JPH03120501A - Manufacture of optical diffraction grating and forming die of the same, and focusing ion beam working device used therefor - Google Patents

Abstract

PURPOSE:To perform work with high accuracy in a short time by performing groove working with high curvature out of the groove working of an optical diffraction grating with a focusing ion beam. CONSTITUTION:The manufacturing of a Fresnel lens 1 is performed by working a circular arc groove 4 making a blade 2 abut on the surface of a workpiece 1 while rotating the workpiece 1 around an axis Z-Z with a well-known machining tool, however, working is performed for only the range of the groove 4 with low curvature to which machining can be applied. Next, two grooves 4 are worked by sputtering in circular shape concentrical to the above groove 4 by the machining on the inner peripheral side of the workpiece 1 with an ion beam 3 by using a well-known focusing ion beam working device, and the working by the ion beam 3 is performed by forming the bottom shape of the groove 4 by a well-known method. In such a way, by machining together with focusing ion beam working, it is possible to perform the work with high working accuracy and efficiently and in a short time.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for manufacturing an optical diffraction element such as a small Fresnel lens for focusing light of a semiconductor laser, and a method for molding an optical diffraction element such as the above-mentioned Fresnel lens. The present invention relates to a method of manufacturing a mold for manufacturing a mold, and a focused ion beam processing device used in the manufacturing method.

[Conventional technology]

2. Description of the Related Art Optical elements that use light diffraction, such as 7-resnel lenses for condensing semiconductor lasers, have recently been required to be made smaller and have improved performance. For this reason, in a workpiece such as an optical diffraction element or a mold for molding the optical diffraction element, it is necessary to process grooves with a fine pitch and a defined shape with a specified curvature.

Conventionally, the above-mentioned workpiece, for example, a groove 4 as shown in FIG.
In the Fresnel lens 1 having the above structure, the grooves 4 can be processed by the following methods: 1. Machining 2. Lithography, dry etching, and focused ion beam processing.

The machining process in 1 above is performed using K as shown in Figures 5 and 6.
, a cutter 2 having a thickness t and a clearance angle α is used to process the machining 11iA and BK groove 4 of a workpiece 1 such as a Fresnel lens.

The above-mentioned phosphorography and dry etching can draw any curved pattern.

Processing using a focused ion beam as described in 5 above is described, for example, in the document “J, Vao, Sol, Teohnol, B6(5)*
5eP10at198 B ('l'h@use o
f veotor soanning forprod
uoing arbitrar75urfaoe oo
Tours with fousadion
b@am) P 16G5 to PI 607 J K As shown, it is possible to process a groove whose bottom surface is a slope.

[Problem to be solved by the invention]

However, with the machining described in 1 above, there is no problem in the case of a straight machined surface A as shown in Fig. 5, but when the machined surface B has a large curvature (small radius r) as shown in Fig. 6. In this case, since the relief angle α becomes negative, it is almost impossible to process the groove 4 having a large curvature (small radius) among the grooves 4 of the Fresnel lens 1 shown in FIG.

In addition, in the lithography and dry etching described in 2 above, it is difficult to obtain the bottom surface of the slope of the groove with high precision due to the drag/f etching.

Furthermore, processing using the focused ion beam described in 3 above has a slow processing speed. For example, when the ion beam current is 1 nA and the workpiece is 810 square meters, the processing speed is as follows:
03μ-/sea. For this purpose, for example, when the diameter of the 7-Renel lens 1 is 5-, the length 1 of one groove 4 is given by the following formula 1, and the cross-sectional area A of the groove 4 to be machined is given by the following formula 2, the processing The volume V is given by the following formula 3, and the processing time t at that time is given by the following formula 4, which is extremely long and cannot be used for practical manufacturing.

1-50GOμm (diameter) x π...1A-12,
5μ Bi...2V-Al-1962
50pd, 5 to the value Vμ-÷13μ-/sea #180Hr-,4
In this way, it takes approximately 180 hours to process one groove 4.

An object of the present invention is to efficiently and quickly produce an optical diffraction element.
Furthermore, it is an object of the present invention to provide a manufacturing method that allows manufacturing with high processing accuracy.

Another object of the present invention is to provide a manufacturing method capable of efficiently manufacturing features for molding an optical diffraction element in a short time and with high processing accuracy.

Another object of the present invention is to easily control the deflection of an ion beam without using a complicated ion beam deflection control device in the above-mentioned manufacturing method for producing an optical diffraction element or an optical diffraction element molding machine. It is an object of the present invention to provide a focused ion beam processing apparatus capable of processing.

[Means to solve the problem]

The present invention as described in rust claim IK (hereinafter referred to as the first invention).

) uses a focused ion beam to process grooves with large curvatures, which are almost impossible with machining, in optical diffraction elements, in order to solve the above problems. In order to solve the above-mentioned problem, the present invention according to claim 2 (hereinafter referred to as the second invention) is characterized in that the process is carried out by machining. The present invention according to claim 3 (hereinafter referred to as the present invention), characterized in that grooves with a large curvature, which is almost impossible to machine, are processed by a focused ion beam, and grooves with a small curvature, which are possible by machining, are processed by machining. , referred to as the third invention) is characterized in that, in order to solve the above problem, the stage on which the workpiece is placed is equipped with a rotation mechanism that rotates around an axis that substantially coincides with the ion beam axis. do.

[Effect]

The first invention uses a focused ion beam to process grooves with large curvature, which is almost impossible to do with machining, in the optical diffraction element. Grooving with small curvature, which is possible with machining, is done by machining.

Processing can be performed more efficiently and in a shorter time than with a focused ion beam.

The second invention uses a focused ion beam to process grooves with a large curvature close to 11, which cannot be achieved by mechanical processing, in the groove processing of the optical diffraction element mold, so that the processing accuracy is better than that performed by one mechanical processing. Since a groove with a small curvature that can be machined is machined, the process can be performed more efficiently and in a shorter time than when using a focused ion beam.

The third invention is that the workpiece can be rotated around the ion beam axis by a stage equipped with a rotating mechanism that rotates around an axis that almost coincides with the ion beam axis, so that the deflection of the ion beam can be controlled in one axis direction. It's only a storm, so
Deflection control of one ion beam can be easily performed without using an ion beam deflection control device having a complicated structure in which the deflection control of the ion beam is performed in multiple axial directions.

〔Example〕

Hereinafter, one embodiment of the method for manufacturing an optical diffraction element according to the first invention and the method for manufacturing an optical diffraction element molding according to the second invention will be described with reference to FIGS. 1 to 5.

Further, an embodiment of the focused ion beam processing apparatus of the fifth invention will be described with reference to the fourth factor.

FIGS. 1 to S show an embodiment of the method for manufacturing a large diffraction element of the first invention, and FIG. FIG. 2 is a sectional view showing the state of machining in the method of manufacturing an optical diffraction element of the first invention, and FIG. 5 is a sectional view showing the state of focused ion beam processing in the method of manufacturing an optical diffraction element of the first invention. It is.

In this method of manufacturing an optical diffraction element, when manufacturing a Fresnel lens (hereinafter also referred to as a workpiece) 1 as shown in FIG. 1, first, as shown in FIG. (not shown) to move the workpiece 1 to the axis 2-2
While rotating the workpiece 1, the cutter 2 is placed on the surface of the workpiece 1.
Then, process the arc groove 4. This groove machining is performed from the outside of the workpiece 1 to the fourth groove 4, that is, to the groove 4 with a small curvature that can be machined.Here, the curvature of #14 of the circular arc is even smaller. As shown in , when the clearance angle becomes negative, it becomes impossible to form grooves by machining.

Next, as shown in FIG. 3, the ion beam 6 of a known focused ion beam machining apparatus (rIA not shown) is used to apply two
The groove 4 of the book is sputtered to be concentric with the groove 4 formed by the previous machining process. Note that the shape of the bottom surface of the groove 4 formed by this focused ion beam processing can be controlled by the method (dose distribution) described in the above-mentioned literature.

In addition, in the method for manufacturing an optical diffraction element of the first invention, among the grooves on the workpiece (7-Renel lens) 1, grooves with a small curvature that can be machined are processed by machining, so that the focused ion Machining can be performed more efficiently and in a shorter time than with a beam. Furthermore, since grooves with large curvatures, which are nearly impossible to machine, are processed using a focused ion beam, the processing accuracy is better than that achieved by mechanical processing.

Next, the manufacturing method of the optical diffraction element molding of the second invention, for example, the manufacturing method of the female deaf for molding the 7 Renel lens 1 shown in FIG. , the grooves are simply machined so that the unevenness is reversed, and the essence of the other processing methods remains the same. Therefore,
The same effects as those of the method for manufacturing an optical diffraction element according to the first aspect of the invention described above can be achieved.

FIG. 4 is a schematic diagram showing an embodiment of a focused ion beam processing apparatus according to the third invention.

In the figure, 6 is a chamber wall forming a vacuum processing chamber. ' 20 is a stage on which the workpiece 1 is placed, and this stage 20 includes a rotation stage 40 equipped with a rotation mechanism (not shown) that rotates around an axis that substantially coincides with the 5 axes of the ion beam, which will be described later. It is composed of an X stage 41 arranged on a stage 40, and an X stage 42 arranged on the X stage 41 and on which the workpiece 1 is placed.

The rotation stage 40 is connected to the bottom of the rotation stage 40 and a rotation shaft 45 of a rotation mechanism disposed outside the chamber wall 6.
It is connected to a rotating shaft 43 whose axis substantially coincides with the five axes of the ion beam, and is configured to rotate around an axis substantially coincident with the three axes of the ion beam.

The X stage 41 is equipped with this X stage 414CX direction i micrometer head (not shown), and has an X direction operation knob (not shown) that can be engaged with the X direction micrometer head.
(not shown) is installed on the chamber wall 6,
By operating the X-direction operating knob from outside the chamber wall 6, the ion beam can be moved in the X-direction perpendicular to the 5-axis of the ion beam.

The X-stage 42 is equipped with an x-direction micrometer head 34, and an X-direction operation knob 44 that can be engaged with the x-direction micrometer head 34 is equipped on the chamber wall 6. By operating this X-direction operating knob 44 from outside the chamber wall 6, it is possible to move in the X-direction perpendicular to the 5-axis ion beam and the moving direction of the X stage 41.

In addition to the above-mentioned moving operation means for the X stage 42 and the X stage 41, the means for moving the X stage 42 and the X stage 41 includes a motor disposed within the chamber wall 6, and the motor is linked to the X stage 42 and the X stage 41, respectively. A power supply device such as a slip ring may be disposed on the chamber wall 6, and the power supply device and the motor may be electrically connected.

Reference numeral 7 denotes an ion beam source (or ion gun), and the ion beam source 7 includes an ion generator 1'1, an extraction electrode 31 for extracting the ion beam 5 emitted from the ion generator 11, and a limiting aperture 13. A focusing electrostatic lens 14 that focuses the ion beam 3 passing through the limiting aperture 15, a blanking electrode 16 connected to a blanking power source 15, a blanking aperture 17, and a deflection controller 224. and a deflection electrode 18.

In this ion beam source 7, ions emitted from an ion generator 11 are extracted by an extraction electrode 31, passed through a limiting aperture 13, and focused by a focusing electrostatic lens 14, and a blanking electrode 16 and a blanking aperture. 17
The ion beam is deflected by the deflection electrode 18 in a direction perpendicular to the 5-axis of the ion beam, and is irradiated onto the workpiece 1 on the X stage 42 .

52 is a control power source that controls the ion generator 11, the extraction electrode 51, and the focusing electrostatic lens 14.

Reference numeral 25 denotes a computer as a control section, and this combiator 25 is connected to the deflection controller 24 and the blanking power supply 15, respectively. This combination gourd 25 is operated by means 504C for inputting design data of the Fresnel lens 1, outputs a command to the deflection controller 24, and the deflection controller 24 is operated to apply a deflection voltage to the front-disposed deflection electrode 18. As a result, the ion beam 5 is deflected to the workpiece 1 on the stage 20.
is irradiated.

8 is a monitor device, and this monitor device 8 is the ion beam 5.
A microchannel plate (MCP) 5 that amplifies the secondary ions ejected from the workpiece 1 by irradiation to produce a large electron current, and an anode that receives the large electron current from the MCP 5 and produces a secondary ion signal. 25, a scanning secondary particle image monitor 26 connected to the anode 23 and the deflection controller 24, respectively, an accelerating power source 27 for the MCP, a bias power source 28 for collecting secondary ions, and the MCP 5 as a secondary electron detector. A bias power supply 29 is provided for use as a bias power source 29. In this monitoring device 8, a secondary ion signal from the anode 23 and a deflection signal from the deflection controller 24 are respectively inputted to the scanning secondary particle image monitor 26. A scanned secondary ion image is projected using the same method.

Here, when the workpiece 1 is an insulator such as 8102, it is desirable to neutralize the charge with an electron gun (not shown) in order to prevent charge-up due to the ion beam 3. First, it is necessary to detect a secondary ion image as described above.

Furthermore, when the workpiece 1 is a conductor such as a mold for an optical diffraction element, since electron supply is not necessary, changing the polarity of the bias power supply 28 for collecting the secondary ions, etc. A secondary electron image can also be obtained by detecting electrons.

The focused ion and one beam processing apparatus of the third invention in this embodiment has the above-mentioned configuration, and its operation and operation will be explained below.

First, the workpiece 1 that has been machined as shown in FIG. The center of the X stage 4 of the stage 20 can be observed on the monitor screen 26 so that the
2 and the X stage 41 to adjust the position of the stage 20 by moving it in the X direction and the X direction.

After completing the alignment of the center of the arc of the workpiece 10 and the axis of the rotary stage 40 as described above, the arc groove 4 is processed using the focused ion beam 5IfC shown in FIG.

At this time, the workpiece 1 can be rotated via the rotation stage 40 of the stage 20. As a result, the ion beam 5 only needs to be deflected in one axis direction. Therefore, the deflection of the ion beam can be easily controlled without using an ion beam deflection control device with a complicated structure (that is, a device that deflects the ion beam 5 in multiple axis directions).

In the above embodiments, a 7-Renel lens IK provided with circular arc grooves 4 has been described, but the method for manufacturing an optical diffraction element according to the first invention, the method for manufacturing an optical diffraction element mold according to the second invention, and the method for manufacturing an optical diffraction element mold according to the second invention are also described. The focused ion beam processing apparatus according to the third invention can also process elliptical grooves, hyperbolic grooves, and other arbitrary curved grooves in addition to the circular arc grooves 4. In addition to the Fresnel lens 1, other optical diffraction elements and their molds can also be manufactured.

〔Effect of the invention〕

As is clear from the above, the method for manufacturing an optical diffraction element according to the first invention and the method for manufacturing an optical diffraction element mold according to the second invention are suitable for processing grooves on an optical diffraction element and grooves on an optical diffraction element mold. Among these, grooves with large curvatures, which are almost impossible to machine, are processed using a focused ion beam, so the processing accuracy is better than that achieved by machining.Moreover, grooves with small curvatures, which are possible with machining, can be processed by machining. Therefore, processing can be performed more efficiently and in a shorter time than with a focused ion beam.

The focused ion beam processing apparatus of the fifth invention is equipped with a rotation mechanism that rotates the stage on which the workpiece is placed about an axis that substantially coincides with the ion beam axis. Since the ion beam stage can be rotated around the ion beam axis, the ion beam can be deflected only in one axis. Therefore, the ion beam can be deflected in multiple axes. Deflection control of the ion beam can be easily performed without using any equipment.

[Brief explanation of drawings]

1 to 3 show an embodiment of the method for manufacturing an optical diffraction element according to the first invention, and FIG. 1 is a cross-sectional view of a 7-Renel lens manufactured by the method for manufacturing an optical diffraction element according to the first invention, Second
The figure is a sectional view showing the state of machining in the method of manufacturing an optical diffraction element of the first invention, and Figure S is a sectional view showing the state of focused ion beam processing in the method of manufacturing an optical diffraction element of the first invention. be. FIG. 4 is a schematic diagram showing an embodiment of a focused ion beam processing apparatus according to the fifth invention. FIG. 5 is an explanatory diagram showing the machining state of a straight-line machined surface, and FIG. 6 is an explanatory diagram showing the machining state of a machined surface with a large curvature. 1...Fresnel lens (workpiece), 2...Blade,
5... Ion beam, 4... Groove, 7... Ion beam source, 8... Monitor device, 20... Stage, 2
5... Computer (control unit). Figure 1 Figure 0 0 0 cake 0

Claims (1)

[Claims] 1. Among the grooves of the optical diffraction element, grooves with a large curvature that are almost impossible to machine are processed by a focused ion beam, and grooves with a small curvature that can be processed by machining are processed by machining. 1. A method of manufacturing an optical diffraction element, characterized in that: 2. Among the grooves of the optical diffraction element mold, grooves with a large curvature, which is almost impossible to machine, are processed using a focused ion beam, and grooves with a small curvature, which are possible with machining, are processed by machining. A method for manufacturing an optical diffraction element mold. 3. A stage on which a workpiece such as an optical diffraction element or an optical diffraction element mold is placed and adjustable in the direction perpendicular to the ion beam axis, and ions that irradiate the workpiece on the stage with ions. A focused ion beam processing device comprising a beam source and a control section for controlling the ion beam source, etc., characterized in that the stage is equipped with a rotation mechanism that rotates around an axis that substantially coincides with the ion beam axis. Focused ion beam processing equipment.