KR100947331B1 - Thin film layer structure having reinforcing layer for lens mold core and method of forming the same - Google Patents

Abstract

In the thin film structure of the lens mold core having the reinforcing layer, the first buffer layer comprises titanium nitride (TiN) and is formed on the surface of the mold core basic material to be coated. The reinforcement layer includes titanium aluminum nitride (TiAlN) and is provided on the first buffer layer, and the second buffer layer is provided on the reinforcement layer. On the second buffer layer, a work layer having a mold releasing property with respect to the glass lens is provided. As described above, since a reinforcing layer including titanium aluminum nitride (TiAlN) is provided under the release thin film deposited on the base material of the lens mold core, the hardness and adhesive strength of the release thin film may be easily supplemented. Therefore, there is an effect that the service life of the lens mold core is remarkably improved.

Description

Thin film structure of lens mold core with reinforcement layer with improved service life and its formation method {THIN FILM LAYER STRUCTURE HAVING REINFORCING LAYER FOR LENS MOLD CORE AND METHOD OF FORMING THE SAME}

The present invention relates to a thin film structure and a method of forming the same, and more particularly, to a method for forming a thin film structure of a mold core for a glass lens having a reinforcing layer and a thin film structure using the same.

In general, an optical glass lens is manufactured by a press molding method in which a glass molding material is placed on a surface of a metal mold core of a precisely processed metal, and molded by applying heat and pressure. As the press molding method is used, mass production of glass lenses becomes possible.

Typically, the mold core used in the press molding method is a metal or alloy base material, a first thin film that provides a mold releasing property between the base material and the glass molding material, and between the base material and the first thin film And a second thin film that provides adhesion.

In order to mass produce a glass lens using such a mold core, the lens can be separated from the mold core without damaging the preformed lens, and the process of forming the next lens must be continuous and fast. To this end, the first thin film is a material having excellent releasability, for example, noble metals such as iridium (Ir), platinum (Pt), rhenium (Re), osmium (Os), ruthenium (Ru) or diamond-like carbon thin film ( DLC; diamond like carbon).

In addition, the second thin film is provided to improve low adhesion between the first thin film having excellent releasability and the base material, and a metal such as chromium (Cr), titanium (Ti), tungsten (W), and zirconium (Zr). It can be formed as.

However, the life time of the mold core is mainly determined by the life of the thin film structure deposited on the mold core. That is, since the service life of the mold core increases as the physical properties of the thin film structure are excellent, thin film structures having various structures have been developed to lower the defective rate of the product and increase the device operation rate.

Accordingly, a first object of the present invention is to provide a thin film structure of a lens mold core having an improved service life.

It is a second object of the present invention to provide a method suitable for forming the aforementioned thin film structure.

The thin film structure of the lens mold core having a reinforcement layer according to an aspect of the present invention for achieving the first object is provided on the surface of the mold core basic material to be coated, and includes titanium nitride (TiN). A first buffer layer, a reinforcing layer provided on the first buffer layer and comprising titanium aluminum nitride (TiAlN), a second buffer layer provided on the reinforcing layer, and a glass provided on the second buffer layer. It may include a working layer having a mold release property for the lens.

According to an embodiment of the present invention, the work layer includes iridium rhenium (IrRe), and the second buffer layer is provided on the chromium (Cr) layer and the chromium (Cr) layer provided on the reinforcement layer. A mixed layer including chromium (Cr) and iridium rhenium (IrRe) may be included.

According to another embodiment of the present invention, the thickness ratio of the work layer to the first buffer layer or the second buffer layer is characterized in that 1: 7 to 1:10.

According to another aspect of the present invention, there is provided a method of forming a thin film structure of a lens mold core having a reinforcing layer, the first buffer layer including titanium nitride (TiN) on a surface of a mold core base material to be coated. To form. Next, a reinforcing layer containing titanium aluminum nitride (TiAlN) is formed on the first buffer layer. A second buffer layer is formed on the reinforcing layer. Finally, forming a working layer having releasability to the glass lens on the second buffer layer.

According to an embodiment of the present invention, the reinforcing layer may be formed at a temperature of 250 to 350 ° C. using a magnetron sputtering method.

According to an embodiment of the present invention, the forming of the second buffer layer may include forming a chromium (Cr) layer on the reinforcement layer and a mixed layer including chromium and iridium rhenium on the chromium (Cr) layer. Forming a, and the work layer may be formed of iridium rhenium (IrRe).

According to the present invention, since a reinforcement layer including titanium aluminum nitride is provided under the release thin film deposited on the base material of the lens mold core, the hardness and adhesive strength of the release thin film may be increased. Accordingly, the service life of the mold core is greatly improved, and the operation rate of the mold apparatus is increased by using the lens mold core, thereby improving productivity.

Hereinafter, a thin film structure of a lens mold core and a method of forming the same according to preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited to the following embodiments. Those skilled in the art may implement the present invention in various other forms without departing from the technical spirit of the present invention. In the accompanying drawings, the dimensions of each component is shown in an enlarged scale than actual for clarity of the invention. In the present invention, when one component is referred to as being formed on, above, or under another component, the one component is formed on or below the other component. It is meant to be positioned, or further components may be additionally formed on the other components. In addition, it is to be noted that the respective components are referred to as "first", "second", and / or "third", not merely to limit each component. Thus, "first", "second" and / or "third" can be used selectively or interchangeably for each component.

Thin film structure of lens mold core with reinforcement layer

1 is a cross-sectional view illustrating a thin film structure of a lens mold core according to an embodiment of the present invention.

Referring to FIG. 1, the thin film structure 190 of the lens mold core 102 having the reinforcing layer according to the present embodiment is stacked on the surface of the base material 102 for the mold core, and the first buffer layer 110 and the reinforcing layer ( 120, the second buffer layer 130, and the work layer 140 may be configured.

The first buffer layer 110 is a layer that provides an adhesive force between the base material 102 and the reinforcing layer 120, and also provides a buffer function to mitigate external impact. For example, the first buffer layer 110 includes cobalt (Co), titanium (Ti), and the like, and preferably, titanium nitride (TiN).

 In this case, when the thickness of the first buffer layer 110 is formed to be 20 nm or less, the buffer function and adhesive force are not sufficient, which is not preferable. This may be undesirable (as described in more detail below), but the thickness of the work layer of the thin film structure of the mold core according to the invention is proportional to the thickness of the buffer layer. Therefore, the first buffer layer 110 is preferably formed of 20 to 40nm.

The reinforcement layer 120 including titanium aluminum nitride (TiAlN) is provided on the first buffer layer 110. Titanium aluminum nitride (TiAlN) has a ceramic property, Vickers hardness of about 2600 to 3000Hv and high temperature oxidation temperature of about 800 ℃ or more has very excellent high temperature oxidation resistance and high hardness properties. Accordingly, there is an effect of easily improving the service life of the mold core together with the work layer 140.

If the reinforcement layer 120 is formed to be 80 nm or less, it is difficult to properly perform the reinforcement function. If the reinforcement layer 120 is formed to 120 nm or more, the deposition time and energy are excessively consumed, which is not preferable. Therefore, the reinforcement layer 120 preferably has a thickness of 80 to 120 nm, more preferably 90 to 110 nm.

Meanwhile, the second buffer layer 130 is provided on the reinforcement layer 120. The second buffer layer 130 is provided to mitigate an impact generated between the work layer 140 and the reinforcement layer 120 having the relatively high hardness when using a mold core, and on the other hand, with the work layer 140. It also has a function of providing an adhesive force between the reinforcing layer 120. For example, the second buffer layer 130 may include titanium (Ti), titanium nitride (TiN), chromium (Cr), tungsten (W), zirconium (Zr), or the like.

The second buffer layer 130 may be formed of a single layer or multiple layers depending on the material of the work layer 140. For example, when the work layer 140 is formed of an iridium rhenium (IrRe) material, the second buffer layer 130 includes a chromium layer 132 and a mixed layer 134 of chromium and iridium rhenium. desirable. In addition, the mixed layer performs a buffer function to relieve stress between the iridium rhenium layer (IrRe) and the chromium layer (Cr) interface formed by a subsequent process.

When the second buffer layer 130 is formed as a single layer, it is preferable that the second buffer layer 130 is formed to 20 to 40nm. This is because when the thickness of the second buffer layer 130 is 20 nm or less, it is difficult to properly perform a buffer function, and when formed to a thickness exceeding 40 nm, peeling or cracking may occur due to an external impact. Even when the second buffer layer 130 is formed as a double layer, each layer preferably has a thickness range of 20 to 40 nm.

The work layer 140 having a releasability to the glass lens is provided on the second buffer layer 130. The work layer 140 has a noble metal-based metal or alloy material such as iridium (Ir), rhenium (Re), platinum (Pt), osmium (Os), ruthenium (Ru), which has excellent hardness and wear resistance. It is preferable. For example, the work layer 140 is formed of an alloy of iridium and rhenium (IrRe). At this time, the rhenium (Re) component is mainly worn by friction with the glass lens, the greater the content of iridium can reduce the wear rate. Therefore, it is preferable to use an alloy having a relatively high iridium content as the work layer 140 in view of the service life.

The work layer 140 may be formed to have a thickness ratio of 1: 7 to 1:10 with respect to the first buffer layer 110 or the second buffer layer 130. When the thickness ratio is 1: 7 or less, since the thickness of the buffer layers 110 and 130 is too thick compared to the thickness of the work layer 140, the soft buffer layers 110 and 130 are deformed so that cracks or peeling may occur. It may occur. In addition, in the case of 1:10 or more, the buffer layers 110 and 130 may not be sufficient for a buffer function, or the work layer 140 may be unnecessarily thick, which is not preferable. Here, when the buffer layers 110 and 130 according to the present embodiment have a thickness of 20 to 40 nm, the work layer 140 has a thickness in the range of 140 to 340 nm. More preferably, the work layer 140 has a thickness of 140 to 200nm.

On the other hand, in the case where the mold core 100 of the present invention is formed for aspherical lens manufacturing, since the shape of the functional surface has a curvature, when the total thickness of the thin film structure 190 exceeds 500 nm, the aspherical surface shape during glass lens molding is formed. Difficult to implement Therefore, the thin film structure 190 is preferably formed to 500nm or less. In addition, although not shown, it should also be considered that the difference between the center thickness and the outer thickness of the mold core functional surface increases as the thin film structure 190 increases. On the other hand, when the mold core 100 is to be regenerated, it takes a lot of processing time to peel off the high density thin film structure in a short time, so that the thin film structure 190 is formed as thin as possible, but has a maximum service life. It is desirable to determine the thickness at.

As described above, the lens mold core according to the present invention is deposited with titanium aluminum nitride, thereby increasing the hardness and adhesive strength of the iridium rhenium alloy which is a releasable thin film. Therefore, it is very economically advantageous to increase the service life of the lens mold core.

Method of forming thin film structure of lens mold core

2 is a process flowchart illustrating a method of forming a thin film structure of a lens mold core according to an embodiment of the present invention, and FIGS. 3, 5 and 6 are thin film structures of a lens mold core according to an embodiment of the present invention. Schematic cross-sectional views for explaining the method of forming a.

2 and 3, first, a base material 102 for lens mold core to be coated is prepared. The base material 102 is formed by molding for a lens mold core using a metal or alloy material, and may be made of, for example, a binderless cobalt tungsten carbide (Co-WC) material. The cobalt tungsten carbide (Co-WC) contains a small amount of cobalt (Co) that acts as a binder, excellent in hardness (Hv), transverse rupture strength (MPa) and low thermal expansion coefficient. Therefore, cobalt tungsten carbide (Co-WC) is very suitable for producing glass lenses under high temperature and high pressure.

Here, the atomic ratio of tungsten carbide (WC) and cobalt (Co) constituting the base material 102 is preferably about 1: 0.01. That is, the atomic content of cobalt (Co) with respect to the base material 102 is about 1%, and has a hardness of 2100 to 2400 Hv. Referring to a scanning electron microscope (SEM) photograph of the cross section of the base material 102 attached to FIG. 4, the particle size of tungsten (W) and carbon (C) is 0.5 to 1.0 μm. Here, the smaller the particle size of tungsten (W) and carbon (C) is, the more suitable as a material for coating.

Referring back to FIG. 2, various pretreatment processes may be performed before the deposition material is formed on the base material 102. The pretreatment process may include a first heat treatment process, a pre-sputter process, an ion etching process, a metal etching process, and the like.

The first heat treatment process removes impurities present on the surface of the mold core, relieves residual stress after molding the mold core, and in particular, diffuses cobalt (Co) in a base material made of cobalt tungsten carbide (Co-WC). Is provided for. For example, the first heat treatment process may be performed in a temperature range of 300 to 700 ° C. in a high vacuum chamber of 5 * 10 ⁻⁶ to 5 * 10 ⁻⁷ Torr.

On the other hand, the pre-sputter process is a process provided for the surface oxide and degassing treatment of the material to be deposited. For example, the pre-sputter process may be performed for 5 to 7 minutes while applying an RF bias of -700 to -900 V in a chamber having a vacuum pressure of 0.8 to 1.2 mTorr.

On the other hand, the ion etching process is a process provided to etch the surface of the base material 102 using argon ions (Ar ⁺ ) having a high energy. Here, argon ion is applied by applying an RF bias of -500 to -800 V to the base material 102 seated in a chamber (not shown) having a process pressure of 4 * 10 ^-5 Torr to 6 * 10 ^-5 Torr. It is desirable to improve the reflection effect of (Ar ⁺ ). The reason is that since argon ions reach the surface of the base material 102 with a strong energy, only the absorption and reflection of the argon ions occurs without applying a high bias. Therefore, it is preferable to apply a high bias capable of strongly pulling argon ions as in this embodiment.

On the other hand, the metal etching process removes impurities remaining on the surface of the base material and serves as a pretreatment process of ion deposition. For example, a metal etching process may be performed by applying a DC power source of 100 to 400 W to a target material region on which chromium (Cr) or titanium (Ti) is mounted, thereby providing chromium ions (Cr ⁺ ), titanium ions (Ti ⁺ ) or argon ions ( Ar ⁺ ) to form a stable plasma. In this case, argon gas (Ar) is used to provide a high-purity gas of 6-nine or more (6-nine) or more, 5 to 20sccm (standard cubic centimeter per minute), the base material to the RF bias of -300 to -1000V It can be carried out in a temperature range of 100 to 450 ℃ in the applied state.

The pretreatment process including the first heat treatment process, the pre-sputter process, the ion etching process, and the metal etching process may be optionally performed in one to three processes. Most preferred in terms of quality of the core.

2 and 5, the first buffer layer 110 including titanium nitride (TiN) is formed on the surface of the base material 102. The first buffer layer 110 improves the adhesion to the base material 102 of the reinforcement layer 120 including titanium aluminum nitride (TiAlN), which is subsequently formed, so that the reinforcement layer 120 is formed on the surface of the base material 102. It can be prevented from separating from. For example, the first buffer layer 110 may be formed by chemical vapor deposition (CVD), plasma chemical vapor deposition, low pressure chemical vapor deposition, physical vapor deposition (PVD), plasma physical vapor deposition, and magnetron. It may be formed using a sputtering method (magnetron sputtering) or the like. In particular, the first buffer layer 110 is preferably formed by a magnetron sputtering method capable of a relatively low temperature process compared to other processes.

When the first buffer layer 110 is formed by a direct current magnetron sputtering method, a power of 100 to 350 W is applied to a titanium (Ti) target provided in a magnetron sputtering chamber (not shown), and titanium ions (Ti ⁺ ). , Stable plasma is formed with argon ions (Ar ⁺ ) or nitrogen ions (N ⁺ ). At this time, argon (Ar) and nitrogen gas (N ₂ ) is provided in a ratio of 1 to 0.8 to 1.2 by using a 6-nin ultra-high purity gas, DC bias applied to the base material at -100 to -300V and 100 It may be carried out for 10 to 20 minutes in the temperature range of 450 ℃.

Next, a reinforcement layer 120 including titanium aluminum nitride (TiAlN) is formed on the first buffer layer 110. The reinforcement layer 120 may be formed by various methods, but in the present embodiment, the reinforcement layer 120 may be formed by a DC magnetron sputtering method capable of a relatively low temperature process. Specifically, by applying a DC power of 120 to 350W to a target material made of titanium aluminum (TiAl) having a high purity of 99.95% or more, titanium ions (Ti ⁺ ), aluminum ions (Al ⁺ ), argon ions (Ar ⁺ ) or Form a stable plasma of nitrogen ions (N ⁺ ).

Here, a DC bias of -70 to -200 V is applied to the base material in an argon (Ar) and nitrogen gas (N ₂ ) atmosphere provided at a ratio of 1: 0.8 to 1: 1.2, and is applied at a temperature in the range of 100 to 450 ° C. It may be carried out for minutes to 60 minutes. Preferably, a DC bias of -120 to -180V is applied to the base material and has a process temperature of 250 to 350 ° C. The crystal structure and density of the titanium aluminum nitride (TiAlN) formed according to the temperature and the bias are different, because under the above conditions, columnar grains are grown in the structure zone model and the growth film shows excellent density. to be. In addition, since the reinforcing layer can be formed at a low temperature compared with the conventional, productivity can be greatly improved.

Meanwhile, the above-described processes for forming the first buffer layer 110 and the reinforcement layer 120 may be performed in-situ in the same chamber.

2 and 6, a second buffer layer 130 is formed on the reinforcement layer 120. For example, the second buffer layer 130 may be formed of titanium (Ti), titanium nitride (TiN), chromium (Cr), or the like. When the work layer 140 is formed of iridium rhenium (IrRe) material, it is preferable that the second buffer layer 130 is formed of a chromium layer 132 and a mixed layer 134 of chromium and iridium rhenium. In addition, the second buffer layer 130 may be formed using a method similar to the first buffer layer 110.

Specifically, when the chromium layer Cr is formed by the magnetron sputtering method, a chromium ion (Cr ⁺ ) and argon ion (Ar ⁺ ) atmosphere is applied by applying DC power of 100 to 350 W to the chromium (Cr) target material. Applying a DC bias of -80 to -120V to the base material at, may be performed under a temperature of 100 to 450 ℃.

In addition, the mixed layer 134 may be provided as a buffer layer to relieve stress between the work layer 140 of the iridium rhenium layer (IrRe) and the chromium layer (Cr) 132 interface formed by a subsequent process. For example, when the mixed layer is formed by the magnetron sputtering method, a DC power of 100 to 350 W is applied to chromium (Cr) and iridium rhenium (IrRe) target materials having high purity of about 99.95% or more, and chromium ions (Cr ⁺ ), Iridium ions (Ir ⁺ ), rhenium ions (Re ⁺ ) and argon ions (Ar ⁺ ) plasma may be generated. Here, it is preferable to apply a bias of -100 to -140V with respect to the base material on which the chromium layer is formed. When the bias is applied below -100V, the density of the mixed layer 134 is formed to be low, which may cause deformation and cracks in a small impact. When the bias is above -140V, the deposition rate is excessively long, and the deposition is dense. As a result, spontaneous delamination occurs due to internal stress, and if it gradually increases to -200V, -300V, or -400V, the deposition rate may drop rapidly due to reflection.

Meanwhile, the processes of forming the reinforcement layer 120 and the second buffer layer 130 described above may be performed in-situ in the same chamber.

Referring back to FIGS. 1 and 2, the work layer 140 is formed on the second buffer layer 130. The work layer 140 may include iridium (Ir), rhenium (Re), or may be formed of an iridium rhenium alloy (IrRe) alloy. For example, in the case of using iridium rhenium (IrRe), mainly when the friction with the glass lens occurs, the rhenium (Re) component is worn, the greater the content of iridium, the lower the wear rate, so the service life may be longer. As an example, it is preferable to form the work layer 140 using an alloy target composed of iridium and rhenium having an atomic ratio of 7: 3.

For example, when the work layer 140 is to be formed of iridium rhenium using the magnetron sputtering method, a DC power source of 100 to 350 W is applied and iridium ions (Ir ⁺ ), rhenium ions (Re ⁺ ), and argon ions (Ar ⁺ ) to form a plasma. In addition, the workpiece layer 140 may be formed at a temperature of 100 to 450 ° C. by applying a DC bias of −70 to −200 V to the base material 102.

Meanwhile, the processes of forming the second buffer layer 130 and the work layer 140 may be performed in-situ in the same chamber. In addition, when the above-described processes are performed in the same method, for example, magnetron sputtering, all processes may be performed in one equipment while replacing source materials.

Subsequently, a post-treatment process including a second heat treatment process may be performed on the resultant 190. The second heat treatment process is a process provided to relieve stress generated at each interface inside the thin film structure 190. For example, the chamber can be run under high vacuum, for example a pressure of 1.0 * 10 ⁻⁶ Torr and a temperature of 400 to 700 ° C. Finally, after performing the second heat treatment, while maintaining the chamber at 1.0 * 10 ^-6 Torr or more, a cooling process of dropping the temperature of the resultant product to 100 ° C or less is completed, thereby completing the lens mold core 100. do.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Industrial Applicability The present invention will be recognized in the industrial field using various glass lenses such as optical communication, cell phone cameras, camcorders, digital cameras, laser printers, copiers and the like.

1 is a flowchart illustrating a method of forming a thin film structure of a lens mold core according to an exemplary embodiment of the present invention.

2 and 4 to 6 are schematic cross-sectional views for explaining a method of forming a thin film structure of a lens mold core according to an embodiment of the present invention.

FIG. 3 is a SEM photograph for explaining the mold core base material shown in FIG. 2.

Explanation of symbols on the main parts of the drawings

100: lens mold core 102: the base material

110: first buffer layer 120: reinforcing layer

130: second buffer layer 132: chrome layer

134: mixed layer 140: work layer

Claims (6)

A first buffer layer provided on a surface of a mold core basic material to be coated and including titanium nitride (TiN); A reinforcing layer provided on the first buffer layer and including titanium aluminum nitride (TiAlN); A second buffer layer provided on the reinforcing layer; And The thin film structure of the lens mold core having a reinforcing layer provided on the second buffer layer and including a working layer having a mold releasing property with respect to a glass lens. The method of claim 1, wherein the work layer comprises iridium rhenium (IrRe), The second buffer layer, A chromium (Cr) layer provided on the reinforcing layer; And The thin film structure of the lens mold core having a reinforcing layer provided on the chromium (Cr) layer and including a mixed layer including a chromium (Cr) and iridium rhenium (IrRe). The thin film structure of claim 1, wherein the thickness ratio of the workpiece layer to the first buffer layer or the second buffer layer is 1: 7 to 1:10. Forming a first buffer layer including titanium nitride (TiN) on the surface of the mold core base material to be coated; Forming a reinforcement layer including titanium aluminum nitride (TiAlN) on the first buffer layer; Forming a second buffer layer on the reinforcing layer; And A method of forming a thin film structure of a lens mold core having a reinforcement layer comprising forming a working layer having releasability to a glass lens on the second buffer layer. The method of claim 1, wherein the reinforcing layer is formed at a temperature of 250 to 350 ° C. using a magnetron sputtering method. The method of claim 1, wherein the forming of the second buffer layer comprises: Forming a chromium (Cr) layer on the reinforcing layer; And Forming a mixed layer including chromium and iridium rhenium on the chromium (Cr) layer; And the work layer is formed of iridium rhenium (IrRe).

Images