KR20150021776A - a fabricating method for anti-reflection film with an excellent transmittance and a anti-reflection film fabricated thereof - Google Patents

Abstract

To an antireflection film having excellent light transmittance and an antireflection film produced thereby. The present invention is characterized in that, in forming an antireflection film on a substrate using magnetron sputtering, the gas process pressure in the vacuum chamber is 20 to 200 mTorr, and the antireflection film is a porous thin film. According to the present invention, when a porous thin film is deposited by reactive deposition using a magnetron evaporation source at a high process pressure of 20 to 200 mTorr, the reflectance of the glass substrate may be decreased and the transmittance may be increased due to the pore formation of the thin film. Further, when the antireflection film according to the present invention is applied to an amorphous silicon solar cell, energy conversion efficiency can be increased. According to the present invention, since the porous silicon oxide thin film can be deposited on a glass substrate under a high process pressure condition in one vacuum chamber, instead of the multilayer antireflection film method or glazing angle deposition method, It is possible to fabricate an antireflection film on a glass substrate of an amorphous silicon thin film solar cell without a process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an antireflection film having excellent light transmittance and an antireflection film fabricated by the method,

The present invention relates to an antireflection film excellent in light transmittance and a method for producing the same. More particularly, the present invention relates to a method of depositing a porous silicon oxide thin film on a surface of a glass substrate to reduce the reflectance of the glass substrate and increase the transmittance.

In general, the glass substrate of the amorphous silicon thin film solar cell is formed with surface texturing or anti-reflection coating to reduce the reflectance of light. Surface organization can be performed by wet etching using an etching solution (Materials Science and Engineering B, Volume 178, Issue 9, May 15, 2013, Pages 617-622, "Thin-film silicon solar cell development on imprint-textured glass substrates" (Solar Energy Materials & Solar Cells, Volume 94, Issue 3, March 2010, Pages 583-587, "Enhanced transmittance of glass plates using solar cells using nano-imprint lithography") using photolithography as etching. In the case of photolithography, wet etching using an etching solution is used more frequently because of its high cost. However, when etching solutions are used, they are subjected to a complicated cleaning process, which is not effective in terms of yield of the product.

The antireflection film is formed by a vacuum deposition method such as sputtering or plasma chemical vapor deposition (PE-CVD). Generally, a multi-layer thin film in which a silicon oxide thin film and a silicon nitride thin film are alternately stacked And a method of reducing the reflectance of light is mainly used.

Among the methods using sputtering, glancing angle deposition is performed by tilting the sample at an angle of 80 to 90 degrees with respect to the sputtering deposition source, and then rotating it to deposit a silicon oxide thin film or a magnesium fluoride thin film. (2005), pp. 2634-2637, " Anti-reflection Coatings with Helical SiO2 Films Prepared by ", Journal of the Korean Physical Society, Vol. Using Glancing Angle Deposition ") However, it is difficult to commercialize large-area deposition.

The present invention provides a method for producing an antireflection film having excellent light transmittance and an antireflection film produced by the method.

The present invention also provides a method of manufacturing an antireflection film on a glass substrate of an amorphous silicon thin film solar cell without a separate process by a simple method.

According to an aspect of the present invention, there is provided a method of forming an antireflection film on a substrate using magnetron sputtering, wherein a gas process pressure in the vacuum chamber is 20 to 200 mTorr and the antireflection film is a porous thin film And a method for producing the antireflection film.

The magnetron sputter deposition source may comprise silicon or silicon oxide.

The porous thin film may be silicon oxide, in which case the magnetron sputtering may be a reactive sputtering process using a mixed gas plasma of argon and oxygen.

Pulsed DC or RF power can be applied to the magnetron sputter deposition source.

Another aspect of the present invention may be an antireflection film produced by the above manufacturing method.

According to the present invention, when a porous thin film is deposited by reactive deposition using a magnetron evaporation source at a high process pressure of 20 to 200 mTorr, the reflectance of the glass substrate may be decreased and the transmittance may be increased due to the pore formation of the thin film.

Further, when the antireflection film according to the present invention is applied to an amorphous silicon solar cell, energy conversion efficiency can be increased.

According to the present invention, it is possible to provide a method of forming a porous silicon oxide film in a single vacuum chamber at a high process pressure of 20 to 200 mTorr, instead of using a multilayer antireflection film deposition method or a glazing angle deposition method which is manufactured by depositing a silicon oxide thin film and a silicon nitride thin film. Since the thin film can be deposited on the glass substrate, it is possible to manufacture the antireflection film on the glass substrate of the amorphous silicon thin film solar cell without a separate process by a simpler method.

1 is a graph showing reflectance and transmittance measurement results of Examples, Comparative Examples and glass substrates themselves.
2 is a schematic view showing the structure of a deposition apparatus for depositing a porous silicon oxide thin film according to the present invention.
FIG. 3 is a graph showing a result of measuring the refractive index of a glass substrate without a vapor deposition and a case of depositing a porous silicon oxide thin film on the glass substrate of Example 1. FIG.
4 is an SEM image (A) of a cross section of a dense silicon oxide thin film formed on a silicon substrate at a process pressure of 2 mTorr and an SEM image of a cross section of the porous silicon oxide thin film formed on the silicon substrate at a process pressure of 20 mTorr (B).

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings may be exaggerated for clarity of description, and the elements denoted by the same reference numerals in the drawings are the same elements.

2 is a schematic view schematically showing an apparatus for depositing a porous silicon oxide thin film according to the present invention. Referring to FIG. 2, the deposition apparatus may have a vacuum chamber 1 for thin film deposition using magnetron sputtering. And a power supply device 2 for applying pulse DC or RF power to the sputtering target 3 mounted on the magnetron evaporation source. The plasma 4 generated by the sputtering target 3 mounted on the magnetron evaporation source can be generated. And a sample mounting table 5 capable of supporting the glass substrate. And a gas flow rate regulating device 7 for regulating the flow rate of the process gas 6 used for plasma generation. A vacuum gauge 8 for measuring the degree of vacuum, a vacuum pump 9 for maintaining a high vacuum in the vacuum tank, and a low vacuum pump 10 for assisting the operation of the high vacuum pump.

The principle of the porous silicon oxide thin film deposition according to the present invention is as follows. That is, after the glass substrate sample is mounted on the sample mounting table 5 located inside the vacuum chamber 1, the degree of vacuum inside the vacuum chamber 1 is exhausted to the high vacuum region by using the vacuum pump 9. Then, argon (Ar) gas, which is an inert gas, and oxygen (O2) gas, which is an activation gas, are introduced through a gas flow rate regulator 7 to regulate the pressure inside the vacuum chamber to 20 to 200 mTorr. When the pressure inside the vacuum chamber is stabilized after the process gas is introduced, pulse DC or RF power is applied to the silicon sputtering target 3 attached to the magnetron deposition source attached to the upper end of the vacuum chamber to remove the glass The porous silicon oxide thin film can be deposited on the substrate.

In the case of silicon oxide thin film deposition using a conventional reactive sputtering method, deposition is performed at a low process pressure of typically less than 10 mTorr in order to deposit silicon oxide thin films having high density and low pores. However, since the refractive index of the silicon oxide thin film deposited in this manner is almost the same as that of the glass substrate, the antireflection effect can not be expected. In order to prevent effective reflection of light, it is preferable that the refractive index of the thin silicon oxide film to be deposited be made smaller than the refractive index (~1.5) of the glass substrate.

In the present invention, by using a high process pressure of 20 to 200 mTorr when depositing a silicon oxide thin film, the silicon oxide thin film constituent elements (silicon, oxygen) incident on the glass substrate are scattered to lose directionality, It is possible to reduce the refractive index of the deposited silicon oxide thin film, thereby reducing the reflection of light.

On the other hand, when the silicon oxide thin film is deposited, it is difficult to deposit the porous silicon oxide thin film at a process pressure of 20 mTorr or less, whereas when the process pressure is higher than 200 mTorr, the scattering of the sputtering element due to high process pressure is serious, And there is a high possibility of arcing, which makes it difficult to efficiently deposit the porous silicon oxide thin film.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

Example  One

An Eagle-2000 glass substrate was placed in a vacuum chamber and the inside of the vacuum chamber was evacuated to 10 ^-6 Torr. Then, 10 sccm of argon (Ar) gas and 0.5 sccm of oxygen (O 2) gas were introduced, The process pressure was controlled with mTorr. A pulsed DC power (-482 V, 0.416 A) with a frequency of 25 kHz and a 60% occupancy rate was applied for 4 minutes and 30 seconds to a magnetron sputtering deposition source equipped with a silicon sputtering target with a diameter of 75 mm to form a porous A silicon oxide thin film was formed.

Example  2

A silicon oxide thin film was formed in the same manner as in Example 1, except that the process pressure was adjusted to 200 mTorr.

Comparative Example  One

A silicon oxide thin film was prepared in the same manner as in Example 1 except that the pressure in the vacuum chamber was 2 mTorr.

Comparative Example  2

A silicon oxide thin film was prepared in the same manner as in Example 1 except that the pressure in the vacuum chamber was 250 mTorr.

Whether a porous thin film is formed

In order to confirm whether or not the silicon oxide thin films deposited according to Examples and Comparative Examples were porous, a silicon oxide thin film was deposited on a silicon wafer in a thickness of 2100 Å for 10 minutes under the same conditions as those of Examples and Comparative Examples, The cross section was observed by SEM and the results are summarized in Table 1. SEM photographs of cross sections are shown in Fig. 4 for Comparative Example 1 and Example 1. Fig.

Referring to Table 1 and FIG. 4, in the case of Comparative Example 1 (FIG. 4A), that is, the silicon oxide thin film deposited under a low process pressure of 2 mTorr was deposited very densely, (B), that is, the thin film deposited under a high process pressure of 20 mTorr has a porous structure in which a large number of pores exist. In the case of Comparative Example 2, however, the film deposition rate is too low due to too high process pressure, It is not possible to evaluate the microstructure and optical characteristics of the porous silicon oxide thin film. From this, it can be seen that the refractive index of the deposited silicon oxide thin film can be lowered when the pores are porous, and as a result, the light reflectance can be decreased and the light transmittance can be increased have.

Optical properties

Fig. 1 shows the light reflectance (A) and the light transmittance (B). Referring to FIG. 1, the optical reflectance at a wavelength of 450 to 600 nm is 10.5% for an Eagle-2000 glass substrate without a deposition, 6.8% for Example 1, and the light transmittance is 89 % To 93%, respectively. In the case of Example 1, since it has a porous silicon oxide thin film, the refractive index is low, thereby reducing the light reflectance and increasing the light transmittance. It can be seen that the decrease in light reflectance and the increase in light transmittance are very small in the case of a thin film of XY thin film deposited under a process pressure as low as 2 mTorr (Comparative Example 1).

FIG. 3 shows the refractive index measurement results of the glass substrate itself and the sample obtained by depositing the silicon oxide thin film on the glass substrate according to Example 1. FIG. Referring to FIG. 3, it can be seen that the refractive index of Example 1 is smaller than the refractive index of the glass substrate itself. From this, it can be seen that in Example 1, the light reflectance decreases and the light transmittance increases due to the low refractive index (~ 1.44) of the deposited porous silicon oxide thin film.

Table 1 shows the optical characteristics of the silicon oxide thin films prepared according to Examples and Comparative Examples.

division Process pressure Light reflectance Light transmittance Thin film microstructure Glass substrate - 10.5% 89% - Comparative Example 1 2 mTorr 9.6% 90% Dense Example 1 20 mTorr 6.8% 93% Existence of pore Example 2 200 mTorr 5.9% 94% Existence of pore Comparative Example 2 250 mTorr Not measurable Not measurable Not measurable

The optical reflectance and light transmittance in Table 1 are values measured at 450 to 600 nm. Referring to Table 1, it can be seen that the light reflectance and light transmittance are excellent when the process pressure is 20 to 200 mTorr.

The terms used in the present invention are intended to illustrate specific embodiments and are not intended to limit the invention. The singular presentation should be understood to include plural meanings, unless the context clearly indicates otherwise. The word " comprises " or " having " means that there is a feature, a number, a step, an operation, an element, or a combination thereof described in the specification. The present invention is not limited by the above-described embodiments and the accompanying drawings, but is intended to be limited only by the appended claims. It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

1: Vacuum tank 2: Power supply unit
3: Sputtering target 4: Plasma
5: Sample mounting stand 6: Process gas
7: Gas flow rate control device 8: Vacuum gauge
9: Vacuum pump 10: Low vacuum pump

Claims (6)

Wherein the gas processing pressure in the vacuum chamber is 20 to 200 mTorr in forming the antireflection film on the substrate using magnetron sputtering, and the antireflection film is a porous thin film.
The method according to claim 1,
Wherein the magnetron sputtering evaporation source comprises silicon or silicon oxide.
The method according to claim 1,
Wherein the porous thin film comprises a silicon oxide thin film.
The method of claim 3,
Wherein the magnetron sputtering is a reactive sputtering process using a mixed gas plasma of argon and oxygen.
The method according to claim 1,
Wherein pulse DC or RF power is applied to the magnetron sputtering deposition source.
An antireflection film produced by any one of claims 1 to 6.

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