JP3428720B2 - Optical element molding die - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die used when an optical element made of glass such as a lens or a prism is manufactured by press-molding a glass material. It is. 2. Description of the Related Art A technique of manufacturing a lens by pressing a glass material without a polishing step eliminates the complicated steps required in the conventional lens manufacturing.
It has made it possible to manufacture lenses easily and inexpensively, and nowadays it is used not only for manufacturing lenses but also for manufacturing optical elements made of prisms and other glasses. [0003] The properties required of a mold used for press molding of such a glass optical element include scratch resistance,
It is excellent in heat resistance, mold release properties, mirror workability and thermophysical properties suitable for molding. Conventionally, many proposals have been made for this type of mold material, such as metals, alloys, ceramics, and materials coated with them. If some examples, JP 49-51112 Patent 13Cr martensitic steels in Publication, Japanese Patent Publication No. Sho 52-45613 is SiC and Si ₃ N _4, JP 60-246230
In the publication, a material in which a noble metal is formed on a hard metal is proposed. [0005] Japanese Patent Application Laid-Open No. 61-13628 discloses a composite base material composed of a metal and a ceramic, in which a nitride, a carbide,
A material in which a noble metal is formed via an intermediate layer of an oxide and a metal has been proposed. Also, Japanese Patent Application Laid-Open No. 60-81032 proposes a mold material of glassy carbon, silicon carbide, and sialon. Further, in accordance with recent advances in thin film technology, Japanese Patent Application Laid-Open No. 61-183134 proposes forming a diamond or diamond-like carbon film on a cemented carbide to form a mold. [0006] However, 13Cr disclosed in Japanese Patent Application Laid-Open No. 49-51112 has a problem.
Although martensitic steel is excellent in workability, it cannot be said to be a good mold material due to insufficient scratch resistance, heat resistance, and releasability. SiC and Si ₃ N ₄ disclosed in JP-A-52-45613 are excellent in abrasion resistance and heat resistance, but have problems in workability and mold release. Further, the glassy carbon disclosed in Japanese Patent Application Laid-Open No. Sho 60-81032 is excellent in terms of releasability, but has problems in terms of specularity and strength of the material. As described above, a single mold material cannot sufficiently satisfy the performance required as a glass mold, and as disclosed in Japanese Patent Application Laid-Open No. The releasability, which is insufficient for the cemented carbide, is compensated for by the surface treatment of the noble metal, but it needs to be improved in terms of scratch resistance. Also, an attempt has been made to improve the scratch resistance without impairing the releasability by forming a diamond or diamond-like carbon film on a cemented carbide disclosed in JP-A-61-183134. Has a problem that the surface roughness is large, mirror polishing is required after film formation, and the mirror polishing is difficult.On the other hand, the diamond-like carbon film undergoes film quality change and stress change during the press forming process at high temperature. There is a drawback in that abrasion resistance is reduced and adhesion to a mold base material is reduced. According to the present invention, a metal film is used as a first layer, and an amorphous or amorphous crystal is used as a second layer, counting from a mold base material side of a molding surface. Mixed quality and electric resistance 1 × 1
0 ¹⁰ Omega following nitride or carbide or carbonitride composed mainly of (Si or B and Ti, Zr, Hf, V, Nb, 1 or more double compound of a metal of Ta) membrane, the The third layer is formed by ion beam deposition on the third layer
Membrane or an ion beam assisted deposition of forms carbon main component
By forming the predominant metal main component film formed by the method as a release film, mirror workability and thermophysical properties suitable for molding are given to the mold base material selected in consideration of the forming process, For the abrasion and release properties, the third layer of carbon-based film or precious metal-based film has its performance, and the second layer of nitride, carbide or carbonitride film increases the surface hardness. In addition, by providing a high-density high-temperature oxidation resistance and by taking a surface layer structure that prevents spark damage due to dielectric breakdown during ion beam application deposition of the third layer, a mold with good mold release and high durability as a whole Was realized. In other words, in order to form a mixing layer at the interface between the second layer and the third layer by a high-speed ion beam for the purpose of preventing peeling during the formation of a carbon-based film or a noble metal-based film as a release film, The layer must be electrically conductive enough to allow ions to enter. In addition, since the second layer does not undergo film quality change and deformation under high temperature and high pressure during molding, it is necessary to be chemically stable and high hardness under high temperature. Therefore, nitride, carbide or carbonitride is an appropriate material. It is possible. It is desirable that the second layer is dense. When the second layer is formed by a usual ion plating method or sputtering method, other compounds excluding a silicon compound or a boron compound (for example, TiN, Zr
(N, TaN, TiC, ZrC, TaC, etc.) shows a crystallized columnar structure, which hasten the reaction deterioration with glass at the time of molding. This disadvantage can be remedied by forming a composite nitrided or composite carbonized or carbonitrided film of Si or B as an amorphizing element and Ti, Zr, Ta or Hf. The first metal film has a thickness of 10 nm to several hundreds.
By forming the layer in nm, the adhesion of the second layer film can be improved without impairing the surface roughness of the molding surface. Hereinafter, the present invention will be described by way of examples. Embodiment 1 FIG. 1 shows a first embodiment of the present invention, in which 1 is a cemented carbide as a mold base material, 2 is a metal film formed on the molding surface of the mold base material 1, and 3 is An amorphous or mixed amorphous and crystalline nitride, carbide, or carbonitride film formed on the metal film 2, and ions formed on the nitride, carbide, or carbonitride film 3 are formed on the metal film 2. A film mainly composed of carbon formed by a beam film forming method or a film mainly composed of a noble metal formed by an ion beam assisted film forming method. Next, a method of manufacturing the optical element molding die having the above-described configuration will be described. A cemented carbide as a mold base material is processed into a predetermined mold shape, and the formed surface is mirror-polished to a surface roughness of 0.0
The mold base material 1 was made 2 μm or less. The mold base material 1 is cleaned, set on a substrate holder of an ion plating film forming apparatus capable of dual deposition of Zr and Si, evacuated to 1 × 10 ⁻³ Pa, and then Ar
Gas is introduced to a vacuum of 0.5 Pa, and 5
A high-frequency power of 00 W was applied to cause a high-frequency discharge to clean the mold-formed surface for 3 minutes. Thereafter, a voltage of +40 V is applied to the ionization electrode set near the electron gun hearth, and a substrate bias voltage of -10 is applied to the substrate holder.
In a state where 0 V was applied, Zr metal was subjected to electron beam evaporation at 0.05 μm to form a metal film 2. The film thickness was controlled using a quartz crystal film thickness meter. Further, while maintaining the ionization conditions, N ₂ gas was introduced to a degree of vacuum of 5 × 10 ⁻² Pa, and Zr and Si were simultaneously evaporated to form a ZrSiN double nitride film 3 having a thickness of 1 μm. The surface resistance of this film was set to 3 mm square Al shown in FIG.
The electrodes were deposited at a distance of 10 mm, and the measurement results showed that 5 × 10
⁹ Ω. Further, from the result of the evaluation of the crystallinity by X-ray diffraction, it was confirmed that the film was made amorphous as shown in FIGS. The hard film 3 is formed by this ion plating.
In order to form the release film 4 on the molding surface of the molding die
The mold was set on the substrate holder of the ion beam film forming apparatus, evacuated to 1 × 10 ⁻³ Pa, and Ar gas was introduced into the ECR discharge ion gun at 10 sccm to generate microwave power of 5 μm.
The cleaning of the film formation surface was performed for 3 minutes under the conditions of 00 W, magnet power for plasma control of 1 kW, ion acceleration voltage of 2 kV, substrate bias voltage of −300 V, and ion current density of 0.1 mA / cm ² , and then gas introduced into the ion gun To CH
₄ and H ₂ , and the flow rates were 10 sccm and 20 s, respectively.
As ccm, microwave power 500 W, plasma control magnet power 1 kW, ion acceleration voltage 9 kV, substrate bias voltage -500 V, ion current density 0.5 mA / c
Under a processing condition of m ² and a deposition time of 15 minutes, a mold release film 4 having a thickness of about 50 nm was formed as a main component of carbon and an element component of the hard film 3 and hydrogen. Next, an example of molding an optical element using the mold of the present invention will be described. SK1 as a lens molding material
2 (refractive index nd = 1.58313, vd = 59.4,
A predetermined approximate spherical gob (Tg = 550 ° C., At = 588 ° C.) was used. This gob is inserted into a molding chamber of a molding machine operated at an atmospheric pressure of nitrogen gas (not shown) via vacuum substitution, and heated in the molding die of the present invention described above, and after reaching a predetermined temperature, 100 kg / cm. pressurized two minutes with ² pressure. After the pressure was removed, the pressure was reduced to 20 ° C / min. After cooling at a cooling rate of not more than the glass transition point, the molded lens is transferred from the molding die to a lens receiver which has been previously heated to about 300 ° C., and the lens is cooled to about 200 ° C., and then subjected to vacuum replacement. Remove to atmosphere. As a result of repeating the above steps and examining the state of deterioration of the molding surface of the mold and the state of the surface of the molded lens, the surface of the molded lens is in a good state without surface roughness deterioration and without clouding. Although a slight increase in the oxygen content in the film was observed, it was confirmed that the decrease in the carbon component was very small and the deterioration of the molded surface was small. This is considered to be an effect of preventing oxidation invasion from film grain boundaries due to densification and amorphization of the second hard film. In the present molding example, SK glass having relatively high stability has been described, but other glass materials such as LaK12 (nd)
= 1.6790, νd = 55.3, Tg = 554 ° C., A
(t = 596 ° C.), the same effect can be obtained. [Embodiment 2] A second embodiment using a film forming method different from that of Embodiment 1 will be described. The mold base material is cleaned, set on a substrate holder of a high-frequency magnetron sputtering apparatus provided with a Ta target and a Si target, evacuated to 1 × 10 ⁻³ Pa, and then Ar gas is reduced to a vacuum of 0.4 Pa. After introducing the substrate holder and supplying high-frequency power of 500 W to the substrate holder and cleaning the molding surface of the mold base material 1 for 5 minutes in high-frequency discharge,
A high-frequency power of 1.5 kW is supplied to the Ta target, and a DC bias voltage of -100 V is supplied to the substrate holder, so that the mold base material 1 is formed.
Then, a Ta metal film 2 is formed to a thickness of 0.1 μm on the molding surface of, and then N ₂ gas is supplied for 5 seconds while maintaining Ta sputtering conditions.
Ccm is introduced, the degree of vacuum is set to 0.45 Pa, and high-frequency power of 500 W is supplied to the Si target to obtain Ta.
A multiple nitride film 3 of SiN was formed to about 1 μm. The method of forming the release film 4 containing carbon as a main component on the outermost surface of the forming die formed up to the double nitride film 3 is the same as that of the first embodiment. [Embodiment 3] A Zr metal film 2 as a first layer and a double nitride film (hard film) 3 as a second layer are formed on the surface of the mold base material 1 in the same manner as in the embodiment 1. Then, a method of forming the release film 4 containing a noble metal as a main component using an ion plating film forming apparatus equipped with a high-speed ion gun will be described. The mold having the hard film 3 formed thereon is set on a substrate holder in an ion plating apparatus, and is set to 1 × 10 ^-3.
After evacuating to a vacuum degree of Pa, Ar gas was
After introducing 0 sccm and supplying microwave power of 500 W and magnet power for plasma control of 1 kW to start ECR discharge, an acceleration voltage of 2 kV and a substrate bias of −300 V were applied, and cleaning with Ar ions was performed for 3 minutes. A release film 4 was formed by forming a platinum film by electron beam evaporation while maintaining Ar ion irradiation conditions. Electron gun conditions during platinum deposition, acceleration voltage 9 kV, emission current 300
The film thickness was 100 nm when the mA, the SCAN memory 1 and the film formation time were 10 minutes. As described above, the first layer counted from the mold base material side on the molding surface of the mold base material processed into a predetermined shape as described above. To
Metal thin film for improving the adhesion between the second hard film and the mold base material. The second layer is dense and has high oxidation resistance at high temperature and is charged by the third layer ion beam application deposition. Hard film that is an amorphous or mixed amorphous and crystalline electrically conductive nitride film or carbide film or carbonitride film to prevent film up. In addition, a mold composed of a release film mainly composed of carbon by an ion beam deposition method for realizing mixing to the second layer or a release film mainly composed of a noble metal by an ion beam assisted film formation method, An optical element molding die is obtained, and by using this molding die as an optical element, it is possible to obtain a molded article having a good appearance while maintaining stable release properties,
There was an effect of reduction by improving the operation rate of the molding device and the non-defective product rate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram schematically showing a configuration of a molding surface film of an optical element molding die of the present invention. FIG. 2 is a diagram schematically showing a method of measuring the surface resistance of a film. FIG. 3 is an X-ray diffraction diagram of an ion-plated ZrN film. FIG. 4 is an X-ray diffraction diagram of an ion-plated ZrSiN film. [Description of References] 1 type base material 2 1st layer metal film 3 2nd layer hard film 4 3rd layer release film 5 type

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuyuki Nakai 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-3-153535 (JP, A) JP-A Heihei 6-72728 (JP, A) JP-A-1-153542 (JP, A) JP-A-61-136928 (JP, A) JP-A-5-178628 (JP, A) (58) Fields investigated (Int. Cl. ^7, DB name) C03B 11/00 C03B 40/02

Claims (1)

(57) [Claims 1] At least on a molding surface, a metal film as a first layer and a nitride, carbide or carbonitride as a main component in a second layer from a mold base material side. Hard film, 3rd layer ion beam deposition
Membrane or ion beam A carbon main component formed by the law
In an optical element molding die coated with a film of a noble metal main component formed by a cyst film forming method , the nitride, carbide and carbonitride forming the second hard film are Si or B and T
It is a complex compound of at least one of i, Zr, Hf, V, Nb, and Ta, and is characterized by being amorphous or a mixture of amorphous and crystalline and having electric conductivity. Mold for forming an optical element.