KR20170024839A - Fabrication Technology of High Transparency DLC Film Having Excellent Hardness and Wear Resistance - Google Patents

Abstract

The present invention relates to a fabrication technology of a high transparency diamond like carbon (DLC) film having excellent hardness and wear resistance. According to the present invention, even if a film is deposited in the thickness capable of maintaining excellent wear resistance, a film of the thickness of 1 or more without degradation of a penetration ratio is formed, so a high transparency DLC thin film having excellent wear resistance, hardness and transparency can be manufactured. To this end, provided is a glass substrate in which a transparent DLC film containing SiO is formed on the glass substrate.

Description

[0001] The present invention relates to a DLC film having excellent hardness and abrasion resistance and a high transparency,

The present invention relates to a high transparency DLC film having excellent hardness and abrasion resistance.

More specifically, the present invention relates to a technique for producing a high-transparency DLC thin film having at least one film having a thickness without permeability degradation and having abrasion resistance, hardness and transparency at the same time, even though a thickness capable of maintaining excellent abrasion resistance is maintained.

DLC (Diamond Like Carbon) is a mixture of sp ² and sp ³ carbon atoms, which means an amorphous carbon material that has unique properties similar to natural diamonds, and is generally used to form protective coatings.

Because DLC can be deposited at room temperature, any material compatible with a vacuum environment can be used without restriction. By controlling the hydrogen atom content with the carbon atom ratio of sp ² and sp ³ , Can be adjusted in various ways.

Commonly used DLC coatings are used as surface protectors for hard disks as well as mold surfaces, bearings and cutting tools with high hardness, good chemical stability and low coefficient of friction. Another area is that it is applied to sunglass or special cover materials by using high transparency to infrared ray and low transparency of visible light region.

However, the conventional DLC film having such characteristics can be applied to a display cover glass used for a display device such as an LCD, an LED, or an OLED, which requires a high transmittance in a visible light region It is almost impossible to form a transparent glass of automobile glass, window, or solar cell, and it was practically impossible to manufacture a DLC film having a high transmittance.

On the other hand, sapphire crystal and the like are being considered as display cover materials of high hardness. Sapphire crystal is a high-purity aluminum oxide (Al ₂ O ₃ ) component, which is characterized by a very high surface hardness because the crystal structure is uniformly arranged unlike glass.

Sapphire crystal is known to have good corrosion resistance and chemical resistance to acid and alkali, and excellent thermal conductivity. However, due to its high price and low transmittance compared to glass, it is not suitable for use as a display cover material.

Numerous references are referenced throughout the specification and are cited therein. The disclosure of the cited document is incorporated herein by reference in its entirety to more clearly describe the state of the art to which the present invention pertains and the content of the present invention.

Korean Patent Publication No. 2005-0069986

The present invention relates to an amorphous carbon thin film (DLC) layer doped with a carbon (C) mixed structure (Sp ¹ , Sp ² , Sp ³ ) by doping SiO x to improve the transmittance of a film by forming a SiO x C y film, This is a technique for imparting wear resistance.

The conventional DLC film has a problem that the hardness is increased but the transparency is increased. Further, when the thickness of the film is decreased in order to increase the transparency, there is a problem that the abrasion resistance can not be secured. However, the inventors of the present invention have found that a highly transparent DLC thin film excellent in abrasion resistance, hardness and transparency The present invention has been completed.

It is therefore an object of the present invention to provide a highly transparent DLC film formed on a glass substrate and having high hardness and high abrasion resistance.

It is another object of the present invention to provide a glass substrate on which the transparent DLC film is formed and a method of manufacturing the same.

It is still another object of the present invention to provide an article comprising the glass substrate on which the transparent DLC film is formed.

Other objects and advantages of the present invention will become more apparent from the following detailed description of the invention, claims and drawings.

One aspect of the present invention is to provide a glass substrate on which a transparent DLC (Diamond Like Carbon) film formed on a glass substrate and including SiO 2 having a thickness of at least 200 ± 5 nm is formed.

The inventors of the present invention have found that although a DLC film is formed on a glass substrate with a thickness of at least 200 ± 5 nm in order to secure substantial scratch performance as a result of hardness improvement, it is desired that the transmittance of the glass is not lowered and the abrasion resistance, hardness, So that a highly transparent DLC thin film was produced, thereby completing the present invention.

In the present invention, the glass substrate on which the transparent DLC film is formed is not particularly limited as long as it is an amorphous (amorphous) transparent solid substrate of a material known in the art to which the present invention belongs. For example, soda lime silicate glass -lime silicate glass, borosilicate glass, phosphate glass, alumino-silicate glass and the like can be used. An aluminosilicate glass substrate can be preferably used.

In one embodiment of the present invention, the transparent DLC film formed on the glass substrate is formed in a multilayer structure.

In this case, although the high transparency of the same level as that of glass can still be secured, there is an advantage that even more excellent hardness and abrasion resistance can be secured than when a single layer is formed.

When the transparent DLC film is formed into a multilayer structure, the DLC film may have a total thickness of at least 300 ± 20 nm.

On the other hand, the present inventors found that a transparent thin film such as SiO ₂ is formed in a DLC film having a composition of SiOxCy and a composition ratio of x is high and a composition ratio of y is low, but the value of surface hardness is lowered to a level similar to that of glass, The higher the composition ratio of y, the higher the surface hardness value becomes, but it becomes opaque.

In the case of using HMDSO [Si ₂ O (C ₆ H ₁₈ )] and O ₂ as a precursor for preparing a transparent DLC film, for example, although not necessarily limited to the above composition of SiO x C y, go carried, it can have the following composition of the film Si ₂ OC _6, i.e. SiO _{0 .5} C ₃ to be finally deposited.

Going C blown by reaction with CO ₂ in accordance with the O ₂ content of the formula with base, may be a SiO _2, thus, depending on the O ₂ content of x = 0.5 ~ 1.95, the composition for the y = 0.1 ~ 3 free Can be manufactured.

Thus, in one embodiment of the present invention, the DLC film may have a composition of SiOxCy (x = 0.5 to 1.95 and y = 0.1 to 3).

In another embodiment of the present invention, when the DLC film is formed into a multilayer structure, two or more films having different SiOxCy compositions may be successively laminated.

Also, since the final hardness of the DLC film having the composition of SiOxCy differs depending on the composition ratios of x and y, the two or more films formed by the successive lamination may have different hardness from each other.

According to a preferred embodiment, in the case where two or more films having different hardnesses are successively laminated on a glass substrate, they may be stacked in this order from a higher hardness to a lower one in this order.

The reason why the upper layer and the lower layer are formed differently in this way is that a thin film having a high hardness causes a large decrease in transmittance even if the thickness is 100 nm. (N = 2.2 to 2.6), the transmittance decreases when used as an outermost layer. On the contrary, when the hardness is lowered, the refractive index also decreases as the hardness increases (n = 1.4 to 1.6) As shown in FIG.

Therefore, in the case of laminating a thin film having a high hardness from a thin film having a high hardness within a range not lowering the transmittance for each composition, a thin film can be formed without decreasing the transmittance, and at the same time, And wear resistance can be ensured.

The DLC film formed as a single layer or a multilayer on the glass substrate may be formed to have a total thickness of 200 ± 5, 300 ± 20, 500 ± 50, or 1000 ± 100 nm.

Another aspect of the present invention is a process for preparing a DLC film precursor comprising: (i) preparing a DLC film precursor comprising C, Si and O; And (ii) doping the precursor onto a glass substrate to form a transparent DLC film having a thickness of at least 200 +/- 5 nm. .

(i) C, Si  And O DLC Preparing a membrane precursor

In this step, in order to solve the problem that the DLC shows high hardness but has opaque characteristics, a material including silicon and oxygen impurities is used as a precursor.

The precursor to, for example hexamethyldisiloxane (HMDSO), tetramethylsilane (TMS), hexamethyl disilane (HMDS), tetraethyl orthosilicate (TEOS), silane (silane), and acetylene and the like CH ₄ Hydrocarbons, and the like, but the present invention is not limited thereto.

As the carrier gas, hydrogen, helium, oxygen, or the like can be used. However, the carrier gas is not limited thereto, and various gases may be appropriately selected as the carrier gas according to the composition of the desired thin film.

In one embodiment of the present invention, a mixture of hexamethyldisiloxane (HMDSO) and oxygen (O ₂ ) may be used as the precursor containing C, Si and O.

In this case, the inflow amount (sccm) of HMDSO is controlled so that the gas ratio (HMDSO / (HMDSO + O ₂ )) divided by the inflow amount (sccm) summing up the sum of HMDSO and O ₂ is 0.1 to 1 to form a transparent DLC film .

When the gas ratio is low, C is reacted with O ₂ during the process to be carbonized, so that a thin film is not formed. In this case, a thin film close to SiO ₂ (glass composition) is formed. Therefore, the transmittance is not reduced as compared with the glass, and the surface hardness becomes equal to the glass.

On the contrary, when the gas ratio is increased, the tendency of C to react with O ₂ to carbonize is reduced, so that the bond between CCs is formed, and as a result, the transmittance is decreased and the surface hardness is increased.

The membrane prepared by the method of controlling the gas ratio of 0.1 to 1 has a stoichiometric characteristic of SiO x C y (x = 0.5 to 1.95, y = 0.1 to 3). As the composition ratio of x is high and the composition ratio of y is low, a transparent thin film such as SiO ₂ is formed, but the surface hardness value is lowered to a level similar to that of glass. The lower the composition ratio of x and the higher the composition ratio of y, But it becomes opaque.

(ii) depositing the precursor onto a glass substrate Doping  step

In this step, the precursor is doped on a glass substrate to form a transparent DLC thin film having a thickness of at least 200 ± 5 nm.

When the thickness of the thin film to be doped is different, the transmittance tends to decrease as the thickness increases because of the visible light absorption property of the DLC film.

In order to produce a thin film having excellent scratch resistance, a thin film having a high surface hardness should have a thickness of at least 100 nm or more. In general DLC, there is a limit that the thickness can not be increased by 200 nm or more due to the decrease in transmittance, In the case of the present invention, it is characterized in that a high transparency of the same level as that of glass can be ensured while doping such that the thickness is at least 200 ± 5 nm in order to secure substantial scratch performance.

The present doping step may be performed by one or more selected from the group consisting of a chemical vapor deposition process, a plasma deposition process, a filtered vacuum arc (FVA) process, and a laser ablation process, But is not limited to.

The transparent DLC film doped on the glass substrate may have a multilayer structure.

In one embodiment of the present invention, when a multilayered transparent DLC film is laminated using a mixture of hexamethyldisiloxane (HMDSO) and oxygen (O ₂ ) as a precursor, the gas ratio is controlled within the range of 0.1 to 1, The multi-layer structure can be formed by a process of continuously laminating two or more films different from each other.

On the other hand, another aspect of the present invention is to provide a product comprising the glass base material.

The glass substrate in which the transparent DLC film of the present invention is laminated can be preferably used for a display device, a solar cell, an optical device, a window, an automobile front glass, and a tempered glass because the transmittance of the glass substrate is similar to that of glass but can realize high hardness and wear resistance. have.

By applying the technique of the present invention, it is possible to solve the problem of visible light transmittance degradation caused by depositing a conventional DLC film thickness of 50 nm or more, and to obtain a DLC thin film having high hardness and high transparency, can do. This has the following effects.

 First, it has a hardness level of sapphire material, which makes it possible to replace expensive sapphire glass at a low price.

 Second, the process rate is low because the SiOxCy thin films with different composition ratios can be continuously deposited by controlling the gas flow rate in a single process.

 Third, it can be applied to various fields such as display cover glass as well as solar cell cover glass, contributing to industrial development.

1 is a schematic view showing a state in which a SiOxCy thin film is deposited on a glass substrate.
2 is a schematic view showing a state in which two or more SiOxCy thin films are deposited on a glass substrate.
3 is a photograph of the surface of sapphire after wear resistance test using Garnet.
4 is a photograph of the glass surface after the abrasion resistance test using Garnet.
5 is a photograph of the surface of the thin film 3 after the abrasion resistance test using garnet.
6 is a photograph of the surface of the thin film 4 after the abrasion resistance test using Garnet.
7 is a photograph of the surface of the thin film 5 after the abrasion resistance test using garnet.
8 is a photograph of the surface of the thin film 6 after the abrasion resistance test using garnet.
9 is a photograph of the surface of the thin film 7 after the abrasion resistance test using garnet.
10 is a photograph of the surface of the thin film of Example 2 after the abrasion resistance test using Garnet.
11 is a photograph of the surface of the thin film of Example 3 after the abrasion resistance test using Garnet.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are only for describing the present invention more specifically and that the scope of the present invention is not limited by these embodiments.

Example

One. SiO  Depending on the content DLC  Identification of changes in film properties (hardness and transparency)

In this experiment, chemical vapor deposition (CVD) method was used to control SiOxCy thin film by controlling hexamethyldisiloxane (HMDSO) as a precursor and oxygen gas at a specific flow rate ratio (Q_HMDSO: Q_O ₂ ) And deposited using the method.

Specifically, the SiOxCy thin film was deposited on an Alumino-Silicate Glass using a CVD apparatus under the control of a gas flow ratio. The ratio (Q_ratio) of the inflow (sccm) of HMDSO / (HMDSO + O ₂ ) Proceeding from 0.1 to 1. At this time, the ratio (Q_ratio) of the inflow (sccm) of the used HMDSO / (HMDSO + O ₂ ) is as shown in Table 1 below.

The thickness of the deposited thin film was measured by alpha-step, the visible light transmittance was measured by a spectrophotometer, the hardness was measured by nanoindentation (Fischerscope HM500), converted into Hv (Vickers Hardness) Respectively.

pellicle Gas ratio
(Q_ HMDOS / Q_Total) Thin film thickness (nm) Visible light
Transmittance (%) Hv
(GPa) friction
Coefficient One 0.1 200 ± 5 92% 0.7 0.8 2 0.1 100 ± 5 92% 0.7 0.7 3 0.2 200 ± 5 90% 1.3 0.8 4 0.2 100 ± 5 91% 1.3 0.8 5 0.2 300 ± 5 88% 1.3 0.8 6 0.5 200 ± 5 71% 1.7 0.5 7 0.5 100 ± 5 74% 1.6 0.6 8 1.0 200 ± 5 54% 2.1 0.3 9 1.0 100 ± 5 61% 1.9 0.5

Experimental results show that as the gas ratio increases (HMDOS increases), the hardness increases, but the permeability decreases. On the other hand, as the gas ratio decreases, the permeability increases but the hardness decreases. From the results shown in Table 1, it was confirmed that when the SiOx component is added to the DLC film, the transparency increases but the hardness decreases and the transparency and the hardness are inversely proportional to each other.

On the other hand, Table 2 shows the results of comparing the characteristics of sapphire, glass and DLC film.

Comparative Example Material Thin film thickness (nm) Transmittance (%)
at? = 550 nm Hv
(GPa) friction
Coefficient One Sapphire Bulk 87% 2.5 0.5 2 Glass Bulk 92% 0.7 0.7 3 DLC 10 86% 0.7 0.7 4 DLC 100 ± 5 55% 2.5 0.2

When the characteristics of the sapphire, glass and DLC film of Table 2 are compared with those of the thin films of Table 1, it is confirmed that the thin films 3 and 4 of Table 1 have high transmittance at the same level as that of glass, ) Values.

2. Excellent both hardness and transparency DLC Fabrication of membranes

In this experiment, the SiOxCy thin film was deposited on Alumino-Silicate Glass by using CVD method and at least one SiOxCy thin film was deposited. In this case, a film having a relatively transparent but hardness composition was deposited on the lowermost layer And the uppermost layer (the layer farthest from the glass) has a film which is transparent but has a relatively higher hardness than glass.

That is, as the hardness increases, the thin film having a high refractive index (n = 2.2 to 2.6) is used. Therefore, when the film is used as the outermost layer, the transmittance decreases. On the other hand, as the hardness decreases, the refractive index decreases A DLC film excellent in both hardness and transparency was produced.

In addition, in the above basic structure, a sample was prepared by having an intermediate layer having a composition ratio between the lowest layer and the uppermost layer. In this case, the ratio (Q_ratio) of the inflow (sccm) of HMDSO / (HMDSO + O ₂ ) is as shown in the table, the thickness of the deposited thin film was measured by alpha step, and the visible light transmittance was measured by spectrophotometer. Hardness was measured by nano-indentation (Fischerscope HM500) and expressed as Hv (Vickers Hardness). In the case of the layer No., the layer near the glass was named Layer 1.

Example Layer No. Gas ratio
(Q_ HMDOS / Q_Total) Thin film thickness (nm) Visible light
Transmittance (%) Hv
(GPa) friction
Coefficient One One 0.2 200 ± 5 91% 1.3 0.7
2 One 0.3 200 ± 5
91%
1.5
0.7 2 0.1 100 ± 5
3 One 0.5 50 ± 5
90%
1.5
0.8 2 0.2 200 ± 5  3 0.1 100 ± 5

As a result of the experiment, it was confirmed that the SiOxCy thin film prepared in this manner had a similar transmittance to that of glass but could attain high hardness at the same time.

3. Manufactured DLC Determination of abrasion resistance of membrane

The DLC film should be formed with a film thickness of at least 100 nm, generally 200 nm or more, in order to ensure substantial wear resistance performance or hardness characteristics. The thicker the DLC film is, the more advantageous it is, but in this case, the transparency is reduced. In the case of a general DLC film, it was confirmed that the thickness could not be increased to more than 100 nm due to decrease in transmittance (see Comparative Examples 3 and 4 in Table 2).

In order to evaluate the abrasion resistance according to the surface hardness and thickness given by each composition, the abrasion resistance of sapphire and glass and the abrasion resistance of the DLC films prepared above were compared Respectively. Specifically, an abrasion resistance test was carried out under the conditions of a load of 1 kgf and reciprocating 10 times using Garnet # 150, and the results are shown in FIG. 3 to FIG.

As a result of the experiment, the glass (FIG. 4) having a high transmittance of the same or almost the same level as the glass and a high hardness (Hv) value higher than that of the glass in the case of the thin film 3 of Table 1 (Example 1, The abrasion resistance is much better than that of the conventional method. On the other hand, the thin film 4 (FIG. 6) in Table 1 is excellent in terms of transmittance and hardness, but has a thickness of only 100 nm and can not secure the ability to suppress the occurrence of substantial wear or scratches Respectively.

Also in the case of the DLC thin film of Example 2 (Fig. 10) and Example 3 (Fig. 11) including SiOx and formed in multiple layers together with the thin film 3 (Example 1) It has been confirmed that it has high abrasion resistance.

As a result, it was confirmed that even though a thickness capable of maintaining excellent abrasion resistance is deposited in the embodiment of the present invention, one or more films can be deposited at a thickness without decreasing the transmittance of glass to maintain a high hardness and to produce a highly transparent thin film.

Claims (16)

A glass substrate on which is formed a DLC (Diamond Like Carbon) film formed on a glass substrate and comprising SiO with a thickness of at least 200 +/- 5 nm. The glass substrate according to claim 1, wherein the DLC film has a multilayer structure. The glass substrate according to claim 2, wherein the DLC film has a total thickness of at least 300 ± 20 nm. The glass substrate according to claim 2, wherein the DLC film is formed by sequentially laminating two or more films having different compositions. The glass substrate according to claim 2, wherein the DLC film is formed by sequentially laminating two or more films having different hardness. The glass substrate according to claim 5, wherein the two or more films having different hardnesses are stacked in this order on the substrate in the order of high hardness to low hardness. The method of claim 1, wherein the glass substrate is selected from the group consisting of soda-lime silicate glass, borosilicate glass, phosphate glass, and aluminosilicate glass . The glass substrate according to claim 1, wherein the DLC film has a composition of SiOxCy (x = 0.5 to 1.95 and y = 0.1 to 3). (i) preparing a DLC film precursor comprising C, Si and O; And
(ii) doping the precursor onto a glass substrate to form a transparent DLC thin film having a thickness of at least 200 +/- 5 nm
The method according to claim 1, wherein the glass substrate is a glass substrate. The method according to claim 9, wherein the step (ii) is performed at least one selected from the group consisting of a chemical vapor deposition process, a plasma deposition process, an FVA (Filtered Vacuum Arc) process, and a laser ablation process ≪ / RTI > The method of claim 9 wherein the precursor is selected from the group consisting of hexamethyldisiloxane (HMDSO), tetramethylsilane (TMS), hexamethyldisilane (HMDS), tetraethylorthosilicate (TEOS), silane, and hydrocarbon hydrocarbons, and mixtures thereof. 10. The method of claim 9, wherein the precursor is characterized in that it comprises a hexamethyldisiloxane (HMDSO) and oxygen (O _2). The method according to claim 12, wherein the inflow (sccm) of the HMDSO is controlled so that the gas ratio (HMDSO / (HMDSO + O ₂ )) divided by the inflow (sccm) of the sum of HMDSO and O ₂ is 0.1 to 1, Thereby forming a transparent DLC film. 14. The method of claim 13, wherein the transparent DLC film has a multilayer structure. 15. The method according to claim 14, wherein the multilayer structure is formed by continuously laminating two or more films having different composition ratios by controlling the gas ratio within a range of 0.1 to 1. A product selected from the group consisting of a display device, a solar cell, an optical device, a window, an automobile windshield and a tempered glass, characterized by comprising the glass substrate according to claim 1.

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