JPH08227007A - Formation of surface shape of object and production of metal mold - Google Patents

Abstract

PURPOSE: To exactly form a desired shape on an object to be worked by working a working layer in accordance with the distribution of the etching rates of the object and working layer within the plane perpendicular to an etching direction. CONSTITUTION: The working layer 2 is so worked that the desired shape is formed on the surface of the object to be worked 1 in accordance with the distribution of the etching rates of the object 1 and the working layer 2 within the plane orthogonal with the etching direction by anisotropic etching. The depth of the grooves formed on the working layer 2 is made deep at the center and shallow on the periphery in the case, for example, the object 1 is formed with a diffraction optical element having the specified groove depth on its surface as an optical member. In such a case, the distribution of the selection ratio within the plane orthogonal with the etching direction is obtd. by determining the selection ration from the etching rates of the object 1 and the working layer 2 at plural measurement points within this plane. The depth of the grooves formed in the working layer 2 is obtd. by determining the groove depth from the selection ratio = the groove depth of the object 1/the groove depth of the working layer 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a surface shape of an object for producing an optical element having a desired structure on a surface, and a gold used for producing an optical element having a desired structure on a surface. The present invention relates to a method for manufacturing a mold.

[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. It is known that in a diffractive optical element having a relief type grating structure, high diffraction efficiency can be obtained by blazing the groove cross-sectional shape.

Conventionally, as a method of manufacturing a diffractive optical element, for example, as disclosed in Japanese Patent Laid-Open No. 60-103311, a resist is coated on a substrate, and exposure and development accompanied by dose amount modulation are performed. Method of forming a predetermined pattern shape on the resist, then transferring the pattern shape of the resist to the substrate by dry etching Method of directly processing the grating groove on the substrate using a ruling engine, lathe, etc. Using a focused ion beam A method of directly processing a lattice groove on a substrate is known.

However, the above method has a problem that the resolution is limited to the same level as the thickness of the resist. In addition, since the resist has a property that the residual film thickness does not change linearly with the exposure amount, for example, when a blazed shape is formed on the resist surface by electron beam exposure, it is necessary to match the characteristics of the resist. The exposure dose must be precisely controlled, and for that purpose the electron beam intensity or line width must be precisely controlled. Therefore, there is a problem that the device is complicated and expensive, and drawing of a large area becomes difficult. Further, the pattern shape may be greatly deviated from the design value in the fine pattern portion due to scattering of electron beam used for exposure, far-ultraviolet light, ultraviolet light, etc. in the resist or proximity effect. There is a problem that it becomes difficult to manufacture in.

Further, in the above-mentioned method, for example, in the case of glass which is often used as a material for the diffractive optical element, direct machining of glass is not practical because the wear of the tool is remarkable and the efficiency is low. It takes a large amount of money and a huge amount of time to manufacture a diffraction grating having a large area. For this reason, there is a problem that the material of the substrate is practically limited to that which can be easily processed such as metal or plastic.

Further, according to the above method, the spot diameter of the focused ion beam is as small as about 0.1 μm and fine processing is possible, but on the other hand, it is affected by the instability of the ion source and the penetration depth is shallow. Therefore, the desired depth may not be obtained. Further, since the processing speed of the ion beam is slow, there is a problem that the processing takes a very long time.

In order to solve such a problem, the applicant of the present invention discloses, in Japanese Patent Laid-Open No. 7-5318, that a machining layer formed on a substrate is machined into a predetermined shape, and the shape is anisotropic. It proposes a method of manufacturing an optical element having a blazed shape by transferring it to a substrate by etching.

According to the above-mentioned manufacturing method, since the processing layer is cut by a numerical control type cutting machine or the like, it is possible to easily form a predetermined shape as compared with the method of exposing and developing, and it is possible to perform precise processing. A diffractive optical element can be manufactured. Further, since the shape of the processed layer is transferred to the substrate by anisotropic etching, there is an advantage that the optical element can be formed regardless of the machinability of the substrate.

On the other hand, when these optical elements are actually used, it is necessary to reduce the manufacturing cost per piece. Therefore, it is conceivable to manufacture using a mold as used in a normal optical lens. However, the mold material, especially the mold material used for glass press molding,
Since the hardness is extremely high, it is difficult to form a fine shape such as a blazed grating by machining.

Therefore, the applicant of the present invention forms a processing layer formed on a substrate into a predetermined shape by machining, and transfers this shape to the substrate by anisotropic etching to produce a master master, and this master master is manufactured. Has been proposed (Japanese Patent Application No. 6-306321) for manufacturing an optical element using a mold produced by reversing and transferring the shape of FIG.
issue).

According to the above manufacturing method, a mold having a desired shape can be easily manufactured. Therefore, by using this mold, an optical element having high diffraction efficiency and light collection efficiency can be obtained.
It has the advantage of being mass-produced and inexpensive.

Further, the applicant of the present invention uses a machined layer formed on a substrate to form a predetermined shape by mechanical processing, and transfers this shape to the substrate by anisotropic etching as a part of a mold. , A method of manufacturing an optical element is also proposed (Japanese Patent Application No. 6-306322).
issue).

According to the above-mentioned manufacturing method, since the predetermined shape formed on the processed layer is transferred to the substrate by anisotropic etching as a part of the mold, the mold can be manufactured more easily. In addition, since an optical element is manufactured using this mold, there is an advantage that a glass molded product can be easily manufactured.

[0014]

By the way, in the manufacture of the diffractive optical element, if it is formed on a spherical surface, the degree of freedom in designing an optical system using the diffractive optical element can be increased, and the diffractive optical element can be designed as a spherical surface. It is known that since the power can be shared with the diffractive optical element, the pitch of the diffraction grating can be widened, and the manufacturing is easy.

However, most diffractive optical elements currently realized have a diffraction grating formed on a plane, and the manufacturing method is often not taken into consideration when the substrate has a spherical surface. .

Further, in the above methods, it is assumed that when the shape of the processing layer is transferred to the substrate by anisotropic etching, the etching rate of the processing layer and the etching rate of the substrate are constant over the entire surface of the substrate. In the case of reactive ion etching, the parameters for controlling these etching rates include the pressure of the discharge gas, the frequency of the applied voltage, the composition of the gas, and the discharge power density.

However, according to the experiment by the present inventor, when the etching is performed with the same parameters for controlling the etching rate of the substrate and the processing layer, when the substrate is a curved surface, it is different from the case where the substrate is a flat surface. Differently, the etching rate of both of them in the plane perpendicular to the etching direction changes depending on the location. Therefore, when etching is performed with the groove depth of the diffraction grating formed in the processing layer being constant, the etching rate is transferred to the substrate. It was found that the groove depth deviated from the design value depending on the location. As described above, when the groove depth of the diffraction grating deviates from the designed value depending on the location, the diffraction efficiency is reduced, and ghost and flare are generated by the diffracted light of the unnecessary order.

The present invention has been made in view of the above-mentioned problems, and a first object thereof is to provide a method for producing a surface shape of an object which can accurately manufacture, for example, a blazed diffractive optical element. Is.

A second object of the present invention is to provide a method of manufacturing a mold for accurately manufacturing a mold used for manufacturing a blazed diffractive optical element, for example.

[0020]

In order to achieve the above-mentioned first object, a method for producing a surface shape of an object according to the present invention comprises a step of forming a processing layer on an object to be processed, and a step of processing the processing layer. And a step of anisotropically etching the processing layer and the object to be processed to form the shape of the processing layer on the surface of the object to be similar in the depth direction. In the step of, the desired shape is generated on the surface of the object to be processed based on the distribution of the etching rates of the object to be processed and the processing layer in the plane orthogonal to the etching direction by the anisotropic etching. In addition, the processing layer is processed.

In order to achieve the second object, the method of manufacturing a mold of the present invention is such that the step of forming a processing layer on an object to be processed, the step of processing the processing layer, the processing layer and Anisotropically etching the object to be processed to form a shape of the processing layer on the surface of the object to be processed in a depth direction, and a step of forming the object having the shape of the processing layer. And a step of forming a mold as a master master, and in the step of processing the processing layer, the distribution of the etching rate of the object to be processed and the processing layer in a plane orthogonal to the etching direction by the anisotropic etching. On the basis of the above, the processing layer is processed so that a desired shape is generated on the surface of the object to be processed.

Further, according to the method of manufacturing a mold of the present invention, the step of forming a processing layer on the object to be processed, the step of processing the processing layer, and the step of anisotropically etching the processing layer and the object to be processed. And forming the shape of the processed layer on the surface of the object to be processed in a depth direction, and in the step of processing the processed layer, the shape is orthogonal to the etching direction by the anisotropic etching. Based on the distribution of the etching rate of the object to be processed and the processing layer in the plane, so that a desired shape is generated on the surface of the object to be processed,
It is characterized in that the processed layer is processed, and the object to be processed obtained by the anisotropic etching is at least a part of a mold.

[0023]

According to the method of generating a surface shape of an object of the present invention, a processing layer is formed on an object to be processed, and after the processing layer is processed, anisotropic etching is performed to change the shape of the processing layer in the depth direction. Similar to the above, it is formed on the object to be processed. Here, when the etching rates of the object to be processed and the processing layer are different depending on the location in a plane perpendicular to the etching direction, for example, when the following is selected ratio: etching rate of object to be processed / etching rate of processing layer, When the selection ratio becomes smaller from the center of the object to be processed to the periphery, as shown in FIG. 14a, a shape having a constant groove depth is formed in the processed layer 2,
When the shape is transferred to the object 1 to be processed in a similar manner by anisotropic etching, the groove depth generated on the surface of the object 1 is as shown in FIG. 14b. It will be different.

Therefore, in the present invention, the object 1 to be processed in the plane orthogonal to the etching direction by anisotropic etching.
And based on the distribution of the etching rate of the processed layer 2,
In order to generate a desired shape on the surface of the workpiece 1,
The processing layer 2 is processed. For example, in the case of forming a diffractive optical element having a constant groove depth on the surface by using the object to be processed 1 as an optical member, as shown in FIG. Make it deep and shallow around. In this way, the diffractive optical element 3 having a constant groove depth on the surface can be obtained as shown in FIG. 1b.

Here, the distribution of the selection ratio in the plane orthogonal to the etching direction is as follows:
It can be obtained by obtaining the selection ratio from the etching rates of the object to be processed 1 and the processed layer 2, respectively. The groove depth formed in the processed layer 2 depends on the etching rates of the processed layer 2 and the processed object 1, and
Therefore, the distribution of the above selection ratio is determined by the groove depth formed in the processed layer 2 and the groove actually transferred to the object to be processed 1 at a plurality of measurement points in a plane orthogonal to the etching direction. It can also be obtained by determining the ratio with the depth, that is, the selection ratio = the groove depth of the object 1 to be processed / the groove depth of the processed layer 2.

In the mold manufacturing method of the present invention, after the working layer is formed on the work object, the work object and the work layer are etched in a plane orthogonal to the etching direction by anisotropic etching. Based on the distribution of rates
A desired shape on the surface of the object to be processed by the following anisotropic etching, for example, when a mold for an optical element is produced, a shape corresponding to the target optical element is generated,
Process the processing layer. Processing the processing layer in this way, then,
When anisotropic etching is performed, a shape that exactly corresponds to the target optical element is generated on the surface of the object to be processed, so if you use this object as a master master to form a mold, The shape of the master master is inverted,
That is, a shape obtained by inverting the shape of the target optical element is accurately formed. Therefore, by using this mold, the target optical element with an accurate shape,
It is possible to manufacture in large quantities.

Further, in the method for manufacturing a mold of the present invention, after forming a processing layer on the processing object, the etching of the processing object and the processing layer in a plane orthogonal to the etching direction by anisotropic etching. Based on the distribution of the rate, the desired shape on the surface of the object to be processed by the next anisotropic etching, for example, in the case of manufacturing a mold for an optical element, a shape obtained by inverting the shape of the target optical element Process the working layer as produced. When the processed layer is processed in this way and then anisotropically etched, a shape that is the inverse of the shape of the target optical element is accurately formed on the surface of the object to be processed. By using an object as at least a part of the mold of the target optical element, the mold can be manufactured by an extremely simple process, and by using this mold, the target optical element can be formed in an accurate shape. It becomes possible to manufacture in large quantities.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. In all of the drawings, parts not directly related to the gist of the present invention are partially exaggerated or omitted for easy understanding of the description.

In the first embodiment of the present invention, a machined layer which is easy to machine is formed on a substrate such as glass, the machined layer is machined into a predetermined shape, and then anisotropic etching is performed. A diffractive lens, which is a diffractive optical element, is manufactured on the basis of a method in which the processed shape is transferred in a similar manner. In this implementation, first, the substrate and the processed surface in a plane orthogonal to the etching direction by anisotropic etching It is necessary to know the distribution of the etching rate of the layer, that is, the distribution of the selection ratio. Here, the selection ratio is, as described above,

[Equation 1] The groove depth formed in the processed layer is transferred to the substrate depending on the etching rate of the processed layer and the substrate.

[Equation 2] You can also ask by. Hereinafter, a case where the selection ratio is obtained using the equation (2) will be described.

First, as shown in FIG. 2A, a metal such as A1 (aluminum) which is easy to machine is formed on the spherical surface side of a quartz substrate 11 having a flat surface as a sample and a spherical surface (convex surface) having a predetermined radius of curvature. A processed layer 12 made of is formed with a predetermined thickness t is prepared. Here, as a method of forming the processed layer 12, vacuum deposition, sputtering, or the like can be used. It should be noted that the thickness t of the processing layer 12 is set to be smaller than the maximum processing depth in the entire processing area in order to prevent the cutting tool from coming into contact with the substrate 11 even if there is some error in the movement of the cutting tool in the subsequent machining. The thickness t may be large, and the thickness t may be slightly changed depending on the place.

Next, as shown in FIG. 2b, a machining machine,
For example, the substrate 11 on which the processing layer 12 is formed as a work is attached to a numerically controlled lathe type processing machine (not shown), and the tool 13 is moved based on the design data of the diffractive lens to be manufactured while rotating the work, The processing layer 12 is processed. The processing data used at this time is created assuming that the selection ratio is constant over the entire surface of the substrate. In this embodiment, for the sake of simplicity, light of the same diffraction order is used on the entire surface, so the groove depth is constant. After the machining is completed, the groove depth d _k is measured with a measuring device, for example, a stylus type step gauge. The groove depth d _k is constant over the entire surface if the machining is performed according to the machining data.

Next, as shown in FIG. 2c, anisotropic etching, for example, reactive ion etching, is performed to obtain the structure shown in FIG. 2d.
As shown in, the shape of the processed layer 12 is transferred onto the substrate 11 in a similar manner. In this case, the groove depth of the diffraction grating transferred to the substrate 11 becomes deeper toward the periphery, as is clear from FIG. 2D, because the selection ratio changes in the plane perpendicular to the etching direction. The groove depth d _e (n) is measured in the radial direction from the center with a stylus type step gauge or the like. After that, the selection ratio (i) of the i-th grating is given by n

(Equation 3) Calculate according to.

FIG. 3 is a plot of the above calculation results of the selection ratio (i) in the radius r direction from the center (O) of the diffraction grating. As you can see from the figure, in this case,
It can be seen that the substrate 11 is more likely to be etched as it goes to the periphery. The method of changing the selection ratio changes depending on various factors such as the material of the substrate 11 and the radius of curvature of the convex surface.

After the in-plane distribution of the selection ratio is obtained as described above, the substrate 11 is then determined based on the in-plane distribution of the selection ratio.
When a diffraction grating having a constant groove depth d _e is formed in the groove, the groove depth d _k (i) of the i-th diffraction grating processed in the processing layer 12
Is calculated from the following equation to obtain the processing data of the processing layer 12 when actually manufacturing the diffractive lens.

[Equation 4]

FIG. 4 shows the groove depth d _k (i) of the above processed layer.
The result of the calculation is plotted in the radius r direction from the center (O) of the diffraction grating. As is clear from the figure, it is understood that the groove depth d _k (i) of the processed layer 12 should be shallower toward the periphery.

As described above, after obtaining the processed data in consideration of the spatial change of the selection ratio, a desired diffractive lens is manufactured using this processed data. In manufacturing this diffractive lens, first, as shown in FIG. 5a, similarly to FIG. 2a, a spherical surface of a quartz substrate 11 made of a flat surface and a spherical surface (convex surface) having a predetermined radius of curvature, Processing layer 1 made of a metal such as A1 (aluminum) that is easy to machine
2 is formed with a predetermined thickness t.

Next, as shown in FIG. 5b, a substrate 11 having a processing layer 12 formed thereon as a work is attached to a machine such as a numerically controlled lathe type machine, and while the work is rotated, the spatial ratio of the selection ratio is increased. The processing layer 12 is processed by moving the cutting tool 13 based on the above-described processing data in consideration of the change. Thereafter, as shown in FIG. 5c, the shape of the processed layer 12 is transferred to the substrate 11 in a similar manner by reactive ion etching. Note that the composition of the gas, the discharge power density, and the like during the reactive ion etching are the same as those for the reactive ion etching when examining the spatial change of the selection ratio in FIG. 2c.

As described above, the processing layer 12 is processed in consideration of the spatial change of the selection ratio in advance, thereby obtaining the diffraction lens 14 having the diffraction grating with a constant groove depth as shown in FIG. 5d. You can

According to this embodiment, when the processing layer 12 which is easy to machine is machined and the diffraction lens 14 is manufactured by the etching process, the groove depth formed in the processing layer 12 is set to the surface of the selection ratio. Since it is decided based on the internal distribution, the desired groove depth (in the case of FIG. 5, a constant groove depth)
The diffractive lens 14 having the diffractive grating can be obtained.

Further, the recent numerical control processing machine has a processing accuracy of submicron and can process a desired shape with extremely high accuracy, and the shape is transferred to the substrate 11 by anisotropic etching. It is possible to manufacture a diffractive optical element having an accurate shape. Further, by changing the processing data, not only the above-mentioned diffraction grating having a constant groove depth, but also various shapes of optical elements such as Fresnel lenses can be easily obtained.

Although Al (aluminum) is used as the material of the processing layer 12 in the above description, another material that is easily machined, such as resin or a metal that is easily machined, is used. You can Also, the material of the substrate 11 is
In addition to quartz, SiO ₂ glass, CaF ₂ or the like can be used, and at this time, the surface of the formed diffractive lens can be coated with Al or the like to form a reflective diffractive lens. The material of the substrate 11 is molybdenum (Mo) or silicon carbide (Si).
A reflective diffractive lens can also be obtained by using C) or the like. Further, the shape of the substrate 11 is not limited to a plano-convex lens shape in which one surface is a flat surface and the other surface is a spherical surface, and other shapes, for example, various shapes such as both spherical surfaces or both aspherical surfaces are available. can do.

As a case where the selection ratio changes within the plane, the case where one side of the substrate is a spherical surface has been mentioned. For example, even when the performance of the etching apparatus is poor and the shape of the substrate is a plane parallel plate, it is selected depending on the place. When the ratio changes, the in-plane distribution of the selection ratio is similarly obtained, and the processed layer is processed, whereby an optical element having a desired surface shape can be manufactured.

Further, in the above description, the selection ratio is (2)
Although it is obtained according to the equation, it can be obtained according to the equation (1). In this case, it is necessary to obtain the etching rates of the processed layer and the substrate, respectively. Therefore, first, regarding the case of obtaining the in-plane distribution of the etching rate of the processed layer,
This will be described with reference to FIGS.

First, as shown in FIG. 6a, the processing layer 12 is formed on the substrate 11 with a predetermined thickness t to a position slightly outside the effective diameter φ _e as an optical element. Next, as shown in FIG. 6B, the mask 21 is placed on the region of the substrate 11 where the processed layer 12 is not formed. The thickness of the mask 21 is preferably substantially the same as the thickness t of the processed layer 12. Thereafter, as shown in FIG. 6c, anisotropic etching is performed for a certain period of time. After the etching is completed, the mask 21 is removed, and FIG.
In the state shown in (1), the thickness of the processed layer 12 is measured by using a measuring instrument such as a stylus type step gauge, an atomic force microscope or an interferometer. In this way, when the thickness of the processed layer 12 at each measurement point is measured, the measured value at each measurement point and the original thickness t
Is divided by the etching time to obtain the in-plane distribution of the etching rate of the processed layer 12.

Next, the case of obtaining the in-plane distribution of the etching rate of the substrate will be described with reference to FIGS.
First, as shown in FIG. 7A, a donut-shaped mask 21 is placed on the substrate 11. The mask 21 has the same outer diameter as the substrate 11 and has an inner diameter slightly larger than the effective diameter φ _e as an optical element. Next, as shown in FIG. 7b, anisotropic etching is performed for a certain period of time. After that, as shown in FIG. 7c, with the mask 21 removed, the measuring device with the upper surface 11a of the region where the mask 21 was placed as the origin,
For example, the etched surface (depth) is measured by a stylus type step gauge. After the depth at each measurement point of the substrate 11 is measured in this manner, the measurement value at each measurement point is divided by the etching time to obtain the in-plane distribution of the etching rate of the substrate 11.

In FIG. 6 and FIG. 7, the substrate 11 is a parallel plate for the sake of clarity.
Even when 1 has a curved surface, the respective etching rates can be obtained from the above method.

If the etching rates of the processed layer and the substrate are obtained in this way, there are advantages as described below. For example, it is assumed that the etching rate of the processed layer changes from the center to the radial direction as shown in FIG. In this case, in order to simplify the drawing, a parallel plane plate will be described as an example. As shown in FIG. 9A, when the shape formed on the processing layer 12 is transferred to the substrate 11, the surface of the etching rate of the processing layer 12 is reduced. As shown in FIG. 9B, the time when the etching of the processed layer 12 is finished differs depending on the location, depending on the internal distribution. Therefore, if the entire surface of the processing layer 12 is etched, an error will occur in the coordinates of the diffraction grating in the etching direction, as shown in FIG. 9c. In this case, considering the selection ratio, the processing layer 1
It is not enough to determine the depth of the groove formed in 2.

Therefore, in order to eliminate such a deviation in the etching direction, the etching is simultaneously completed on the entire surface of the processing layer 12 as shown in FIG. 10 based on the etching rate of the processing layer shown in FIG. The machining layer 12 is machined. The groove depth in each diffraction grating at this time is calculated based on the selection ratio.

In the second embodiment of the present invention, the mold used for manufacturing the diffractive optical element is manufactured. Therefore, in this embodiment, first, as shown in FIG. 11A, a resin, for example, a resist, is formed on the curved surface side of the substrate 31 made of Ni (nickel) made of a flat surface and a curved surface (convex surface) having a predetermined curvature. The processed layer 32 is formed with a predetermined thickness t. here,
When the processing layer 32 is made of resin, it can be formed by using a spin coater or the like, and the processing layer 32 can be made to have a hardness suitable for the subsequent steps by selecting baking conditions at that time. it can.

Next, the processed layer 32 is machined into a shape having a predetermined depth distribution, for example, a blaze shape. here,
When the mold manufactured in this example is used to manufacture an optical element having a ring pattern, for example, a diffractive lens, as shown in FIG. 11b, a cutting machine, for example, a numerically controlled lathe machine (see FIG. Machining layer 3 as a work (not shown)
The substrate 31 on which 2 is formed is attached, the cutting tool 33 is moved based on the processing data while rotating the work, and the processing layer 32 is cut. Note that the processing data at this time is the same as in the first embodiment, and the etching rate distribution or the selection ratio distribution of the substrate 31 and the processing layer 32 is obtained in advance, and the substrate after anisotropic etching is processed based on the obtained distribution. A desired shape is formed on 31.

Thereafter, as shown in FIG. 11C, anisotropic etching is performed to change the shape of the processed layer 32 to the substrate 31.
To obtain a master master 34 as shown in FIG. 11d. The anisotropic etching may be, for example, etching using reactive gas plasma such as reactive ion etching, plasma etching, reactive ion beam etching, ion beam etching, sputter etching, or microwave plasma etching. However, it is suitable in terms of controllability of selection ratio and anisotropy.

Next, as shown in FIG. 11e, a conductive metal such as nickel is deposited on the surface of the master disk 34 by a method such as sputtering or vapor deposition to form an electrode body 35, and then as shown in FIG. 11f. Then, electroforming is performed to form the nickel electroformed layer 36. Then, the nickel electroformed layer 36
To obtain a mold.

According to this embodiment, since the working layer 32 is machined, it is possible to perform processing with extremely high precision, and therefore, it is possible to manufacture the master master 34 having an accurate shape, and at the same time, to the master master 34. By electroforming, faithfully follow the shape of the master master 34 and mold 36
Since it is manufactured, a highly accurate mold 36 can be obtained.

Although the resist is used as the processing layer 32 in the second embodiment, it is also possible to use another metal or the like which can be easily machined. Further, the substrate 31 is not limited to Ni, but quartz, SiO ₂ glass, or the like can be used. Furthermore, not only for the mold for the diffractive lens, but also for general diffraction gratings and so-called Fresnel lens molds,
It can be manufactured in a similar manner.

In the third embodiment of the present invention, using the mold 36 manufactured in the second embodiment, a diffractive optical element is manufactured by, for example, known injection molding of plastic or the photopolymer method (2P method). . Thus, if a diffractive optical element is manufactured using the mold 36 manufactured in the second embodiment,
As described above, the precision of the mold itself is high, so that it is possible to manufacture a large number of optical elements having an accurate shape.

Here, the photopolymer method (2P method) is
An ultraviolet-curable resin (photopolymer) layer is formed on a transparent substrate, a mold is pressed against the resin, and the resin is cured by irradiating ultraviolet rays, thereby manufacturing an optical element, which has no temperature cycle. Therefore, as compared with the case where an optical element is manufactured by injection molding, there is an advantage that the life of the mold can be prolonged because the process is shortened and birefringence and coma are less likely to occur.

In the fourth embodiment of the present invention, a mold used for manufacturing a diffractive lens is manufactured. For this reason,
In this embodiment, first, as shown in FIG. 12a, Cr ₂ composed of a flat surface and a spherical surface (concave surface) having a predetermined radius of curvature is used.
On the spherical surface side of the substrate 41 made of O ₃ (chromium oxide), a processing layer 42 made of a resin, for example, a resist is formed with a predetermined thickness t.

Next, as shown in FIG. 12b, a substrate 41 having a processing layer 42 formed thereon as a work is attached to a cutting machine such as a numerically controlled lathe type machine, and the tool is rotated based on the processing data while rotating the work. Move 43,
The processing layer 42 is machined into a shape having a predetermined depth distribution, for example, a blaze shape. The processing data at this time is the first
As in the embodiment, the etching rate distribution or the selection ratio distribution of the substrate 41 and the processing layer 42 is obtained in advance so that a desired shape can be obtained on the substrate 41 after the anisotropic etching process. create. In addition,
In this embodiment, the shape of the processed layer 42 is the shape of the diffractive surface of the diffractive lens to be manufactured.

Thereafter, as shown in FIG. 12c, anisotropic etching, for example, argon ion etching is performed,
The shape of the processed layer 42 is transferred to the substrate 41 in a similar manner in the depth direction to obtain a diffractive lens mold 44 as shown in FIG. 12d.

Here, the argon ion etching means
This is a method in which argon ions accelerated by a high voltage are made to collide with the surface of the material, whereby the material atoms are repelled to scrape the surface, and etching is mainly performed by physical action. Therefore, this argon ion etching has the following features. 1. Since the material selectivity of the etching rate is lower than that of the chemical etching, it is possible to etch a material having a high chemical resistance such as platinum or rhodium. 2. Since it has essentially high anisotropy, high processing accuracy can be obtained.

According to this embodiment, the machining layer 42, which is easy to machine, is machined and the shape thereof is transferred to the substrate 41 by etching to manufacture the mold 44. Therefore, the substrate 41 is finely machined. Materials that cannot be processed into shapes with high precision, such as glass molding die materials (WC, SiC)
Even in the case of etc.), a highly accurate diffraction grating pattern can be formed on the substrate 41. Therefore, it is possible to obtain a mold for manufacturing a diffractive lens made of, for example, glass by press molding with an extremely simple process.

Further, since the machining layer 42, which is easy to machine, is machined, it is possible to easily obtain a shape having a desired depth distribution, and recent numerical control machining machines have submicron machining accuracy. Therefore, a desired shape can be obtained with extremely high accuracy. Moreover, since the shape of the processing layer 42 is transferred to the substrate 41 in a similar manner by anisotropic etching, the processing layer 42 can be machined with high accuracy, and the mold 44 with extremely high accuracy can be manufactured. .

In this embodiment, the processing layer 42 is made of resin, but other easily machined materials such as metal such as Al can be used. The substrate 41 is also made of Cr ₂ O.
Not limited to ₃ , WC (Dungsten Carbide), SiC
(Silicon carbide) or the like can also be used. However, in the case of using WC or SiC, it is desirable to coat the surface with platinum, TiN, or the like in order to prevent fusion with the glass when manufacturing the diffractive lens made of glass.

In the fifth embodiment of the present invention, the mold 44 manufactured in the fourth embodiment is used as a part of a mold for a diffractive lens to manufacture a diffractive lens made of glass. Therefore, in this embodiment, as shown in FIG.
The optical glass 46 formed in the general shape of the diffractive lens to be manufactured is placed on the lower mold 45, the optical glass 46 is heated to the glass softening point or higher, and then the mold manufactured as the upper mold in the fourth embodiment. The optical glass 46 is pressure-molded by using 44, and thereby a diffractive lens made of glass is manufactured. The lower mold 45 is formed by polishing the upper and lower surfaces of a cylinder containing WC (tungsten carbide) as a main component into mirror surfaces, and coating the upper surface with platinum for preventing fusion between the glass and the mold. .

According to this embodiment, a large number of diffractive lenses can be manufactured by a simple process, and the most important mold 44 for forming the diffraction grating has extremely high precision as described above, and therefore, accurate manufacturing is possible. A diffractive lens having a shape can be manufactured.

In this embodiment, the mold 44 is used as the upper mold and the glass is pressed to manufacture the optical element. However, another method using the mold, for example, a method of injection molding plastic or The optical element can also be manufactured by a commonly used method such as a photopolymer method (2P method) using an ultraviolet curable resin.

In the fifth embodiment, the diffractive lens is manufactured, but a general diffraction grating or a so-called Fresnel lens can be manufactured in the same manner.

In the first, second and fourth embodiments,
The machining layer was machined to obtain the desired shape,
The processing layer can be processed by methods other than mechanical processing, such as drawing with an electron beam or ion beam.At that time, the processing data can be created by taking the distribution of the selection ratio into consideration. The desired shape can be formed on the substrate by anisotropic etching of.

Appendix 1. A step of forming a processing layer on the object to be processed, a step of processing the processing layer, and anisotropically etching the processing layer and the object to be processed, the shape of the processing layer on the surface of the object to be processed. And a step of forming the same in the depth direction,
In the step of processing the processing layer, a desired shape is formed on the surface of the processing object based on the distribution of the etching rates of the processing object and the processing layer in a plane orthogonal to the etching direction by the anisotropic etching. A method for generating a surface shape of an object, characterized in that the processing layer is processed so as to generate. 2. The method of generating a surface shape of an object according to attachment 1, wherein the object to be processed is an optical member. 3. A step of forming a processing layer on the object to be processed, a step of processing the processing layer, and anisotropically etching the processing layer and the object to be processed, the shape of the processing layer on the surface of the object to be processed. In the step of processing the processing layer, the method has a step of forming the processing layer in a similar manner, and a step of forming a mold by using the object to be processed in which the shape of the processing layer is formed as a master disc. Based on the distribution of the etching rates of the object to be processed and the processing layer in a plane orthogonal to the etching direction by anisotropic etching, a desired shape is generated on the surface of the object to be processed, A method for manufacturing a mold, comprising: 4. A step of forming a processing layer on the object to be processed, a step of processing the processing layer, and anisotropically etching the processing layer and the object to be processed, the shape of the processing layer on the surface of the object to be processed. And a step of forming the same in the depth direction,
In the step of processing the processing layer, a desired shape is formed on the surface of the processing object based on the distribution of the etching rates of the processing object and the processing layer in a plane orthogonal to the etching direction by the anisotropic etching. So that the processed layer is processed so that the object to be processed obtained by the anisotropic etching is at least a part of the mold. 5. In the method of manufacturing a die according to Appendix 3, the step of forming the die includes a step of forming an electrode body made of a conductive metal on the object to be processed, and an electroforming process using the electrode body as an electrode by electroforming. A method of manufacturing a mold, comprising: a step of forming a layer; and a step of peeling the electroformed layer from the object to be processed. 6. The method according to any one of Additions 1 to 5, wherein the step of processing the processing layer is mechanical processing. 7. In the method according to any one of Supplementary Notes 1 to 6, the processing of the processing layer is performed by examining a distribution of etching rates of the object to be processed and the processing layer in a plane orthogonal to an etching direction by the anisotropic etching, and A method characterized in that processing data created in advance based on distribution is used. 8. In the method according to Appendix 7, in examining the etching rate distribution of the object to be processed and the processing layer,
Assuming that the etching rate of the object to be processed and the processing layer is constant, the step of processing the processing layer, the step of measuring the surface shape of the processed processing layer, the step of performing anisotropic etching, And a step of measuring the surface shape of the object to be processed formed by anisotropic etching. 9. A method for manufacturing an optical element, which comprises manufacturing an optical element using the mold manufactured by the method according to any one of Supplementary Notes 3 to 8. 10. An optical element or a mold manufactured by the method according to any one of appendices 2 to 9.

[0070]

As described above, according to the method for generating the surface shape of an object of the present invention, the distribution of the etching rates of the object to be processed and the processing layer in the plane perpendicular to the etching direction is taken into consideration in advance, Since the processing layer is processed, a desired surface shape can be accurately generated on the object to be processed.

Also in the mold manufacturing method of the present invention, similarly, the processed layer is processed in consideration of the distribution of the etching rates of the object to be processed and the processed layer in the plane perpendicular to the etching direction. Since this is done, the desired surface shape can be accurately generated on the object to be processed. Therefore, a high-precision mold can be obtained by manufacturing a mold by using this processed object as a master master, and by using this processed object as at least a part of the mold, high-precision mold can be obtained. A mold can be easily obtained, and by using the mold thus manufactured,
It is possible to mass-produce the desired optical element with an accurate shape.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the operation of the first invention.

FIG. 2 is a diagram for explaining a process of obtaining a selection ratio.

FIG. 3 is a diagram showing an example of a distribution of selection ratios.

FIG. 4 is a diagram showing a calculation result of a groove depth of a processed layer in consideration of distribution of selection ratio.

FIG. 5 is a diagram for explaining the first embodiment of the present invention.

FIG. 6 is a diagram showing a sequential process of obtaining an in-plane distribution of an etching rate of a processed layer.

FIG. 7 is a diagram showing a sequential process of obtaining an in-plane distribution of an etching rate of a substrate.

FIG. 8 is a diagram showing an example of an etching rate distribution of a processed layer.

FIG. 9 is a diagram for explaining a defect due to the distribution of the etching rate of the processed layer.

FIG. 10 is a diagram showing an aspect in which the processed layer is processed in consideration of the distribution of the etching rate of the processed layer.

FIG. 11 is a diagram for explaining the second embodiment of the present invention.

FIG. 12 is also a diagram for explaining the fourth embodiment.

FIG. 13 is also a diagram for explaining the fifth embodiment.

FIG. 14 is a diagram for explaining a defect due to the distribution of the etching rates of the object to be processed and the processing layer.

[Explanation of symbols]

 1 Object to be processed 2 Processing layer 3 Diffractive optical element 11, 31, 41 Substrate 12, 32, 42 Processing layer 13, 33, 43 bytes 14 Diffractive lens 21 Mask 34 Master master 35 Electrode body 36 Nickel electroformed layer 44 Mold 45 Lower mold 46 Optical glass

Claims (3)

[Claims] 1. A step of forming a processing layer on an object to be processed, a step of processing the processing layer, anisotropically etching the processing layer and the object to be processed,
A step of forming the shape of the processing layer on the surface of the object to be processed in a depth direction in a similar manner, and in the step of processing the processing layer, a plane orthogonal to an etching direction by the anisotropic etching. The surface shape of the object is characterized in that the processing layer is processed so that a desired shape is generated on the surface of the processing object based on the distribution of the etching rates of the processing object and the processing layer. Generation method. 2. A step of forming a processing layer on an object to be processed, a step of processing the processing layer, anisotropically etching the processing layer and the object to be processed,
A step of forming the shape of the processing layer on the surface of the object to be processed in a depth direction, and a step of forming a mold by using the object having the shape of the processing layer as a master master. Having the step of processing the processing layer, based on the distribution of the etching rate of the object to be processed and the processing layer in a plane orthogonal to the etching direction by the anisotropic etching, on the surface of the object to be processed. A method for manufacturing a mold, comprising processing the processing layer so as to generate a desired shape. 3. A step of forming a processing layer on a processing object, a step of processing the processing layer, anisotropically etching the processing layer and the processing object,
A step of forming the shape of the processing layer on the surface of the object to be processed in a depth direction in a similar manner, and in the step of processing the processing layer, a plane orthogonal to an etching direction by the anisotropic etching. Based on the etching rate distribution of the object to be processed and the processing layer in, the processing layer is processed so that a desired shape is generated on the surface of the object to be processed, and is obtained by the anisotropic etching. A method of manufacturing a mold, wherein the object to be processed is at least a part of the mold.