JPH08160210A - Production of metal mold and production of optical element using the same - Google Patents

Abstract

PURPOSE: To provide a process for exactly producing a metal mold for production of blaze-shaped optical elements and a process for production of the optical elements capable of exactly producing the optical elements having high diffraction efficiency and light condensing efficiency in a large quantity using this metal mold. CONSTITUTION: This metal mold is formed by forming a working layer 2 on a base plate 1, machine this working layer 2 into desired shapes, etching the working layer 2 machine into desired shapes and the base plate 1 to form the shapes of the working layer 2 so as to be similar to the base plate 1 in its depth direction and using the etched base plate 1 as a master disk.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a mold for an optical element such as a relief type grating having a predetermined structure on the surface, and a method for manufacturing an optical element using the same.

[0002]

2. Description of the Related Art In recent years, diffractive optical elements and Fresnel lenses have attracted attention due to demands for higher performance and smaller size and lighter weight of optical systems. In the case of a diffractive optical element having a relief type grating structure, it is useful to blaze the groove cross-sectional shape because high diffraction efficiency can be obtained.

The applicant of the present application has previously filed Japanese Patent Application No. 5-3311.
In the specification of No. 53, a method of manufacturing a blazed optical element by forming a predetermined shape on a processing layer by machining and transferring this shape to a substrate by anisotropic etching was proposed. According to this method, since the processing layer is cut by a numerical control type cutting machine or the like, a predetermined shape can be formed more easily than the method by exposure and development, and the diffractive optical element is manufactured accurately. be able to. Further, since the shape of the processed layer is transferred to the substrate, there is an advantage that an optical element can be formed regardless of the workability of the substrate. However, in this method,
Since a machining process and an erosion process are required for each element, there is a problem that mass productivity is not good.

On the other hand, focusing on mass productivity, a method of mass-producing optical elements, optical disks, etc. by using a mold has been proposed in Japanese Patent Laid-Open No. 4-229211 as follows. That is, first, as shown in FIG. 7A, a photoresist 72 is applied on a glass substrate 71, cut by a laser beam 73 as shown in FIG. A predetermined uneven pattern 74 shown is formed. Next, using the concavo-convex pattern 74 as a mask, the glass substrate 71 is etched as shown in FIG. 6D, and then a tantalum thin film 75 and a nickel thin film 76 are formed as shown in FIG. A nickel passivation film is formed on the surface. After that, an electroforming process is performed to form a nickel electroformed layer 77 as shown in FIG. 1F, and then the nickel electroformed layer 77 is peeled off to obtain a master. Although this method relates to a method for manufacturing a stamper for an optical disc, it may be applied to manufacturing a diffraction grating.

Another method for mass-producing optical elements and the like using a mold has been proposed in Japanese Patent Laid-Open No. 5-297210. That is, first, as shown in FIG. 8 (a), a diffraction grating master 81 processed in advance with high precision is prepared, and a thin film 82 as shown in FIG. 8 (b) is formed on the surface thereof, and then, as shown in FIG. 8 (c). As shown, only the thin film 82 in which the inverted shape of the diffraction grating is copied is separated from the diffraction grating master 81. This thin film 8
The back surface of No. 2 is flatly polished as shown in FIG. 3D and bonded to the front surface of the base material 83 via an adhesive layer. Next, the same figure (e)
As shown in, a platinum-based alloy 84 is formed as a protective layer on the thin film 82, and this is used as a mold to manufacture a diffraction grating.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The method of Japanese Patent Publication No. 211 is suitable for mass production because a mold is used, but since only a rectangular concave-convex pattern is taken into consideration as a cross-sectional shape, when this method is applied to the manufacture of a diffraction grating. However, it is difficult to obtain high diffraction efficiency.

Further, in the method of the above-mentioned Japanese Patent Laid-Open No. 5-297210, a ruling engine is cited as a method of manufacturing a diffraction grating master, and since the ruling engine can generally only engrave a linear grating, it has a ring pattern. The master of the diffractive lens cannot be manufactured. Generally, it is difficult to manufacture a blazed diffractive lens having a ring pattern, and the method is not described in Japanese Patent Laid-Open No. 5-297210.

The present invention has been made in view of the above-mentioned problems, and a method for accurately manufacturing a mold for manufacturing a blazed optical element, and a method for producing a diffraction efficiency and a light collection efficiency using the mold. It is an object of the present invention to provide a method for manufacturing an optical element, which enables accurate and mass production of high optical elements.

[0009]

To this end, a method of manufacturing a mold according to claim 1 of the present invention comprises a step of forming a processing layer on a substrate and machining the processing layer into a desired shape. A step, a step of etching the processing layer and the substrate machined into a desired shape to form the shape of the processing layer on the substrate in a depth-wise manner, and a master master of the etched substrate. And a step of forming a mold.

Further, according to a second aspect of the present invention, there is provided a method of manufacturing a die, which comprises a step of forming a working layer on a substrate, a step of machining the working layer into a desired shape, and a machining into a desired shape. And a step of anisotropically etching the processed layer and the substrate by changing a selection ratio, and a step of forming a mold by using the anisotropically etched substrate as a master master. Is.

According to a third aspect of the present invention, there is provided a method of manufacturing an optical element, which comprises a step of forming a processing layer on a substrate, a step of machining the processing layer into a desired shape, and a machining into a desired shape. Etching the processed layer and the substrate, the step of forming the shape of the processed layer in the depth direction in a similar manner to the substrate, and the step of forming a mold using the etched substrate as a master. And a step of manufacturing an optical element using the mold.

According to a fourth aspect of the present invention, there is provided a method of manufacturing an optical element, which comprises a step of forming a processed layer on a substrate, a step of machining the processed layer into a desired shape, and a mechanical processing into a desired shape. Anisotropically etching the processed layer and the substrate by changing the selection ratio, forming a mold using the anisotropically etched substrate as a master, and optically using the mold. And a step of manufacturing an element.

[0013]

According to the method of manufacturing a mold of claim 1 of the present invention,
First, a processing layer is formed on a substrate, then the processing layer is machined, and then the shape of the processing layer is formed on the substrate in a similar manner in the depth direction by etching. As a result, a shape corresponding to the optical element to be manufactured is formed on the substrate. next,
A mold is formed using this substrate as a master master. In this mold, the shape of the master disc is reversed, that is,
An inverted shape of the optical element to be manufactured is formed.

Further, according to the method for manufacturing a mold of the second aspect of the present invention, the processed layer 2 and the substrate 1 processed into desired shapes as shown in FIG. 4A, for example, are anisotropically etched. At this time, the selection ratio is changed, and the shape of the processed layer 2 is changed and transferred to the substrate 1. Here, the selection ratio is defined as follows.

[0015]

[Equation 1] When the selection ratio is gradually reduced, for example, from 1 to 0.
If the etching rate of the processing layer is not changed for the sake of simplification of description when the processing layer is reduced to 6 and 0.2 in three steps, the shape of the processing layer 2 is as shown in FIGS. ), It is transferred to the substrate 1. In this case, it is assumed that the etching time is the same at each selection ratio.
As can be seen from FIGS. 4A to 4D, when the anisotropic etching is performed while changing the selection ratio, the substrate 1 can be formed in a shape in which the shape of the processed layer 2 is changed. Since a mold is manufactured by using this substrate 1 as a master master, it is possible to form a mold having a cross-sectional shape different from that of the machined shape which has been machined.

When anisotropic etching is performed by continuously changing the selection ratio, for example, the shape of the processed layer whose cross-sectional shape is processed into a straight line can be formed as a curved line on the substrate. This is because if you want to process the cross-sectional shape into an ideal shape, generally a curved shape, when you manufacture a die for a diffraction grating or Fresnel lens, you can process the processing layer into a straight line, so it is a simple process. Data can be processed in a short time.

Alternatively, when the selection ratio is changed stepwise, it is possible to form the processing layer whose cross-sectional shape is processed into a straight line by changing the shape of the substrate into a bent shape for the number of times when the selection ratio is changed. This is, for example, 1
It can be applied to the case of forming a die for a diffraction grating which is blazed for two wavelengths and has a shape which is bent once. In the method of manufacturing a die according to the second aspect of the present invention, it is not necessary to process one grid groove twice, unlike the conventional method.
It is possible to form a lattice whose cross-sectional shape is simply a straight line in the processing layer, and to change the selection ratio stepwise during anisotropic etching to make it a bent shape once. And the processing time is greatly reduced.

According to the method of manufacturing an optical element of claim 3 of the present invention, first, a working layer is formed on a substrate, then the working layer is machined, and then the shape of the working layer is formed by etching. Are similarly formed on the substrate in the depth direction. As a result, a shape corresponding to the optical element to be manufactured is formed on the substrate. Next, a mold is formed using this substrate as a master master. A shape in which the shape of the master master is inverted, that is, an inverted shape of the optical element to be manufactured is formed in this mold. Therefore, when an optical element is formed using this mold, an optical element having a desired shape is formed.

According to the method of manufacturing an optical element of claim 4 of the present invention, the processed layer on the substrate having a desired shape is anisotropically etched while changing the selection ratio,
The shape of the processed layer is changed and transferred to the substrate. Since a mold is formed using this substrate as a master master, it is possible to form a mold having a cross-sectional shape different from that of the machined shape that is machined. When an optical element is manufactured using this mold, the optical element can be given a shape that is the reverse of the shape of the mold, and this shape is different from the shape of the processing layer.

When anisotropic etching is performed by continuously changing the selection ratio, for example, the shape of the processed layer whose cross-sectional shape is processed into a straight line can be formed as a curved line on the substrate. This is because if you want to process the cross-sectional shape into an ideal shape, generally a curved shape, when you manufacture a die for a diffraction grating or Fresnel lens, you can process the processing layer into a straight line, so it is a simple process. Data can be processed in a short time. A mold is formed by using the substrate as a master master,
A diffraction grating or Fresnel lens having an ideal shape can be manufactured by using the mold.

Alternatively, when the selection ratio is changed stepwise, it is possible to form the processing layer whose cross-sectional shape is processed into a straight line by changing the shape of the substrate into a bent shape for the number of times when the selection ratio is changed. This is, for example, 1
It can be applied to the case of forming a die for a diffraction grating which is blazed for two wavelengths and has a shape which is bent once. In the method of manufacturing an optical element according to the present invention, it is not necessary to process one grating groove twice as in the conventional method, and a grating having a cross section of a mere straight line is formed in the processed layer.
Since the shape can be bent once by changing the selection ratio stepwise once during the anisotropic etching, the processing data becomes simple and the processing time is greatly shortened. When a mold is formed using the substrate as a master master, a blaze diffraction grating for two wavelengths can be manufactured by using a mold for two wavelengths.

[0022]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 (a) to 1 (i) are views for explaining a first embodiment of the present invention. In the first embodiment, the method of the present invention is applied to manufacture of a diffractive lens which is a diffractive optical element. First, as shown in FIG. 1A, a processing layer 2 is formed on one surface of a substrate 1 with a predetermined thickness t. Further, in order to prevent the cutting tool from coming into contact with the substrate 1 even if some error occurs in the movement of the cutting tool 3 in the subsequent machining process, the value of the thickness t is made larger than the maximum processing depth d. Next, FIG.
By machining as shown in (b) or 1 (c), a shape having a predetermined depth distribution as shown in FIG. 1 (d) is formed in the processed layer 2. After that, anisotropic etching is performed with an etching gas 5 as shown in FIG.
As shown in FIG. 5, the shape of the processed layer 2 is transferred to the substrate 1 in a similar manner in the depth direction. Next, a mold is manufactured using the substrate 1 as a master master. Next, a diffractive lens is manufactured by plastic injection molding using the mold.

Hereinafter, each step of this embodiment will be described in detail. First, the step of forming the processed layer 2 on the substrate 1 will be described. The material of the substrate 1 is preferably one having sufficient rigidity because it is attached to a machine tool during machining. In addition, since the shape of the processed layer is transferred by anisotropic etching in a later step, a material having processability against etching is preferable, such as quartz, synthetic quartz, or SiO _2.
System glass, LiF, MgF ₂ , CaF ₂ , BaF ₂ , sapphire, KBr, KI and the like are preferable.

As the material of the processing layer 2, a material which is easily machined, for example, a resin or a metal which is easily machined can be used. Examples of metals that can be easily machined include Al and P-Ni (electroless nickel). Processing layer 2
Can be formed by using a spin coater or the like when the processed layer 2 is made of resin. By appropriately selecting the baking conditions, it is possible to make the hardness suitable for the subsequent steps. When the processing layer 2 is made of metal, the processing layer 2 can be formed by vacuum vapor deposition, sputtering, plating or the like.

Next, a process of machining the processed layer 2 into a shape having a predetermined depth distribution, for example, a blaze shape will be described. When manufacturing an optical element having a ring pattern, for example, a diffractive lens, a substrate on which a processing layer 2 is formed as a work on a cutting machine, for example, a numerically controlled lathe machine (not shown), as shown in FIG. 1B. Attach 1. Then, while rotating the work, the cutting tool 3 is moved based on the design data of the lens to be manufactured, and the processing layer 2 is cut into a desired shape.

On the other hand, when manufacturing an optical element having a linear pattern, for example, a diffractive cylindrical lens,
Using a cutting machine, for example, a numerically controlled milling machine type machine or a ruling engine type machine, as shown in FIG. 1 (c), the work is moved vertically or horizontally with the tool 3 fixed. In a fixed state, the cutting tool 3 is moved vertically and horizontally to cut the processing layer 2 into a desired shape.

By cutting the working layer 2 as described above, a shape having a desired depth distribution can be easily obtained. Further, since recent numerical control processing machines have submicron processing accuracy, it is possible to obtain a desired shape with extremely high accuracy. Furthermore, by changing the processing data, it is possible to easily obtain shapes corresponding to optical elements of various shapes, such as Fresnel lenses and diffraction gratings having a linear pattern, without being limited to the above-mentioned examples. Further, for example, a lathe-type processing machine, a milling machine-type processing machine, and a ruling engine-type processing machine have versatility, and since the same processing machine can be used for various purposes, the cost for manufacturing an optical element can be suppressed. .

Next, a process of anisotropically etching the shape formed on the processed layer 2 and transferring it to the substrate 1 will be described. As the anisotropic etching, for example, etching using reactive gas plasma is suitable in terms of controllability of selection ratio and anisotropy. Examples of etching using reactive gas plasma include reactive ion etching, plasma etching, reactive ion beam etching, ion beam etching, sputter etching, and microwave plasma etching. At this time, the value of the etching selection ratio between the substrate 1 and the processed layer 2 can be changed by means such as adjusting the composition of the etching gas 5. When the selection ratio is 1, the pattern shape of the processed layer 2 is directly transferred to the substrate. When the selection ratio is other than 1, the value in the depth direction of the pattern formed on the processed layer 2 may be determined according to the selection ratio.

Next, as shown in FIG. 1F, a conductive metal, as shown in FIG. 1G, is formed on the surface of the substrate 1 onto which the shape of the processed layer 2 is transferred in a depth direction. For example, nickel is deposited by a method such as sputtering or vapor deposition to form the electrode body 6. Next, as shown in FIG. 1 (h), an electroforming process is performed to form a nickel electroformed layer 7. After that, FIG. 1 (i)
As shown in (1), the nickel electroformed layer 7 is peeled off, and using this as a mold, a diffraction grating is manufactured by plastic injection molding. A known method can be used for plastic injection molding using a mold.

The method of manufacturing an optical element using a mold is not limited to injection molding, and a photopolymer method (2P method) can also be used. This is a method of manufacturing an optical element by forming an ultraviolet curable resin (photopolymer) layer on a transparent substrate, pressing a mold and irradiating with ultraviolet rays to cure the resin. Since this method has no temperature cycle, compared with injection molding, (1) the process is shorter, (2) birefringence and coma are less likely to occur, and (3) the life of the mold is prolonged. There is an advantage that you can. Further, a master using glass as a substrate material was prepared by the above method, and the above-mentioned JP-A-1-2972.
The mold can also be manufactured by the method disclosed in Japanese Patent Laid-Open No. 10. By using this method, an optical element made of glass can be manufactured by press molding.

As can be seen from the above, according to the method of the first embodiment of the present invention, since the processing of the processing layer 2 is mechanical processing, extremely high precision processing is possible, and the processing layer 2 is formed by the processing. Since the shape is transferred to the substrate by anisotropic etching, an accurate master master can be manufactured.
An electroforming process is performed on the master master, which faithfully traces the shape of the master so that the mold can be manufactured with high accuracy. Further, since the processing on the processing layer 2 is mechanical processing, it is possible to easily process various shapes by changing the processing data, and it is possible to easily manufacture dies having various shapes. Optical elements of various shapes can be easily mass-produced using a mold.

FIGS. 2A to 2I are views for explaining the second embodiment of the present invention. In the second embodiment, the method of the present invention is applied to manufacture a diffractive lens having a high diffraction effect. When a diffractive lens is considered as the diffractive optical element, the groove cross-sectional shape that achieves the maximum diffraction efficiency is a blazed shape that reflects the phase distribution function of the diffractive lens. In this case, the hypotenuse portion 4 of the groove shown in FIG. 3A is generally a curved line rather than a straight line. Therefore, the ideal shape to be formed in the processed layer is, for example, the shape shown in FIG. In order to form this shape by cutting with a cutting tool, it is necessary to perform point cutting, for example, diamond point turning, but the point cutting requires enormous processing data and the processing time becomes long. Therefore, actually, as shown in FIG. 3B, the shape of the hypotenuse portion 4 is made straight to simplify the processing data and improve the workability to perform the processing. In this case, if the cross-sectional shape of the groove is approximated by a straight line, the influence on the reduction of the diffraction efficiency becomes large especially when the number of grooves is small, which is a practical problem.

Further, the spectral grating, which is a kind of diffractive optical element, is often blazed due to the need for high diffraction efficiency. However, it is difficult to cover a wide wavelength range with a conventional diffraction grating that is blazed for one wavelength. Therefore, a blazed diffraction grating for two wavelengths was published in 1983 in "Optics".
VOL12, page 201. This diffraction grating 1 has a cross-sectional shape as shown in FIG. 6 (b), and is effective not only for widening the wavelength range used, but also for reducing abnormalities in diffracted light intensity (anomaly). This diffraction grating is manufactured by using two kinds of cutters according to the blaze angle and performing cutting twice on one groove.

In the case of such a diffraction grating blazed into two wavelengths, two types of cutters have to be used for cutting twice, so that the relative position intervals of the cutters must be controlled with high precision. Further, since the cutting is performed twice, there is a problem that it takes time to manufacture. Further, when the material of the diffraction grating is hard, it takes a long time to process, which makes the process difficult. As explained above, when it is desired to form the cross-sectional shape of the groove into a shape that is not a straight line, it is difficult to machine the cross-sectional shape of the machined layer to something other than a straight line from the viewpoint of machining time, etc. Is. The second embodiment was devised with this problem in mind.

The second embodiment will be described below with reference to FIGS. First, as shown in FIG. 2A, the processing layer 2 is formed on one surface of the substrate 1 to have a predetermined thickness t. Next, as shown in FIG. 2 (b) or FIG. 2 (c), it is machined to form a shape having a predetermined depth distribution in the processed layer 2 as shown in FIG. 2 (d). After that, as shown in FIG. 2E, anisotropic etching is performed with the etching gas 5 while changing the selection ratio, and the shape of the processed layer 2 is changed and transferred to the substrate 1, as shown in FIG. Obtain a master master with such a shape. As described in the description of the operation of the first embodiment, when the selection ratio is gradually changed, the shape of the processed layer 2 is transferred to the substrate 1 as shown in FIG. It is possible to obtain a master master of an optical element. A mold is created from this master master, and an optical element is manufactured by injection molding of plastic using the mold.

Next, each step of the second embodiment will be described in more detail, but the description of the steps common to the first embodiment will be partially omitted. First, a process of machining a shape having a predetermined depth distribution in the processed layer 2, for example, a blazed shape will be described. When manufacturing an optical element having a ring pattern, for example, a diffractive lens, FIG.
As shown in (b), the substrate 1 on which the processing layer 2 is formed as a work is attached to a cutting machine, for example, a numerically controlled lathe machine (not shown). Then, while rotating the work, the cutting tool 3 is moved based on the design data of the lens to be manufactured, and the working layer 2 is cut into an ideal shape. At this time, the machining data is simplified by making the groove cross-sectional shape straight, and the workability is improved to perform the machining.

Next, the shape formed on the processed layer 2 is shown in FIG.
A process of anisotropically etching and transferring to the substrate 1 while changing the selection ratio as shown in (e) will be described. As the anisotropic etching, for example, etching using reactive gas plasma is suitable in terms of controllability of selection ratio and anisotropy. Examples of etching using reactive gas plasma include reactive ion etching, plasma etching, reactive ion beam etching, ion beam etching, sputter etching, and microwave plasma etching. For example, in the case of manufacturing a diffractive lens having a function of a convex lens, the processing layer 2 is formed as shown in FIG.
The substrate 1 processed into the blazed shape as shown in (d) is etched while reducing the selection ratio. 4 (a)-
In (d), for the sake of clarity, it is shown that a shape having two bent portions is transferred from the processing layer 2 in which the hypotenuse portion is processed into a straight line, but the selection ratio is continuously changed. As a result, the hypotenuse portion can be formed into a curved shape as shown in FIG.

On the other hand, for example, when manufacturing a diffractive lens having the function of a concave lens, the substrate 1 in which the processing layer 2 is processed into a blazed shape as shown in FIG. 5A is etched while increasing the selection ratio. As a result, the shape of the processed layer 2 is the substrate 1
And the master master as shown in FIG. 5B is formed. As described above, the blazed shape formed on the processed layer 2 can be transferred to an ideal shape as shown in FIG. 2F or 5B by etching while changing the selection ratio. A diffractive optical element with high diffraction efficiency can be easily manufactured.

By using this second embodiment, FIG.
A diffraction grating having two wavelengths blazed as shown in (b) can be easily manufactured. That is, the processing layer 2 is formed as shown in FIG.
Forming a blazed diffraction grating shape as shown in (a),
This is etched by changing the selection ratio in two steps. For example, when the etching is performed with a large selection ratio at the beginning and the etching is performed with a small selection ratio in the middle, the substrate 1 shown in FIG.
The shape as shown in (b) can be formed. A mold may be manufactured by using this as a master master of an optical element.

Next, a method of changing the selection ratio will be described. For example, in the case of reactive ion etching, there are methods such as changing the composition of the gas in plasma, changing the discharge power density, changing the pressure of the discharge gas, and changing the frequency of the applied voltage. When the composition of the gas in the plasma is changed, the types and proportions of the reactive species and neutral species, the energy of ions, etc. are changed, and the reaction on the surface and the speed thereof are changed. Also, the degree of physical or chemical etching changes. Therefore, the selection ratio can be changed. This phenomenon is not limited to reactive ion etching,
This is common to plasma, and the selection ratio can be similarly changed in etching using plasma.

By changing the composition of the gas in the plasma, the selection ratio can be changed relatively large. Further, the gas flow rate can be precisely controlled by a mass flow rate controller, etc., and the selection ratio can be precisely controlled. For example, if the working layer is a resist, the resist is oxidized is removed by O ₂ for an organic substance, the addition of O ₂ gas in the etching gas etching rate of the resist is increased, a change in selectivity. When H ₂ gas is added to the etching gas, a polymer film is formed on the surface, the etching rate changes, and the selection ratio changes. The applicant of the present application has experimentally confirmed that the selective ratio can be changed by adding O ₂ gas to CF ₄ gas in reactive ion etching and changing the addition amount.

On the other hand, when the discharge power density is changed, the types, densities, energies, etc. of the reactive species and neutral species are changed, and the energy of the ions is also changed, similarly to the case where the gas composition is changed. The selection ratio can be changed. This phenomenon is common not only to reactive ion etching but also to plasma, and in etching using plasma, the selection ratio can be changed similarly. Therefore, the selection ratio can be changed subtly by changing the discharge power density, which is particularly effective when the selection ratio is slightly changed.

The applicant of the present application has also confirmed through experiments that the selection ratio can be changed by changing the discharge power density in the reactive ion etching. When the pressure of the discharge gas or the frequency of the applied voltage is changed, the energy of ions and the average energy of electrons are changed, and the selectivity is changed. This is common to etching in which an ion-assisted reaction occurs, and the selective ratio can be changed not only by reactive ion etching but also by plasma etching, reactive ion beam etching, microwave plasma etching, ion beam milling, or the like.

By changing the pressure of the discharge gas or the frequency of the applied voltage, the selection ratio can be changed in the etching utilizing the ion assist reaction. The etching gas used is, for example, CF ₄ gas or CHF gas in the case of quartz glass used in the visible region or ultraviolet region.
Fluorine-based gas such as ₃ gas can be used. In the case of Si used in the infrared region, for example, fluorine-based gas such as CF ₄ gas, SF ₆ gas, NF ₃ gas, or chlorine-based gas such as Cl ₂ gas or CCl ₄ gas can be used.

By using the above method, the selection ratio can be easily changed. In particular, by controlling the composition of the gas in the plasma and the discharge power density, the selection ratio can be changed in a wide range with high accuracy.

After the master master is produced, the first
By a method similar to the method shown in the embodiment, FIG.
A mold is produced as in (g) to (i). Using this mold, a predetermined optical element is manufactured by a method such as injection molding, compression molding, or 2P method.

As can be seen from the above, according to the second embodiment, the processing layer 2 formed on the substrate 1 is machined and the formed shape is anisotropically etched while changing the selection ratio. It is possible to change the shape of the processed layer 2 to 1 and transfer it. Therefore, when manufacturing a diffractive lens, a Fresnel lens, or the like having an ideal shape corresponding to the phase distribution, it is sufficient to machine the oblique side of the groove when machining the machining layer 2, so that the machining layer 2 can be machined straight. It is possible to prevent the amount of processing data and the processing time from becoming huge. Also, when manufacturing a blazed diffraction grating for two wavelengths,
Since it is only necessary to machine the oblique side of the groove in a straight line at the time of machining, it is possible to prevent the amount of machining data and the machining time from becoming enormous during machining. Further, since one cutting operation is performed using one type of cutting tool, steps such as replacement of the cutting tool and position adjustment are omitted, so that mass production can be easily performed.

It should be noted that the present invention is not limited to the above-described embodiments, but various changes or modifications can be added. For example, in the above-mentioned claim 2, the anisotropic etching is etching using reactive gas plasma, and as a means for changing the selection ratio, the composition of the gas in the plasma is changed, the discharge power density is changed, and the discharge is changed. At least one of changing the gas pressure and changing the frequency of the applied voltage may be used. In that case, etching using reactive gas plasma is used as anisotropic etching, and a method of changing the composition of gas in plasma or changing the discharge power density is used as means for changing the selection ratio. And the type and ratio of reactive species and neutral species, and the energy of ions change, so the reaction on the surface and its speed change,
As a result, the selection ratio changes. If a method of changing the pressure of the discharge gas or changing the frequency of the applied voltage is used as a means for changing the selection ratio, the energy of ions and the average energy of electrons are changed, and the selection ratio is changed.

If the selection ratio changes during the anisotropic etching, the shape of the processed layer changes and is transferred to the substrate. Since the etching using the reactive gas plasma is excellent in anisotropy, the shape in the in-plane direction is faithfully transferred to the substrate.
Since the mold is formed using the substrate as a master master, it is possible to manufacture a mold whose shape in the in-plane direction is accurate and whose shape in the depth direction is controlled. Further, since the etching using the reactive gas plasma is used as the anisotropic etching means, the anisotropy is excellent. In addition, there are many parameters that control etching, such as gas composition, discharge power density, discharge gas pressure, and applied voltage frequency.When changing the selection ratio, it is possible to select appropriate parameters according to the amount of change. it can.

Further, in the above-mentioned claim 1 or 2, the step of forming a mold comprises a step of forming an electrode body of a conductive metal on a substrate, and an electroforming process using the electrode body as an electrode to form an electroformed layer. You may make it have the process of forming and the process of peeling an electroformed layer from a board | substrate. In that case, after the master master is manufactured, an electrode body is formed on the surface with a conductive metal. Using this as an electrode, an electroformed layer is formed on the electrode body. The electrode body and the electroformed layer are manufactured by faithfully following the shape of the master original disc, and when the electroformed layer is peeled off thereafter, a shape in which the shape of the master original disc is inverted is formed in the electroformed layer. Further, since the electroforming process is used to manufacture the mold from the master master, accurate shape transfer is performed.

Further, in the above-mentioned claim 4, the anisotropic etching is etching using reactive gas plasma, and as a means for changing the selection ratio, the discharge power density for changing the composition of the gas in the plasma is used. At least one of changing, changing the pressure of the discharge gas, and changing the frequency of the applied voltage may be used.
In that case, as anisotropic etching, etching using reactive gas plasma is used, and as a means for changing the selection ratio, a method of changing the composition of the gas in the plasma or changing the discharge power density is used. When used, the types and proportions of the reactive species and neutral species and the ion energy change, so that the reaction on the surface and the rate thereof change, and as a result, the selectivity changes. When a method of changing the pressure of the discharge gas or changing the frequency of the applied voltage is used as a means for changing the selection ratio, the energy of ions and the average energy of atoms are changed, and the selection ratio is changed.

If the selection ratio changes during the anisotropic etching, the shape of the processed layer in the depth direction changes and is transferred to the substrate. Since the etching using the reactive gas plasma is excellent in anisotropy, the shape in the in-plane direction is faithfully transferred to the substrate. Since the mold is formed by using the substrate as a master master to form the optical element, it is possible to manufacture an optical element having an accurate shape in the in-plane direction and a suppressed shape in the depth direction. Further, since the etching using the reactive gas plasma is used as the anisotropic etching means, the anisotropy is excellent. There are many parameters for controlling etching, such as gas composition, discharge power density, discharge gas pressure, and applied voltage frequency, and when changing the selection ratio, appropriate parameters can be selected according to the amount of change. .

Further, in the above-mentioned claim 3 or 4, in the step of forming a mold, the step of forming an electrode body of a conductive metal on a substrate, and the electroforming process using the electrode body as an electrode to form an electroformed layer. You may make it have the process of forming and the process of peeling an electroformed layer from a board | substrate. In that case, after the master master is manufactured, an electrode body is formed on the surface with a conductive metal. Using this as an electrode, an electroformed layer is formed on the electrode body. The electrode body and the electroformed layer are manufactured by faithfully following the shape of the master original disc, and when the electroformed layer is peeled off thereafter, a shape in which the shape of the master original disc is inverted is formed in the electroformed layer. By using this mold, an optical element in which the shape of the master master is precisely formed is manufactured. Also, since the electroforming process was used to manufacture the mold from the master master,
Since the accurate shape is transferred and the optical element is formed by using the mold, the optical element can be manufactured accurately.

[0054]

As described above, according to the mold manufacturing method of the first aspect of the present invention, since the machining layer is machined to form a predetermined shape, it is easy to change the machining data. Various shapes can be formed, and molds of various shapes can be easily manufactured.

Further, according to the method for manufacturing a mold of claim 2 of the present invention, a processing layer which is easy to machine is formed on the substrate,
This processed layer is machined into a predetermined shape, and the shape of the processed layer is transferred to the substrate by anisotropic etching while changing the selection ratio. Therefore, the shape of the processed layer can be deformed and transferred to the substrate. . Therefore, a desired shape can be obtained as a die even if a shape that can be easily processed, for example, a blazed shape whose cross-sectional shape is approximated by a straight line is formed on the processing layer.

Further, according to the optical element manufacturing method of the third aspect of the present invention, a mold is manufactured by using the master having the shape of the processed layer transferred to the substrate by etching, and the optical element is manufactured by using the mold. Since it is manufactured, it is suitable for mass production.

Further, according to the optical element manufacturing method of the fourth aspect of the present invention, since the optical element can be manufactured by using the mold having the desired shape, the optical element having high diffraction efficiency and light collecting efficiency can be obtained. The device can be easily manufactured.

[Brief description of drawings]

FIG. 1 (a) to (i) are views for explaining a first embodiment of the present invention.

2A to 2I are views for explaining a second embodiment of the present invention.

3A and 3B are views for explaining the shape of a processed layer according to the second embodiment.

4A to 4D are views for explaining the principle of anisotropic etching performed while changing the selection ratio in the present invention.

5A and 5B are views for explaining the second embodiment.

6A and 6B are views for explaining a second embodiment.

7A to 7F are views for explaining a conventional technique.

8A to 8E are views for explaining a conventional technique.

[Explanation of symbols]

 1 Substrate 2 Processing Layer 3 Byte 4 Groove Side 5 Etching Gas 6 Electrode Body 7 Electroformed Layer

Claims (4)

[Claims] 1. A step of forming a processing layer on a substrate, a step of machining the processing layer into a desired shape, an etching of the processing layer and the substrate machined into the desired shape, and the processing A method of manufacturing a mold, comprising: a step of forming a layer shape on the substrate in a similar manner in a depth direction; and a step of forming a mold by using the etched substrate as a master master. 2. A step of forming a processing layer on a substrate, a step of machining the processing layer into a desired shape, and a processing layer and the substrate machined into the desired shape,
A method of manufacturing a die, comprising: a step of anisotropically etching by changing a selection ratio; and a step of forming a die by using the anisotropically etched substrate as a master. 3. A step of forming a processing layer on a substrate, a step of machining the processing layer into a desired shape, and a step of etching the processing layer and the substrate machined into the desired shape to perform the processing. A step of forming a layer shape on the substrate so as to be similar to the depth direction; a step of forming a mold using the etched substrate as a master master; and a step of manufacturing an optical element using the mold. A method for manufacturing an optical element, which comprises: 4. A step of forming a processed layer on a substrate, a step of machining the processed layer into a desired shape, and a processed layer and the substrate machined into the desired shape,
Anisotropic etching by changing a selection ratio, a step of forming a mold using the anisotropically etched substrate as a master, and a step of manufacturing an optical element using the mold. And a method for manufacturing an optical element.