WO2008156224A1

WO2008156224A1 - Laminated structure having high resistance metal thin film of enhanced durability and reliability and forming method thereof

Info

Publication number: WO2008156224A1
Application number: PCT/KR2007/002943
Authority: WO
Inventors: Min A Lee
Original assignee: Min A Lee
Priority date: 2007-06-18
Filing date: 2007-06-18
Publication date: 2008-12-24
Also published as: KR100848288B1

Abstract

Provided is a metal thin film and a forming method thereof. More particularly, provided is a laminated structure with enhanced durability and reliability, which is manufactured by adjusting the thickness of a thin film, the grain size, etc. to maintain the metallic luster and forming a metal thin film with high resistance similar to a dielectric substance and an isolation layer between metal thin film layers to minimize the change of optical and electrical characteristics of the high resistance metal thin film caused by external environments, and a forming method thereof. The laminated structure for an outward appearance of an item includes: a plurality of metal thin film layers, each being formed with a metal thin film of a crystal metal or an alloy,- and an isolation layer being disposed between the plurality of metal thin film layers, wherein a sheet resistance of the metal thin film for a luster is controlled by a plurality of 2D planar grains and grain boundaries.

Description

LAMINATED STRUCTURE HAVING HIGH RESISTANCE METAL THIN FILM OF ENHANCED DURABILITY AND RELIABILITY AND FORMING

METHOD THEREOF

Technical Field

The present invention relates to a metal thin film and a forming method thereof. More particularly, the present invention relates to a laminated structure with the enhanced durability and reliability, which is manufactured by adjusting the thickness of a thin film of a crystal metal and alloy, the grain size, and the like to thereby maintain the metallic luster as is and forming a metal thin film with high resistance similar to a dielectric substance and an isolation layer between metal thin film layers to thereby minimize the change of optical and electrical characteristics of the high resistance metal thin film caused by external environments, and a forming method thereof.

Background Art Generally, with the advancement of electronic product manufacturing technologies, communication devices, precise measurement instruments, load-cell type of electronic scales, microcomputers, home and industrial electrical/electronic products, and the like have been highly precise and developed. In correspondence thereto, there have been increasing demands for improvement of performance of active or passive devices. In particular, high precision and high resistance of most widely used resistor devices among them becomes an issue.

A pyrolysis scheme, an electroplating scheme, an electroless plating scheme, a physical vapor deposition

(PVD) scheme, and the like may be used to form a resistance material of a resistor in a thin film and thereby make the thin film have high precision and high resistance.

Currently, a most widely used thin film manufacturing scheme of the resistor device is a sputtering scheme which is one of PVD schemes .

Specifically, the conventional resistance thin film material that is applied, as a thin film, on the surface of a resistor base using the sputtering scheme may be formed by synthesizing nickel (Ni) -chrome (Cr) , cupper (Cu) -manganese (Mn) , nickel (Ni) -chrome (Cr) -silicon (Si) , nickel (Ni) - chrome (Cr) -aluminum (Al), and the like. However, it is difficult to form a high resistance material with a sheet resistance greater than or equal to about 1 KΩ/αif using the above materials of the resistance thin film and the materials are expensive. In addition, when designing a circuit of a precise electronic device such as an electronic measurement instrument and a microcomputer with temperature coefficient of resistance (TCR) characteristic greater than or equal to ±100PPM/^°C, an error range may be extended, deteriorating the precision. Here, the TCR denotes the stability with respect to a temperature change. Accordingly, in order to develop the precise electronic device such as the electronic measurement instrument and the microcomputer, there is a need for development of materials with resistivity greater than and TCR characteristic less than the existing resistance thin film material .

The metal thin film may be used as a coating structure for protecting an exposed portion of an item such as a mobile phone, a liquid crystal display (LCD) , a cosmetic case, and the like, and for exhibiting aesthetic sense using the metallic luster. However, referring to FIG.l, when coating a metal thin film 20 on a target substrate 10 of a glass, a plastic, and the like using a general resistor manufacturing scheme such as a sputtering scheme, and the like, the metal thin film 20 may be formed in an amorphous type in the thickness of about tens of nm. In this instance, a sheet resistance may be within the range of about some ohms to some kilo ohms. When using the metal thin film 20 as the coating structure for protecting the exposed portion, a high conductive characteristic may not be required and thus it may be desirable to increase the sheet resistance as much as possible and to maximally exhibit the optical characteristic of the metallic luster. However, in order to increase the sheet resistance of the metal thin film 20, the metal thin film 20 may be oxidized or nitrated. In this instance, it may be difficult to control the metal thin film 20 using a very small amount of oxidation or nitration. When the oxidation or nitration of the metal thin film 20 is proceeded too much, an oxide thin film or nitride thin film may be formed, which results in maximally removing the optical characteristic of the metal .

Also, when the metal thin film 20 is formed to have the; high resistance, a protective layer may be formed on the top surface or the bottom surface of the metal thin film 20 by thick film coating using paints, for example, spray coating, and the like, in order to improve the durability of the high resistance metal thin film. However, although the metal thin film 20 is formed to have the high resistance, when the metal thin film 20 is used as a coating structure for various types of electronic products and the like, the characteristic of the metal thin film 20 may be changed due to electromagnetic waves, leakage current, displacement current, and the like. Specifically, due to the above external environmental factors, undesired problems according to various types of characteristic change may occur such as change of sheet resistance, loss of metallicity and metallic luster, and the like. Accordingly, there is a need for a high resistance metal thin film with high durability and high reliability in which the optical and electrical characteristics of the metal thin film does not change in a reliability test based on various types of worst external environments . Disclosure of Invention Technical Goals

An aspect of the present invention provides a high resistance metal thin film, which is manufactured by- adjusting the thickness of a thin film to about tens of nm, and adjusting the grain size, a number of grain boundaries, and the like, to thereby form a grain of crystal metal and alloy on the two-dimensional (2D) plane, without implanting oxide, nitride, impurities, so as to form a metal thin film with high resistance similar to a dielectric substance with maintaining the metallic luster as is, also a laminated structure with enhanced durability and reliability, which is manufactured by forming an isolation layer between metal thin film layers to thereby minimize the change of optical and electrical characteristics of the high resistance metal thin film caused by external environments, and the forming method thereof .

Technical solutions

According to an aspect of the present invention, there is provided a laminated structure for outward appearance of an item including: a plurality of metal thin film layers, each being formed with a metal thin film of a crystal metal or an alloy; and an isolation layer being disposed between each of two layers of the plurality of metal thin film layers, wherein a sheet resistance of the metal thin film for a luster is controlled by a plurality of grains and a plurality of grain boundaries that are formed on a two- dimensional (2D) plane. In this instance, the isolation layer may include at least one coating layer of metal oxide, inorganic material, and organic material with a sheet resistance greater than the sheet resistance of the metal thin film.

Also, the laminated structure may further include an organic layer being coated on at least one of the top surface of a highest layer and the bottom surface of a lowest layer among the plurality of metal thin film layers .

Also, the laminated structure may further include a coating layer being formed of the same material as the isolation layer to be provided on at least one of the top surface of a highest layer and the bottom surface of a lowest layer among the plurality of metal thin film layers.

Also, the laminated structure may further include an organic layer being coated on at least one of the top surface of a highest layer and the bottom surface of a lowest layer among all the layers comprising the plurality of metal thin film layers, the isolation layer, and the coating layer.

Also, the size of grain may be less than or equal to about 500 nm, the thickness of the metal thin film may be less than or equal to about 50 nm, and a melting temperature of the metal or the alloy may be less than or equal to about 350 C°.

According to another aspect of the present invention, there is provided a laminated structure for outward appearance of an item including: a metal thin film being formed of a crystal metal or alloy; and an organic layer being coated on at least one of the top surface and the bottom surface of the metal thin film, wherein a sheet resistance of the metal thin film for a luster is controlled by a plurality of grains and a plurality of grain boundaries that are formed on the 2D plane.

According to still another aspect of the present invention, there is provided a method of forming a laminated structure for outward appearance of an item, the method including: forming a metal thin film layer and an isolation layer on a substrate in turn at least once, wherein the metal thin film layer is coated using a crystal metal or an alloy and a sheet resistance of the metal thin film layer for a luster is controlled by a plurality of grains and a plurality of grain boundaries that are formed on the 2D plane.

Advantageous Effect

According to the present invention, a high resistance metal thin film may be formed by adjusting the thickness of a thin film to about tens of nm so that a grain may be formed on the two-dimensional (2D) plane, without implanting oxide, nitride, or impurities, and by adjusting the grain size, a number of grain boundaries, and the like. Therefore, it is possible control a sheet resistance of the thin film up to tens of Ω/D to 10¹² Ω/D which is near to a dielectric substance and it is also possible to maintain the metallic luster as is.

Also, a high resistance metal thin film according to the present invention may form a thin film in a laminated structure where an insulating layer is formed between metal thin film layers. Therefore, it is possible to minimize the change of optical and electrical characteristics of the high resistance metal thin film caused by external environments and thereby improve the durability and the reliability.

Brief Description of Drawings

FIG. 1 is a cross-sectional view of a metal thin film formed on a substrate according to a conventional art;

FIG. 2 is a cross-sectional view of a metal thin film formed on a substrate according to an embodiment of the present invention;

FIG. 3 is a perspective view of a metal thin film formed on a substrate according to an embodiment of the present invention;

FIG. 4 is a diagram for describing the property of a grain boundary of a metal thin film according to an embodiment of the present invention; FIG. 5 is a mimetic diagram of resistivity between a grain and a grain boundary of a metal thin film according to an embodiment of the present invention;

FIG. 6 illustrates an example of a scanning electron microscope (SEM) picture (10OK times) of a thin film made of alloys of tin and silver according to an embodiment of the present invention;

FIG. 7 is a cross-sectional view of a metal thin film formed on a substrate in a laminated structure according to an embodiment of the present invention;

FIG 8 is cross-sectional views for describing various embodiments of a metal thin film in a laminated structure;

FIG. 9 is a cross-sectional view illustrating an actual usage example of a metal thin film in a single layer structure according to an embodiment of the present invention; and

FIG. 10 is a cross-sectional view illustrating an actual usage example of a metal thin film in a laminated structure according to an embodiment of the present invention.

Best Mode for Carrying Out the Invention

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures .

FIG. 2 is a cross-sectional view of a metal thin film

100 formed on a substrate 10 according to an embodiment of the; present invention. Referring to FIG. 2, the metal thin film 100 is formed on the substrate 10 using crystal metal or alloy.

Various types of materials, for example, a glass, aciryl resin such as polymethyl methacrylate (PMMA) , plastic resin such as polycarbonate (PC) , and the like may be used for the substrate 10. In a vacuum deposition device, the metal thin film 100 is formed on the substrate 10 using sputtering, vacuum deposition, ion plating, and the like. Sputtering enables metal atoms or molecules, emitted when high energy particles collide on the surface of solid metal and the like, to be deposited on the substrate. Vacuum deposition heats a material in the vacuum state and vaporizes the heated material to attach the vapor on the substrate. Sputtering may be used when coating an element or compounds of which vacuum deposition is impossible or difficult.

As shown in FIG. 3, according to an aspect of the present invention, the metal thin film 100 includes a plurality of grains 110 and a plurality of grain boundaries 120 that are formed on the two dimensional (2D) plane of one or two layers. A sheet resistance of the metal thin film 100 is controlled according to the size of the grain 110 and a number of grain boundaries 120.

According to an aspect of the present invention, the grain 110 may be formed in a thin film state of a thin thickness by decreasing plasma energy in metal plating and thereby reducing the energy of metal atoms or clusters to be deposited. It may be desirable to maintain the average size (lεirgest width) of grains 110 to be less than or equal to about 500 nm and to maintain the thickness of the metal thin film 100 to be less than or equal to about 50 nm. Also, it may be desirable that a melting temperature of material of the metal thin film 100 is less than or equal to about 350 °C. For example, metal such as tin (Sn) , zinc (Zn) , and the like, or alloys thereof with silver (Ag) may be used. As described above, according to an aspect of the present invention, a thin film consisting of only 2D planar grains 110 may be formed by adjusting a number of grains 110 or the grain size with respect to the thickness of the metal thin film 100. Through this, the plurality of grains 110 may be connected to each other in series and the sheet resistance of the thin film may have greater dependency on the grain boundary 120.

Generally, metal may have the following characteristics : 1) forming a crystal structure in a solid state, 2) being a thermal and electrical conductor, 3) having ductility and malleability, 4) having metallic luster, and 5) being solid in the room temperature, except for mercury. Metal with some of the above-described characteristics may be referred to as "metalloid" and metal with none of them may be referred to as "nonmetal". Specifically, the metal has the crystal structure in the solid state. General metal forms poly crystals by irregularly gathering various sizes of crystal-structured grains.

The size of grain 110, that is, the maximum width between the grain boundaries 120 may reach tens of angstrom to macroscopic size. Each grain boundary 120 is shown as sheet defect rather than point defect or line defect. The sheet defect of the grain boundary 120 may have significant affect on poly crystal characteristics, that is, mechanical strength, or electrical, chemical, and optical characteristics, and the like. In particular, according to an aspect of the present invention, there may be provided a metal thin film that has similar high resistance to a dielectric substance, with maintaining the optical clraracteristic of a metal using the affect that the grain boundary 120 affects the sheet resistance of the thin film.

FIG. 4 is a diagram for describing the property of a grain boundary 120 of a metal thin film 100 according to an embodiment of the present invention. As shown in FIG. 4, a thin film is uneven and segregation occurs in a perimeter 150 of the grain boundary 120. When the thin film is formed, defect particles 115 occur around the grain boundary 120 in a medium with the different property. The detect particles 115 may be separated from normal particles 105 to move toward the grain boundary 120 and thereby generating a void region 130. The void region 130 may increase electrical resistance. FIG. 5 is a mimetic diagram of resistivity between the grain 110 and the grain boundary 120 of the metal thin film 100 according to an embodiment of the present invention. As shown in FIG. 5, a peak 125 with high resistivity is formed in the void region 130 formed near the grain boundary 120. Therefore, according to the present invention, it is possible to form a high resistance thin film in proportion to the number of grain boundaries 120 by forming the thin film to connect the grain boundaries 120 with the resistivity greater than the grains 110. Specifically, when increasing the number of grain boundaries 120 under the condition of the same thickness, it is possible to macroscopically increase the sheet resistance of the thin film.

For example, in the case of a polycrystal varistor formed of metal oxide ZnO, ZnO grains are connected to each other in series and in parallel and grain boundaries function as energy walls to exhibit characteristic like Zener diode between the grains and the grain boundaries . In this instance, it can be explained as conductivity in a conduction band forming electrical conductivity of a metal in a grain bulk and it can be explained as hoping conductivity in a grain boundary. Specifically, as shown in FIG. 2 or 3, the grains 110 may be formed on the 2D plane of one or two layers . In this instance, the metal thin film 100 may be in the structure where the grains 110 are connected to each other in series. In this case, the electrical conductivity may be determined depending on a hoping mechanism rather than a conduction mechanism. Consequently, the sheet resistance may be controlled by the number of grain boundaries 120. If the thickness of the thin film needs to consider the parallel connection in connection of the grains 110 constituting the thin film, it may be difficult to control the sheet resistance of the thin film. Also, the resistance of the thin film may generally depend on the bulk resistance.

According to an aspect of the present invention, in order to form the metal thin film 100 with an appropriate thin film thickness of tens of nm and to form the grains 110 that are connected in series on the 2D plane of one or two layers, it is possible to appropriately select a vacuum state, a substrate temperature, a deposition source energy, a type of deposition material, and the like in sputtering, vacuum deposition, and the like. As described above, it is possible to form the thin film with the thickness less than or equal to about 50 nm and with the grain size less than or equal to about 500 nm, using a metal material of the melting temperature less than or equal to about 350C° . When the metal material reaches the melting temperature, many point defects existing in crystals due to spreading of atoms may move, which results in increasing a void region around the graiin boundary 120 and thereby increasing the entire sheet resistance of the thin film as shown in FIG. 4. Accordingly, by using metal or alloy with a low melting temperature, it is possible to more easily form the grain 110 and the grain boundary 120. In this case, resistivity or sheet resistance characteristic of the grain boundary 120 may be changed according to various types of conditions such as material of a substrate, a metal type, a substrate temperature when forming the thin film, a thin film forming energy, and the like.

FIG. 6 illustrates an example of a scanning electron microscope (SEM) picture (10OK times) of a thin film made of alloys of tin and zinc according to an embodiment of the present invention. The thin film of FIG. 6 showed high resistance characteristics that the thickness of the thin film is about 20 nm, the average grain size is less than or equal to about 500 nm, and the sheet surface reaches about 10¹² Ω/D.

However, when an Al metal thin film was exhibited as amorphous by sputtering and the like, the sheet resistance was some Ω/D to tens of Ω/D in the thin film with about 20nm thickness. Also, even in the case of alloys of tin and silver or alloys of tin and zinc, when the average size of grains was some μm in the thickness of about 20nm, the sheet resistance was tens of /D to hundreds of Ω/D.

FIG. 7 illustrates an embodiment of a structure where the metal thin film 100 shown in FIGS. 2 and 3 is formed in a laminate structure 200. Referring to FIG. 7, the laminated structure 200 including the metal thin film 100 includes a plurality of metal thin film layers 210 and a plurality of isolation layers 220 that are formed on a substrate 10.

Each metal thin film layer 210 is formed in the metal thin film 100 made of crystal metal or alloy as shown in FIGS. 2 and 3. As described above, the sheet resistance of the metal thin film of each metal thin film layer 210 may be controlled by the plurality of grains 110 and the plurality of grain boundaries 120 that are formed on the 2D plane. As shown in FIG. 7, the isolation layer 220 may be disposed between the metal thin film layers 210. The isolation material 220 may use a material with the sheet resistance at least several times more than the sheet resistance of the metal thin film 100 that is controlled by the grains 110 and the grain boundaries 120. For example, the isolation layer 220 may use a high resistance inorganic insulating layer using various types of metal oxides, for example, SiO2, TiO2, MgO, and the like, or Si that can be disposed in the vacuum deposition device. Also, the isolation layer 220 may use an organic insulating layer coated outside the vacuum deposition device using a spray scheme .

As described above, by forming the metal thin film 110 and the isolation layer on the substrate 10 in turn at least once and thereby forming the thin film in the laminated structure, it is possible to minimize the change of optical and electrical characteristics of the high resistance metal thin film caused by external environments such as vapor in the air, oxygen, and high temperature, and thereby enhance the durability and the reliability.

Mode for Carrying Out the Invention

FIG. 8 is cross-sectional views for describing various embodiments associated with the laminated structure 200 including the plurality of metal thin film layers 210 and the isolation layers 220. As shown in a view 310 of FIG. 8, it is possible to form a coating layer of the same material as the material of the isolation layer 220 on both the top surface of a highest layer and the bottom surface of a lowest layer among the plurality of metal thin film layers 210. Also, as shown in a view 320, it is possible to form the coeiting layer of the same material as the material of the isolation layer 220 only on the top surface of the highest layer among the plurality of metal thin film layers 210. Also, as shown in a view 330, it is possible to form the coeiting layer only on the bottom surface of the lowest layer among the plurality of metal thin film layers 210. Also, as shown in a view 340, it is possible to not form any coating layer on the top surface of the highest layer and the bottom surface of the lowest layer among the plurality of metal thin film layers 210.

According to an aspect of the present invention, the high resistance metal thin film 100 with the controlled sheet resistance, described above with reference to FIGS. 2 and 3, may need to maintain the high resistance at a required value and also to maintain the metallic cluster, that is, reflectivity. However, in an environment with vapor, oxygen, and high temperature, metal oxidation may occur. With the thin film changing into a metal oxide thin film, a metal portion may be thinned whereby the metallic luster may be gradually disappeared to be transparent.

In this case, as shown in a laminated structure 400 of FIG. 9, it is possible to delay a change level using an organic layer 430 of urethane and the like, and thereby protect change of the surface resistance or characteristic of metallic luster. In this instance, the organic layer 430 is medium-surface coated on a metal thin film 410 using a spray, a roller, and a brush from an outside of a vacuum deposition device. Also, when a substrate 10 made of polymethyl methacrylate (PMMA) , polycarbonate (PC) , and the like is not mirror-surface processed, it is possible to coat an organic layer 420 of urethane and the like on the substrate 10 using a spray, a roller, and a brush and then coat the metal thin film 410 on the organic layer 420 as shown in FIG. 9.

According to the laminated structure 400 of FIG. 9, it is possible to prevent the metallic cluster from disappearing to thereby be transparent. A thin film exposed in the air may be easily affected by, particularly, vapor and oxygen. A film or a thin film used for an outward appearance of an item such as an LCD, a plasma display panel (PDP) , and the like considers a water vapor transmission rate (WVTR) or an oxygen transmission rate (OTR) as an important factor. The structure according to the present invention is also invented to have the excellent characteristics with respect to the important factors .

Also, when an environment corresponding to a worse condition than a general reliability condition occurs, oxygen and vapor permeates the metal thin film 410 and oxidizes the metal thin film 410 according to characteristics of the WVTR and the OTR basically included in the generally used medium- surface coated organic layer 430. Accordingly, optical characteristics such as reflectivity of a metal and the like may be reduced, thereby deteriorating the metallic luster. The reliability condition may include most basic tests such as a high temperature test, a low temperature test, a high temperature high vapor test, a thermal impact test, and the like. In addition, the reliability condition may include a reliability test consistent with a function employed by each applied product. For example, when the structure of the present invention is used for an electronic product case contacting with the skin such as a mobile phone and the like, a cosmetic-resistant test may be included. However, although all the tests are passed, when the reliability test is added with respect to the effect of electromagnetic waves coming from a high frequency circuit of a transformer or a converter of electronic products, or displacement current occurring due to the electromagnetic waves, the reliability may be a failure with respect to a corresponding condition.

When a high environment resistance is required based on a basic vapor permeability or an oxygen permeability with respect to all the external materials or environments, it is possible to use a structure of including an organic layer 540 of urethane and the like. The organic layer 540 is medium- surface coated on a laminated structure 500 with a controlled sheet resistance, using a spray, a roller, a brush, and the like, as shown in FIG. 10. Also, when a substrate 10 of PMMA, PC, and the like is not mirror-surface processed, it is possible to coat an organic layer 530 of urethane and the like on the substrate 10 using a spray, a roller, a brush, and the like and then form the laminated structure 500 on the organic layer 530 as shown in FIG. 9.

The laminated structure 500 of FIG. 10 may use various types of laminated structures 200, described above with reference to FIGS. 7 and 8. Accordingly, in FIG. 10, a laminated structure according to the present invention may be a structure where the organic layer 530 or 540 is added to the laminated structure 500 including a plurality of metal thin film layers 510 and isolation layers 520. In this instance, the organic layer 530 or 540 may be medium-surface or premier coated on the top surface of a highest layer or on the bottom surface of a lowest layer among the plurality of metal thin film layers 510, using a spray, a roller, a brush, and the like. Also, as shown in the views 310, 320, and 330 of FIG. 8, the laminated structure 500 of FIG. 10 may include a coating layer of the same material of the isolation layer 520 on the top surface of the highest layer or on the bottom surface of the lowest layer among the plurality of metal thin film layers 510. In this instance, the laminated structure according to the present invention may include the organic layer 530 or 540 to be coated on the top surface or the bottom surface of the coating layer using a spray, a roller, a brush, and the like. Specifically, when including the plurality of metal thin film layers 510, the isolation layer 520 disposed between the plurality of metal thin film layers 510, and the coating layer on the top surface of the highest layer or on the bottom surface of the lowest layer among the plurality of metal thin film layers 510, the laminated structure of the present invention may include the organic layer 530 or 540 to be medium-surface coated or premier coated on the top surface or the bottom surface of a highest layer of all the layers .

As described above, in the laminated structure shown in FIG. 10, although vapor or oxygen permeates to thereby oxidize a metal oxide film of a first layer, a metal thin film of a subsequent layer of the first layer may maintain characteristics. Therefore, it is possible to maintain a desired sheet resistance value, reflectivity, and the like as is. Also, although vapor or oxygen may permeate up to a second metal thin film layer in the worse condition, permeability of vapor or oxygen may be significantly reduced with respect to the isolation layer 520 of inorganic oxide. Therefore, a third metal thin film layer may be nearly completely preserved. Specifically, according to the environment resistance or reliability of an applied product, it is possible to apply a laminated structure with a single layer, two layers, or at least three layers of metal thin film and thereby satisfy a durability standard of the product. Accordingly, as a number of layers of the metal thin film increases, a cost of thin film increases. Therefore, it may be desirable to laminate a minimum number of metal thin film layers, and construct a thin film that can maintain the high resistance capable of satisfying the durability and reliability of a product and also can maintain the optical characteristic such as reflectivity and the like. Although a few embodiments of the present invention have been shown and described, the present invention is not limited to the described embodiments. Instead, it would be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Industrial Applicability A laminated structure according to the present invention may be very usefully adopted as a coating structure for protecting an exposed portion of an electronic product case, a cosmetic container, and the like, formed of a glass, a plastic, or various resins, and for exhibiting aesthetic sense using the metallic luster.

Claims

1. A laminated structure for outward appearance of an item comprising: a plurality of metal thin film layers, each being formed with a metal thin film of a crystal metal or an alloy,- and an isolation layer being disposed between each of two layers of the plurality of metal thin film layers, wherein a sheet resistance of the metal thin film for a luster is controlled by a plurality of grains and a plurality of grain boundaries that are formed on a two- dimensional (2D) plane.

2. The laminated structure of claim 1, wherein the isolation layer comprises at least one coating layer of inorganic material and organic material with a sheet resistance greater than the sheet resistance of the metal thin film.

3. The laminated structure of claim 2, wherein the inorganic material comprises metal oxide.

4. The laminated structure of claim 1, further comprising: an organic layer being coated on at least one of the top surface of a highest layer and the bottom surface of a lowest layer among the plurality of metal thin film layers .

5. The laminated structure of claim 1, further comprising: a coating layer being formed of the same material as the isolation layer to be provided on at least one of the top surface of a highest layer and the bottom surface of a lowest layer among the plurality of metal thin film layers.

6. The laminated structure of claim 5, further comprising: an organic layer being coated on at least one of the top surface of a highest layer and the bottom surface of a lowest layer among all the layers comprising the plurality of metal thin film layers, the isolation layer, and the coating layer.

7. The laminated structure of claim 1, wherein the size of grain is less than or equal to about 500 nm.

8. The laminated structure of claim 1, wherein the thickness of the metal thin film is less than or equal to about 50 nm.

9. The laminated structure of claim 1, wherein a melting temperature of the metal or the alloy is less than or equal to about 350 C° .

10. A laminated structure for outward appearance of an item comprising: a metal thin film being formed of a crystal metal or alloy; and an organic layer being coated on at least one of the top surface and the bottom surface of the metal thin film, wherein a sheet resistance of the metal thin film for a luster is controlled by a plurality of grains and a plurality of grain boundaries that are formed on the 2D plane .

11. A method of forming a laminated structure for outward appearance of an item, the method comprising: forming a metal thin film layer and an isolation layer on a substrate in turn at least once, wherein the metal thin film layer is coated using a crystal metal or an alloy, a sheet resistance of the metal thin film layer for a luster is controlled by a plurality of grains and a plurality of grain boundaries that are formed on the 2D plane.