KR100211473B1 - Optical element molding die and method of manufacturing the same - Google Patents

Abstract

It is an object of the present invention to provide an optical element forming die having high hardness, high surface smoothness and high durability without fusion with glass. In order to achieve this object, the optical element forming die of the present invention is formed by a method in which a thin film containing lithium element or a compound thereof is formed as a release layer on at least the forming surface of the optical element forming die by ion plating or sputtering. Are manufactured. In the case of molding the glass optical element using the molding die according to the present invention, the release property between the glass and the die is very good. As a result, a molded article having good surface roughness, surface precision, transmittance, and shape accuracy can be obtained. Further, by using the die, even if the compression molding is repeatedly performed for a long time, defects such as peeling or cracking of the film, and damage do not occur, thereby improving durability. In addition, in the method of manufacturing an optical element molding die for producing a glass optical element using the molding die, an optical element molding die can be manufactured at low cost without causing deterioration of the film and surface roughness of the molded glass. It is improved and the cost is reduced.

Description

Optical element molding die and method of manufacturing the same

TECHNICAL FIELD The present invention relates to an optical element forming die and a method for manufacturing the same, which are used in the production of an optical element such as a lens or prism from a glass raw material by compression molding.

Techniques for producing optical elements, such as lenses, by compression molding without the need for any glossiness step, can eliminate the need for complicated processes required for conventional manufacturing, making the optical elements simple and low cost. In particular, the technique has recently begun to be used in the manufacture of prisms and other specialty glass optical elements and lenses.

The material of the die used for the compression molding of the optical element is required to have high hardness, high heat resistance, good release property and high mirror surface workability. In general, methods have been proposed in which metals and ceramics are selected as the die material and different methods, for example molding surfaces are coated with any of the above materials.

For example, Japanese Patent Laid-Open Nos. 49-51112, 52-45613, and 60-246230 show materials of 13Cr martensitic steel, SiC and Si ₃ N ₄ , and cemented carbide coated with precious metal, respectively. It is. Japanese Patent Laid-Open Nos. 61-183134, 61-281030, and 1-301864 show a diamond thin film or a diamond-like carbon film. Japanese Patent Laid-Open No. 64-83529 discloses a material coated with a light carbon film. Further, Japanese Patent Publication No. 2-31012 discloses a method in which a carbon film of 5 to 500 nm thickness is formed on a lens or a molding die.

Unfortunately, the 13Cr martensite steel is easily oxidized and the Fe of the steel diffuses into the glass to form colored glass at high temperatures. In general, SiC and Si ₃ N ₄ are considered not readily oxidized. However, these materials are oxidized at high temperatures to form SiO ₂ on the surface, causing fusion of the glass. Materials coated with precious metals are not easily fused. However, because the coating layer is very soft, the material is susceptible to damage and deformation.

It is also generally believed that molding dies using diamond-like carbon films, a-C: H films, or light carbon films improve releasability between the die and the glass and do not fuse with the glass. However, when weak glass materials are used, the glass easily cracks when it is released from the die. Therefore, there is a need to further improve releasability. Diamond thin film has high hardness and excellent heat resistance. However, this diamond-like carbon film is poor in releasability between die and glass than the diamond-like carbon film, a-C: H film, and light carbon film, that is, an amorphous carbon film. Therefore, this film also needs improvement of releasability.

Further, in the embodiment described in Japanese Patent Publication No. 2-31012, the carbon film is formed by vacuum deposition. However, this carbon film is generally weak in adhesion to the substrate and peels off during the formation process. That is, this film has a problem of durability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide an optical element forming die and a manufacturing method thereof having high hardness, high surface smoothness and high die durability without being fused with glass.

1A and 1B are schematic cross-sectional views showing an optical element forming die of the present invention.

2 is a schematic view showing a release layer forming apparatus using the ion plating method according to the first embodiment.

3 is a schematic view showing a release layer forming apparatus using sputtering according to the first embodiment.

4 is a schematic view showing a lens forming apparatus using the optical element forming die according to the present invention.

5 is a table showing the results of Examples 2 to 5 and Comparative Examples 1 to 4 of the first embodiment.

6 is a table showing the results of Examples 6 to 10 and Comparative Examples 5 and 6 of the first embodiment.

7 is a table showing the results of Examples 11 to 16 and Comparative Examples 7 and 8 of the first embodiment.

8 is a table showing the results of Examples 19 to 21 of the first embodiment.

9 is a table showing the results of Examples 22 to 24 of the first embodiment.

10 is a schematic view showing a release layer forming apparatus using sputtering according to the second embodiment.

11 is a table showing the results of Examples 2 to 5 and Comparative Examples 1 to 4 of the second embodiment.

12 is a table showing the results of Examples 6 to 11 and Comparative Examples 5 and 6 of the second embodiment.

13 is a table showing the results of Examples 12-15 and Comparative Examples 7 and 8 of the second embodiment.

14 is a table showing the results of Examples 16 to 20 and Comparative Examples 9 and 10 of the second embodiment.

Explanation of symbols for the main parts of the drawings

1: die base metal

2: thin film

3: layer interface

21: vacuum tank

22: gas exhaust

23: gas supply unit

24: gas flow control device

25: RF power

26: matcher

27: RF antenna

28: substrate holder

29: substrate

31: vacuum tank

32: gas exhaust

33: substrate holder

34: substrate

35: gas supply unit

36: target material

37: RF power

38: matcher

41: vacuum tank

42: upper mold

43: lower mold

44: upper mold compressor

45: mandrel

46: mold holder

47: burner

48: Pushing Bar

49: air cylinder

121: vacuum tank

122: gas exhaust

123: substrate holder

124: substrate

125: gas supply unit

126: target

127: alkali target

128: RF power

129: matcher

123: substrate rotating mechanism

210: DC power

211: electron source

212: power source for electron source

213: evaporation source

310: substrate holder rotator

410: oil rotary pump

411, 412, and 413: valve

414: inert gas inlet valve

415: valve

416: leak valve

417: valve

418: temperature sensor

In order to solve the above problems and achieve the above object, the optical element forming die of the present invention has the following features as a first feature.

That is, the optical element forming die of the present invention is an optical element forming die for producing a glass optical element by compression molding, in which a thin film of TaN containing a lithium element or a lithium compound is formed as a release layer on at least the molding surface. .

As a second feature, the optical element forming die of the present invention has the following features.

That is, the optical element shaping die of the present invention is an optical element shaping die for producing a glass optical element by compression molding in which a thin film of TiN containing a lithium element or a lithium compound is formed as a release layer on at least the molding surface.

As a third feature, the optical element forming die of the present invention has the following features.

That is, the optical element shaping die of the present invention is an optical element shaping die for producing a glass optical element by compression molding in which a thin film of ZrN containing a lithium element or a lithium compound is formed as a release layer on at least the molding surface.

As a fourth feature, the optical element forming die of the present invention has the following features.

That is, the optical element shaping die of the present invention is an optical element shaping die for producing a glass optical element by compression molding, wherein a thin film of TiC containing a lithium element or a lithium compound is formed as a release layer on at least the molding surface.

As a fifth feature, the optical element shaping die of the present invention has the following features.

That is, the optical element shaping die of the present invention is an optical element shaping die for producing a glass optical element by compression molding, in which a thin film of TiCN containing a lithium element or a lithium compound is formed as a release layer on at least a molding surface.

As a sixth feature, the optical element forming die of the present invention has the following features.

That is, the optical element shaping die of the present invention is an optical element shaping die for producing a glass optical element by compression molding in which a thin film of MoC containing a lithium element or a lithium compound is formed at least as a release layer on the molding surface.

As a seventh feature, the optical element forming die of the present invention has the following features.

That is, the optical element shaping die of the present invention is an optical element shaping die for producing a glass optical element by compression molding, in which a thin film of SiC containing a lithium element or a lithium compound is formed as a release layer on at least a molding surface.

As an eighth feature, the optical element forming die of the present invention has the following features.

That is, the optical element shaping die of the present invention is an optical element shaping die for producing a glass optical element by compression molding in which a thin film of SiN containing a lithium element or a lithium compound is formed as a release layer on at least the molding surface.

As a ninth feature, the optical element forming die of the present invention has the following features.

That is, the optical element shaping die of the present invention is an optical element shaping die for producing a glass optical element by compression molding in which a thin film of CrC containing a lithium element or a lithium compound is formed as a release layer on at least a molding surface.

Moreover, the manufacturing method of the optical element shaping | molding die of this invention has the following characteristics according to 1st characteristic.

That is, in the method of manufacturing an optical element forming die for producing a glass optical element by compression molding, the thin film of TaN containing a lithium element or a lithium compound is ion plated using a metal supply material containing a lithium element or a lithium compound. Is formed as a release layer on at least the molding surface of the molding die.

According to the second aspect, the manufacturing method of the optical element forming die of the present invention has the following characteristics.

That is, in the method of manufacturing an optical element forming die for producing a glass optical element by compression molding, the thin film of TiN containing a lithium element or a lithium compound is ion plated using a metal supply material containing a lithium element or a lithium compound. Is formed as a release layer on at least the molding surface of the molding die.

According to a third aspect, the manufacturing method of the optical element forming die of the present invention has the following characteristics.

That is, in the method for producing an optical element forming die for producing a glass optical element by compression molding, the thin film of ZrN containing a lithium element or a lithium compound is ion plated using a metal supply material containing a lithium element or a lithium compound. Is formed as a release layer on at least the molding surface of the molding die.

According to a fourth aspect, the manufacturing method of the optical element forming die of the present invention has the following characteristics.

That is, in the method for producing an optical element forming die for producing a glass optical element by compression molding, the thin film of TiC containing lithium element or lithium compound is ion plated using a metal supply material containing lithium element or lithium compound. Is formed as a release layer on at least the molding surface of the molding die.

According to a fifth aspect, the method for producing an optical element shaping die of the present invention has the following characteristics.

That is, in the method of manufacturing an optical element forming die for producing a glass optical element by compression molding, the thin film of TiCN containing a lithium element or a lithium compound is ion plated using a metal supply material containing a lithium element or a lithium compound. Is formed as a release layer on at least the molding surface of the molding die.

According to a sixth aspect, the method for producing an optical element forming die of the present invention has the following characteristics.

That is, in the method of manufacturing an optical element forming die for producing a glass optical element by compression molding, the ion plating method is performed by using a metal feed material containing a lithium element or a lithium compound in a thin film of MoC containing a lithium element or a lithium compound. Is formed as a release layer on at least the molding surface of the molding die.

According to a seventh aspect, a method for producing an optical element forming die of the present invention has the following characteristics.

That is, in the method for producing an optical element forming die for producing a glass optical element by compression molding, the thin film of SiC containing a lithium element or a lithium compound is ion plated using a metal supply material containing a lithium element or a lithium compound. Is formed as a release layer on at least the molding surface of the molding die.

According to an eighth aspect, the method for producing an optical element forming die of the present invention has the following characteristics.

That is, in the method of manufacturing an optical element forming die for producing a glass optical element by compression molding, the thin film of SiN containing a lithium element or a lithium compound is ion plated using a metal supply material containing a lithium element or a lithium compound. Is formed as a release layer on at least the molding surface of the molding die.

According to a ninth aspect, a method for producing an optical element forming die of the present invention has the following characteristics.

That is, in the method for producing an optical element forming die for producing a glass optical element by compression molding, a thin film of CrC containing a lithium element or a lithium compound is subjected to the sputtering method using a metal supply material containing a lithium element or a lithium compound. Thereby at least as a release layer on the forming surface of the forming die.

According to a tenth aspect, the method for producing an optical element forming die of the present invention has the following characteristics.

That is, in the method for producing an optical element forming die for producing a glass optical element by compression molding, a thin film of SiC containing a lithium element or a lithium compound is subjected to the sputtering method using a metal feed material containing a lithium element or a lithium compound. Thereby at least as a release layer on the forming surface of the forming die.

According to an eleventh aspect, the method for producing an optical element forming die of the present invention has the following characteristics.

That is, in the method for producing an optical element forming die for producing a glass optical element by compression molding, the thin film of TiN containing lithium element or lithium compound is subjected to sputtering method using a metal supply material containing lithium element or lithium compound. Thereby at least as a release layer on the forming surface of the forming die.

According to a twelfth aspect, the method for producing an optical element forming die of the present invention has the following characteristics.

That is, in the method for producing an optical element forming die for producing a glass optical element by compression molding, a thin film of TaN containing a lithium element or a lithium compound is subjected to sputtering using a metal supply material containing a lithium element or a lithium compound. Thereby at least as a release layer on the forming surface of the forming die.

According to a thirteenth aspect, the manufacturing method of the optical element forming die of the present invention has the following characteristics.

That is, in the method for producing an optical element forming die for producing a glass optical element by compression molding, a thin film of ZrN containing a lithium element or a lithium compound is subjected to sputtering using a metal supply material containing a lithium element or a lithium compound. Thereby at least as a release layer on the forming surface of the forming die.

According to a fourteenth aspect, the method for manufacturing the optical element forming die of the present invention has the following characteristics.

That is, in the method for producing an optical element forming die for producing a glass optical element by compression molding, a thin film of TiC containing lithium element or a lithium compound is subjected to sputtering using a metal supply material containing lithium element or a lithium compound. Thereby at least as a release layer on the forming surface of the forming die.

According to a fifteenth aspect, the method for producing an optical element shaping die of the present invention has the following characteristics.

That is, in the manufacturing method of the optical element shaping die for manufacturing the glass optical element by compression molding, the thin film of TiCN containing lithium element or lithium compound is subjected to sputtering method using a metal supply material containing lithium element or lithium compound. Thereby at least as a release layer on the forming surface of the forming die.

According to a sixteenth aspect, the manufacturing method of the optical element forming die of the present invention has the following characteristics.

That is, in the method for producing an optical element forming die for producing a glass optical element by compression molding, a thin film of MoC containing a lithium element or a lithium compound is subjected to the sputtering method using a metal feed material containing a lithium element or a lithium compound. Thereby at least as a release layer on the forming surface of the forming die.

According to a seventeenth aspect, a method for producing an optical element forming die of the present invention has the following characteristics.

That is, in the method for producing an optical element forming die for producing a glass optical element by compression molding, a thin film of SiN containing a lithium element or a lithium compound is subjected to the sputtering method using a metal supply material containing a lithium element or a lithium compound. Thereby at least as a release layer on the forming surface of the forming die.

According to an eighteenth aspect, the method for producing an optical element forming die of the present invention has the following characteristics.

That is, the method of the present invention is directed to a sputtering method using two or more targets (at least one target comprises an alkali metal and at least one remaining target is a target for forming metal carbide, metal nitride or metal carbonitride). It is a manufacturing method of the optical element shaping | dying die formed by having and having the mold release layer containing 1 or more types of alkali metals on a molding surface.

According to a nineteenth aspect, the manufacturing method of the optical element forming die of the present invention has the following characteristics.

That is, the method of the present invention is directed to a sputtering method using two or more targets (at least one target comprises an alkali metal and at least one remaining target is a target for forming metal carbide, metal nitride or metal carbonitride). Alkali metals and metal carbides, metals by having a release layer formed on the molding surface and containing at least one alkali metal on the molding surface, and sputtering a target containing alkali metals and a target for forming a metal carbide, metal nitride or metal carbonitride It is a manufacturing method of the optical element shaping die | dye in which the mixed layer with nitride or metal carbonitride is formed in the area | region at least 100 nm or more from the optical element shaping surface.

The present inventors completed the present invention by performing the following studies. That is, in view of the problems of conventional optical element forming dies, the present inventors thoroughly tested the effect of additives on the molding performance of the release layer used as the surface layer of the molding surface. As a result, the inventors have identified the effects of alkali metals, especially lithium, on the molding performance.

The surface of conventional molding dies and ceramic thin films of any metal carbide, metal nitride and metal carbonitride have a relatively strong adhesion to glass and thus have problems in releasability. Therefore, the glass cracks and adheres to the die when weak glass, an optical element having a large lens diameter, or an optical element having a small curvature is formed. Therefore, the present inventors have studied in depth and added various elements to the release layer to obtain better release properties. As a result, the inventors found that the adhesion between the die and the glass is greatly reduced when the lithium element or the lithium compound is added to the release layer.

That is, lithium element has a high reactivity even when included in many kinds of glass. Conventionally, forming a film containing lithium element on the surface of a die and using it as a release film has not been proposed at all. However, the present inventors have discovered through the in-depth study that the releasability between the die and the glass is improved when a trace amount of lithium element or a compound thereof is present on the surface of the die. Although many reasons for this fact have not been given yet, compounds of lithium and lithium, such as oxides, have a low melting point and are vaporized at the glass forming temperature so that the lithium elements or compounds are released from the interface between the glass and the die. In the case of a gas layer).

The present invention has been established in this way to achieve an optical element forming die having high hardness, high surface smoothness and high die durability without fusion with glass.

In addition, in the method for producing an optical element forming die having a release layer comprising at least one alkali metal on a molding surface, the release layer may include two or more targets (at least one target comprises an alkali metal and at least one remaining target Formed by sputtering), which is a target for forming metal carbide, metal nitride or metal carbonitride. This method realizes the formation of an optical element forming die having high hardness, high surface smoothness and high die durability without fusion with glass.

In addition, in the present invention, the release layer comprising at least one alkali metal may comprise at least two targets (at least one target comprises an alkali metal and at least one remaining target is for forming a metal carbide, metal nitride or metal carbonitride). On the forming surface by a sputtering method using a target). As a result, the alkali metal can be added to the metal carbide, metal nitride or metal carbonitride with easy adjustment.

Other objects and advantages other than those discussed above will be apparent to those skilled in the art from the description of the preferred embodiments of the present invention described below. Embodiments are described with reference to the accompanying drawings, which form a part of the embodiments and illustrate embodiments of the invention. However, these examples do not limit the different embodiments of the present invention, and therefore, reference should be made to the claims that follow the specification in determining the scope of the invention.

Example

First embodiment

The manufacturing method of the optical element forming die of the present invention is described in detail below with reference to the accompanying drawings. 1A and 1B are schematic cross-sectional views of a forming die. In Figures 1A and 1B, (1) denotes a die based metal and (2) any metal carbide, metal nitride and metal carbonaceous comprising at least one element selected from lithium, potassium and sodium or at least one compound of these elements It means a thin film prepared from the cargo. In FIG. 1B, the layer interface 3 is formed between the die base metal 1 and the thin film 2 of metal carbide, metal nitride or metal carbonitride.

Although this embodiment shows a convex lens forming die, the present invention is not limited to this convex lens forming die. That is, the present invention can be similarly applied to concave lens forming dies, aspherical lens forming dies, cylindrical lens forming dies, and the like.

In the present invention, the release layer containing at least one element selected from lithium, potassium and sodium or a compound of these elements and used as a thin film on the forming surface of the forming die is at least one element selected from lithium, potassium and sodium or these It is formed by ion plating or sputtering using a metal source comprising at least one compound of the element or using a material selected from metal carbides, metal nitrides and metal carbonitrides. The result is a forming die in which any thin film of metal carbide, metal nitride and metal carbonitride comprising at least one element selected from lithium, potassium and sodium or at least one compound of these elements is formed on at least the forming surface. .

2 is a schematic view of a film forming apparatus used in the ion plating method. In Fig. 2, reference numeral 21 denotes a vacuum tank, 22 denotes a gas exhaust unit connected to an oil diffusion pump, a rotary pump and a vacuum pump (not shown), 23 denotes a gas supply unit, 24 denotes a steel gas cylinder, Indicates a gas flow rate regulator connected to a pressure regulator and a valve (not shown).

Reference numeral 25 denotes an RF power supply, 26 a matching device, 27 an RF antenna, 28 a substrate holder, and 29 a substrate. A negative DC bias can be applied to this substrate and the substrate holder by the DC power supply 210. Reference numeral 211 denotes an electron source, and 212 denotes a power source for the electron source 211. The metal source or raw material (hereinafter referred to as evaporation source 213) selected from metal carbide, metal nitride and metal carbonitride may be hot melted and evaporated by an electron beam emitted from the electron source 211.

The steps of the ion plating method are as follows.

(1) A gas at least partially containing one or both of carbon and nitrogen is fed to a vacuum tank.

(2) The evaporation source 213 is melted and evaporated by an electron beam.

(3) A high frequency is applied to convert a gas and an evaporation source material containing one or both of carbon and nitrogen into plasma and then to ions.

(4) A negative bias is applied to the substrate to irradiate ions onto the substrate.

(5) Allow gas and evaporation source materials comprising one or both of carbon and nitrogen to react with each other in the plasma or at the surface of the substrate.

(6) A thin film of any metal carbide, metal nitride and metal carbonitride is formed on the substrate surface.

The ion plating method of the present invention is not limited to the above apparatus and system at all. For example, a method of applying a power source to heat melting and evaporating the evaporation source or a method of melting and evaporating the evaporation source by DC arc discharge may be used. DC discharge may also be used to form a plasma of gas and evaporated metal. In addition, a method of applying a high frequency can be used as the substrate bias.

3 is a schematic view of a film forming apparatus used in the sputtering method. In Fig. 3, reference numeral 31 denotes a vacuum tank, 32 denotes an oil diffusion pump, a rotary pump and a gas exhaust connected to a vacuum pump (not shown), 33 denotes a substrate holder, 34 denotes a substrate, 35 Denotes a gas supply connected to a steel gas cylinder, a pressure regulator and a valve (not shown).

Reference numeral 36 denotes a raw material selected from metal carbide, metal nitride and metal carbonitride (hereinafter referred to as target material 36), 37 denotes an RF power source, and 38 denote a matching device.

When the sputtering method is used in the apparatus, the forming surface of the forming die is formed as follows.

(1) Supply a gas to the vacuum tank at least partially comprising one or both of carbon and nitrogen.

(2) A high frequency is applied to the target material to convert the gas and evaporation source material containing at least partially one or both of carbon and nitrogen into plasma and then into ions.

(3) Sputter the target material.

(4) Allow the gas and target material comprising one or both of carbon and nitrogen to react with each other in the plasma or at the surface of the substrate.

(5) A thin film of any metal carbide, metal nitride and metal carbonitride is formed on the substrate surface.

The sputtering method of the present invention is not limited to the above apparatus and system at all. For example, a device or system that uses a DC power source instead of an RF power source can be used. It is also possible to use a magnetron sputtering method in which magnets are disposed near the target material or an opposite sputtering method in which the target materials are disposed opposite to each other.

In order to form a thin film of any metal carbide, metal nitride and metal carbonitride in both the ion plating method and the sputtering method, the following means are required.

(1) A metal source or raw material selected from metal carbide, metal nitride and metal carbonitride is evaporated on the substrate surface by melting or sputtering.

(2) Convert a gas at least partially comprising one or both of carbon and nitrogen into a plasma.

(3) Allow a gas comprising one or both of carbon and nitrogen and an evaporation source or target material to react with each other in the plasma or at the surface of the substrate.

(4) A thin film of any metal carbide, metal nitride and metal carbonitride is formed on the substrate surface.

Metal carbides can be formed by adding a carbon containing gas, such as a hydrocarbon gas, such as methane, ethane, ethylene or acetylene, carbon monoxide or halogenated carbon, to the film forming atmosphere gas and reacting the gas with the metal. The metal nitride can be formed by adding a nitrogen containing gas, such as nitrogen gas, ammonia or nitrogen halide to the film forming atmosphere gas and reacting the gas with the metal. Metal carbonitrides can be formed by adding both a carbon containing gas and a nitrogen containing gas to the film forming atmosphere gas and reacting these gases with the metal.

In the formation process, a gas containing hydrogen or a rare gas (for example, helium, argon and neon) may be appropriately added to the film forming atmosphere gas. In particular, it is preferable to add a rare gas such as argon having a significant sputtering effect in the sputtering method.

In the present invention, when the thin film is formed by ion plating using any metal carbide, metal nitride and metal carbonitride, the metal source or raw material selected from metal carbide, metal nitride and metal carbonitride is selected from lithium, potassium and sodium. One or more elements selected from lithium, potassium and sodium may be added to the thin film of any one of metal carbides, metal nitrides and metal carbonitrides formed by adding one or more elements selected or one or more compounds of these elements. .

In the present invention, when the thin film is formed by sputtering using any metal carbide, metal nitride and metal carbonitride, at least one element selected from lithium, potassium and sodium or at least one compound of these elements is added to the target material. To a thin film of any metal carbide, metal nitride and metal carbonitride formed by adding or placing a pellet comprising at least one element selected from lithium, potassium and sodium or at least one compound of these elements on a target material One or more elements selected from lithium, potassium and sodium can be added.

The content of at least one element selected from lithium, potassium and sodium in the thin film of any metal carbide, metal nitride and metal carbonitride is 0.05 to 5 atomic%, preferably 0.1 to 2 atomic%, more preferably 0.5 to 1 atomic%. The content (atomic%) referred to herein is the content of the corresponding element when only one element among lithium, potassium and sodium is included in the thin film, and the total content of the corresponding element when two or more elements are included.

If the content is less than 0.05 atomic%, the effect of addition of at least one element selected from lithium, potassium and sodium does not occur at all. If the content is greater than 5 atomic%, the thin film of any metal carbide, metal nitride and metal carbonitride deteriorates the film quality considerably even if the release property is relatively good.

Lithium, potassium and sodium all have good release properties for glass. In particular, lithium has good release properties and high die durability.

The effect of this lithium addition is particularly noticeable in the molding of large diameter lenses or meniscus lenses. In the molding of large diameter lenses (e.g., 30 [deg.] Or more), large stresses generally occur on the die, which significantly degrades the release film. In addition, in forming a meniscus lens (especially a convex meniscus lens), a large stress is generated on the outer circumference, so that the outer circumference easily cracks and deteriorates the release layer. In contrast, the optical element forming die according to the present invention having a thin film of any metal carbide, metal nitride and metal carbonitride containing lithium as a release layer has good release properties and suppresses deterioration of the release layer and cracking of the glass. This optical element forming die is particularly suitable for dies for forming large diameter lenses or meniscus lenses.

Examples of methods of adding one or more elements selected from lithium, potassium and sodium are methods of adding lithium, potassium and sodium elements to an evaporation source or target material and adding these elements to various compounds such as oxides, halides, carbos To the evaporation source or target material in the form of nates, sulphates and nitrates. In addition, lithium, potassium and sodium elements or compounds of these elements may be vaporized by evaporation or sputtering and introduced into the film-forming atmosphere. As a result, these elements can be added to the thin film of any metal carbide, metal nitride and metal carbonitride formed.

However, the proportion of at least one element selected from lithium, potassium and sodium added to the evaporation source or target material is in many cases lithium, potassium and sodium included in the thin film formed of any metal carbide, metal nitride and metal carbonitride Care should be taken because it is not equal to the ratio of one or more elements selected from among them. This is because the sputtering rate of vapor pressure or evaporation source or target material is different from the vapor pressure or sputtering rate of each of lithium, potassium and sodium elements or compounds of these elements.

Therefore, in the present invention, the addition amount of at least one element selected from lithium, potassium and sodium in the thin film of any metal carbide, metal nitride and metal carbonitride is at least one selected from lithium, potassium and sodium in the evaporation source or target material. Unlike the addition amount of the element should be set within the above range.

The thin films of any of the metal carbides, metal nitrides and metal carbonitrides according to the present invention can be produced differently depending on the kind of glass, the molding temperature and the molding atmosphere gas. However, in consideration of hardness and heat resistance, it is preferable to use carbides, nitrides and carbonitrides of group 4A, 5A and 6A elements of the periodic table and silicon. In this embodiment the Group 4A elements of the periodic table are Ti, Zr and Hf, the Group 5A elements of the periodic table are V, Nb and Ta and the Group 6A elements of the periodic table are Cr, Mo and W.

Silicon is not generally classified as a metal. However, carbides, nitrides and carbonitrides of silicon in the present invention are referred to broadly as metal carbides, metal nitrides and metal carbonitrides, respectively.

Carbide, nitride and carbonitrides of Group 4A, 5A and 6A elements of the periodic table and silicon have a high hardness (Vickers hardness of 1000 or more, generally 2000 or more) and hardly deform during molding. In addition, carbides, nitrides and carbonitrides of these elements have a high melting point (1500 ° C. or higher, generally 2000 ° C. or higher) and thus high heat resistance. Therefore, these compounds hardly react with the glass and have high molding durability.

As described above, the release layer of the optical element forming die having good release properties and high molding durability may be formed of one or more elements selected from lithium, potassium and sodium, carbides of group 4A, 5A and 6A elements and silicon of any periodic table, It can be obtained by adding to thin films of nitrides and carbonitrides. In contrast, when adding at least one element selected from lithium, potassium and sodium to a thin film of any metal or alloy outside the scope of the present invention, the elements 4A, 5A and 6A of the periodic table within the scope of the present invention and silicon The release property is not improved as much as in the case of the thin film of carbide, nitride and carbonitride. The reason for this is not known yet, but it appears that an alloy of lithium, potassium and sodium elements is formed in the metal thin film or the alloy thin film to stabilize the film so that the film does not function as a release layer. In addition, thin films of metals or alloys generally have a low melting point and are unstable at high temperatures. In addition, this type of thin film is susceptible to reaction, deformation, abrasion and damage with glass, resulting in low molding durability of the film.

At least one element selected from lithium, potassium and sodium need not be added to the entire thin film of any metal carbide, metal nitride and metal carbonitride. That is, it is sufficient to add the element near the surface of the thin film of any metal carbide, metal nitride and metal carbonitride. Near the surface of the thin film of any metal carbide, metal nitride and metal carbonitride means an area of several hundred nm from the surface of the film. In particular, the concentration of at least one element selected from lithium, potassium and sodium in the region of less than 100 nm from the surface contributes greatly to the molding properties. Thus, in the initial stage of thin film formation of any metal carbide, metal nitride and metal carbonitride, the amount of addition of at least one element selected from lithium, potassium and sodium is reduced or no element is added. The concentration (0.05 to 5 atomic%) specified in the present invention may be set for at least one element selected from lithium, potassium and sodium only in the final stage of film formation, that is, in a region having a film thickness of several hundred nm or less.

Examples of substrates used in the present invention include oxide based ceramics such as alumina and zirconia, carbide and nitride based ceramics such as silicon carbide, silicon nitride, titanium carbide, titanium nitride and tungsten carbide, WC based superalloys and Metals such as molybdenum, tungsten and tantalum.

In this embodiment, the shape of the substrate may be appropriately determined depending on the shape of the film forming apparatus or the lens to be molded. For example, when the lens is molded, the forming surface is curved in accordance with the curvature of the lens diameter. Thin films of any metal carbide, metal nitride and metal carbonitride can be formed on the curved surface using vapor phase synthesis.

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

Example 1

In this embodiment, a release layer made of tantalum nitride was formed by the embodiment shown in FIG. 2, that is, the ion plating method. The used die base metal was formed by processing the SiC sintered body into a predetermined shape, forming a polycrystalline SiC film by CVD, and then polishing the molded surface with a mirror surface of R _max = 0.04 μm.

This molding die was washed well and installed in the ion plating apparatus shown in FIG. Tantalum (powder, 100 mesh) was used as a metal source, and 0.1 atomic% of lithium chloride (LiCl) was mixed with tantalum. After evacuating the vacuum tank 21 to a predetermined vacuum, nitrogen and argon gas were introduced from the gas supply section 23 at a flow rate of 20 ml / min, respectively.

The pressure was 2.7 x 10 ^-2 Pa. Plasma was formed near the RF coil 27 by applying an RF voltage of 500 W using an RF power source 25 (frequency 13.56 MHz). In addition, a bias voltage of -150 W was applied to the substrate 29 and the substrate holder 28 using the DC power supply 210. In addition, the tantalum source 213 was dissolved using the electron source 211. By the above operation, a titanium nitride film having a thickness of 1.5 mu m was formed on the molding surface of the die base metal. An analytical sample formed under the same synthetic conditions as the tantalum nitride thin film described above was measured by secondary ion mass spectrometry (SIMS). As a result, the lithium content in the tantalum nitride thin film in the vicinity of the surface (area of about 20 nm from the surface) was about 1.0 atomic%.

Hereinafter, the result of performing the compression molding of the glass lens using the optical element shaping | molding die of a present Example is demonstrated. In the glass lens forming apparatus shown in Fig. 4, reference numeral 41 denotes a vacuum tank, 42 denotes an upper mold for molding an optical element, 43 denotes a lower mold, and 44 denotes an upper mold for compressing an upper mold. A mold compressor, 45 a mandrel, 46 a mold holder, 47 a heater, 48 a pushing bar for pushing up the lower mold, 49 an air cylinder for actuating the pushing bar, 410 ) Are oil rotary pumps, 411, 412 and 413 are valves, 414 are inert gas inlet valves, 415 are valves, 416 are leak valves, 417 are valves, and 418 ) Is the temperature sensor.

The glass to be molded was Flint-based optical glass SF14 (softening point Sp = 586 ° C, transition point Tg = 485 ° C), and a concave lens having a diameter of 30 mm and a thickness ratio of 4 was formed from this glass. Molding conditions were 588 degreeC of compression temperature under nitrogen atmosphere. The release properties between the molding die and the molded optical element were good during molding. The die surface was inspected by irradiating the molding die with light from a light collecting path and visually observing the surface. In the case where peeling or cracking of the film or fusion of the glass occurs, a clear mark can be seen in that part. However, when the optical element forming die formed by the present Example was observed by the said inspection method, the mirror surface characteristic was very favorable, and the indication by peeling of a film | membrane or a crack, or fusion of glass was not observed. In order to confirm this, the surface of the said optical element shaping | dye die was observed at the magnification of 500-5000 times using the scanning electron microscope. As a result, no peeling and cracking of the film occurred and the glass did not fuse. In addition, the surface properties of the molded glass lens were also visually observed in the same manner, and no peeling, marks and fine meniscus of the film on the lens surface were observed.

An optical element forming die was formed under the same conditions as described above except that lithium was not added to the tantalum nitride film. As a result, glass molding was performed using the same glass material and the same shape as described above, but the release force between the die and the glass was very strong. Thus, the glass was cracked and partially fused to the forming die.

Example 2-5, Comparative Example 1-4

Hereinafter, Examples 2 to 5 and Comparative Examples 1 to 4 will be described. In the present Example and the comparative example, various elements were added to the titanium nitride thin film, and the effect was evaluated. Titanium nitride thin films were synthesized by ion plating. WC-based cemented carbide was processed into a predetermined shape as a die base metal. The obtained molding die was washed well, installed in the apparatus shown in Fig. 2, and titanium nitride was synthesized. Titanium (powder, 100 mesh) was used as a metal source, and various additives were added at 0.2 atomic%, respectively. As other synthesis conditions, nitrogen and argon gas were introduced at a flow rate of 20 ml / min, respectively, with a bias voltage of -120 V, an RF output of 400 W, and a pressure of 3.3 x 10 ^-2 Pa. Under the above conditions, a titanium nitride film having a film thickness of about 1.2 mu m was formed.

Next, compression molding of the glass lens was performed using the said optical element shaping | molding die. Molding was carried out using a continuous molding apparatus (not shown), and Flint-based optical glass SF14 (softening point Sp = 586 ° C, transition point Tg = 485 ° C) was used as the glass to be molded. 5000 compression molding was performed at a compression temperature of 588 ° C. under a nitrogen atmosphere. The lens shape was the same as in Example 1. The results are shown in FIG.

In FIG. 5, the concentration of various elements in the titanium nitride film was determined by measuring the sample for evaluation separately prepared under the same conditions as the synthesis conditions of the molding die using the SIMS method.

The surface properties of the molded article were evaluated by irradiating the molded lens with light of a light collecting path and visually observing the surface properties (blur, marks and fine meniscus on the surface). Evaluation criteria were measured by comparing whether a molded lens can be used as a product with a sample called a limit sample. The limit specimens each have about one Newton's ring for asperity and flow-line (difference from a given lens shape), and a maximum surface roughness (PV value) of about 30 Nm, the average surface roughness (RMS) is about 5 nm, the number of marks having a size of up to about 10 mu m is two of all lenses, and the condition that these marks are not close to each other is satisfied. Molded articles with poorer surface characteristics than this limit sample cannot be used as products. In the evaluation criteria, x means that the surface properties are inferior to the limit samples, so that the molded article cannot be used as a product. Δ means that the surface properties at the same level as the limit sample can be obtained or the surface properties at the same level as the limit sample can be obtained by simply wiping and washing. (Circle) means that a surface characteristic is superior to a limit sample. ◎ means that the surface characteristics are excellent and no blur or the like occurs. Molding durability was evaluated by whether or not it was possible to mold a specified quantity of products at or above the limit sample. × means that the product of specified quantity cannot be molded due to fusion or cracking of the glass. (Triangle | delta) means that the product nearly moldable can be shape | molded. (Circle) means that many products which are 1.5 times or more of the prescribed quantity can be molded. (◎) means that many products can be molded more than twice the specified quantity.

In Examples 2 to 5, by adding at least one element selected from lithium, potassium and sodium to the titanium nitride film, the surface characteristics and molding durability of the molded article satisfactory as the optical element molding die could be obtained. On the other hand, in Comparative Examples 1 to 4, since the additive element was out of the above range, the surface properties and molding durability of the molded article were lowered. In particular, in Comparative Examples 1 to 3, the adhesive force between the molding die and the glass was so great that the mold release properties of the die and the glass were deteriorated during molding, and some of the molded glass products had cracks. Moreover, it was necessary to clean the die during the molding test because the glass cracked and adhered to the molding die. Further, in Comparative Example 4, the titanium nitride film was significantly degraded and peeled off. As a result, the surface properties of the molded glass were lowered and the molded glass was not suitable for practical use.

As described above, in the present invention, by adding at least one element selected from lithium, potassium and sodium to the titanium nitride film, it is possible to obtain surface characteristics and molding durability of a molded article satisfactory as an optical element forming die.

Examples 6-10, Comparative Examples 5 and 6

Hereinafter, Examples 6 to 10 and Comparative Examples 5 and 6 will be described. In the present Example and the comparative example, the concentration of the additional element in the titanium nitride thin film was evaluated. Titanium nitride was formed in the same manner as in Example 2 using the ion plating method. In addition, the die base metal was previously processed into a predetermined shape. The obtained molding die was washed well, installed in the apparatus shown in Fig. 2, and a titanium nitride thin film was formed. The amount of lithium added to the titanium nitride film was changed by changing the amount of lithium chloride added to the metal titanium material during film formation. In other synthesis conditions, the gas source flow rate was 20 ml / min for nitrogen, 30 ml / min for argon, the bias voltage was -100V, the RF output was 400W, and the pressure was 3.5 x 10 ^-2 Pa. As a result, a titanium nitride film having a film thickness of about 1 mu m was formed.

Subsequently, compression molding of the glass lens was performed using this optical element shaping | molding die. The said molding was performed using the continuous molding apparatus, and flint type optical glass SF14 (softening point Sp = 586 degreeC and transition point Tg = 485 degreeC) was used as glass to shape | mold. 5000 compression molding was performed at a compression temperature of 588 ° C. under a nitrogen atmosphere. The lens shape was the same as in Example 1. The results are shown in FIG.

In FIG. 6, the lithium concentration in the titanium nitride film was determined by measuring the sample for evaluation separately prepared under the same conditions as the synthesis conditions of the molding die using the SIMS method.

In Examples 6 to 10, by setting the lithium element concentration to 0.05 to 5 atomic%, satisfactory molded article surface characteristics and molding durability as optical element molding dies could be obtained. On the other hand, in Comparative Examples 5 and 6, since the lithium element concentration was out of the above range, the surface characteristics and molding durability of the molded article were lowered. Moreover, in the comparative example 5, the density | concentration of lithium element was low, and the adhesive force between die | dye and glass was large. As a result, the release properties of the die and glass deteriorated during molding and some of the molded glass articles cracked. In addition, it was necessary to wash the die during the molding test because the glass cracked and adhered to the molding die. In Comparative Example 6, the titanium nitride film was deteriorated due to the high concentration of lithium element, and the film was worn and peeled off when forming. As a result, the surface properties of the molded glass were lowered and the molded glass was not suitable for practical use. As mentioned above, when the concentration of the additive element was less than 0.05 atomic%, the release properties of the die and the glass during molding were not satisfactory. When the concentration of the added element was more than 5 atomic%, the film quality of the titanium nitride thin film was degraded, resulting in abrasion or peeling of the film.

As described above, in the present invention, at least one element selected from lithium, potassium, and sodium is added to the release layer so that the element concentration is 0.05 to 5 atomic%, thereby obtaining satisfactory molded article surface characteristics and molding durability as an optical element forming die. Could.

Examples 11-16, Comparative Examples 7 and 8

Hereinafter, Examples 11 to 16 and Comparative Examples 7 and 8 will be described. In this example and a comparative example, various release films were formed and evaluated. These release films were formed in the same manner as described above using the ion plating method. In addition, the die base metal was previously processed into a predetermined shape. The obtained molding die was washed well, installed in the apparatus shown in Fig. 2, and a release layer (thin film) was formed. Various metal sources were used in the film formation and the gas was selected as follows.

(1) When forming a metal nitride: 20 ml / min nitrogen and 20 ml / min argon.

(2) When forming metal carbide: 20 ml / min of methane and 20 ml / min of argon.

(3) When forming metal carbonitride: 10 ml / min of nitrogen, 10 ml / min of methane and 20 ml / min of argon.

(4) When forming a metal film: 30 ml / min of argon.

In addition, lithium was added to the release layer by adding lithium chloride to the metal source. As other synthesis conditions, the bias voltage was -100V, the RF output was 400W, the pressure was 3.5 x 10 ^-2 Pa, and the film thickness was about 1 m.

Subsequently, compression molding of the glass lens was performed using this optical element shaping | molding die. The said molding was performed using the continuous molding apparatus, and flint type optical glass SF14 (softening point Sp = 586 degreeC and transition point Tg = 485 degreeC) was used as glass to shape | mold. 5000 compression molding was performed at a compression temperature of 588 ° C. under a nitrogen atmosphere. The lens shape was the same as in Example 1. The results are shown in FIG.

In FIG. 7, the lithium concentration in a release film was calculated | required by measuring the sample for evaluation created separately on the same conditions as the synthesis conditions of a shaping | die die using SIMS method. The lithium concentration was found to be 0.5 to 1.2 atomic percent in all of the samples.

In Examples 11 to 16, satisfactory molded article surface characteristics and molding durability were obtained as optical element forming dies by using thin films of carbides, nitrides, and carbonitrides of periodic table 4A, 5A, and 6A elements and silicon. On the other hand, in Comparative Examples 7 and 8, since the additive element was out of the above range, the surface properties and molding durability of the molded article were lowered.

In particular, in Comparative Example 7, the reactivity with the glass was high, and the adhesion between the die and the glass was large. As a result, the release properties of the die and glass deteriorated during molding, and some of the molded glass products had cracks. Moreover, it was necessary to clean the die during the molding test because the glass cracked and adhered to the molding die.

Further, in Comparative Examples 7 and 8, the film deteriorated, presumably because of the low hardness of the film, and the film was worn and peeled off when forming. As a result, the surface properties of the molded glass were lowered and the molded glass was not suitable for practical use.

Example 17

Example 17 will now be described. In this embodiment, a release layer made of a chromium carbide thin film was formed by sputtering. This chromium carbide film was formed using a sputtering apparatus as shown in FIG. In this example, chromium containing 1 atomic% of lithium oxide (Li ₂ O) was used as a target. Further, a die base metal made of a cemented carbide material processed into a predetermined shape was installed in the apparatus shown in Fig. 3 to form a chromium carbide thin film. As the conditions for forming, the gas flow rate was 20 ml / min for methane and 10 ml / min for argon, the substrate temperature was room temperature, the RF output was 400 W, and the pressure was 5 × 10 ⁻¹ Pa. Under these conditions, a chromium carbide film having a thickness of about 800 nm was formed.

The evaluation sample prepared separately under the synthesis conditions of the said molding die was measured using the SIMS method. As a result, it was found that the lithium element concentration in the chromium carbide film was 2.1 atomic%.

The molding durability test was done using the said molding die. This compression molding was performed using a continuous molding apparatus, and crown type optical glass SK12 (softening point Sp = 672 degreeC and transition point Tg = 550 degreeC) was used as glass to shape | mold. A concave lens having a diameter of 35 mm and a thickness ratio of 4 was molded. 5000 compression molding was performed at a compression temperature of 620 ° C. under a nitrogen atmosphere.

As a result, the release property between the die and the molded optical element was good during molding. When the die surface was observed using a scanning electron microscope after molding, no peeling and cracking of the film occurred and the glass did not fuse, showing good die surface properties. In addition, the molded glass lenses actually had satisfactory surface roughness.

Except not adding lithium to the chromium carbide film, the optical element shaping | dye die was created on the same conditions as mentioned above, and glass forming was performed using the same glass material and the same shape as mentioned above. As a result, the releasing force between the die and the glass was strong and the glass cracked and partially fused to the die.

Example 18

Example 18 is described below. In this embodiment, a silicon carbide thin film was formed as a release layer using the sputtering method. This silicon carbide film was formed using a sputtering apparatus as shown in FIG. In this example, silicon carbide was used as a target, and lithium was added to the silicon carbide thin film by placing pellets of lithium boride (LiB ₂ ) on the surface of the target.

A die base metal made of cemented carbide material processed into a predetermined shape was installed in the apparatus shown in FIG. 3 to form a silicon carbide thin film. Formation conditions were gas flow rates of 10 ml / methane and 30 ml / m of argon, substrate temperature of 200 ° C., RF output of 400 W, and pressure of 5 × 10 ⁻¹ Pa. Under the above conditions, a silicon carbide film having a thickness of about 1.2 mu m was formed on the molded surface.

The evaluation sample prepared separately under the synthesis conditions of the said molding die was measured using the SIMS method. As a result, it was found that the lithium element concentration in the silicon carbide film was 2.1 atomic%.

The molding durability test was done using the said molding die. This compression molding was performed using a continuous molding apparatus, and crown type optical glass SK12 (softening point Sp = 672 degreeC and transition point Tg = 550 degreeC) was used as glass to shape | mold. A concave lens having a diameter of 35 mm and a thickness ratio of 4 was molded. 5000 compression molding was performed at a compression temperature of 620 ° C. under a nitrogen atmosphere.

As a result, the release property between the die and the molded optical element was good during molding. When the die surface was observed using a scanning electron microscope after molding, no peeling and cracking of the film occurred and the glass did not fuse, showing good die surface properties. In addition, the molded glass lenses actually had satisfactory surface roughness.

Except not adding lithium to the silicon carbide film, the optical element shaping | dying die was created on the same conditions as mentioned above, and glass forming was performed using the same glass material and the same shape as above-mentioned. As a result, the releasing force between the die and the glass was strong and the glass cracked and partially fused to the die.

Example 19-21

In Examples 19 to 21, a release layer composed of a titanium nitride thin film was formed by sputtering. This titanium nitride film was formed using a sputtering apparatus as shown in FIG. In this example, titanium was used as a target, and lithium was added to the titanium nitride thin film by placing the pellets shown in FIG. 8 on the surface of the target.

A die base metal made of cemented carbide material processed into a predetermined shape was installed in the apparatus shown in FIG. 3 to form a titanium carbide thin film. Formation conditions were a gas flow rate of 10 ml / min nitrogen and 15 ml / min argon, a substrate temperature of 180 ° C., an RF output of 420 W, and a pressure of 4 × 10 ⁻¹ Pa. Under the above conditions, a titanium carbide film having a thickness of about 1.5 mu m was formed. The lithium element concentration in the titanium nitride film was measured using a SIMS method for an evaluation sample separately prepared under the synthesis conditions of the molding die. The results are shown in FIG.

The molding durability test was done using the said molding die. This compression molding was performed using a continuous molding apparatus, and crown type optical glass SK12 (softening point Sp = 672 degreeC and transition point Tg = 550 degreeC) was used as glass to shape | mold. A concave lens having a diameter of 35 mm was molded. 5000 compression molding was performed at a compression temperature of 620 ° C. under a nitrogen atmosphere.

As shown in Fig. 8, the release property between the die and the molded optical element during the molding was good. When the die surface was observed using a scanning electron microscope after molding, no peeling and cracking of the film occurred and the glass did not fuse, showing good die surface properties. In addition, the molded glass lenses actually had satisfactory surface roughness. Except not adding lithium to the titanium nitride film, an optical element forming die was produced under the same conditions as described above, and glass molding was performed using the same glass material and the same shape as described above. As a result, the release force between the die and the glass increased, causing the glass to crack and partially fuse to the die.

Example 22-24

In Examples 22 to 24, convex meniscus glass lenses (equivalent to SF8) were molded. A release layer made of titanium nitride was formed using the same sputtering method as in Examples 19 to 21. In Examples 22 to 24, an alkali element was added to the titanium nitride thin film by using titanium as a target and placing pellets as shown in FIG. 9 on the surface of the target.

A die base metal made of a WC-based cemented carbide processed into a predetermined shape was installed in the apparatus shown in FIG. 3 to form a titanium nitride film. Formation conditions were gas flow rates of 8 ml / min of nitrogen and 13 ml / min of argon, substrate temperature of 100 deg. C, RF output of 1000 W, and pressure of 0.35 Pa. Under these conditions, a silicon carbide film having a thickness of about 0.8 mu m was formed. The alkali concentration in the said film measured the sample for evaluation prepared separately on the same conditions as the synthesis conditions of the said molding die using SIMS method. The results are shown in FIG.

Molding durability tests were conducted using the molding die and continuous molding apparatus. The glass to be molded was equivalent to SF8, and a convex meniscus lens having a diameter of 25 mm was molded. Molding conditions were nitrogen atmosphere and compression temperature of 590 degreeC.

As shown in FIG. 9, the release properties between the die and the molded optical element were substantially satisfactory. In particular, when a titanium nitride film containing lithium was used as the release film (Example 22), the surface properties of the molded article were very good. When the die surface was observed using a scanning electron microscope after molding, film peeling and fusion of glass did not occur, thereby showing good die surface properties.

Except not adding an alkali element to a titanium nitride film, the optical element shaping | dye die was created on the same conditions as mentioned above, and glass forming was performed using the same glass material and the same shape as mentioned above. As a result, the outer periphery of the molded glass cracked and the glass partially fused to the die.

Second embodiment

In this embodiment, the structure of the optical element forming die is the same as that shown in Fig. 1, and only the manufacturing method of the die is different.

10 is a schematic view showing a film forming apparatus using the sputtering method.

In FIG. 10, reference numeral 121 denotes a vacuum tank, and 122 denotes a gas exhaust portion connected to an oil diffusion pump, a rotary pump, and a vacuum valve (not shown). Reference numeral 123 denotes a substrate holder, 124 denotes a substrate, and 125 denotes a gas supply unit to which a gas flow rate regulator, a steel gas cylinder, a pressure regulator, a valve, and the like (not shown) are connected. Reference numeral 126 denotes a target of a metal source or a metal carbide, metal nitride and metal carbonitride, and 127 denotes a target containing an alkali metal or an alkali compound (hereinafter referred to as an alkali target material), (128 ) Denotes an RF power supply, and 129 denotes a matcher. Reference numeral 310 denotes a substrate rotating mechanism for rotating the substrate holder 123.

For example, the operation of the apparatus is as follows.

(1) Into the vacuum tank, a gas containing any one or both of carbon or nitrogen and a film forming atmosphere gas containing at least one rare gas are introduced.

(2) High frequency is applied to the metal source or the target and alkali target material of any one of metal carbide, metal nitride and metal carbonitride.

(3) The target material is sputtered by changing the film-forming atmosphere gas into plasma.

(4) A thin film of any one of metal carbide, metal nitride and metal carbonitride containing an alkali metal is formed on the substrate surface.

The sputtering method of the present invention is not limited to the above apparatus and method at all. For example, DC power may be used instead of RF power. It is also possible to use a magnetron sputtering method in which magnets are placed near the target material, or an opposing sputtering method in which target materials are disposed to face each other.

In the case of using a metal target, a thin film of any one of metal carbide, metal nitride and metal carbonitride can be formed by adding a gas containing either or both of carbon and nitrogen to the film forming atmosphere gas. When using a target of any one of metal carbide, metal nitride, and metal carbonitride, any rare metal alone, metal carbide, metal nitride, or metal carbonitride can be used without using a gas containing either or both carbon and nitrogen. One thin film can be formed. In order to improve carbonization and nitriding of the metal, it is also possible to add a gas containing either or both of carbon and nitrogen.

That is, a metal carbide can be formed by adding a hydrocarbon gas such as methane, ethane, ethylene or acetylene, a carbon-containing gas such as carbon monoxide or a halide to react with the metal in the film forming atmosphere gas. In addition, a metal nitride can be formed by adding a nitrogen-containing gas such as nitrogen gas, ammonia or nitrogen halide to the film-forming atmosphere gas and reacting the gas with a metal. In addition, metal carbonitride can be formed by adding both a carbon-containing gas and a nitrogen-containing gas to a film forming atmosphere gas and reacting the gases with a metal. In addition, a gas containing hydrogen or a rare gas (for example, helium, argon and neon) may be appropriately added to the film forming atmosphere gas. In particular, in the sputtering method, it is desired to add a rare gas such as argon having a large sputtering effect.

The content of at least one element selected from lithium, potassium and sodium in the thin film of any one of metal carbide, metal nitride and metal carbonitride is 0.05 to 5 atomic%, preferably 0.1 to 2 atomic%, more preferably 0.5 To 1 atomic%. The content (atomic%) referred to herein refers to the content of one element when only one of lithium, potassium and sodium is contained in the thin film, and the total content of elements when two or more elements are contained. If the content is less than 0.05 atomic%, there is no effect of adding at least one element selected from lithium, potassium and sodium. If the content exceeds 5 atomic%, the thin film of any one of metal carbide, metal nitride and metal carbonitride deteriorates considerably.

The at least one element selected from lithium, potassium and sodium is a compound of various kinds, such as oxides, halides, carbonates, sulfates and nitrates of the element or the element, apart from the target of any one of metal carbide, metal nitride and metal carbonitride. It can be added by sputtering the created target after making the target of. Lithium, potassium and sodium elements or compounds of these elements are vaporized by sputtering and introduced into a film forming atmosphere. These elements are added in the thin film of any one of the metal carbide, metal nitride, and metal carbonitride which have just been formed.

The thin film of any one of metal carbide, metal nitride and metal carbonitride may be selected from various thin films depending on the shape of the glass, the molding temperature and the molding atmosphere. However, when considering hardness, heat resistance and the like, it is desired to use carbides, nitrides and carbon compounds of the 4A, 5A, 6A group elements and silicon of the periodic table. In this embodiment, the Group 4A elements of the periodic table are Ti, Zr and Hf, the Group 5A elements of the periodic table are V, Nb and Ta, and the Group 6A elements of the periodic table are Cr, Mo and W. Silicon is not generally classified as a metal, but in the present invention, carbides, nitrides and carbonitrides of silicon are called metal carbides, metal nitrides and metal carbonitrides, respectively. Carbide, nitride and carbonitrides of Group 4A, 5A and 6A elements and silicon of the periodic table have a high hardness (1000 or more in Vickers hardness, generally 2000 or more) and less deformation during molding. In addition, carbides, nitrides and carbonitrides of these elements have a high melting point (1500 ° C. or higher, generally 2000 ° C. or higher) and have high stability at high temperatures. Thus, the compounds hardly react with the glass and have high molding durability.

One or more elements selected from lithium, potassium and sodium need not be added to the entire thin film of any one of metal carbide, metal nitride and metal carbonitride. That is, the element may be added only near the surface of the thin film of any one of metal carbide, metal nitride and metal carbonitride. Near the surface of the thin film of any one of metal carbide, metal nitride and metal carbonitride means an area of several hundred nm from the surface of the thin film. In particular, the concentration of at least one element selected from lithium, potassium and sodium in the region of 100 nm or less from the surface greatly contributes to the molding properties. Therefore, in the initial stage of film formation of the thin film of any one of metal carbide, metal nitride and metal carbonitride, the addition amount of at least one element selected from lithium, potassium and sodium is not reduced or added. The concentration (0.05 to 5 atomic%) specified in the present invention may be set for at least one element selected from lithium, potassium and sodium only in the final stage of film formation, that is, in a region having a film thickness of several hundred nm or less.

Examples of the substrate used in the present invention include oxide-based ceramics such as alumina and zirconia, carbides and nitride-based ceramics such as silicon carbide, silicon nitride, titanium carbide, titanium nitride, tungsten carbide, WC-based cemented carbide, and molybdenum, tungsten and tantalum; There is the same metal. The shape of the substrate can be arbitrarily determined according to the shape of the film forming apparatus or the lens to be molded. For example, when the lens is to be molded, the molding surface is curved to match the curvature of the lens diameter. On this curved surface, a vapor phase synthesis method can be used to form a thin film of any one of metal carbide, metal nitride and metal carbonitride.

Hereinafter, the present embodiment will be described in detail with reference to Examples.

Example 1

In this embodiment, a release layer made of tantalum nitride was formed by the sputtering method shown in FIG.

The die base metal used was formed by processing the SiC sintered body into a predetermined shape, forming a polycrystalline SiC film by the CVD method, and then polishing the molded surface with a mirror surface of R _max = 0.04 μm. This molding die was washed well and installed in the sputtering apparatus shown in FIG. Tantalum was used as a metal target and lithium chloride (LiCl) was used as an alkali source target. After evacuating the vacuum tank 121 to a predetermined degree of vacuum, nitrogen and argon gas were introduced from the gas supply section 125 at a flow rate of 20 ml / min, respectively. The pressure was 5 × 10 ⁻¹ Pa. An RF voltage of 800 W was applied to the tantalum target and an RF voltage of 25 W to the lithium chloride target using an RF power source 129 (frequency 13.56 MHz). At this time, the substrate holder 123 was rotated at 10 rpm. By the above operation, a titanium nitride film having a thickness of 1.5 mu m was formed on the molding surface of the die base metal. An analytical sample formed under the same synthetic conditions as the tantalum nitride thin film described above was measured by secondary ion mass spectrometry (SIMS). As a result, the lithium content in the vicinity of the surface of the tantalum nitride thin film (area of about 20 nm from the surface) was about 2.0 atomic%.

The compression molding of the glass lens was performed using the optical element shaping die of this embodiment. As the glass lens forming apparatus, the apparatus shown in FIG. 4 as in the first embodiment was used.

The glass to be molded was a concave lens having a flint optical glass SF14 (softening point Sp = 586 ° C, transition point Tg = 485 ° C), having a diameter of 30 mm and a thickness ratio of 4. Molding conditions were 588 degreeC of compression temperature under nitrogen atmosphere. During molding, the release properties of the molding die and the molded optical element were good. The die surface was observed with a scanning electron microscope after molding. As a result, no peeling or cracking of the film occurred, and no fusion of lead or the glass itself, which is a reduction analyte for lead oxide in the glass, was observed. That is, the die had good surface properties. Molded glass lenses also had satisfactory surface roughness. An optical element forming die was produced under the same conditions as described above except that lithium was not added to the tantalum nitride film, and glass molding was performed using the same glass material and the same shape as described above. As a result, the release force between the die and the glass was so strong that the glass cracked and partially fused to the forming die.

Example 2-5, Comparative Example 1-4

In the present Example and the comparative example, various elements were added to the titanium nitride thin film, and the effect was evaluated.

The titanium nitride thin film was synthesized by the sputtering method shown in FIG. 10. WC-based cemented carbide was processed into a predetermined shape as a die base metal. The obtained molding die was washed well, installed in the apparatus shown in Fig. 10, and titanium nitride was synthesized. Titanium was used as the metal target, and various alkali compound targets were prepared and added to the titanium nitride by sputtering with the titanium target. In other synthesis conditions, nitrogen and argon gas were introduced at a flow rate of 25 ml / min, respectively, and the RF output to the titanium target was 750 W, the RF output to the alkali compound target was 20 W, and the pressure was 6 x 10 ^-1 Pa. . Under the above conditions, a titanium nitride film having a film thickness of about 1.2 mu m was formed. Subsequently, compression molding of the glass lens was performed using this optical element shaping | molding die. Molding was carried out using a continuous molding apparatus (not shown), and Flint-based optical glass SF14 (softening point Sp = 586 ° C, transition point Tg = 485 ° C) was used as the glass to be molded. 5000 compression molding was performed at a compression temperature of 588 ° C. under a nitrogen atmosphere. The lens shape was the same as in Example 1. The results are shown in FIG.

In FIG. 11, the concentration of various elements in the titanium nitride film was determined by measuring the sample for evaluation separately prepared under the same conditions as the synthesis conditions of the molding die using the SIMS method.

In Examples 2 to 5, by adding at least one element selected from lithium, potassium and sodium to the titanium nitride film, the surface characteristics and molding durability of the molded article satisfactory as the optical element molding die could be obtained. On the other hand, in Comparative Examples 1 to 4, since the additive element was out of the above range, the surface properties and molding durability of the molded article were lowered. In Comparative Examples 1 to 3, the adhesive force between the molding die and the glass was so great that the mold release properties of the die and the glass were deteriorated during molding, and some of the molded glass products were cracked. Moreover, it was necessary to clean the die during the molding test because the glass cracked and adhered to the molding die. In Comparative Example 4, the titanium nitride film was significantly degraded and peeled off. As a result, the surface properties of the molded glass were lowered and the molded glass was not suitable for practical use. As described above, by adding at least one element selected from lithium, potassium and sodium to the titanium nitride film, it is possible to obtain surface characteristics and molding durability of a molded article satisfactory as an optical element forming die.

Examples 6-11, Comparative Examples 5 and 6

In this example and a comparative example, various release films were formed and evaluated.

These release films were formed by the sputtering method as in Example 2.

The die base metal was processed into a predetermined shape in advance. The obtained molding die was washed well, installed in the apparatus shown in Fig. 10, and a release thin film was formed. Various metal sources were used in the film formation and the gas was selected as follows.

(1) When forming a metal nitride: 20 ml / min nitrogen and 20 ml / min argon.

(2) When forming metal carbide: 20 ml / min of methane and 20 ml / min of argon.

(3) When forming metal carbonitride: 10 ml / min of nitrogen, 10 ml / min of methane and 20 ml / min of argon.

(4) When forming a metal film: 30 ml / min of argon.

In addition, lithium fluoride was used as the alkali source target to add lithium to the release layer.

As other synthesis conditions, the RF power to the metal target was 800 W, the RF power was 25 W at the alkali source target, the pressure was 3.5 × 10 ⁻² Pa, and the film thickness was about 1.2 μm. Subsequently, compression molding of the glass lens was performed using this optical element shaping | molding die. Molding was performed using a continuous molding apparatus, and Flint-based optical glass SF14 (softening point Sp = 586 ° C, transition point Tg = 485 ° C) was used as the glass to be molded. 5000 compression molding was performed at a compression temperature of 588 ° C. under a nitrogen atmosphere. The lens shape was the same as in Example 1. The results are shown in FIG.

The lithium concentration in a release film was calculated | required by measuring the sample for evaluation created separately on the same conditions as the synthesis conditions of a molding die using SIMS method. As a result, the lithium concentration was 0.5 to 1.2 atomic percent in all of the samples.

In Examples 6 to 11, by using a thin film of carbide, nitride, or carbonitride of periodic table 4A, 5A, and 6A elements and silicon, satisfactory molded article surface characteristics and molding durability as optical element forming dies were obtained. On the other hand, in Comparative Examples 5 and 6, since the additive element was out of the above range, the surface properties and molding durability of the molded article were lowered. In Comparative Example 5, the adhesion between the die and the glass was large because of its high reactivity with the glass. As a result, the release properties of the die and glass deteriorated during molding, and some of the molded glass products were cracked. Moreover, it was necessary to clean the die during the molding test because the glass cracked and adhered to the molding die. In Comparative Examples 5 and 6, the film deteriorated, perhaps because of the low hardness of the film, and the film was worn and peeled off during molding. As a result, the surface properties of the molded glass were lowered and the molded glass was not suitable for practical use.

Examples 12-15, Comparative Examples 7 and 8

In the present Example and the comparative example, the release layer comprised from the silicon carbide thin film was formed by the sputtering method.

This silicon carbide film was formed using a sputtering apparatus as shown in FIG.

In this example and the comparative example, lithium was added to the silicon carbide thin film by using silicon carbide as the metal carbide target and lithium boride (LiB ₂ ) as the alkali source target. In this example and a comparative example, lithium was added only near the surface of each silicon carbide thin film by applying a high frequency to the lithium boride target during film formation.

A die base metal made of a cemented carbide material processed into a predetermined shape was installed in the apparatus shown in Fig. 10 to form a silicon carbide thin film. Formation conditions include a gas flow rate of 10 ml / methane and 30 ml / m of argon, substrate temperature of 200 ° C., RF output to silicon carbide of 800 W, RF output to lithium boride target of 25 W, and pressure of 5 × 10 ^{−. It} was set to ¹ Pa. High frequency was applied to the lithium boride target during film formation, and the application time was changed to form a silicon carbide-doped silicon carbide film having various thicknesses. Note that the total thickness of the silicon carbide film without lithium and the silicon carbide film with lithium was set to 1.2 m.

The lithium element concentration in the lithium-added silicon carbide film was measured using the SIMS method for an evaluation sample separately prepared under the synthesis conditions of the molding die, and found to be 2.1 atomic%.

The molding durability test was done using the said molding die. This compression molding was performed using a continuous molding apparatus, and crown type optical glass SK12 (softening point Sp = 672 degreeC and transition point Tg = 550 degreeC) was used as glass to shape | mold. A concave lens having a diameter of 35 mm and a thickness ratio of 4 was molded. 5000 compression molding was performed at a compression temperature of 620 ° C. under a nitrogen atmosphere. The results are shown in FIG.

In Examples 12 to 15, the release properties between the die and the molded optical element during molding were good. When the die surface was observed using a scanning electron microscope after molding, no peeling and cracking of the film occurred and the glass did not fuse, showing good die surface properties. In addition, the molded glass lenses actually had satisfactory surface roughness. In Comparative Examples 7 and 8 in which the lithium-containing layer in the silicon carbide film was less than 0.1 µm, the releasing force between the die and the glass was strong, so that the glass cracked and partially fused to the die.

Examples 16-20, Comparative Examples 9 and 10

In the present Example and the comparative example, the concentration of the additional element in the titanium nitride thin film was evaluated.

Titanium nitride was formed by the sputtering method as in Example 2.

The die base metal was processed into a predetermined shape. The obtained die was washed well and installed in the apparatus shown in FIG. 10 to form a titanium nitride thin film. Metal titanium and lithium fluoride were used as the target, and the amount of lithium added in the titanium nitride film was changed by changing the RF application force to the lithium fluoride during film formation. In the synthesis conditions, the gas source flow rate was 20 ml / min for nitrogen and 30 ml / min for argon, the RF output to the titanium target was 750 W, and the pressure was 4 × 10 ⁻¹ Pa. Under the above conditions, a titanium nitride film having a thickness of about 1 μm was formed. Compression molding of the glass lens was performed using this optical element molding die. Molding was performed using a continuous molding apparatus, and Flint-based optical glass SF14 (softening point Sp = 586 ° C, transition point Tg = 485 ° C) was used as the glass to be molded. 5000 compression molding was performed at a compression temperature of 588 ° C. under a nitrogen atmosphere. The lens shape was the same as in Example 1. The results are shown in FIG.

In Fig. 14, the lithium concentration in the titanium nitride film was determined by measuring an evaluation sample separately prepared under the same conditions as the synthesis conditions of the molding die using the SIMS method.

In Examples 16 to 20, by forming the lithium element concentration of 0.05 to 5 atomic%, satisfactory molded article surface characteristics and molding durability as optical element molding dies could be obtained. On the other hand, in Comparative Examples 9 and 10, since the lithium element concentration was out of the above range, the surface characteristics and molding durability of the molded article were lowered. In Comparative Example 9, the low lithium element concentration resulted in high adhesion between the molding die and the glass, which deteriorated the release property of the die and the glass during molding and cracked some of the molded glass products. Moreover, it was necessary to clean the die during the molding test because the glass cracked and adhered to the molding die. In Comparative Example 10, the titanium nitride film was deteriorated due to the high lithium element concentration, and the film was worn and peeled off during molding. As a result, the surface properties of the molded glass were lowered and the molded glass was not suitable for practical use. That is, when the additive element concentration was less than 0.05 atomic%, the release properties of the die and the glass were not satisfactory during molding. When the added element concentration exceeded 5 atomic%, the film quality of the titanium nitride thin film deteriorated, resulting in abrasion or peeling of the film. As described above, by setting the addition concentration of at least one element selected from lithium, potassium and sodium to 0.05 to 5 atomic%, it is possible to obtain surface characteristics and molding durability of a molded article satisfactory as an optical element molding die.

The present invention is not limited to the above embodiments, and various changes and modifications can be made within the spirit and scope of the present invention. Therefore, the following claims are attached to show the scope of the present invention.

As mentioned above, when shape | molding a glass optical element using the shaping | molding die which concerns on this invention, the release property between glass and die is very favorable. As a result, a molded article having good surface roughness, surface precision, transmittance, and shape accuracy can be obtained. Further, by using the die, even if the compression molding is repeatedly performed for a long time, defects such as peeling or cracking of the film, and damage do not occur, thereby improving durability. In addition, in the method of manufacturing an optical element molding die for producing a glass optical element using the molding die, an optical element molding die can be manufactured at low cost without causing deterioration of the film and surface roughness of the molded glass. It is improved and the cost is reduced.

Claims (7)

In compression molding, a thin film made of a material selected from the group consisting of TaN, TiN, ZrN, TiC, TiCN, MoC, SiC, SiN and CrC containing a lithium element or a lithium compound is formed at least as a release layer on the molding surface. Optical element molding die for producing a glass optical element. A method for producing an optical element forming die for producing a glass optical element by compression molding, the method comprising: from the group consisting of TaN, TiN, ZrN, TiC, TiCN, MoC, SiC, SiN, and CrC containing lithium element or lithium compound Wherein the thin film of the selected material is formed as a release layer on at least the forming surface of the forming die by ion plating or sputtering using a metal feed material comprising a lithium element or a lithium compound. A method for producing an optical element molding die having a release layer comprising at least one alkali metal on a molding surface, wherein the release layer is formed by a sputtering method using two or more targets, at least one of the targets being alkali A metal, wherein at least one of the remaining is a target for forming metal carbide, metal nitride, or metal carbonitride. The metal carbide, metal nitride and metal carbonitride thin film constituting the release layer has a content of 0.05 to 5 atoms on the molding surface of at least one element selected from the group consisting of lithium, potassium and sodium. Which is%. 4. The mixed layer of alkali metals and metal carbides, metal nitrides or metal carbonitrides according to claim 3, wherein the mixed layer of alkali metals and metal carbides, metal nitrides or metal carbonitrides is at least optical by simultaneously sputtering said targets comprising alkali metals and said targets for forming metal carbides, metal nitrides or metal carbonitrides. And formed in an area of 100 nm or more from the device shaping surface. The metal carbide, metal nitride and metal carbonitride thin film constituting the release layer has a content of 0.05 to 5 atoms on the molding surface of at least one element selected from the group consisting of lithium, potassium and sodium. Which is%. An optical element molding die produced by the method of claim 3.

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