JP2007003921A - Method for manufacturing fine optical aspherical lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently manufacturing a fine optical aspherical lens typified by, such as a microarray lens with many fine lens-shaped parts are arranged on one surface, in a short time. <P>SOLUTION: In the case of forming the fine optical aspherical lens, a plurality of masks M of a three-dimensional lens shape are arranged on a material to be processed, and the mask itself is gradually shaved by etching in the aforesaid state; then a primary lens-shaped part is produced, and next each lens-shaped part is modified and finished by applying a beam-working on each lens-shaped part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing an optical aspherical lens group having a minute size such as a microlens array.

In recent years, optical components with fine dimensions, for example, micro-convex lens arrays and individual lenses for high-density applications such as DVDs, which record minute data using light and read recorded data, are manufactured industrially. The demand to do is increasing.
Conventionally, as a method for manufacturing a fine shape, a focused ion beam processing method is known in which a sample is sputtered using a finely focused ion beam. However, in this method, since the lens shape is removed one by one from the block-shaped or plate-shaped sample, it takes a lot of time to process a large number of samples, resulting in a high manufacturing cost. . In practice, it is not a three-dimensional shape, it can only be processed in 2.5 dimensions, and at the same time, the etching mask has a flat surface (flat plate). Had a problem of 2.5 dimensions.
Japanese Patent Laid-Open No. 6-349784 JP 2002-226290 A JP 2003-68720 A JP 2002-75960 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical aspheric lens product in which a large number of convex and concave curved lenses are arranged on one surface. It is to provide a method that can efficiently create a file in a short time.

  In order to achieve the above object, the present invention provides a plurality of masks having a three-dimensional lens shape on a work material in order to produce a fine optical aspheric lens, and the mask itself is gradually removed by etching in this state. It is characterized in that a primary lens-shaped product is made by cutting and then beam processing is performed on the lens-shaped portion.

  According to the present invention, the shape of the mask is not a flat plate but a three-dimensional lens before etching, and ion etching is performed on the mask so that the etching rate between the mask and the workpiece (the workpiece and the mask Since a large number of three-dimensional lens shapes are created on the workpiece using the different ratios to be removed, the processing time for the next beam processing can be shortened, and the precision is fine. The manufacturing cost of such an optical aspheric lens can be reduced. For this reason, for example, a high-density crystalline micro-convex lens array or lens for DVDs can be easily manufactured at low cost.

Any of the following is suitable for the lens-shaped mask.
1) Created by melting a metal flat mask, shaping the surface into a lens shape by surface tension, and cooling and solidifying.
2) A microlens array or the like is transferred to create a reversal mold, the mold is filled with a mask metal to create a lens-shaped metal body, and only the metal body portion is pasted on the workpiece.
3) It is a lens-shaped optical modeling product in which the optical modeling resin is modeled at multiple points by a multi-point optical modeling apparatus.
According to these, a mask having a three-dimensional lens shape suitable for producing a fine optical aspheric lens can be easily manufactured.

Examples of the beam processing method for the primary lens-shaped product include the following modes.
First aspect:
Using the main body of the beam irradiation device and secondary electron detectors arranged at two or more locations in the vicinity of the irradiation beam, secondary electrons or secondary ions emitted from the processing point during the processing by the irradiation beam are extracted at the two locations. By simultaneously taking in the above secondary electron detector, the information of the three-dimensional shape of the machining surface is measured, the machining acceleration of the beam at each machining coordinate is measured from the shape measurement information of the machining surface, and the remaining machining distance Processing time is calculated and beam processing is performed up to a desired position in the depth direction.
Second aspect:
When beam processing is performed on a primary lens shape product, the lens shape to be processed is created by CAD, the CAD data is processed by CAM, CL data is created, and the output pitch of the CL data is divided into multiples to obtain XYZ Create point cloud data of coordinates, and use the secondary electron detector located in the vicinity of the beam irradiation device main body and the irradiation beam, and perform beam processing using the point cloud data and calculate the beam residence time at each coordinate. Control.
Third aspect:
When beam processing is performed on a primary lens shape product, the lens shape to be processed is created by CAD, a mesh is created on the image created by the CAD data at a predetermined pitch, and XYZ coordinate data is read from the coordinates of the intersection of the mesh Point beam data is created by using the beam irradiation device main body and a secondary electron detector arranged in the vicinity of the irradiation beam, and the beam time at each coordinate is controlled while performing beam processing using the point cloud data. A method for producing a micro-optical aspherical lens according to claim 1.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIGS. 1 to 3 show a process for obtaining a primary lens-shaped product.
In FIG. 1, reference numeral 3 denotes a workpiece, and an amorphous material such as glass, which is a melt softening material, can be transferred by a mold, so that it is usually crystalline, such as single crystal diamond, single crystal ruby, single crystal. Crystal silicon, single crystal sapphire, etc. The material form is arbitrary, such as a block, a plate, a sheet, and a film, and the planar size is also arbitrary, but the diameter is usually 15 cm or less.
According to the present invention, in this step, a mask M having a three-dimensional lens shape is disposed at a lens processing scheduled position in the workpiece 3. In this example, since it is a convex lens, it has a surface m 1 having a required curvature and a flat bottom surface m 2, and the flat bottom surface m 2 is fixed to the processing scheduled surface of the workpiece 3.

The three-dimensional lens shape mask M is preferably made of a metal such as aluminum or an alloy thereof, but an optical modeling resin can also be used. The manufacturing method of such a three-dimensional lens shape mask M is arbitrary, but some examples are as follows.
The first method is a method of creating a lens-shaped metal mask by melting a metal flat mask by heat treatment, forming the surface into a lens shape using the surface tension of the metal, and cooling and solidifying the surface.
More specifically, a metal 3 such as aluminum is deposited on the surface of the workpiece 3 such as diamond by a method such as vapor deposition, sputtering, and bonding, and then photolithography or the like (photolitho film coating, drawing, The description of the etching process is omitted), and circular masks M ′ are created so as to be scattered on the workpiece 3 as shown in FIG.

Thereafter, the workpiece 3 and the circular mask M ′ are heated in a vacuum state to melt the mask constituent metals simultaneously. The mask constituent metal (aluminum in this example) is melted and at the same time has a lens shape with a convex center part due to surface tension. This is the state shown in FIG.
The use of aluminum as a mask material is advantageous in that a high etching rate can be obtained because oxygen plasma etching is often employed when the workpiece is diamond. Further, it is easy to coat an aluminum thin film or finely process it by photolithography, etc., and then it can be easily melted and formed into a lens shape using surface tension.

The contact angle θ of the molten metal is determined by the properties of the interface between the diamond and the molten aluminum. By plasma-treating the diamond surface, the contact angle θ of the material surface can be increased or decreased as shown in FIG. You can do it.
The contact angle can be controlled by changing the gas for generating plasma, and the contact angle can be changed in a wide range by changing the gas flow ratio by using a mixed gas.

However, the actual mask thickness may be about one-tenth of the desired lens thickness if the etching rate is night and the etching rate is 10. That is, the calculation method of the thickness of the mask, when fabricating a hemispherical mask as a maximum, the volume becomes 2.pi.r ^3/3 (half the volume of a sphere). When the height of the cylinder for producing this volume is calculated, it becomes 2r / 3. However, as described above, the thickness of the mask may be about 1/10 of the one that changes depending on the etching rate. If the desired lens thickness is r, it is as small as 2r / 30. Therefore, it is not necessary to increase the contact angle θ so much, and 0.1 to 9 degrees is sufficient, so that the manufacture is easy.

Second method: a method of producing a lens-shaped metal mask by transfer.
Explaining the process, the existing microlens array ML (resin material, glass, etc.) is used as a model as shown in FIG. 6 (a), and the lens shape is shown in FIG. 6 (b) by electroforming transfer method. 6 is manufactured and released from the mold as shown in FIG. 6C, and a mask metal such as aluminum is formed in the cavity 120 with respect to the mold 12 as shown in FIG. 6D. The mt is filled by an arbitrary method such as vapor deposition, sputtering, or casting, and transferred to the surface of the workpiece 3 such as diamond as shown in FIGS.
In this mask manufacturing method, the shape of the mask can be obtained by transfer processing into a desired shape, so that the shape accuracy of the lens shape portion of the workpiece after etching can be increased, and the beam for correction and finishing There is an advantage that processing can be reduced.

Third method: A lens-shaped stereolithography product obtained by modeling a stereolithography resin such as a photocurable resin or a photoresist film with a multipoint stereolithography apparatus at multiple points is used. That is, a photo-curing resin or a resin of a photoresist film is used, and the shape of this resin is processed into a three-dimensional lens shape and used as a mask.
More specifically, as this method, a photocurable resin is sprayed at multiple points by an ink jet method, and the sprayed optical modeling resin becomes a lens shape due to the surface tension. The aspect which obtains the lens shape mask which the shape solidified is mentioned.

It is also possible to make a lens-shaped mask by stereolithography. However, since the size of the spot diameter of the laser beam is large (about 100 microns) in a general stereolithography apparatus, it is impossible to form a small lens shape with a diameter smaller than the spot diameter in additive manufacturing. Using a thin-film stereolithography apparatus with a small diameter, a micro-size lens-shaped stereolithography mask is prepared. Since these stereolithography products have a stacking pitch, there are steps on the surface. Etching using this mask is roughing, and then ion beam processing is performed to finish the lens with high accuracy. , The effect of steps is not a problem.
However, since a resin thin film for stereolithography and photolithography is damaged and disappears immediately at the time of oxygen plasma etching, a method that does not use oxygen radicals as a main etching species may be employed in dry etching. In this case, the resist mask can be used as an etching mask for dry etching of diamond.

  In addition to the inkjet method and dispenser method described above (a method in which a photocurable resin is dropped one by one on the tip of the needle at the desired location), a cylindrical photoresist film is heated and melted. Thus, it is possible to select a method of forming a lens shape by utilizing the surface tension of the resin and a method of forming a lens shape by stacking by optical modeling.

  In the present invention, the three-dimensional lens shape mask M manufactured as described above is arranged at multiple points on the workpiece 3, and the three-dimensional lens shape mask M and the other portions are used as shown in FIGS. By etching the exposed workpiece 3 with the etching element E until the solid lens shape mask M disappears, the height approximate to the thickness of the target lens as shown in FIG. A primary lens shape product 3 ′ having a thickness (H) and having a lens shape portion 30 having a curved surface 300 approximate to the curvature of a lens to be manufactured is created.

Specifically, the etching includes a wet etching method using a reactive reagent and a dry etching method using a gas, that is, a dry etching method using low-vacuum plasma, but the latter is preferably used. It was used a reactive gas (CF _4, CCl _4, etc.) active species reaction products having volatile reacted on the surface of the processed material (CF _4, CCl ₄ and halogen gas at the plasma In some cases, a halogen compound) is generated and etched away from the surface of the workpiece, so that isotropic processing is achieved by processing accuracy, plasma directionality, adhesion between the mask and workpiece material, etc. It is recommended because it is excellent.

When dry etching is reactive ion etching, the workpiece 3 shown in FIG. 1 is placed in a chamber, and a necessary reaction gas is introduced in a state where the pressure is reduced to a vacuum. When a high frequency electric field is applied to the electrode outside the chamber, plasma is generated, and highly reactive species (radicals) are generated. When the workpiece 3 is diamond, oxygen can be generated and etched by using oxygen as a reaction gas. That is, the gas is turned into plasma, and in the plasma, charged particles such as positive and negative ions and electrons, neutral active species, and the like are present in a dispersed state. When the etching species are adsorbed on the workpiece, a chemical reaction occurs on the surface, the product is detached from the surface and exhausted to the outside, and etching proceeds.
Since such etching can remove a large area at a high speed at a time, it is possible to efficiently manufacture a primary lens shape product 3 ′ having a large number of 2.5-dimensional curved lens shape portions 30.

Explaining the etching mechanism, when oxygen plasma etching is performed on a workpiece made of diamond, aluminum is transformed into alumina during processing by using aluminum as a mask material, and the etching rate for oxygen plasma etching is increased. improves.
In this case, when the mask shape is flat, the etching rate between the diamond and the mask is about 20 at the maximum. The etching rate of diamond is about 1 micrometer / hour although it depends on gas conditions. This indicates that if the mask thickness of aluminum is 1 micrometer, diamond can be etched by about 20 micrometers. When the mask disappears completely by etching, the shape of the workpiece remains the same even though the entire workpiece is relatively thin even if etching is continued. The present invention takes advantage of these properties.

In the present invention, the mask M is not a flat film shape but a three-dimensional lens shape. A part of this is microscopically as shown in FIG. That is, as shown in FIG. 3A, the mask M1 having a mask thickness of 1 micrometer and a diameter of 100 micrometers and the mask M2 having a diameter of 50 micrometers are aligned on the diamond surface and etched. Corresponds to the case. As the etching proceeds, the mask M1 disappears by etching as shown in FIG. 3B, and the mask M2 below the mask M1 remains on the diamond in the same shape as the mask M1.
The unmasked portion of diamond is removed by a certain thickness by ion etching, and the portion covered with the mask M2 remains without being etched. Further, by continuing the ion etching, the remaining portion of the mask M2 is removed by etching as shown in FIG. 3C, but the portion not covered with the mask is removed by the etching. Although the shape varies depending on the etching rate, the shape of the mask is transferred to diamond, and the lens shape is created by increasing this step and reducing the thickness of the mask. Is gradually reduced by etching, but the diamond etching also proceeds, and the workpiece 3 is etched into a lens shape, resulting in a primary lens shape product 3 'in FIG.

However, it is difficult to perform processing with the desired shape accuracy by this etching because there is a difference in removal amount with respect to the inclined surface due to the crystal orientation of the workpiece.
Therefore, in the present invention, as the next step, the primary lens shape product 3 ′ is corrected to the target lens shape by beam processing and finished. FIG. 7 schematically shows this finished state, and all or part of the height (thickness), surface roughness, and curvature of the primary lens shape product 3 ′ by etching indicated by the dotted line is corrected and finished. The lens product 3S interspersed with the curved lens-shaped portions 30S having the finishing curvature 300S indicated by the solid line is obtained. FIG. 8A shows the entire product. When individual products 3S such as micro-convex lenses are desired as shown in FIG. 8B, the product may be cut at a position indicated by a dotted line in FIG. 8A.

This beam processing method has three modes, which will be described in detail below.
[Beam machining first method]
FIG. 9 to FIG. 12 show this method, which is characterized in that three-dimensional beam finishing is performed on each lens shape portion 30 created by etching using two electron detectors. Yes, by using two electron detectors, it is possible to obtain the processing depth by calculating the difference between the speeds of secondary electrons and secondary ions that reach the detector at the same time. Can do.

  9 and 10 show an outline of the apparatus and method. Reference numeral 1 denotes a vacuum chamber, which is connected to the vacuum pump 10 via a valve 11. Reference numeral 2 denotes a main body of a beam irradiation apparatus disposed in the vacuum chamber 1, and a focused ion beam apparatus or an electron beam processing apparatus is used. The primary lens-shaped product 3 ′ obtained in the above process is placed on the stage 4 that is in a relative position facing the beam irradiation apparatus main body 2.

  As shown in FIG. 9B, the beam irradiation apparatus main body 2 includes a gallium ion source 20, a focusing lens 21, a blanking electrode 22, a diaphragm 23, an octupole aberration correction electrode 24, and a lens barrel. The objective lens 25 and the scanning deflector 26 are provided, and an ion beam (or electron beam, hereinafter referred to as a beam) 5 is irradiated from the front end to the lens shape portion 30 of the primary lens shape product 3 ′, thereby performing removal processing. It has come to be.

The beam irradiation apparatus main body 2 is intended to scan the beam 5 with the lens shape portion 30 of the primary lens shape product 3 ′ by moving the beam 5 freely in both X and Y coordinates by the scanning deflector 26. The curved surface shape is processed.
The stage 4 is tilted around the beam processing point 50 even if the primary lens-shaped product 3 ′ is tilted, and the processing point is maintained at the same position even when the primary lens-shaped product 3 ′ is rotated. Preferably, it consists of a eucentric mechanism.

6 and 6 'capture and detect secondary electrons (or secondary ions) emitted during beam processing, and a plurality of secondary electrons for monitoring the depth of the finished surface (machined surface). It is a detector.
Each of the secondary electron detectors 6 and 6 ′ is arranged such that the detection surface always faces the beam irradiation position of the beam irradiation apparatus body 2, that is, the processing point 50 with respect to the lens shape portion 30. It is fixed to the frame of the vacuum chamber 1. The signal output side is connected to a computer described later.

When there are two secondary electron detectors 6 and 6 ', they are usually arranged at positions displaced by 90 degrees or symmetrical positions by 180 degrees. By taking the difference between the electrons or ions generated in the respective directions by the secondary electron detectors 6 and 6 ', the inclination angle of the processed surface with respect to the irradiated ions or the electron beam is calculated, and the shape measurement is performed by integrating the angle. Done. That is, in principle, the secondary ion intensity or secondary electron intensity from the two detectors L and R at the surface tilt angle θ is a and b, and the secondary ion intensity or secondary electron intensity in vertical irradiation is ln. , Rn, and k being a proportional constant, the fact that tan θ = k (L ² −R ² ) / (Ln ² + Rn ² ) holds is used.

  Reference numeral 7 denotes a computer as a controller attached to the beam irradiation apparatus main body 2, and includes a control device 7a and a monitor 7b. The control device 7a includes a CAD function unit for creating desired lens shape data as shown in FIG. Based on this CAD data, it has a CAM function unit for creating machining data, that is, rough machining shape data, finishing machining shape data, and a beam locus.

  Further, the control device 7a measures the shape in order to drive and control the actual beam irradiation device main body 2 based on the processing data created by the CAM function unit and the detection signals from the secondary detectors 6 and 6 '. It has a function part, a processing speed calculation function part, a beam control function part, and a workpiece control function part. These are built in the form of hardware and / or software.

The shape measurement function unit and the processing speed calculation function unit receive the signal of the three-dimensional lens shape information from the secondary detectors 6 and 6 ′, and process the beam coordinates, the beam stay time at the coordinates, and the remaining processing distance. Performs various calculations such as time calculation.
The beam control function unit sends a signal to the X-axis direction moving device 8 and the Y-axis direction moving device 9 of the beam irradiation apparatus main body 2 based on the processing data to control the beam position and the staying time, and the beam irradiation apparatus main body 2 The beam intensity (acceleration voltage) is controlled by sending a signal to the ion gun or electron gun, and the beam position, dwell time or beam intensity is adjusted by signals from the shape measurement function unit and processing speed calculation function unit . The staying time and the beam intensity are parameters related to the machining depth, and the beam intensity (acceleration voltage) during a series of machining is usually fixed.
The undercut portion is for sending a signal to the stage 4 in accordance with the processing data or signals from the shape measurement function portion and the processing speed calculation function portion to control the position and inclination angle of the primary lens shape product 3′3. is there.

In addition, what is illustrated is only an example of the present invention, and is not limited thereto.
1) The beam 5 of the beam irradiation apparatus main body 2 and the primary workpiece 3 need to be moved relative to each other, and the beam of the beam irradiation apparatus main body 2 is usually moved in the X and Y axis directions for processing accuracy. When the accuracy is good, the primary workpiece side (stage) may be moved in the X, Y axis direction, or further in the Z axis direction, tilt direction, or the like.
2) The number of secondary detectors 6 and 6 'is not limited to two, but may be three or four.

3) The present invention is linked with CAD and CAM to create processing data. However, they are not necessarily limited to being performed inside the computer 7 attached to the beam irradiation apparatus main body 2, and the virtual lines in FIG. As described above, the data (CAD data, CAD conversion data, CAM data, point cloud data, etc.) may be exchanged on a network or via another medium.

  Next, the beam processing step will be described. Basically, the beam 5 is irradiated to the lens shape portion 30 which is the rough shape accuracy of the primary lens shape product 3 ′ by the beam irradiation apparatus main body 2, while the beam 5 is irradiated with X, Scanning is performed in both Y coordinates, and the stage 4 is moved as necessary to control the position and inclination angle of the primary lens-shaped product 3 ′.

  At this time, the time during which the processing beam 5 is applied to the lens shape portion 30 is controlled. The principle is that a stay time of a certain machining beam with respect to the lens shape portion 30 is T1, and that of the next machining beam is T2, and when T2 is longer than T1, the removal amount of the latter machining beam is increased. In the present invention, the curved surface of the lens shape portion 30 is corrected using the difference in processing amount.

  The number of beam irradiations on the processed surface may be one scan if the shape is relatively shallow, and in the case of deep, the removed “debris” is not removed from the processed part in one operation. Since there is a strong tendency to remain, machining with a plurality of times does not leave any machining residue on the machined surface, resulting in a good surface. The scanning may be zigzag or spiral. The latter can be realized by moving the stage 4 and rotating the primary lens-shaped product 3 ′.

  The present invention is normally executed by the program shown in FIG. 11, and based on data created by CAD / CAM, rough machining data is first created by CAD / CAM assuming rough machining by a strong beam. Based on this, high-speed removal processing with a strong beam is performed by the beam control function unit, and then the beam is switched to a weak but accurate beam with a small spot diameter, and the processed surface is finely finished. Furthermore, it is possible to cope with design changes by linking with CAD / CAM.

  In addition, in the present invention, two or more secondary detectors 6 and 6 'are attached to the beam irradiation apparatus body 2 to detect secondary ions or secondary electrons emitted during processing simultaneously with the beam processing. The processing depth of the processing surface is monitored, the beam position, the staying time or the beam intensity is adjusted based on the detection result, and a signal is sent to the stage 4 so that the position and inclination of the primary lens shape product 3 'are sent. Control the corners.

More specifically, high-precision machining can be realized if the machining can be performed while measuring the coordinates of the beam tip in the beam machining. In order to detect this beam processing position, the beam is scanned and three-dimensional shape data must be calculated from the difference in shape data by two or more secondary electron detectors. The beam processing position cannot be detected.
In machining, the tip position of the tool is maintained at a constant position unless the machine is moved. However, in the case where removal processing is performed with the beam 5, the removal progresses depending on the irradiation time of the beam 5 without moving the beam 5. Further, the removal efficiency differs between when the beam is irradiated on a flat surface and when the inclined surface is irradiated. These are factors that make it difficult to process into a three-dimensional shape with high accuracy.

  Therefore, the present invention provides a plurality of secondary electrons, secondary ions, etc. emitted from a beam used for processing during processing in order to process a target shape including an inclined surface in beam processing. The surface shape is measured by the detectors 6 and 6 ', and the depth at each coordinate is measured from the difference. In addition, the measurement of the surface shape is performed twice or more, the processing acceleration at each coordinate including the inclined surface is obtained by these two surface shape measurements, and the processing energy of each coordinate for processing into the final target shape, that is, each Processing is performed by predicting the stay time of coordinates.

More specifically, 300S shown in FIG. 7 is set as a machining target shape. This shape may be a target shape for roughing by CAD, or may be a final shape when roughing is not required.
Assume that the depth is machined from the curved surface shape before machining indicated by the broken line to the shape of 300S by changing the stay time or beam intensity of the machining beam. First, a beam scan of the machining surface is performed at this time, and the machining shape of the entire surface is measured by the secondary detectors 6 and 6 ′ in order to measure the machining depth with respect to the position. At this time, it is preferable to weaken the beam intensity in order to avoid processing by the shape measurement beam.

In addition, when it becomes necessary to proceed with machining under the same machining conditions (beam stay time and machining time T), the machining shape of the entire surface in the state after the second machining is similarly measured.
Based on the difference between the machining speeds (v1 = dA / dt) and (v2 = dD / dt) due to these several removal processes, the machining speed calculation function unit performs machining acceleration {(v2-v1) for each coordinate. / Dt} is calculated. Based on the obtained machining acceleration, the machining time for the remaining machining allowance is predicted, and the beam control function unit performs control so that the subsequent beam stay time is changed to the target machining amount.

Especially in beam processing, the removal rate differs between the flat part and the inclined part even with the same intensity beam, and the removal amount increases in the inclined part. Therefore, it is essential to measure the shape in the removing process including the inclined part.
When the above-described processing is rough processing, the finishing process is performed by further reducing the beam intensity with respect to the finishing allowance Δt, that is, by reducing the spot diameter of the beam 5. However, since the beam also changes with respect to Δt, the above-described machining is performed twice or more, and the machining acceleration for each coordinate is similarly calculated to perform the finishing machining.

Note that, at the time of measurement by the secondary detectors 6 and 6 ', it is preferable to perform scanning while reducing the beam intensity to such an extent that removal processing by the beam is not performed.
Although the number of times to measure the machined surface was described as 2 or more machining operations, it is possible to perform machining once on the initial curved surface and predict machining acceleration from the difference, This is because the accuracy is considered poor. Thus, the present invention is not without a single process.

  As described above, secondary electrons or secondary ions emitted from a processing point in the course of processing by an irradiation beam with respect to one three-dimensional lens shape portion 30 created by etching are used as the secondary electrons at the two or more locations. The information of the three-dimensional shape of the machining surface is measured by simultaneously taking in the detector, and further, the machining acceleration of the beam at each machining coordinate is measured from the shape measurement information of the machining surface, and the machining time with respect to the remaining machining distance is calculated. Since the beam processing is performed up to the desired position in the depth direction, the processing time is much shorter than when etching into a planar columnar shape.

Hereinafter, as shown in FIG. 12, each lens shape portion 30 is modified by the above-described method. Thus, as shown in FIG. 8A, a lens product 3S in which a large number of accurate curved lens-shaped portions 30S having a predetermined curvature 300S on a plane are scattered is completed.
The observation of the processed shape is not limited to the case of performing the processing with the beam processing apparatus itself, and the shape is measured by moving the primary lens-shaped product 3 ′, which is a processed sample, to another apparatus for observation. Additional work may be performed by returning the sample.

[Second beam processing method]
This second method is characterized in that three-dimensional beam processing is performed using one detector for each lens shape portion 30 created by etching.
Figures 13 to 19 illustrate this method. FIG. 13 (a) shows the outline of the apparatus, which is basically the same as that in the case of the first processing method. However, secondary electrons or ions emitted during beam processing are captured and detected, and the processing surface is shown. In order to observe the shape of the (processed surface) as an image, only one secondary detector 6 is used, and the beam is positioned so that the detection surface always faces the beam irradiation position of the beam irradiation apparatus main body 2, that is, the processing point 50. It is fixed to the lens barrel of the irradiation apparatus main body 2 or the frame of the vacuum chamber 1. The signal output side is connected to a computer described later. Of course, it does not prevent the use of two or more secondary detectors.

  Reference numeral 7 denotes a computer as a controller attached to the beam irradiation apparatus main body 2, and includes a main body 7a and a monitor 7b. Reference numeral 7 ′ denotes a computer as an external controller. As shown in FIG. 14, the main body 7a has a CAD function unit 70 for creating three-dimensional lens shape data desired to be processed and CL data ( (Cutter Location Data), that is, a CAM function unit 71 for creating data including a beam movement locus, a beam movement speed, and a command to the machine.

  Further, a point cloud data conversion function unit 72 for converting the CL data created by the CAM function unit 71 into point cloud data is provided. The point cloud data conversion function unit 72 may be hardware, but is usually constructed in the form of software, and exchanges data with the main body 7a on the network or other media.

  The main body 7a receives lens shape processing data information made up of the point cloud data created by the point cloud data conversion function unit 72, whereby the beam coordinates, the beam dwell time at the coordinates, and the machining time for the remaining machining distance. Various calculations such as calculation of. The main body 7a has a beam control function unit and a workpiece control function unit. These are built in the form of hardware and / or software.

The beam control function unit sends signals to the X-axis direction moving device and the Y-axis direction moving device of the beam irradiation apparatus main body 2 based on the processing database to control the beam position and the staying time, and the ion of the beam irradiation apparatus main body 2 A signal is sent to the gun to control the beam intensity (acceleration voltage), and the beam position and stay time or beam intensity are adjusted by signals from the shape measurement function unit and the processing speed calculation function unit. The staying time and the beam intensity are parameters related to the machining depth, and the beam intensity (acceleration voltage) during a series of machining is usually fixed.
The CAD function unit 70, the CAM function unit 71, and the point cloud data conversion function unit 72 may be provided inside the computer 7 attached to the beam irradiation apparatus main body 2 instead of an external computer.

  The three-dimensional shape machining process by this method will be described. First, as shown in the program shown in FIG. 15, the CAD function unit 70 creates shape data according to the shape of the microlens, and based on this, the CAM function unit 71 creates the shape data. Create CL data. Then, the point data conversion function unit 72 multi-divides the CL data and obtains the XYZ coordinates of one end point of each segment.

  This point group data is sent from the main body 7a 'to the main body 7a, and the beam irradiation apparatus main body 2 is driven by the position measurement function section, the processing speed calculation function section, the beam control function section, and the work control function section, and the beam 5 is moved to the primary lens. While irradiating the lens shape portion 30 of the shaped product 3 ′, the beam 5 is scanned in both X and Y coordinates, and the stage 4 is moved as necessary to change the position and inclination angle of the primary lens shaped product 3 ′. Control, scan the beam and process. The scanning may be zigzag or spiral. The latter can be realized by moving the stage 4 and rotating the primary lens-shaped product 3 ′.

At the same time as the beam processing, a comparison is made with the processing database to control the beam residence time at each coordinate. That is, the machining depth is estimated depending on whether or not the beam has reached the machining time set for each coordinate. When it is determined that the set processing time has not been reached, the processing is continued and deeply cut, and when it is determined that the set processing time has been reached, the processing is completed and the beam is moved.
Further, since the removal amount is determined by the total beam stay time, the beam may be scanned by dividing the front surface of the processing region several times so that the total total stay time of each point becomes the same. By performing such processing on each lens shape portion 30 shown in FIG. 13B, a lens product 3S in which a large number of accurate curved lens shape portions 30S are scattered on a plane as shown in FIG. To do.

  The processing data creation process for focused ion beam processing, which is a feature of the present invention, will be described by taking the case of creating a microlens as an example. As a first process, line 1 is defined by the CAD function unit 70 as shown in FIG. To do. Next, as a second step, line 1 is rotated 360 degrees as shown in FIG. 17A to define a bowl-shaped surface, and CAD data is obtained.

  Next, as a third step, the CAM function unit 71 creates CL data 1 to CL data n from CAD data as shown in FIG. FIG. 18A is an XY plane, and FIG. 18B is an XZ plane. The data output pitch of the CL data corresponds to or exceeds the maximum resolution of the beam irradiation device to be used. For example, the data output pitch is 1000 divisions, but it can be increased by the memory.

  Next, the CL data is sent to the point cloud data conversion function unit 72, and as a fourth step, as shown in FIGS. 19 (a) and 19 (b), each CL data is divided into multiple parts, for example, 1000 parts in the intersecting direction, The XYZ coordinates of the end points are obtained. FIG. 19A shows the case of viewing with one CL data on the XY plane and FIG. 19B on the XZ plane. Thus, for example, 1000 × 1000 point cloud data is obtained.

In FIG. 15, “processing conditions” are the beam residence time (basically Z height), beam processing voltage, beam processing current, processing pitch (coordinates and coordinate distance), and material of the workpiece. Since the processing speed is determined by measuring the lens shape of the processed product after determining this, the processing depth data for each material is stored for each beam processing voltage, beam processing current, and processing pitch. Collecting and accumulating to create a “processing database”.
Therefore, by comparing the processing conditions to be processed with the “processing database”, the beam stay time to the target depth can be predicted.

  In the present invention, CL data is generated by the CAM function unit 71, and the CL data is further divided by the point cloud data conversion function unit 72, and the XYZ coordinates of one end point of each segment whose data does not have a length. Therefore, it is used as machining data, so that it is possible to create a “machining database” for precise control of machining pitch and beam residence time.

  In this second method, the most important processing data for lens shape processing with a beam can be created easily, quickly and accurately, and CAD / CAM linked to the beam irradiation device body and three-dimensional coordinate data creation. Therefore, the beam irradiation apparatus main body is processed using the means for converting the CL data created by the CAM into point cloud data, so that the processing conditions are compared with the processing data stored in the database. Since the processing time under the same processing conditions, that is, the total beam stay time can be found by comparison, the lens shape can be processed with relatively high accuracy even with a single detector.

[The third beam processing method]
This method also performs three-dimensional beam processing using at least one detector on the lens shape portion 30 that is an individual rough shape accuracy created by etching, but the CAM function portion 71 and point cloud data are used. It is characterized in that the beam processing data is created more easily without using the conversion function unit 72.
That is, in this embodiment, as shown in FIG. 20, a mesh is stretched on the surface of the image created by the CAD function unit 70, and the XYZ coordinates of the intersection of each mesh are obtained as processed data. The subsequent steps are the same as in the first embodiment.

In addition, although the output method of the data of Z coordinate with respect to each X, Y coordinate for beam position control is arbitrary, the following aspects are mention | raise | lifted, for example.
1) Starting from the starting point, sequentially output (1, 0), (2, 0) in the X direction, increasing by one pitch (n, 1) in the Y direction at the end (n, 0), and in the opposite direction (n -1,1) and (n-2,1) are output.
2) Jump to (0, 1) at the end and output sequentially in the X direction.
3) First output in the Y direction from the origin.

4) Since data with a Z coordinate value of 0 is not used for processing, Z coordinate data other than 0 is output. This is preferable because the number of data to be handled is reduced.
5) The data is output in the X direction, Y method, or the method of creating contour lines, and the data is output clockwise or counterclockwise from the smallest coordinate value.
6) The order in which data is output may not be data of continuous XY coordinates, such as skipping one data instead of data next to the current location.

  In this third processing method, since three-dimensional processing data for beam processing is created from CAD data without using expensive CAM, processing data can be created easily and inexpensively. By comparing the processing conditions with the database, each coordinate can be processed to a desired depth, so that relatively high-precision lens shape processing can be performed without using an expensive CAM.

In lens processing by beam processing, creating many convex lens shapes in a plane requires removal of a portion other than the objective, and removal of this portion by FIB requires a large removal area and a long time.
In contrast, in the present invention, a method other than the beam processing method is used to remove a portion other than the target convex lens shape, in particular, a plurality of masks having a three-dimensional lens shape are arranged on the workpiece, and etching is performed in this state. By removing the mask itself gradually and removing it in a short time by the method of making the primary lens shape product, and then correcting and finishing each rough lens shape part by beam processing method, so many A product having a fine and highly accurate lens shape portion can be efficiently produced in a short time.
The fine lens shape portion is, for example, a size of 0.1 to 400 microns and a thickness of 30 nanometers or more, and about 1000 pieces having a size of 50 microns can be made on a 2 mm square workpiece.

  Note that the present invention includes a workpiece preforming method for manufacturing a micro-optical aspherical lens in which correction / finishing is not limited to beam processing.

It is a top view which shows the state of the workpiece at the time of manufacture start of the micro optical aspherical lens by this invention. (a) is a state at the time of an etching process start, (b) is sectional drawing which shows the state in the middle of etching. (a) (b) (c) is explanatory drawing which shows typically the state change of the local at the time of an etching. (A) is sectional drawing which shows the state of the primary lens shape goods obtained at the etching process, (b) is the elements on larger scale. (a) is a perspective view which shows the process first stage in the 1st method of producing the mask in this invention, (b) is a perspective view of a mask completion state, (c) is the enlarged view. (a)-(f) is sectional drawing which shows the 2nd method of producing the mask in this invention in steps. It is sectional drawing which shows the primary lens shape and the secondary processing shape which corrects / finishes this. (A) The perspective view which shows an example of the fine lens product manufactured by this invention, (b) is a perspective view which shows a single lens product. (A) is explanatory drawing of the state which is performing the 2nd process of this invention by the beam processing 1st method, (b) is structure explanatory drawing of a beam irradiation apparatus. It is a control system diagram of the beam processing first method. It is a chart figure showing a processing process of beam processing the 1st method. It is a perspective view which shows the processing state of the beam processing 1st method. (A) is a front view which shows the outline | summary of the 2nd beam processing method, (b) is a perspective view which shows a processing state. It is a control system diagram of the 2nd beam processing method. It is a chart figure showing a processing process of the beam processing 2nd method. It is explanatory drawing which shows the 1st process of process data creation. (A) and (b) are explanatory drawings showing the 2nd process of processing data creation. (A) (b) is explanatory drawing which shows the 3rd process of process data preparation. (A) and (b) are explanatory drawings showing the 4th process of processing data creation. It is a chart which illustrates the processing process of the beam processing 3rd method.

Explanation of symbols

3 Work material 3 'Primary lens shape product 3S Product M Stereolens shape mask E Etching element 5 Beam
30 Lens shape part 30S Curved lens shape part

Claims (8)

In creating a fine optical aspheric lens, a plurality of masks made into a three-dimensional lens shape are placed on the workpiece, and etching is performed in this state to gradually scrape the mask itself to create a primary lens shape product. Next, a method for manufacturing a micro-optical aspheric lens, wherein each lens shape portion is processed by a beam processing method.   2. The micro optical aspherical lens according to claim 1, wherein the lens-shaped mask is formed by melting a metal flat mask, molding the surface into a lens shape by surface tension, and cooling and solidifying the lens. Manufacturing method.   The lens-shaped mask creates a reversal mold by transferring a microlens array, etc., fills the mold with a mask metal to create a lens-shaped metal body, and affixes only the metal body portion to the workpiece The method for producing a micro-optical aspheric lens according to claim 1.   The method for producing a micro-optical aspherical lens according to claim 1, wherein the lens-shaped mask is a lens-shaped optical modeling product in which an optical modeling resin is modeled at multiple points by a multi-point optical modeling apparatus. The manufacturing method of the micro optical aspherical lens of Claim 1 which performs the beam processing with respect to a primary lens shape goods by the following method.
1) Using the main body of the beam irradiation device and secondary electron detectors arranged at two or more locations in the vicinity of the irradiation beam,
2) During the processing by the irradiation beam, the secondary electron or secondary ion emitted from the processing point is simultaneously captured by the two or more secondary electron detectors to measure the three-dimensional shape information of the processing surface. , The processing acceleration of the beam at each processing coordinate is measured from the shape measurement information of the processing surface, the processing time with respect to the remaining processing distance is calculated, and the beam is processed to a desired position in the depth direction. When beam processing is performed on a primary lens shape product, the lens shape to be processed is created by CAD, the CAD data is processed by CAM to create CL data, and the output pitch of the CL data is divided into multiple parts to obtain XYZ Create point cloud data of coordinates, and use the secondary electron detector located in the vicinity of the beam irradiation device main body and the irradiation beam, and perform beam processing using the point cloud data and calculate the beam residence time at each coordinate. The manufacturing method of the micro optical aspherical lens of Claim 1 controlled. When beam processing is performed on a primary lens shape product, the lens shape to be processed is created by CAD, a mesh is created on the image created by the CAD data at a predetermined pitch, and XYZ coordinate data is read from the coordinates of the intersection of the mesh Point beam data is created by using the beam irradiation device main body and a secondary electron detector arranged in the vicinity of the irradiation beam, and the beam time at each coordinate is controlled while performing beam processing using the point cloud data. A method for producing a micro-optical aspherical lens according to claim 1. The method for producing a micro-optical aspherical lens according to claim 1, wherein the beam processing is FIB processing.

Images