the porous structure formed on the surface of the silicon (Si) and silicon nitride (SiNx) compound in FIGS. 4 and 5 is preferably an electron microscope However, the scope of the present invention is not limited by these examples, and is merely an example of the results achieved by the present invention.

The water tanks of the first and second embodiments are used in a general concept to define the light energy transfer medium 120. When the light source is transmitted as shown in FIG. 2, the water tank should be formed of a material having high light transmittance However, it is not necessary to limit the configuration, the shape and the material in accordance with the purpose of the solution means of the present invention, and various implementations can be realized.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, . Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and from the concept are to be construed as being included in the scope of the present invention .

110: Light source
111: direction of incidence of the light source
120: light energy transfer medium
130: material to be processed
140: First type of tank
150: The second type of tank

Claims (13)

And irradiating the surface of the irradiated object in contact with the medium with light passing through the medium, the surface texturing method comprising:
The light is incident directly on the medium,
The object to be irradiated is silicon or silicon nitride (SiNx) or silicon carbide (where x = 0.2-2)
Wherein the medium is selected from water, ethanol, methanol and mixtures of two or more thereof,
Wherein the light source is a laser having a wavelength of 500 nm to 550 nm,
The output of the light source is 0.5 W to 1.5 W,
The light is irradiated for 10 to 50 minutes,
The irradiation interval of the light is 15 Hz to 25 Hz,
The duration of the pulsed light is 7 ns to 15 ns,
Wherein the surface microstructure formed by the surface texturing is a structure in which a plurality of grooves having a diameter of 10 占 퐉 to 20 占 퐉 are adjacent to each other. The method according to claim 1, wherein the light source is impregnated in the medium or may be located outside the medium. delete delete delete delete delete The surface texture processing method according to claim 1, wherein the light source is a laser diode having a linearity, a laser, or the like. delete delete 9. A survey target textured to a surface according to any one of claims 1, 2 and 8. 12. An element for a solar cell comprising an object to be irradiated according to claim 11. 11. A catalyst comprising an object to be irradiated according to claim 11.
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Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
L.A.Dobrzanski, et al., "Surface texturing of multicrystalline silicon solar cells", JAMME 2008, Vol.31, pages 77-82
Malcolm Abbott et al., "Optical and Electrical Properties of Laser Texturing for High-efficiency Solar Cells", Prog. Photovolt: Res. Appl. 2006, Vol.14, pages 225-235*

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