JPH0672728A - Mold for molding optical element and its production - Google Patents

Abstract

PURPOSE:To provide the mold having a mirror finished surface which does not generate peeling and cracking of films and has less surface defects in molding of glass. CONSTITUTION:This mold for molding optical elements is used for press forming of the optical elements consisting of glass and at least the molding surface of the base material of this mold is a mixing layer consisting of carbon and at least >=1 kinds of the elements constituting the mold. This process for production of the mold for molding the optical elements consists in forming the above mixing layer by a carbon ion beam of >=5kev ion energy. As a result, the mold having the mirror finished surface which does not generate peeling and cracking of the films and has less surface defects is obtd. The release property of the glass and the mold is extremely good if the optical elements are molded by using this mold. The molded parts having good surface roughness, surface precision transmittance and shape accuracy are obtd. over a long period of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold used for manufacturing an optical element made of glass such as a lens and a prism by press molding of a glass material, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A technique for manufacturing a lens by press-molding a glass material without requiring a polishing step eliminates the complicated steps required in the conventional manufacturing, and makes it possible to manufacture a lens easily and inexpensively. In recent years, it has come to be used for manufacturing not only lenses but also optical elements made of glass such as prisms.

The properties required of the mold material used for press molding of such glass optical elements include excellent hardness, heat resistance, mold release property, mirror surface workability and the like. Heretofore, many proposals have been made for this type of mold material such as metals, ceramics and materials coated with them. To give some examples, JP-A-49-
51112 is made of 13Cr martensitic steel.
2-45613 includes SiC and Si ₃ N ₄ , which are disclosed in
No. 0-246230 is a material obtained by coating a noble metal on a cemented carbide, and is also disclosed in JP-A-61-183134 and 61-
281030, JP-A-1-301864 discloses a diamond thin film or diamond-like carbon film, JP-A-64-8.
3529 proposes a hard carbon film, and Japanese Examined Patent Publication No. 31012 proposes a material coated with a carbon film.

[0004]

[Problems to be Solved by the Invention] However, 13Cr
Martensitic steel is easily oxidized, and further has a defect that Fe diffuses into the glass at a high temperature and the glass is colored. It is generally said that SiC and Si ₃ N ₄ are difficult to oxidize, but at high temperature, oxidation also occurs and a SiO ₂ film is formed on the surface, so that glass fusion occurs. Further, it has a drawback that the workability of the mold itself is extremely poor due to the high hardness. Materials coated with precious metals do not easily cause fusion,
Since it is extremely soft, it has the drawback that it is easily scratched and deformed.

The diamond thin film has high hardness and excellent thermal stability, but since it is a polycrystalline film, it has a large surface roughness and needs to be mirror-finished. DLC film, aC:
The mold using the H film and the hard carbon film has good mold releasability between the mold and the glass, and does not cause glass fusion, but when the molding operation is repeated several hundred times or more, the film is partially peeled off. However, a molded product may not have sufficient molding performance.

The following are possible causes for this.

Each of the above-mentioned films has a very large compressive stress, and peeling, cracking, etc. occur as a result of the stress release associated with rapid heating and rapid cooling in the molding process. Similarly, a similar phenomenon occurs due to the difference in thermal expansion coefficient between the mold base material and the film and the thermal stress caused by the thermal cycle.
Depending on the surface condition, the film may not be partially formed or the film thickness may be thin depending on the mold base material. For example, WC-
In a sintered body of Co, SiC, Si ₃ N ₄ or the like, the lack of grains and the bore during sintering are unavoidable, and holes of several μm or more exist on the molded and polished surface. When a film is formed on such a surface, no film is formed in these holes or the film is extremely thin. Therefore, the adhesion strength and the mechanical strength of the film in such a portion are remarkably reduced, so that they easily become the starting points of peeling and cracking. An alloy is formed by diffusion between the above-mentioned film and the sintering aid in the sintered body typified by Co of WC-Co. Such a portion causes fusion of glass during molding and reacts with components contained in the glass to form a precipitate, resulting in deterioration of durability.

As described above, an optical element molding die excellent in moldability, durability and economy has not been realized yet.

Further, in Japanese Patent Publication No. 2-31012, when the film thickness is less than 50 Å, the film becomes non-uniform and the carbon film forming effect is reduced, and when it exceeds 5000 Å, the surface accuracy due to pressure molding deteriorates. If ~ 5,000Å, no problems will occur. However, the carbon film according to the embodiment of the present invention has a small adhesive force with the substrate or has a large compressive stress, so that film peeling occurs in the molding process. As a result, fusion of glass in the peeled portion and poor appearance of the molded product are caused, and a practical mold having excellent durability has not been provided yet.

[0010]

According to the present invention, a mixing layer composed of carbon and at least one element constituting an intermediate layer formed on the surface of the mold base material or the base material is provided on at least the molding surface of the mold base material. The problems described above are solved by using the formed mold and by manufacturing the mixing layer using a carbon ion beam having a high ion energy that uses a carbon-containing gas as a raw material.

The present invention will be described in detail below. The material used as the mold base material in the present invention is WC, S
iC, TiC, TaC, BN, TiN, AlN, Si ₃
N ₄ , SiO ₂ , Al ₂ O ₃ , ZrO ₂ , W, Ta, M
o, cermet, sialon, mullite, WC-Co alloy, etc.

Since carbon has a small adhesion to glass, it has been used for a glass molding die for a long time. In the glass mold, the properties of carbon and glass are used to form the hard and smooth carbon film on the molding surface of the mold base material. As the carbon film, diamond film, DLC film, a-
The C: H film and the hard carbon film can be mentioned, but the diamond film has a problem that it needs a mirror finish because it is polycrystalline and has a rough surface. On the other hand, amorphous DLC film, aC: H
The film and the hard carbon film have a large internal stress and lack thermal stability in a high temperature region where glass is formed, and as the number of times of forming increases, the adhesion strength between the die base material and the film decreases. That is, the problem of the carbon film as the mold surface material in the glass mold is mainly related to the adhesion strength between the mold base material and the film. In this regard, it is possible to solve the conventionally problematic problem by forming a molding surface with carbon and a mold base material or a mixing layer composed of at least one element constituting an intermediate layer formed on the surface of the base material. it can. This mixing layer has extremely good adhesion because carbon is mixed (atomic mixture) with the mold base material or the intermediate layer material formed on the mold base material. Regarding the state of the mixing layer, the carbon atom concentration increases toward the surface and decreases toward the base metal side, whereas the atom concentration other than carbon decreases toward the surface and increases toward the base metal side. ing. FIG. 1 schematically shows this state. In the figure, the horizontal axis represents the depth from the surface to the die base material,
The position where the depth is 0 is the surface. On the other hand, the vertical axis represents the atomic concentration. In particular, if the carbon concentration on the surface is sufficiently high, the releasability from the glass is good and no reaction deposit with the glass component is generated.

Such a mixing layer can be realized by using a carbon ion beam having an ion energy of 5 keV or more. A mold formed with an ion energy of less than 5 keV causes film peeling and glass fusion during the molding process. The ion current density at this time is 0.8
mA / cm ² ~2.0mA / cm ² is preferred. Ion current density, the film forming time becomes longer is less than 0.8 mA / cm ^2, if it exceeds 2.0 mA / cm ^2, the surface roughness of the molding surface with an increase in the molding times although there is no problem in adhesion strength Deterioration is likely to occur. The ion energy may be 5 keV or more, but it is practically 5 keV.
V to 10 keV is preferable.

The thickness of the mixing layer is 1 nm or more and 100 n
m or less is preferable. Here, the thickness of the mixing layer is
It is defined as the depth from the point where the amount of change in carbon concentration is 50% at the interface between the mold base material or the intermediate layer and the mixing layer to the surface. When the thickness is less than 1 nm, the above effect is reduced because the mixing state is not sufficient, and the thickness is 100 nm.
If the thickness is thicker than that, the surface condition becomes rough and the molding performance is deteriorated, and the film stress becomes large, so that minute peeling easily occurs during molding. A more ideal thickness is 20 nm to 5
It is in the range of 0 nm. In this way, the mixing layer is very thin, so there is almost no problem of film peeling due to internal stress or thermal stress of the film, which is a problem when the film thickness is thick. Does not cause a decrease in Further, since the thickness is thin, the surface hardness and the thermal stability at high temperature can depend on the mold base material, and the thermally stable state can be maintained in the molding temperature range. Therefore, a stable mixing state is obtained as the mold base material, and it is easy to bond with carbon (it is easy to form a carbide).
Ideally, it is a material of a single composition consisting of elements, and at the same time, it has high mechanical strength at high temperature, high surface hardness, and excellent oxidation resistance. These conditions can be satisfied by providing the intermediate layer on the molding surface of the die base material. Examples of the intermediate layer include Si, Al, metals of Groups 4A, 5A, and 6A of the periodic table and their carbides, nitrides, carbonitrides, carbonates, carbonitrides, borides, boronitrides, and Boron carbides, nitrides, and compounds or mixtures of at least one of these may be used. The material of the intermediate layer may be selected from materials having high adhesion strength to the die base material, and may have the minimum necessary film thickness. In the mixing layer, in addition to oxygen, hydrogen, and nitrogen, Ar, F, and the like used as raw material gases when forming the mixing layer are several at% to several tens of a.
About t% may be present.

When the mold surface is roughened or defective due to molding, the mixing layer may be removed by a dry process and then the mixing layer may be formed again. This is because the surface hardness of the mold base material is high, so that the defects caused by molding are limited to the mixing layer. As the etching method by the dry process, methods such as plasma etching, sputter etching, ion beam etching, and reactive ion etching are used. As an etching gas, O ₂ , H ₂ , N ₂ , Ar, Ai
r, CF _4, etc. and their mixed gas are used. It is preferable to select etching conditions that do not deteriorate the surface shape of the mold, especially the surface roughness, by etching. In addition,
The film removal is not limited to the dry process,
Mechanical polishing using diamond abrasive grains and a method of chemically etching can be used together.

The mixing layer is formed by an ion beam vapor deposition method, an ion plating method, an ion implantation method, an ion beam mixing method or the like. Gases used for carbon mixing include carbon-containing gases such as methane, ethane,
Hydrocarbons such as propane, ethylene, benzene and acetylene; halogenated hydrocarbons such as methylene chloride, carbon tetrachloride, chloroform and trichloroethane; alcohols such as methyl alcohol and ethyl alcohol; (CH ₃ ) ₂
Ketones such as CO and (C ₆ H ₅ ) ₂ CO; CO and CO ₂
N ₂ gas, and these gases _{etc., H 2, O 2, H} 2
A mixture of gases such as O and Ar can be used.

Here, the case of forming the mixing layer by using the carbon ion beam will be described. The ion energy at this time is several 100 eV to several 1 with respect to the mold base material.
It is in the range of 0 KeV. In particular, as the ion energy increases, the ion implantation effect increases and the mixing layer is easily formed. That is, C of several KeV or more
When the surface of the mold base material is irradiated with (carbon) ions, the surface is sputtered and the irradiated ions penetrate into the surface of the mold base material due to the implantation effect. The invading ions collide with the atoms of the base material, lose energy, and come to rest. As a result, a mixing layer composed of carbon atoms and mold base material atoms is formed. The carbon ion beam is generated by a Kauffman type ion source. FIG. 13 shows a schematic diagram of a typical Kauffman type ion source. In the drawing, 28 is a cylindrical coil for magnetic field generation, 29 is a filament, 30 is a gas introduction part, 31 is an anode, 32 is an extraction electrode, 33 is an ion beam, 34 is a mold base material, 35
Is a substrate holder. The above-mentioned raw material gas, for example, CH ₄ and H ₂ is introduced into the ionization chamber from the gas introduction part to form plasma, and then a voltage is applied to the extraction electrode to irradiate the extraction base material with an ion beam. At this time, an ion source,
The mixing layer is formed by adjusting the substrate position and the like. As one of the methods for controlling the depth profile of carbon atoms and mold base material atoms in the mixing layer, there is a method of changing the energy of irradiation ions with the irradiation time. For example, a desired depth profile can be obtained by irradiating C ions with high ion energy in the initial stage of irradiation, and gradually lowering the voltage of the extraction electrode to lower the irradiation ion energy. Alternatively, when the intermediate layer is provided on the mold base material, the intermediate layer of carbide is formed by irradiating C ions having high ion energy while depositing the material for the intermediate layer. In this state, the deposition rate of the vapor deposition material is gradually reduced, and the vapor deposition is finally stopped. On the other hand, C
Subsequent irradiation with ions can form the intermediate layer and the mixing layer having a desired depth profile.

The mixed state of each atom in the mixing layer is not limited to that shown in FIG. 1, and may be linear, stepped or the like. That is, the C atom concentration and the other atom concentrations may have the same gradient as described above in the mixing layer, and the profile thereof is not limited to one. However, it is ideal that the C atom concentration is 100% and the other atom concentrations are 0% on the surface. Further, the atomic concentration in the mold base material or the intermediate layer does not necessarily have to be stoichiometry.

The present invention provides a mold in which at least a molding surface of a mold base material is provided with a mixing layer composed of carbon and at least one kind of element constituting an intermediate layer formed on the surface of the mold base material or the base material, and By forming the mold with a carbon ion beam having a specific ion energy, an optical element molding mold having excellent durability is realized.

It is needless to say that the present invention is not limited to optical elements such as lenses, mirrors, gratings, prisms and the like, and can be applied to glass and plastic molded products other than optical elements.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings.

[Example 1 (Si, C) mixing layer]
2 and 3 show one embodiment of an optical element molding die according to the present invention. 2 shows the state of the press-molded surface of the optical element, and FIG. 3 shows the state after the optical element is molded. 2, 1 is a mold base material, 2 is a molding surface for molding a glass material, 3 is a mixing layer, 4 is a glass material, and 5 in FIG. 3 is an optical element. As shown in FIG. 2, an optical element 5 such as a lens is formed by press molding a glass material 4 placed between molds.

Next, the optical element molding die of the present invention will be described in detail.

After processing sintered SiC as a mold base material into a predetermined shape, a polycrystalline SiC film is formed by the CVD method, and then the molding surface is Rmax. What was mirror-polished to 0.02 μm was used. After thoroughly cleaning this mold, I shown in FIG.
It was installed in a BD (Ion Beam Deposition) device. In the figure, 6 is a vacuum chamber, 7 is an ion beam device,
8 is an ionization chamber, 9 is a gas inlet, 10 is an ion beam extraction grid, 11 is an ion beam, 12 is a mold base material, 13 is a substrate holder and heater, and 14 is an exhaust port. First, 35 sccm of Ar gas is introduced into the ionization chamber from the gas introduction port for ionization, then a voltage of 500 V is applied to the ion beam extraction grid to extract the ion beam, and the mold base material is irradiated for 5 minutes to clean the molding surface. I went. Next, CH ₄ : 15 sccm, H ₂ : 30 sc
cm is introduced into the ionization chamber and the gas pressure is 3.5 × 10 ⁻⁴ To
rr, an ion beam was extracted at an accelerating voltage of 10 kV and irradiated on the molding surface to form a 35 nm mixing layer.
The ion beam current at this time was 30 mA, and the current density was 2 m.
A / cm ² and the substrate temperature were 300 ° C. The mixing layer of the analysis sample prepared under the same conditions was AES (Auger).
The result of the depth direction analysis by Electron Spectroscopy) is shown in FIG. As is apparent from FIG. 5, the thickness of the mixing layer is 35 nm, and the concentration of carbon C decreases from 100% on the surface side toward the mold base material side. On the other hand, the concentration of Si atoms increases from 0% on the surface side toward the mold base material side. That is, the profile of C and Si concentrations in the depth direction is shown in FIG. C on the mold base material side
The concentrations of Si and Si are 50%, respectively, which is stoichiometry of SiC. The thickness of the mixing layer is, as defined above, the thickness from the depth of 50% of the change amount at which the C concentration becomes maximum to minimum before and after the interface of the mold base material to the surface.

Next, an example in which a glass lens is press-molded by the optical element molding die according to the present invention will be shown. Figure 6
Inside, 51 is a vacuum tank main body, 52 is its lid, 53 is an upper mold for molding an optical element, 54 is its lower mold, 55 is an upper mold holder for holding the upper mold, 56 is a body mold, and 57 is A mold holder, 58 is a heater, 59 is a push-up rod for pushing up the lower mold, 60 is an air cylinder for operating the push-up rod,
61 is an oil rotary pump, 62, 63, 64 are valves, 65
Is an inert gas inflow pipe, 66 is a valve, 67 is a leak valve, 68 is a valve, 69 is a temperature sensor, 70 is a water cooling pipe, and 71 is a stand for supporting a vacuum chamber.

The process of manufacturing the lens will be described below.

The flint optical glass (SF14) is adjusted to a predetermined amount, a spherical glass material is placed in the mold cavity, and this is placed in the molding apparatus. After placing the mold into which the glass material has been put in the apparatus, the lid 5 of the vacuum chamber 51
2 is closed, water is passed through the water cooling pipe 70, and an electric current is passed through the heater 58. At this time, the nitrogen gas valves 66 and 68 are closed, and the exhaust system valves 62, 63 and 64 are also closed.
The oil rotary pump 61 is always rotating. Valve 62
The valve 62 is closed and the valve 66 is opened to introduce nitrogen gas into the vacuum chamber from the cylinder when the temperature becomes 10 ^-2 Torr or less after opening the chamber and starting exhaust. When the temperature reaches a predetermined temperature, the air cylinder 60 is operated to apply a pressure of 200 kg / cm ² for 1 minute. After releasing the pressure, cool down at -5
Cooling to below the transition point at ℃ / min, then-
Cooling is performed at a rate of 20 ° C./min or more, and when the temperature drops to 200 ° C. or less, the valve 66 is closed, the leak valve 63 is opened, and air is introduced into the vacuum chamber 51. Then, the lid 52 is opened, the upper die holder is removed, and the molded product is taken out. As described above, the flint optical glass SF14 (softening point Sp = 5
The lens 5 shown in FIG. 3 was molded by using 86 ° C. and a transition point Tg = 485 ° C.). FIG. 7 shows a molding condition at this time, that is, a time-temperature relationship diagram.

Molding was performed 300 times using the mold. In the mold after molding, defects such as scratches and cracks and fusion of Pb and glass, which are reduction precipitates of Pb0 contained in glass, were not observed by an optical microscope or a scanning electron microscope (SEM). Moreover, the surface roughness, surface accuracy, transmittance, and shape accuracy of the molded product were also good, and there were no problems such as Pb precipitation or gas residue during molding.

Next, this mold was used to perform molding with the molding apparatus shown in FIG.

In FIG. 8, 102 is a molding device, and 104 is a molding device.
Is a replacement chamber for intake, 106 is a molding chamber, and 10
Reference numeral 8 is a vapor deposition chamber, and 110 is a take-out replacement chamber.
Reference numerals 112, 114 and 116 are gate valves, and 118
Is a rail, and 120 is a pallet that can be transported on the rail in the direction of arrow A. 124,138,14
Reference numerals 0 and 150 are cylinders, and 126 and 152 are valves. 128 is a rail 118 in the molding chamber 106.
The heaters are arranged along the line.

Inside the molding chamber 106, a heating zone 106-1 and a pressing zone 106-2 are sequentially arranged along the pallet conveying direction.
And the slow cooling zone 106-3. In the press zone 106-2, the rod 13 of the cylinder 138 is
An upper mold member 130 for molding is fixed to the lower end of 4,
A molding lower die member 132 is fixed to the upper end of the rod 136 of the cylinder 140. These upper mold members 130
The lower mold member 132 is a mold member according to the present invention. In the vapor deposition chamber 108, a container 142 containing a vapor deposition material 146 and a heater 144 for heating the container are arranged.

Crown type glass SK12 (softening point Sp =
(672 ° C., glass transition point Tg = 550 ° C.) was roughly processed into a predetermined shape and size to obtain a blank for molding. The glass blank is placed on the pallet 120, placed at the position 120-1 in the intake / replacement chamber 104, and the pallet at that position is pushed in the direction A by the rod 122 of the cylinder 124 to pass through the gate valve 112 and 120 in the forming chamber 106. −
2 to the molding chamber 10 at a predetermined timing.
6 was sequentially transported to the position of 120-2 → ... → 120-8. In the meantime, in the heating zone 106-1, the glass blank is gradually heated by the heater 128 to make the softening point or higher at the position 120-4, and then the press zone 106-2.
To the upper mold member 130 and the lower mold member 132, and the cylinders 138 and 140 are operated to 200 kg.
/ Cm ² at a pressing temperature of 620 ° C. for 1 minute, release the applied pressure and cool to below the glass transition point, and then operate the cylinders 138 and 140 to operate the upper mold member 130 and the lower mold member 132 with glass. It was released from the molded product. At the time of the pressing, the pallet was used as a body member for molding. After that, the slow cooling zone 106-3
Then, the glass molded product was gradually cooled. The molding chamber 10
The inside of 6 was filled with an inert gas. The pallet that has reached the position 120-8 in the forming chamber 106 is passed through the gate valve 114 in the next transfer to pass the pallet 12 in the vapor deposition chamber 108.
It was transported to the 0-9 position. Usually, vacuum vapor deposition is performed here, but this vapor deposition is not performed in this embodiment. Then, in the next transportation, the material was transported over the gate valve 116 to the position 120-10 in the take-out replacement chamber 110. Then, at the time of the next conveyance, the cylinder 150 was operated and the glass molded product was taken out of the molding apparatus 102 by the rod 148. The molding surface of the mold member and the surface roughness of the molded optical element after molding 3,000 times by the above-described pressing process, and the releasability between the mold member and the molded optical element were good. In particular, when the molding surface of the mold member was observed with an optical microscope or a scanning electron microscope (SEM), defects such as scratches and cracks, reaction precipitates of glass components, and fusion of glass were not observed.

Example 2 (Si, C) mixing layer]
Using the same mold base material as in Example 1, a mixing layer was formed by the same method and under the same conditions. At this time, the thickness of the mixing layer is changed to 0.9 nm, 40 nm, 101 by changing the film formation time.
nm. Using these three molds, the flint type optical glass SF14 (softening point Sp = 586 ° C., transition point Tg = 485 ° C.) was set to 100 by the molding machine of FIG. 8 in the same manner as in Example 1.
Molded 0 times. The results are shown in Table 1.

[0034]

Mold No. after molding Regarding 2, the example 1
Similar to, defects such as scratches and cracks and P contained in glass
No fusion of Pb, which is a reduced precipitate of b0, or glass was observed by an optical microscope or a scanning electron microscope (SEM). Moreover, the surface roughness, surface accuracy, transmittance, and shape accuracy of the molded product were also good, and there were no problems such as Pb precipitation or gas residue during molding. Type No. 1 is 5 molding times
If the number of times exceeds 00, glass fusion is partially observed, and the type N
o. In No. 3, when the number of moldings exceeded 300, minute peeling occurred.

[Example 3 (Ti, N, C) mixing layer, TiN intermediate layer] WC (84%)-Ti as a type base material
After processing a sintered body composed of C (8%)-TaC (8%) into a predetermined shape, the molding surface was Rmax. Mirror polishing to 0.02 μm. After 200 nm of Ti was formed on the molding surface of this die base material by the ion plating method, TiN was added to 1
800 nm was formed. Using this mold base material, a mixing layer having a thickness of 50 nm was formed by the same method and conditions as in Example 1.
Using this mold and using the molding machine of FIG. 8 in the same manner as in Example 1, crown glass SK12 (softening point Sp = 672 ° C.,
The glass transition point Tg = 550 ° C.) was molded 1000 times.
As a result, the same result as in Example 1 was obtained.

[Example 4 (Si, N, C) mixing layer] After processing sintered Si ₃ N ₄ as a mold base material into a predetermined shape, the surface roughness Rmax. Mirror polishing to 0.03 μm. An ion implanter (not shown) was used to apply C ⁺¹² having an energy of 10 keV to the molding surface of this mold at 5 × 10 ¹⁷ ions / c
m ^{2 was} injected to form a mixing layer having a thickness of 20 nm. At this time, the implantation ion energy was gradually changed from 10 keV to 1 keV for implantation. Using this mold, the crown glass SK12 (softening point Sp = 672 ° C., glass transition point Tg =
(550 ° C.) was molded 1000 times. As a result, Example 1
Similar results were obtained.

Example 5 (Si, C) mixing layer,
SiC intermediate layer] Using the same mold base material as in Example 3, a mixing layer was formed by the ion beam mixing apparatus shown in FIG. In the figure, 15 is a vacuum tank, 16 is an exhaust system, 17 is an ion source, 18 is an ionization chamber, 19 is an ion beam extraction grid, 20 is a gas introduction system, 21 is an electron gun, 22
Is a substrate holder and a substrate heating device, 23 is a mold base material, 24
Is a crystal type film thickness monitor, and 25 is an ion beam. First, after placing the mold base material on the substrate holder, 5X inside the device
The gas was evacuated to 10 ⁻⁶ Torr and Ar gas was introduced into the ion source from the gas introduction system. The surface of the die base material was cleaned and the oxide film was removed by this Ar ion beam. At this time, the degree of vacuum was 3 × 10 ⁻⁴ Torr and the ion current was 7 mA. Next, while depositing 99.999% Si using an electron gun, C ₂ H ₆ : 50 sccm, Ar:
10 sccm was introduced from the gas supply system, and 700 V was applied to the ion extraction grid to irradiate the extraction base material with an ion beam. At this time, the ion current was 10 mA, the degree of vacuum was 1 × 10 ⁻³ Torr, and the substrate temperature was 300 ° C. Under these conditions, vapor deposition of Si and irradiation of carbon ion beam are performed simultaneously to form 100 nm of SiC, then the power of the electron gun is gradually reduced, and finally irradiation of only carbon ion beam is performed to emit Si and C of 15 nm.
Was formed into a mixing layer. The depth profile by AES at this time is shown in FIG. Next, as a result of performing a molding test similar to that of Example 1 using these molds, the same result as that of Example 1 was obtained. Note that SiC is used as the intermediate layer.
Besides, Si, Al, metals of 4A group, 5A group and 6A group of the periodic table and their carbides, nitrides, carbonitrides, carbon oxides, carbonitrides, borides, boronitrides, and boron carbides , Nitride, and compounds and mixtures composed of at least one of these, the same results as with SiC were obtained.

Example 6 (Ti, C) mixing layer,
TiC Intermediate Layer] An intermediate layer of TiC and a mixing layer of Ti and C were formed by the same method and under the same conditions except that the same die base material as in Example 5 was used and Ti was replaced by 99.9% Ti. At this time, the film formation time was changed to set the thickness of the mixing layer to 0.8 nm, 25 nm, and 105 nm. Figure 11
Shows the depth profile of AES by the analytical sample prepared under the same conditions. Using these three molds, the crown type glass S is formed by the molding machine of FIG. 8 in the same manner as in Example 1.
K12 (softening point Sp = 672 ° C., glass transition point Tg = 5
50 ° C.) was molded 1000 times. The results are shown in Table 2.

[0040]

Mold No. after molding Regarding Example 5, Example 1
Similar results were obtained. Type No. No. 4 has a molding frequency of 400
When the number of times exceeded, glass fusion was partially observed.
In No. 6, when the number of moldings exceeded 400, minute peeling occurred.

Example 7 (Si, C) mixing layer]
A crown glass SK12 (softening point Sp = 672 ° C., using the same mold base material as in Example 1 and the mold prepared in the same method and under the same conditions as in Example 1 by the molding apparatus of FIG.
The glass transition point Tg = 550 ° C.) was molded 2000 times.
Next, this mold was taken out of the molding machine and placed in the IBD apparatus shown in FIG. After exhausting the inside of the apparatus in the same manner as in Example 1, 35 sccm of Ar gas was introduced into the ionization chamber from the gas supply system for ionization, and then 5 was applied to the ion beam extraction grid.
A voltage of 00V is applied to extract the Ar ion beam,
The mixing layer on the molding surface was irradiated to remove the mixing layer. Subsequently, a mixing layer was formed again under the same conditions as in Example 1. Using this regenerated mold, crown glass SK12 (softening point Sp = 672 ° C., glass transition point Tg = 550 ° C.) was set to 20 by the molding apparatus shown in FIG.
Molded 00 times. As a result, the same result as in Example 1 was reproduced and obtained.

Also, when a grating mold as shown in FIG. 12 was prepared by the same method and under the same conditions as in Example 1 and the crown glass SK12 was molded, the mold releasability was good and the mold shape was faithfully transferred. The produced grating could be repeatedly molded. In FIG. 12, 26 is a grating mold, and 27 is a molded glass grating.

[Example 8 (Formation of (Si, C) mixing layer]] Sintered SiC as a die base material was processed into a predetermined shape, a polycrystalline SiC film was formed by the CVD method, and then the molding surface was mirror-polished. What was done was used. After thoroughly washing this mold, it was installed in the IBD apparatus shown in FIG. First, 35 sccm of Ar gas is introduced into the ionization chamber through the gas introduction port to be ionized, and then 500 sccm is applied to the ion beam extraction grid.
A voltage of V was applied to extract an ion beam, and the mold base material was irradiated for 3 minutes to remove and clean the natural oxide film on the molding surface.

Subsequently, CH ₄ : 20 sccm, H ₂ :
40 sccm was introduced into the ionization chamber and the gas pressure was 4.0 × 1.
The ion beam was extracted at an acceleration voltage of 9 kV and irradiated on the molding surface to form a 40 nm mixing layer at 0 ⁻⁴ Torr. At this time, the current density of the ion beam measured by the movable Faraday cup arranged in front of the substrate is
It was 1.5 mA / cm ² . The distance between the substrate and the extraction grid of the ion source was 100 mm, and the substrate temperature was room temperature. FIG. 14 shows the result of depth direction analysis of the mixing layer of the analysis sample prepared under the same conditions by AES. As is clear from FIG. 14, the thickness of the mixing layer is 40 nm.
Then, the concentration of carbon C decreased from 95% on the surface side toward the mold base material side. On the other hand, the concentration of Si atoms is 5 on the surface side.
% Toward the die base metal side. That is,
FIG. 14 shows a profile of C and Si concentrations in the depth direction. On the die base material side, the concentrations of C and Si are 50% and SiC stoichiometry, respectively.

Using this mold, the flint type optical glass SF14 (softening point S
(p = 586 ° C., transition point Tg = 485 ° C.) was molded 500 times. In the mold after molding, defects such as scratches and cracks and fusion of Pb and glass, which are reduction precipitates of PbO contained in glass, were not observed by an optical microscope or SEM. Moreover, the surface roughness, surface accuracy, transmittance, and shape accuracy of the molded product were also good, and there were no problems such as Pb precipitation or gas residue during molding.

Then, using this mold, crown glass SK12 (softening point Sp = 672 ° C., glass transition point Tg = 550 ° C.) was set to 10 by the molding machine of FIG. 8 in the same manner as in Example 1.
Molded 00 times. The molding surface of the mold after molding, the surface roughness of the molded optical element, and the releasability between the mold and the molded optical element were good. In particular, defects such as scratches and cracks, reaction deposits of glass components, and fusion of glass were not observed even when the molding surface of the mold was observed with an optical microscope or SEM.

Example 9 (Formation of (Si, C) Mixing Layer) Using the same mold base material as in Example 8, a mixing layer was formed by the same method and under the same conditions. At this time, the energy and current density of the ion beam were changed, and the thickness of the mixing layer was set to 30 nm by controlling the irradiation time. Using this mold, the crown glass SK12 (softening point Sp = 672 ° C., glass transition point T
g = 550 ° C.) was molded 1000 times. The results are shown in Table 3.
It was shown to.

[0049]

Mold No. after molding Regarding 8 and 9, defects such as scratches and cracks and fusion of Pb and glass, which are reduction precipitates of PbO contained in glass, were not observed by an optical microscope or SEM as in Example 8. Moreover, the surface roughness, surface accuracy, transmittance, and shape accuracy of the molded product were also good, and there were no problems such as Pb precipitation or gas residue during molding. Type No. In No. 7, the number of times of molding was 300 and partial film peeling occurred. Type No. 10 is a model number. Similar results as in Nos. 8 and 9 were obtained, but the surface roughness of the mold surface slightly deteriorated with the number of moldings.

Example 10 (Formation of (Ti, C) mixing layer, TiN intermediate layer) WC (84%) as a mold base material
After processing a sintered body made of -TiC (8%)-TaC (8%) into a predetermined shape, the molding surface was Rmax. = 0.02
It was mirror-polished to μm. After 200 nm of Ti was formed on the molding surface of this mold base material by the ion plating method, Ti was formed.
N was formed at 1800 nm. Using this mold base material, FIG.
A mixing layer having a thickness of 40 nm was formed by a film forming apparatus having the ECR ion source shown in FIG. In the figure, 36 is a vacuum tank, 37 is an exhaust system, 38 is an ECR ion source, 39 is a microwave oscillator, 40 is a microwave waveguide, 41 is a microwave introduction window, and 42 is a cavity resonator type plasma chamber. , 43 is an external magnetic field, 44 is an extraction electrode, 45 is a shutter and Faraday cup, 46 is a mold base material, 47 is a substrate holder, 48
Is a gas introduction system. First, after the mold base material was placed on the substrate holder, the inside of the apparatus was evacuated to 5 × 10 ⁻⁶ Torr and Ar gas was introduced into the ion source from the gas introduction system. The surface of the die base material was cleaned and the oxide film was removed by this Ar ion beam. The vacuum degree at this time is 3 × 10 ⁻⁴ Torr,
The ion current was 7 mA. C ₂ H ₆ : 5 for ion source
0 sccm and H ₂ : 10 sccm were introduced from the gas supply system, and 10 kV was applied to the ion extraction grid to irradiate the extraction base material with an ion beam. At this time, the ion current density at the Faraday cup was 1.6 mA / cm ² , the degree of vacuum was 1 × 10 ⁻³ Torr, and the substrate temperature was 300 ° C.

Next, using this mold, the crown type glass SK12 (softening point Sp = 672 ° C., glass transition point Tg = 550 ° C.) was set to 1 using the molding machine of FIG. 8 as in Example 1.
Molded 000 times. As a result, the same results as in Example 8 are obtained.

As an intermediate layer, other than TiN, Si, A
1, metal of Group 4A, Group 5A, Group 6A of the Periodic Table and their carbides, nitrides, carbonitrides, carbonates, carbonitrides, borides, boronitrides, and boron carbides, nitrides, Also, the same results as with TiN were obtained when a compound or mixture containing at least one of these was formed.

[0054]

As described above, according to the optical element molding die of the present invention, at least the surface layer of at least the molding surface of the mold base material is made of carbon and at least one intermediate layer formed on the molding base material or the molding surface. According to the method for producing a mold for molding an optical element of the present invention, a carbon ion beam having an ion energy of 5 keV or more is used by using a mixing layer composed of elements of at least two kinds, and at least the molding surface of the mold base material By forming the surface layer as a mixing layer composed of carbon and a mold base material, or at least one kind of element constituting the intermediate layer formed on the molding surface, surface defects that do not cause film peeling or cracks during glass molding It is possible to obtain a mold having a less mirror surface. When a glass optical element is molded using this mold, the releasability between the glass and the mold is extremely good, and the surface roughness,
Molded products with good surface accuracy, transmittance, and shape accuracy can be obtained.
Further, even if press molding is repeated for a long time using this mold, an extremely durable optical element molding mold that does not cause defects such as film peeling, cracking, and scratching can be obtained.

By using the optical element molding die obtained by the present invention, it has become possible to improve productivity and reduce cost.

[Brief description of drawings]

FIG. 1 is a schematic view showing an atom mixed state of a mixing layer formed on a molding surface of an optical element molding die according to the present invention.

FIG. 2 is a sectional view showing an example of an optical element molding die according to the present invention, showing a state before press molding.

FIG. 3 is a cross-sectional view showing an example of an optical element molding die according to the present invention, showing a state after press molding.

FIG. 4 is a schematic diagram showing an IBD device used in an embodiment of the present invention.

FIG. 5: AES of the mixing layer in the embodiment of the present invention
3 shows a depth profile according to FIG.

FIG. 6 is a cross-sectional view showing a lens molding apparatus using the optical element molding die according to the present invention, which is a discontinuous molding type.

FIG. 7 is a time-temperature relationship diagram when molding a lens.

FIG. 8 is a cross-sectional view showing a lens molding apparatus using an optical element molding die according to the present invention, which is a continuous molding type.

FIG. 9 is a schematic view showing an ion beam mixing apparatus used in an embodiment of the present invention.

FIG. 10: AE of the mixing layer in the example of the present invention
It is a figure which shows the depth profile by S.

FIG. 11: AE of the mixing layer in the example of the present invention
It is a figure which shows the depth profile by S.

FIG. 12 is a cross-sectional view showing a grating mold according to an example of the present invention.

FIG. 13 is a schematic diagram showing a Kauffman type ion source used in the present invention.

FIG. 14: AE of the mixing layer in the example of the present invention
The depth profile by S is shown.

FIG. 15 is a schematic view showing an ion beam film forming apparatus having an ECR ion source used in an example of the present invention.

[Explanation of symbols]

 1 Type Base Material 2 Molding Surface 3 Carbon Mixing Layer 4 Glass Material 5 Molded Lens 6 Vacuum Chamber 7 Ion Beam Device 8 Ionization Chamber 9 Gas Inlet Port 10 Ion Beam Extraction Grid 11 Ion Beam 12 Type Base Material 13 Substrate Holder and Heater 14 Exhaust port 15 Vacuum tank 16 Exhaust system 17 Ion source 18 Ionization chamber 19 Ion beam extraction grid 20 Gas introduction system 21 Electron gun 22 Substrate holder and heater 23 type base material 24 Crystal film thickness monitor 25 Ion beam 26 Grating type 27 Molded grating type 28 Magnetic field generating cylindrical coil 29 Filament 30 Gas introduction part 31 Anode 32 Ion beam extraction electrode 33 Ion beam 34 Type base material 35 Substrate holder 36 Vacuum chamber 37 Evacuation system 38 ECR ion source 39 Microwave oscillator 40 Microwave waveguide 41 Microwave introduction window 42 Cavity resonator type plasma chamber 43 External magnetic field 44 Extraction electrode 45 Shutter and Faraday cup 46 Type base material 47 Substrate holder 48 Gas introduction system 51 Vacuum chamber 52 Vacuum Tank Lid 53 Upper Mold 54 Lower Mold 55 Upper Mold Presser 56 Body 57 Mold Holder 58 Heater 59 Push-up Rod Pushing Up Lower Mold 60 Air Cylinder 61 Oil Rotary Pump 62, 63, 64 Valve 65 Inert Gas Introduction Valve 66 Valve 67 Leak pipe 68 Valve 69 Temperature sensor 70 Water cooling pipe 71 Table supporting vacuum chamber 102 Molding device 104 Intake replacement chamber 106 Molding chamber 108 Evaporation chamber 110 Ejection replacement chamber 112 Gate valve 114 Gate valve 116 Gate valve 118 Rail 1 20 Pallet 122 Rod 124 Cylinder 126 Valve 128 Heater 130 Upper mold 132 Lower mold 134 Rod 136 Rod 138 Cylinder 140 Cylinder 142 Container 144 Heater 146 Deposition substance 148 Rod 150 Cylinder 152 Valve

Claims (14)

[Claims] 1. An optical element molding die used for press-molding an optical element made of glass, wherein at least the molding surface of the die base material is made of carbon and at least one or more elements constituting the die, and a carbon atom. An optical element molding characterized by a mixing layer in which the concentration increases toward the surface and decreases toward the base material side, and the concentration of other atoms decreases toward the surface and increases toward the base material side. Type. 2. The thickness of the mixing layer is 1 nm or more 1
The optical element molding die according to claim 1, wherein the optical element molding die has a thickness of 00 nm or less. 3. The optical element molding die according to claim 1, wherein the mixing layer contains at least one kind of oxygen, hydrogen, and nitrogen. 4. An optical element molding die used for press-molding an optical element made of glass, wherein an intermediate layer is formed on at least the molding surface of the die base material, and the intermediate layer surface is
It consists of carbon and at least one element that forms the intermediate layer, and the carbon atom concentration increases toward the surface and decreases toward the base metal side, and the other atom concentrations decrease toward the surface and the base metal side. A mold for molding an optical element, wherein the mixing layer has an increasing number of layers. 5. The thickness of the mixing layer is 1 nm or more 1
The optical element molding die according to claim 4, wherein the optical element molding die has a thickness of 00 nm or less. 6. The optical element molding die according to claim 4, wherein the mixing layer contains at least one kind of oxygen, hydrogen and nitrogen. 7. The intermediate layer comprises Si, Al, and 4 of the periodic table.
Group A, Group 5A, Group 6A metals and their carbides, nitrides, carbonitrides, carbonates, carbonitrides, borides, boronitrides, and boron carbides, nitrides, and at least one of these The optical element molding die according to claim 4, comprising the above compound and mixture. 8. A method for producing a mold for molding an optical element, which comprises removing the mixing layer according to claim 1 by etching and then forming the mixing layer again on at least the molding surface. 9. A method for manufacturing an optical element molding die, which comprises removing the mixing layer according to claim 4 by etching and then forming the mixing layer again on the surface of the intermediate layer. 10. A method for producing an optical element molding die used for press-molding an optical element made of glass, wherein an ion energy of 5 keV is applied to at least the molding surface of the die base material.
A method for producing a mold for molding an optical element, which comprises forming the mixing layer made of at least one kind of element forming a mold with carbon by the above carbon ion beam. 11. The composition of the mixing layer is such that the carbon atom concentration increases toward the surface and decreases toward the base material side, and the other atom concentration decreases toward the surface and toward the base material side. The method for manufacturing an optical element molding die according to claim 10, wherein the number is increasing. 12. A method of manufacturing an optical element molding die used for press-molding an optical element made of glass, wherein an intermediate layer is formed on at least the molding surface of the mold base material, and then ion energy is applied to the surface of the intermediate layer. A method of manufacturing an optical element molding die, which comprises forming a mixing layer composed of carbon and at least one kind of element constituting the intermediate layer by a carbon ion beam of 5 keV or more. 13. The composition of the mixing layer is such that the carbon atom concentration increases toward the surface and decreases toward the base material side, and the other atom concentration decreases toward the surface and toward the base material side. The method for manufacturing an optical element molding die according to claim 12, wherein the number is increasing. 14. The intermediate layer comprises Si, Al, metals of Groups 4A, 5A and 6A of the Periodic Table and their carbides, nitrides, carbonitrides, carbonates, carbonitrides, borides and boron. 13. The method for producing a mold for molding an optical element according to claim 12, comprising a nitride, a carbide of boron, a nitride, and a compound or mixture of at least one or more of these.