JPH06279037A - Mold for molding optical element and its production - Google Patents

Abstract

PURPOSE:To provide a mold having a specular surface with a few defects, causing neither release nor cracks in molding glass. CONSTITUTION:In a mold for molding an optical element, useful for press molding an optical element made of glass, a carbon film formed at least on a molding surface of a parent material of the mold has a ratio I(D)/I(C) of intensity I(D) at 1,360cm<-1> and intensity I(C) at 1,580<-1> of Raman spectroscopy of 0.95<=I(D)/I(C)<=1.45. Consequently, a mold having a specular surface with a few defects, causing neither release nor cracks in molding glass can be obtained. When optical elements are molded by using the mold, mold release characteristics between glass and the mold are extremely excellent and molded articles having excellent surface roughness, face accuracy, transmittance and shape precision are obtained for 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 method of manufacturing a mold used for manufacturing an optical element made of glass such as a lens and a prism by press molding a glass material.

[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, deficiency of grains and pores at the time of sintering cannot be avoided, and holes having a size 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 50Å, the film becomes non-uniform, so that the carbon film forming effect is reduced, and when it exceeds 5000Å, the surface accuracy due to pressure molding is reduced. 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.

[0009]

The present invention provides a Raman spectrum of 1360c on at least the molding surface of the mold base material.
The ratio I of the intensity of m ^-1 I _(D) and the intensity of the 1580 cm ^-1 I _(G)
(D) / I _(G) is 0.95 ≦ I _(D) / I _(G) ≦ 1.45
The above-mentioned problem is solved by the mold having the carbon film.

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, Raman
Intensity I _(D) of the spectrum at 1360 cm ^-1 and 1580c
The ratio I _(D) / I _(G) of the intensity I _(G) of m ⁻¹ is 0.95 ≦ I
By forming a carbon film with _(D) / I _(G) ≤ 1.45, it is possible to solve the problems which have been conventionally considered to be problems. FIG. 1 shows a Raman spectrum of a typical carbon film.
In the figure, 1 is the Raman spectrum of the aC: H film, and 2 is the a-
Raman spectrum of a film obtained by annealing a C: H film, 3 is a Raman spectrum of a hard carbon film (containing no hydrogen) produced by an ion beam sputtering method of graphite. As can be seen in FIG. 1, 136 of these membranes
The ratio I of the intensity of 0 cm ^-1 I _(D) and the intensity of ^{_{1580cm -1 I (G) (D}} ) / I (G) is _{I (D) / I (G} ) <0.95. In addition, the Raman spectrum of the aC: H film 1 in the figure changes significantly as shown by 2 in the figure by annealing. It is considered that this is because hydrogen in the film is desorbed by the heat treatment and the bond state of carbon is changed from sp ³ bond to sp ² bond. In this way, in heat treatment or molding (temperature),
It is presumed that these films cause a structural change, which lowers the adhesion strength with the die base material and causes film peeling. In order to characterize the amorphous carbon film, Raman
1360 cm ^-1 of the spectrum, using the Raman lines of the 1580 cm ^-1. Here, the Raman line of 1580 cm ^-1 (E _2g
Mode) is the Raman line observed in a perfect graphite structure, and the Raman line at 1360 cm ^-1 is the Raman line observed when the crystallite size with disordered structure is several tens of Å to several hundred Å.

On the other hand, the Raman spectrum of the carbon film of the present invention is shown in FIG. In the figure, 4 shows the Raman spectrum after the film formation, and 5 shows the Raman spectrum after the heat treatment. From this, it is understood that the carbon film of the present invention has a substantially unchanged Raman spectrum before and after the heat treatment, that is, it is a thermally stable film in which the film structure does not change due to the heat treatment. As described above, a carbon film having a thermally stable structure and in which film peeling does not occur even when the number of moldings is increased is 0.95 ≦ I _(D) / I _{(G) in} its Raman spectrum.
≦ 1.45. As described above, the carbon film of I _(D) / I _(G) <0.95 has a change in film structure due to molding, resulting in film peeling. The carbon film of I _(D) / I _(G) > 1.45 has many graphitized regions, and the film hardness is lowered, and scratches are generated during molding, and minute glass fusion occurs. The intensity of the Raman spectrum depends on the device used for the measurement and the measurement conditions, but in the present invention, the excitation wavelength is 48
Laser Raman microscope irradiating 8nm laser with 2mW, slit width 500μm (resolution 14.3cm
^-1 ) It depends on the measured value when it is measured. (Single monochromator, detector is MCP (Multi Channel Pla
te), and the number of times of integration was 10 times. ) As a method for producing a carbon film having a Raman spectrum of 0.95 ≦ I _(D) / I _(G) ≦ 1.45, there is a film forming method using a carbon ion beam of high ion energy. In the carbon film produced by this method, carbon is mixed (atomic mixture) with the die base material or the intermediate layer material formed on the die base material at the interface. In the state of the mixing layer, the carbon atom concentration is higher on the surface side than on the base material side, while the atom concentration other than carbon is higher on the base material side than on the surface side. FIG. 3 schematically shows this state. In the figure, the horizontal axis represents the depth from the surface toward the die base material, and 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.

The ion energy of the carbon ion beam is 5
KeV or higher is preferable. Ion energy is 5 keV
The carbon film formed with less than I _(D) / I _(G) <0.95 causes film peeling during the molding process. The ion current density at this time is preferably 0.8 mA / cm ^{2 to} 2.0 mA / cm ² . 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 _{is, I (D) / I (} G)> 1.45 to approach the film In addition, although there is no problem of adhesion strength, deterioration of the surface roughness of the molding surface is likely to occur as the number of molding times increases. The ion energy may be 5 keV or more, but practically 5 keV to 10 keV is preferable.

The thickness of the carbon film is preferably 1 nm or more and 100 nm or less. Here, the thickness of the carbon film (mixing layer) 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.
When the thickness is more than nm, the surface condition becomes rough and the molding performance is deteriorated, and the film stress is increased, so that minute peeling easily occurs during molding. A more ideal thickness is in the range 20 nm to 50 nm. Therefore, as a mold base material, a stable mixing state is obtained, and a single composition material composed of an element that easily bonds with carbon (easily forms a carbide),
At the same time, it is ideal that 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. As the intermediate layer, Si, Al, 4A of the periodic table
Group 5A, 6A metal and their carbides, nitrides, carbonitrides, carbonates, carbonitrides, borides, boronitrides, and also boron carbides, nitrides and at least one or more of these Any compound or mixture 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 a.
You may exist about t% -a dozen at%.

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 carbon ion beam is generated by a Kauffman type ion source. FIG.
Figure 2 shows a schematic diagram of a typical Kauffman ion source. In the figure, 33 is a cylindrical coil for magnetic field generation, 34 is a filament, 3
5 is a gas introduction part, 36 is an anode, 37 is an extraction electrode, 38 is an ion beam, 39 is a mold base material, and 40 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, the ion source, the substrate position, etc. are adjusted so that the extraction voltage is 5 kV or more with respect to the substrate to form the mixing layer.

The mixed state of each atom in the mixing layer is not limited to that shown in FIG. 3, 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.

According to the present invention, the intensity I _{(D) of} Raman spectrum at 1360 cm ^-1 is applied to at least the molding surface of the die base material.
And the ratio I _(D) / I _(G) of the intensity I _(G) at 1580 cm ⁻¹ is
The mold for forming the carbon film satisfying the condition of 0.95 ≦ I _(D) / I _(G) ≦ 1.45 realizes an optical element molding mold having excellent durability.

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.

(Embodiment 1) FIGS. 4 and 5 show one embodiment of an optical element molding die according to the present invention. FIG. 4 shows the state of the press-molded surface of the optical element.
Shows the state after molding the optical element. In FIG. 4, 6 is a mold base material, 7
Is a molding surface for molding a glass material, 8 is a carbon mixing layer, 9 is a glass material, and 10 in FIG. 5 is an optical element. As shown in FIG. 4, an optical element 10 such as a lens is formed by press molding a glass material 9 placed between molds.

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

The mold base material used was one in which sintered SiC was processed into a predetermined shape, a polycrystalline SiC film was formed by the CVD method, and then the molding surface was mirror-polished. After thoroughly cleaning this mold, IBD (Ion Beam Deposition) shown in FIG.
) Installed in the device. In the figure, 11 is a vacuum chamber, 12 is an ion beam device, 13 is an ionization chamber, 14 is a gas inlet, 1
5 is an ion beam extraction grid, 16 is an ion beam, 17 is a mold base material, 18 is a substrate holder and a heater,
Reference numeral 19 indicates an exhaust port. First, Ar gas 3 from the gas inlet
After introducing 5 sccm into the ionization chamber for ionization, 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 3 minutes to remove and clean the native oxide film on the molding surface. It was

Subsequently, CH ₄ : 18 sccm, H ₂ :
Gas pressure of 3.7 × 1 by introducing 36 sccm into the ionization chamber
An ion beam was extracted at an acceleration voltage of 10 kV at a pressure of 0 ⁻⁴ Torr, and a molding surface was irradiated with the ion beam to form a 40 nm carbon film. At this time, the current density of the ion beam measured by the movable Faraday cup arranged in front of the substrate was 1.
It was 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. AES the carbon film of the analytical sample created under the same conditions
The result of depth direction analysis by (Auger Electron Spectroscopy) is shown in FIG. As is clear from FIG. 7, the thickness of the mixing layer is 40 nm and the concentration of carbon C is 9 on the surface side.
It decreased from 5% toward the die base material side. On the other hand, Si
The atomic concentration increased from 5% on the surface side toward the mold base material side. That is, FIG. 7 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. The thickness of the mixing layer is defined as the thickness from the depth to the surface of 50% of the amount of change in the C concentration from the maximum to the minimum before and after the interface of the mold base material. Similarly, FIG. 8 shows the result of Raman spectroscopic analysis of the carbon film. From this, I _(D) / I _(G)
= 1.08.

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 9
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 type 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. Pulp 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 10 shown in FIG. 5 was molded by using 86 ° C. and a transition point Tg = 485 ° C.). FIG. 10 shows a molding condition at this time, that is, a time-temperature relationship diagram.

Molding was performed 500 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 PbO 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, molding was performed using this mold by the molding apparatus shown in FIG.

In FIG. 11, 102 is a molding device and 10 is a molding device.
4 is a substitution chamber for taking in, 106 is a forming chamber, 1
Reference numeral 08 is a vapor deposition chamber, and 110 is a take-out replacement chamber. Reference numerals 112, 114 and 116 are gate valves, and 1
18 is a rail, and 120 is a pallet that can be transported on the rail in the direction of arrow A. 124, 138,
140 and 150 are cylinders, and 126 and 152 are valves. 128 is a rail 1 in the molding chamber 106
The heaters are arranged along the line 18.

Inside the molding chamber 106, a heating zone 106-1 and a pressing zone 106-2 are sequentially arranged in the pallet conveying direction.
And the slow cooling zone 106-3. In the press zone 106-2, the rod 1 of the cylinder 138 is
A molding upper mold member 130 is fixed to the lower end of 34, and a molding lower mold member 132 is fixed to the upper end of the rod 136 of the cylinder 140. These upper mold members 1
30 and the lower mold member 132 are mold members 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 position, and thereafter, the pallets are newly sequentially introduced into the replacement chamber 104 at a predetermined timing in the same manner.
It was conveyed in order to the position of 120-2 → ... → 120-8 within 06. 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.
200 kg by the upper mold member 130 and the lower mold member 132 by operating the cylinders 138 and 140.
/ Cm ² at a pressing temperature of 620 ° C. for 1 minute, then release the 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 pressing process, and the releasability between the mold member and the molded optical element are good. It was 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 Using the same die base material as in Example 1, a carbon film having a thickness of 50 nm was formed by a film forming apparatus having an ECR ion source shown in FIG. In the figure, 20 is a vacuum chamber, 21 is an exhaust system, 22 is an ECR ion source, 23 is a microwave oscillator, 24 is a microwave waveguide, 25 is a microwave introduction window, and 26 is a cavity resonator type plasma chamber. , 27 is an external magnetic field, 28 is an extraction electrode, 29 is a shutter and Faraday cup, 30 is a mold base material, 31 is a substrate holder, 3
2 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 degree of vacuum at this time is 3 × 10 ⁻⁴ Tor
r and an ionic current of 7 mA. Subsequently, C ₂ H ₆ : 45 sccm and H ₂ : 10 sccm were introduced into the ion source from the gas supply system, and a microwave of 2.45 GHz was applied to the ion source 23.
1000W with 24 microwaves and 24 waveguides
Then, an ECR plasma was formed in the plasma chamber 26.
At this time, the external magnetic field 27 causes 1500 G in the introduction window 25.
The ECR condition was 875 Gauss on the side of the 50 mm microwave introduction window from the auss and the extraction electrode 28. next,
By applying 8 kV to the ion extraction electrode and irradiating the extraction base material with an ion beam, the mold No. 1 was produced. The ion current density at this time is 1.3 mA / Faraday cup.
cm ² , the degree of vacuum was 1 × 10 ⁻³ Torr, and the substrate temperature was room temperature. Using the same device, 0.5 for the ion extraction electrode
An ion beam is extracted by applying kV to irradiate the mold base material and mold no. Formed 2. The ion current density at this time was 0.5 mA / cm ^{2 with} a Faraday cup, and the degree of vacuum was 1 × 10.
^-3 Torr, the substrate temperature was room temperature, and the film thickness was 50 nm. Next, the ion extraction electrode 28 shown in FIG. 12 was removed to obtain an ECR plasma CVD device. After cleaning the surface of the die base material with an Ar ion beam and removing the oxide film, CH ₄ : 10 sccm, H ₂ : 310 sccc
m, gas pressure 20 Torr, substrate temperature 650 ° C., 50 nm
Forming a carbon film of the mold No. It was set to 3.

Using this mold, as shown in FIG.
Crown glass SK12 (softening point Sp
= 672 ° C., glass transition point Tg = 550 ° C.) 1000
Molded once. Raman spectrum of each type I _(D) / I _(G)
Table 1 shows the molding results.

[0037]

Mold No. after molding 1 and 2 are PbO contained in the glass and defects such as scratches and cracks as in Example 1.
Fusion of Pb or glass, which is the reduced precipitate of
It was not observed by scanning electron microscopy (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. In No. 3, the number of times of molding was 300 and partial film peeling occurred. Type No. In No. 4, the molding surface was scratched during the molding process, and fine glass fusion occurred.

(Example 3) 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. Example 1 was applied to the molding surface of this mold.
A carbon film was formed by the same method and under the same conditions.

Next, using this mold, the crown glass SK12 (softening point Sp = 672 ° C., glass transition point Tg = 550 ° C.) was molded 1000 times using the molding machine of FIG. 11 as in Example 1. did. As a result, the same results as in Example 1 are obtained.

In addition to TiN, Si, A
1. Metals of Groups 4A, 5A and 6A of the Periodic Table and their carbides, nitrides, carbonitrides, carbonates, carbonitrides, borides, boronitrides, and further carbides of boron, nitrides and Similar results to TiN were obtained when a compound or mixture containing at least one of these compounds was formed.

[0042]

As described above, according to the present invention, at least the molding surface of the mold base material, the ratio of the intensity of the Raman spectrum of 1360cm ^-1 I _(D) and the intensity of _{^{1580cm -1 I (G) I (}} D) /
By forming a carbon film in which I _(G) is 0.95 ≤ I _(D) / I _(G) ≤ 1.45, surface defects such as peeling and cracking of the film do not occur in glass molding. A mold with less mirror surface is obtained. When a glass optical element is molded using this mold, the releasability between the glass and the mold is extremely good, and a molded product having good surface roughness, 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 Raman spectrum of a typical carbon film outside the present invention.

FIG. 2 is a typical Raman spectrum of the carbon film of the present invention.

FIG. 3 is a schematic view showing a mixed state of atoms of a mixing layer formed on a molding surface of a mold for molding an optical element according to the present invention.

FIG. 4 is a cross-sectional view showing an example of an optical element molding die according to the present invention, showing a state before press molding.

FIG. 5 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. 6 is a schematic diagram showing an IBD device used in an embodiment of the present invention.

FIG. 7: AES of a mixing layer in an embodiment of the present invention
3 shows a depth profile according to FIG.

FIG. 8 shows a Raman spectrum of a carbon film in an example of the present invention.

FIG. 9 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. 10 is a time-temperature relationship diagram during lens molding.

FIG. 11 is a sectional view showing a lens molding apparatus using the optical element molding die according to the present invention, which is a continuous molding type.

FIG. 12 is a schematic view showing an ion beam film forming apparatus having an ECR ion source used in an example of the present invention.

FIG. 13 is a schematic diagram showing a Kauffman type ion source according to the present invention.

[Explanation of symbols]

1 Raman spectrum of aC: H film 2 Raman spectrum of heat-treated aC: H film 3 Raman spectrum of carbon film produced by ion beam sputtering of graphite 4 Raman spectrum of carbon film after deposition Spectrum 5 Raman spectrum of carbon film after heat treatment 6 Type base material 7 Forming surface 8 Carbon layer 9 Glass material 10 Molded lens 11 Vacuum tank 12 Ion beam device 13 Ionization chamber 14 Gas inlet 15 Ion beam extraction grid 16 Ions Beam 17 type base material 18 Substrate holder and heater 19 Exhaust port 20 Vacuum chamber 21 Exhaust system 22 ECR ion source 23 Microwave oscillator 24 Microwave waveguide 25 Microwave introduction window 26 Cavity resonator type plasma chamber 27 External Magnetic field 28 Extraction electrode 29 Shutter and Faraday cup 30 type base material 31 substrate holder 32 gas introduction system 33 magnetic field generating coil 34 filament 35 gas introduction system 36 anode 37 ion beam extraction electrode 38 ion beam 39 type base material 40 substrate holder and heater 51 vacuum tank 52 vacuum tank lid 53 Upper mold 54 Lower mold 55 Upper mold retainer 56 Body 57 Mold holder 58 Heater 59 Push-up bar that pushes the 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-cooled pipe 71 table for supporting vacuum chamber 102 molding device 104 replacement chamber for intake 106 molding chamber 108 deposition chamber 110 displacement chamber for extraction 112 gate valve 114 gate valve 116 gate valve 118 rail 120 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 material 148 Rod 150 Cylinder 152 Valve 160 Vacuum tank 161 Type base material 162 Gas introduction system 163 Exhaust system 164 RF power supply 165 Target 166 Plasma chamber 167 type 168 Gas supply system 169 Microwave oscillator, waveguide 170 Exhaust system 171 Base holder 172 Microwave introduction window 173 Electromagnet

Claims (2)

[Claims] 1. An optical element molding die used for press molding of an optical element made of glass. Intensity I _{(D) at} 1360 cm ^-1 of the Raman spectrum of the carbon film formed on at least the molding surface of the die base material. ₎ And the intensity I _(G) of 1580 cm ⁻¹ , the ratio I _(D) / I _(G) is 0.95 ≦ I _(D) / I
_{(G) A} mold for molding an optical element, wherein ≦ 1.45. 2. A type optical element molding for use in press molding of the optical element made of glass, the intensity of the intensity I _(D) and 1580 cm ^-1 of the Raman spectrum of 1360 cm ^-1 to at least the molding surface of the mold base material Ratio of I _(G) I _(D) / I
_A method for producing an optical element molding die, wherein a carbon film in which _(G) is 0.95 ≦ I _(D) / I _(G) ≦ 1.45 is formed.