TW201307621A - Single crystal germanium wafer and preparation method thereof - Google Patents

Abstract

A single crystal germanium wafer and a method of preparing the single crystal germanium wafer are disclosed. More particularly, the present invention discloses a crystalline germanium wafer having a surface composed of a plurality of pyramids, and a method of preparing the crystalline germanium wafer, wherein each pyramid has a radii extending from the apex of the pyramid The curved surface at the bottom maximizes sun absorption and greatly reduces light reflection, thereby improving light conversion efficiency.

Description

Single crystal germanium wafer and preparation method thereof

Related Application This application claims Korean Patent Application No. 10-2011-0054569, filed on June 7, 2011, and Korean Patent Application No. 0-2012-0059142, filed on June 1, 2012, and The priority of Korean Patent Application No. 10-2012-0059966, filed on Jun. 4, 2012, the entire disclosure of which is hereby incorporated by reference.
The present invention relates to a single crystal germanium wafer capable of maximizing solar absorption while substantially reducing light reflection to further increase light conversion efficiency, and a method of preparing the single crystal germanium wafer.

In recent years, solar cells (generally known as "cells") have rapidly spread and are known as the next generation of energy sources, as well as an electron that directly converts clean energy (ie, sunlight) into electricity. Device. Such a device typically includes a PN junction semiconductor substrate in which a P-type germanium semiconductor having boron added to the germanium is used as a base material, and phosphorus is diffused onto the surface of the base material to form an N-type germanium semiconductor layer.
When light such as sunlight is irradiated onto a substrate having an electric field formed by a PN junction, electrons (-) and holes (+) in the semiconductor are excited and freely moved therein. If these moving charges enter the electric field formed by the PN junction during the movement, the electrons (-) move to the N-type semiconductor, and the hole (+) moves to the P-type semiconductor. An electrode is formed on the surface of the P-type semiconductor and the N-type semiconductor, and an electric current is generated in an example in which electrons flow along an external circuit. Based on this principle, solar energy can be converted into electrical energy. Therefore, in order to increase solar energy conversion efficiency, the electrical output per unit area of the PN junction semiconductor substrate should be maximized. For this purpose, it is necessary to increase the light absorption as much as possible while reducing the amount of light reflection.

In consideration of the above, the surface of the germanium wafer for solar cells for fabricating the PN junction type semiconductor substrate has a micropyramid structure to form an antireflection film. The micropyramid structure formed on the surface of the germanium wafer, as shown in Fig. 1, includes a quadrilateral pyramid formed by four triangular faces S and a rectangular bottom B which meet at a single vertex. In general, as shown in Fig. 2, the face S ₁ of the micro-pyramid is in the form of a triangle, wherein the two sides c ₁₁ and c ₁₂ at which the base b ₁ meets to form the bottom are from the vertex a ₁ straight line.
Such a germanium wafer having a micropyramid structure reduces incident light reflection having a wider wavelength band on its surface to increase the intensity of the absorbed light, thereby improving the efficiency of the solar cell. In addition, the efficiency of the solar cell can be further improved by rechecking the micropyramid structure.

Accordingly, it is an object of the present invention to provide a single crystal germanium wafer having a specific structure to greatly reduce light reflection while maximizing solar absorption.
Another object of the present invention is to provide a method of simply preparing a single crystal germanium wafer having a micropyramid structure without using an etching cap.
In order to accomplish the above object, the present invention provides the following.
(1) A single tantalum wafer having a surface on which a pyramid is repeatedly formed, the pyramid having a curved surface extending from the apex of the pyramid to the bottom thereof.
(2) The wafer according to the above (1), wherein the curved surface is a convex curved surface toward a center of the pyramid.
(3) The wafer according to the above (1), wherein the wafer is prepared without using an etching cap.
(4) The wafer according to the above (1), wherein the face of the pyramid and the face of the other pyramid beside the pyramid form a shape, and the vertical section of the shape has a tip end.
(5) The wafer according to the above (1), wherein the wafer is textured by etching using an etching composition.
(6) The wafer according to the above (5), wherein the etching composition contains 0.1 to 20% by weight of a basic compound and 80 to 99.9% by weight of water.
(7) The wafer according to the above (6), wherein the basic compound is a group selected from the group consisting of potassium hydroxide, sodium hydroxide, ammonium hydroxide, tetramethylolmonium, and tetrahydroxyethylammonium. At least one of the groups.
(8) The wafer according to the above (6), wherein the etching composition further contains 10 ^-6 to 10% by weight of a cyclic compound containing a nitrogen atom bonded to a functional group, the functional group The group includes an olefin group having 2 to 6 carbon atoms.
(9) The wafer according to the above item (8), wherein the cyclic compound is selected from the group consisting of N-vinylpiperazine, N-vinylmethylpiperazine, N-vinylethylpiperazine, N- Vinyl-N'-methylpiperazine, N-propylenesulfonylpiperazine, N-propenyl-N'-methylpiperazine, N-vinylmorpholine, N-vinylmethylmorpholine, N -vinylethylmorpholine, N-propenylmorpholine, N-vinylpiperidone, N-vinylmethylpiperidone, N-vinylethylpiperidone, N-propenylhydrazino Pyridone, N-vinylpyrrolidone, N-vinylmethylpyrrolidone, N-vinylethyl-2-pyrrolidone, N-propenylpyrrolidone, N-vinylcarbazole and N-propenylcarbazole At least one of the group consisting of.
(10) The wafer according to the above (6), wherein the etching composition further comprises at least one polysaccharide selected from the group consisting of a polydextrose compound, a polyfructose compound, a polymannose compound, a polygalactose compound, and the like. A group of metal salts.
(11) A method of preparing a single crystal germanium wafer, comprising: texturing a surface of the single crystal germanium wafer by coating an etching composition without using an etching cap, so that a pyramid can be repeatedly formed on the single crystal On the surface of the wafer, each of the pyramids has a curved surface extending from the apex of the pyramid to the bottom.
(12) The method according to the above (11), wherein the curved surface is convexly curved toward a center of the pyramid.
(13) The method according to the above (11), wherein the etching composition contains 0.1 to 20% by weight of a basic compound and 80 to 99.9% by weight of water.
(14) The method according to the above (11), wherein the basic compound is selected from the group consisting of potassium hydroxide, sodium hydroxide, ammonium hydroxide, tetramethylolmonium, and tetrahydroxyethylammonium. At least one of them.
(15) The method according to the above (13), wherein the etching compound further contains 10 ^-6 to 10% by weight of a cyclic compound containing a nitrogen atom bonded to a functional group, the functional group including An olefin group having 2 to 6 carbon atoms.
(16) The method according to the above item (15), wherein the cyclic compound is selected from the group consisting of N-vinylpiperazine, N-vinylmethylpiperazine, N-vinylethylpiperazine, N-ethylene -N'-methylpiperazine, N-propenylhydrazine piperazine, N-propenyl-N'-methylpiperazine, N-vinylmorpholine, N-vinylmethylmorpholine, N- Vinylethylmorpholine, N-propenylmorpholine, N-vinylpiperidone, N-vinylmethylpiperidone, N-vinylethylpiperidone, N-propenylpiperidine Ketone, N-vinylpyrrolidone, N-vinylmethylpyrrolidone, N-vinylethyl-2-pyrrolidone, N-propenylpyrrolidone, N-vinylcarbazole and N-propenylcarbazole At least one of the groups.
(17) The method according to the above (13), wherein the etching composition further comprises a group selected from the group consisting of a polydextrose compound, a polyfructose compound, a polymannose compound, a polygalactose compound, and a metal salt thereof. At least one of them.
Therefore, the single crystal germanium wafer of the present invention has a surface including a plurality of micropyramids each having a curved surface to remarkably increase sunlight absorption while greatly reducing light reflection, thereby improving light conversion efficiency.
Furthermore, the method of preparing a single crystal germanium wafer according to the present invention is capable of forming a plurality of micropyramid structures having curved surfaces without using an alternative etching mask, thus achieving excellent productivity.

The present invention discloses a single crystal germanium wafer capable of maximizing solar absorption while greatly reducing light reflection to further increase light conversion efficiency, and a method of preparing the single crystal germanium wafer.
Hereinafter, the present invention will be more specifically described with reference to the accompanying drawings.
Referring to Fig. 1, the pyramid in the disclosure herein means a quadrangular vertebral body configured with a rectangular bottom B and four triangular faces S that meet at the apex.
The single crystal germanium wafer of the present invention is characterized by having a pyramid repeatedly formed on the surface of the wafer, wherein each pyramid has a curved surface from its apex to the bottom.
More specifically, as shown in FIG. 3, the face S _{2 of the} pyramid has two sides c ₂₁ and c ₂₂ extending from the apex a ₂ and then joined at the base b ₂ to form a bottom, wherein the side c ₂₁ and c ₂₂ are not straight lines and are curved. Therefore, the face S ₂ becomes a curved surface.
The two side edges c ₂₁ and c ₂₂ forming one face of the pyramid may be the same or different from each other. That is, when the face is divided from the vertex a ₂ along the center line L perpendicular to the base b ₂ , the two portions separated by the face may become identical to each other (Fig. 3a) or different (Fig. 3b).
More preferably, as shown in Fig. 6, the vertical section formed in the shape of the face of the pyramid and the face adjacent to the pyramid may have a tip d.
Referring to Figure 6, which is a vertical cross-sectional view illustrating a pyramid of the present invention, the tip d may be a point on a tangent line formed by the side c ₂₁ of the pyramid and the side c ₂₂ of another pyramid adjacent thereto. As shown in Figure 6(a), such a tip may be present on the surface of a single crystal germanium wafer. Alternatively, as shown in FIG. 6(b), if tangent lines of two pyramids having an asymmetrical relationship exist above the surface of the single crystal germanium wafer, the tip may be positioned on the single crystal germanium wafer Above the surface.
Since the inventive wafer has such a structure as illustrated in Fig. 6, the improvement in light conversion efficiency can be further increased. The etch composition can be used to directly etch the object to provide the pyramid structure of the present invention without the use of any etch mask. In the example using such an etching hood, the portion where the pyramid meets the other pyramid inevitably forms a curved surface, so that a repeated pyramid structure having the tip is not obtained.
The face of the pyramid can be a convex curved surface that faces the center of the pyramid.
Further, at least one of the four faces used to form the pyramid may be curved as described above.
As shown in Fig. 4, the formation of the repeated pyramid structure means that a plurality of pyramids formed as described above are placed on the surface of the wafer. More particularly, in the case of forming a pyramid having a face extending from its apex to the bottom in plural, the repeating pyramid structure of the present invention may include different forms mixed together, in addition to a plurality of pyramids having the same shape Multiple pyramids (ie, pyramids as shown in Figures 3(a) and 3(b), pyramids L of different sizes, etc.).
The repeated pyramids do not need to occupy an area in a predetermined ratio relative to the surface area of the wafer. However, to promote maximum solar absorption and reduction in light reflection, the repeating pyramid can occupy at least 50%, preferably at least 70% of the wafer surface area.
A repeating pyramid does not necessarily include a fixed number of pyramids per unit area. However, in order to promote maximum solar absorption and reduction in light reflection, a micro-pyramid having a size of about several nanometers is preferred. For example, a pyramid formed on the surface of a single crystal germanium wafer of about 70% or more may have an average size of 1 to 6 μm. In this context, the average size of the pyramid means the length of the vertical line extending from the apex of the pyramid to the bottom.
As described above, the process of repeatedly forming a pyramid on the surface of the single crystal germanium wafer according to the present invention may be characterized in that no etching cover is used, wherein the pyramid has a curved surface extending from its apex to the bottom.
In accordance with one embodiment of the present invention that does not use an etch mask, the single crystal germanium wafer can have a micro-pyramid structure formed on its surface by texture etching using an alkaline etching solution.
The etching composition of the present invention may contain 0.1 to 20% by weight of a basic compound and 80 to 99.9% by weight of water.
Alternatively, the etching solution may further comprise a cyclic compound containing a nitrogen atom bonded to a functional group including an olefin group having 2 to 6 carbon atoms.
The basic compound is a component for etching the surface of the crystalline germanium wafer, and the type or kind thereof is not particularly limited. For example, the compound may include potassium hydroxide, sodium hydroxide, ammonium hydroxide, tetramethylammonium chloride, tetrahydroxyethylammonium, and the like. Among these, potassium hydroxide and sodium hydroxide are preferred. These compounds may be used singly or in combination of two or more thereof.
The basic compound may be contained therein in an amount of 0.1 to 20% by weight, and more preferably 1 to 5% by weight, based on the total of 100% by weight of the etching composition. When the content of the above compound is within the above range, the surface of the tantalum wafer can be successfully etched.
The cyclic compound is a component for controlling the difference in etching rate between the Si ₁₀₀ and Si ₁₁₁ directions as the twinning direction, and thus the shape of the pyramid can be adjusted, thereby enabling the pyramid to have a curved surface according to the present invention, the ring The compound contains a nitrogen atom bonded to a functional group including an alkene group having 2 to 6 carbon atoms.
The cyclic compound used in the present invention may include, for example, N-vinylpiperazine, N-vinylmethylpiperazine, N-vinylethylpiperazine, N-vinyl-N'-methylpiperidin Pyrazine, N-propenylhydrazine piperazine, N-propenyl-N'-methylpiperazine, N-vinylmorpholine, N-vinylmethylmorpholine, N-vinylethylmorpholine, N - propylene decylmorpholine, N-vinylpiperidone, N-vinylmethylpiperidone, N-vinylethylpiperidone, N-propenylpiperidone, N-vinylpyrrolidone, N-vinylmethylpyrrolidone, N-vinylethyl-2-pyrrolidone, N-propenylpyridrolidone, N-vinylcarbazole, N-propenylcarbazole or the like, which may be used alone or in its Two or more combinations are used.
The cyclic compound may be contained therein in an amount of 10 ^-6 to 10% by weight, and more preferably 10 ^-3 to 1% by weight, based on the total of 100% by weight of the etching composition. When the content of the above cyclic compound is within the above range, the wettability of the surface of the wafer can be effectively improved, thereby minimizing variations in texture quality, and can be easily formed to have a structure different from that described in the related art. The shape of the micro pyramid. If the content exceeds 10% by weight, it is difficult to control the difference in the etching rate in the twinning direction, thus making it difficult to form a desired micropyramid.
The etching composition may further comprise a polysaccharide.
A polysaccharide is a saccharide that generates a macromolecule via a glycosidic bond of two or more monosaccharides, and is a component that prevents over-etching of an alkaline compound and acceleration of etching to prepare a uniform micro-pyramid, and at the same time rapidly from 矽The wafer surface removal creates hydrogen bubbles by etching to thereby improve the appearance of the pyramid.
The polysaccharide may include, for example, a polydextrose compound, a polyfructose compound, a polymannose compound, a polygalactose compound or a metal salt thereof. Among these, the polydextrose compound and its metal salt are preferred. These can be used singly or in combination of two or more thereof.
The polydextrose compound may include, for example, cellulose, dimethylaminoethylcellulose, diethylaminoethylcellulose, ethylhydroxyethylcellulose, methylhydroxyethylcellulose, 4- Aminobenzyl cellulose, triethylaminoethyl cellulose, cyanoethyl cellulose, ethyl cellulose, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl Cellulose, alginic acid, amylose, amylopectin, pectin, starch, dextrin, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, hydroxypropyl-β-cyclodextrin, Methyl-β-cyclodextrin, dextrin, sodium dextrin-like, saponin, glycogen, zymosan, lentinan, Schizophyllum polysaccharide or a metal salt thereof, and the like.
The polysaccharide may have an average molecular weight of 5,000 to 1,000,000, and more preferably 50,000 to 200,000.
The polysaccharide may be contained therein in an amount of 10 ^-9 to 10% by weight, and more preferably 10 ^-6 to 1% by weight, relative to a total of 100% by weight of the etching composition. If the content of the polysaccharide is within the above range, over etching and etching acceleration can be effectively prevented. If the content exceeds 10% by weight, the etching rate of the basic compound is greatly reduced, thus making it difficult to form a desired micropyramid.
Alternatively, the texture etching composition for a crystalline germanium wafer according to the present invention may further include at least one of a surfactant, a lipid acid-proof, and an alkali metal salt thereof, a compound containing cerium oxide, or the like.
The kind of water used in the present invention is not particularly limited, but may include deionized distilled water, and more preferably deionized distilled water for a semiconductor process having a specific electric resistance equal to or greater than 18 MΩ/cm.
Water may be included as the remainder of a total of 100% by weight of the crystalline etch composition.
The kind of water is not particularly limited, but may include deionized distilled water, more preferably deionized distilled water for a semiconductor process, which has a specific resistance equal to or greater than 18 MΩ/cm.
The process of processing a single crystal germanium wafer, including soaking, spraying, or soaking and spraying, by using the etching composition prepared as described above, may have a structure including a micropyramid. The number of times of immersion or spraying procedures is not particularly limited, and in the examples in which immersion and spraying are performed, their order of operation is not limited. Further, the soaking, spraying or soaking and spraying stages may be performed at a temperature of 50 to 100 ° C for 30 seconds to 60 minutes. In this example, a soak, spray, or single wafer type etch process can be used.
The preferred embodiments are described with reference to the examples and comparative examples to more specifically understand the invention. However, those skilled in the art will appreciate that such specific embodiments are provided for the purpose of illustration, and are not intended to limit the scope of the claimed subject matter. Therefore, it is apparent to those skilled in the art that various changes and modifications may be made without departing from the scope and spirit of the invention, and are fully included as defined in the appended claims. In the range.
Sample example 1
2% by weight of potassium hydroxide (KOH), 0.1% by weight of N-vinylpyrrolidone, 0.02% by weight of sodium alginate (AANa), and deionized distilled water as the remainder were mixed together to prepare an etching composition.
The texture etching was completed by immersing the single crystal germanium wafer substrate in the prepared etching composition at 80 ° C for 20 minutes.

Comparative example 1
2% by weight of potassium hydroxide, 0.1% by weight of N-methylpyrrolidone, 0.02% by weight of sodium alginate (AANa), and deionized distilled water as a remainder were mixed together to prepare an etching composition.
The texture etching was completed by immersing the single crystal germanium wafer substrate in the prepared etching composition at 80 ° C for 20 minutes.
Exemplary Example The physical properties of the texture-etched tantalum wafer substrate in the above examples and comparative examples were determined according to the following procedure, and the results are shown in Table 1 below.
(1) Morphology of Micropyramid The morphology of the micropyramid structure formed on the surface of each single crystal wafer substrate was confirmed using a scanning electron microscope (SEM).
(2) Texture uniformity The deviation, that is, uniformity, of the micropyramid structure formed on the surface of the single crystal germanium wafer substrate was visually observed using a digital camera, a 3D optical microscope, and an SEM, and the results were evaluated based on the following criteria.
<Evaluation criteria>
◎: Pyramid is formed on the entire wafer substrate. ○: The pyramid does not exist on part of the wafer substrate (the non-pyramid portion is less than 5% of the wafer substrate)
△: The pyramid does not exist on part of the wafer substrate (the range of the non-pyramid portion is 5 to 50% of the wafer substrate)
×: no pyramid is formed on most of the wafer substrates (the non-pyramid portion is equal to or more than 90% of the wafer substrate)
(3) Reflection (%)
Each single crystal germanium wafer substrate was light-reflected using a UV spectrometer in which light having a wavelength of 600 nm was used to illuminate the surface.
4 and 5 are SEM photographs showing the surfaces of the single-crystal ruthenium wafer substrate of the texture etching in Example 1 and Comparative Example 1, respectively. More specifically, it can be seen that the micro-pyramid formed in Example 1 has two curved sides extending from its apex and meeting at its bottom, i.e., resulting in a curved surface, which then has a small and uniform size.
On the other hand, it can be seen that the micropyramid formed in Comparative Example 1 has two straight sides extending from the apex thereof and meeting at the bottom thereof, that is, providing a plane, which is relative to that in Example 1. The preparer has a larger size.
In short, the single crystal germanium wafer according to the present invention can maximize solar absorption while further reducing light reflection based on differences in the morphology of the micropyramids described above.

As shown in Table 1 above, a single crystal germanium wafer substrate prepared according to Example 1 of the present invention, in which a plurality of micro pyramids each having a curved surface are formed, in comparison with the substrate prepared in Comparative Example 1 The surface of the micro-pyramid exhibits excellent micro-pyramid texture uniformity. Further, it was confirmed that the light reflection was lower than the light reflection in Comparative Example 1 due to the shape of the micropyramid. Therefore, the present invention can achieve an improvement in light conversion efficiency.

a ₁ , a ₂ . . . vertex

B. . . Rectangular bottom

b ₁ , b ₂ . . . Base

c ₁₁ , c ₁₂ . . . Side

c ₂₁ , c ₂₂ . . . Side of the pyramid

d. . . Cutting edge

L. . . Center line

S. . . Four triangular faces

S ₁ . . . Micropyramid face

S ₂ . . . Pyramid face

The above and other objects, features and other advantages of the present invention will become more <RTIgt;
Figure 1 is a perspective view illustrating a micro-pyramid formed on the surface of a conventional single crystal germanium wafer;
Figure 2 is a cross-sectional view showing the micropyramid plane formed on the surface of a conventional single crystal germanium wafer;
Figure 3 is a cross-sectional view showing a micropyramid plane formed on the surface of a single crystal germanium wafer according to the present invention;
4 is a SEM photograph showing (a) a surface and (b) a cross section of a micropyramid formed on a surface of a tantalum wafer according to an embodiment of the present invention;
Figure 5 is a SEM photograph showing the (a) surface and (b) cross section of the micropyramid formed on the surface of the conventional tantalum wafer; and Fig. 6 is a vertical sectional view illustrating two different pyramids, the two Different pyramids are next to each other and formed on the surface of the tantalum wafer in accordance with an embodiment of the present invention.

c ₂₁ , c ₂₂ . . . Side of the pyramid

d. . . Cutting edge

Claims (17)

A single tantalum wafer having a surface on which a pyramid having a curved surface extending from an apex to the bottom of the pyramid is repeatedly formed. The single crystal germanium wafer of claim 1, wherein the curved surface is a convex curved surface toward a center of the pyramid. The single crystal germanium wafer of claim 1, wherein the wafer is prepared without using an etching cap. A single crystal germanium wafer according to claim 1, wherein one side of the pyramid and one side of the other pyramid beside the pyramid form a shape, and a vertical section of the shape has a tip. The single crystal germanium wafer of claim 1, wherein an etching composition is used to texture etch the wafer. The single crystal germanium wafer according to claim 5, wherein the etching composition comprises 0.1 to 20% by weight of a basic compound and 80 to 99.9% by weight of water. The single crystal germanium wafer according to claim 6, wherein the basic compound is selected from the group consisting of potassium hydroxide, sodium hydroxide, ammonium hydroxide, tetramethylol ammonium, and tetrahydroxyethyl ammonium. At least one of the groups. The single crystal germanium wafer according to claim 6, wherein the etching composition further comprises ^10-6 to 10% by weight of a cyclic compound containing a nitrogen bonded to a functional group. An atom, the functional group comprising a monoolefin group having 2 to 6 carbon atoms. The single crystal germanium wafer according to claim 8, wherein the cyclic compound is selected from the group consisting of N-vinylpiperazine, N-vinylmethylpiperazine, N-vinylethylpiperazine, N -vinyl-N'-methylpiperazine, N-propenylhydrazine piperazine, N-propenyl-N'-methylpiperazine, N-vinylmorpholine, N-vinylmethylmorpholine, N-vinylethylmorpholine, N-propenylmorpholine, N-vinylpiperidone, N-vinylmethylpiperidone, N-vinylethylpiperidone, N-propylene fluorenyl Piperidone, N-vinylpyrrolidone, N-vinylmethylpyrrolidone, N-vinylethyl-2-pyrrolidone, N-propenylpyrrolidone, N-vinylcarbazole and N-propenylcarbazole At least one of the group consisting of. The single crystal germanium wafer according to claim 6, wherein the etching composition further comprises at least one polysaccharide selected from the group consisting of a polydextrose compound, a polyfructose compound, a polymannose compound, and a polycondensation. A group consisting of a galactose compound and a metal salt thereof. A method of preparing a single crystal germanium wafer, comprising: texturing a surface of the single crystal germanium wafer by applying an etching composition without using an etching cap to enable the pyramid to be repeatedly formed on the single crystal On the surface of the wafer, each of the pyramids has a curved surface extending from a vertex to the bottom of the pyramid. The method of claim 11, wherein the curved surface is convexly curved toward a center of the pyramid. The method of claim 11, wherein the etching composition comprises 0.1 to 20% by weight of a basic compound and 80 to 99.9% by weight of water. The method of claim 13, wherein the basic compound is at least one selected from the group consisting of potassium hydroxide, sodium hydroxide, ammonium hydroxide, tetramethylolmonium, and tetrahydroxyethylammonium. one of them. The method of claim 13, wherein the etching composition further comprises 10 ^-6 to 10% by weight of a cyclic compound containing a nitrogen atom bonded to a functional group, the functional group The group includes a monoolefin group having 2 to 6 carbon atoms. The method of claim 15, wherein the cyclic compound is selected from the group consisting of N-vinylpiperazine, N-vinylmethylpiperazine, N-vinylethylpiperazine, N-vinyl- N'-methylpiperazine, N-propenylhydrazine piperazine, N-propenyl-N'-methylpiperazine, N-vinylmorpholine, N-vinylmethylmorpholine, N-vinyl Ethylmorpholine, N-propenylmorpholine, N-vinylpiperidone, N-vinylmethylpiperidone, N-vinylethylpiperidone, N-acrylopyrylpiperidone, a group consisting of N-vinylpyrrolidone, N-vinylmethylpyrrolidone, N-vinylethyl-2-pyrrolidone, N-propenylpyrrolidone, N-vinylcarbazole and N-propenylcarbazole At least one of the groups. The method of claim 13, wherein the etching composition further comprises a polyphosphorus compound, a polyfructose compound, a polymannose compound, a polygalactose compound, and a metal salt thereof. At least one of the groups.