WO2017213078A1

WO2017213078A1 - Gas cluster ion beam machining method and machining apparatus

Info

Publication number: WO2017213078A1
Application number: PCT/JP2017/020805
Authority: WO
Inventors: 谷川裕海; 水金貴裕
Original assignee: コニカミノルタ株式会社
Priority date: 2016-06-08
Filing date: 2017-06-05
Publication date: 2017-12-14
Also published as: JPWO2017213078A1

Abstract

Provided is a gas cluster ion beam machining method that allows a work object to be machined into an intended shape even if the work object has a rotationally asymmetric shape. The present invention is provided with: an irradiation step for irradiating a work object (WO) with a gas cluster ion beam (GCIB) via an aperture member (23) for stopping down, to a prescribed size, the GCIB radiated on the work object (WO); and a scanning step for three-dimensionally translating the work object (WO) relative to the aperture member (23) while keeping the distance between an opening (23a) of the aperture member (23) and the work object (WO) constant, wherein the relative scanning speed is controlled so as to achieve a machining target in the scanning step.

Description

Gas cluster ion beam processing method and processing apparatus

The present invention relates to a gas cluster ion beam processing method and processing apparatus capable of precisely processing a mold and an optical element.

In order to mass-produce molded products such as optical elements, press molding using a mold or injection molding is an effective processing means. When the transfer surface of such a molding die is rough or the shape accuracy is poor, the surface roughness and shape accuracy of the molded product after molding are greatly deteriorated, and the performance of the molded product is lowered.

Accordingly, there is a processing method for improving the surface roughness of the processing surface or correcting the shape by irradiating the processing surface with a gas cluster ion beam (GCIB) (see, for example, Patent Documents 1 to 4). ). Patent Document 1 discloses a processing method in which the irradiation time of GCIB is controlled in accordance with the surface position of a spherical mold that is a workpiece, and the shape is created and polished by swinging for vertical irradiation. In Patent Document 2, the posture of a workpiece is controlled so that GCIB is perpendicularly incident at an arbitrary position on the surface of the workpiece, and a predetermined irradiation dose is applied to each position on the surface of the workpiece. A processing method for polishing by controlling the scanning speed of GCIB so that GCIB is irradiated is disclosed. Patent Document 3 discloses a machining method that performs machining by controlling the posture of a workpiece so that GCIB irradiation distance is kept constant and GCIB is irradiated vertically. Patent Document 4 discloses a machining method in which machining is performed by controlling the relative scanning speed of GCIB with respect to a workpiece in a swing stage. In any of the above Patent Documents 1 to 4, processing is performed while rotating the workpiece.

However, the methods of Patent Documents 1 to 4 correspond to processing when the workpiece has a rotationally symmetric shape, and can be applied as it is to processing when the workpiece has a non-rotationally symmetric shape such as a free-form surface. difficult. For example, in the method of Patent Document 3, although the GCIB irradiation distance is kept constant, in the processing of a workpiece having a non-rotationally symmetric shape such as a free-form surface, the angle calculation of the swing axis becomes complicated, and the amount of control is controlled. Is not easy. In the processing methods of Patent Documents 1 to 4, it is assumed that the workpiece is processed while rotating, and a steep step is likely to occur near the center of rotation.

JP 2005-120393 A JP 2007-32185 A JP 2009-190068 A JP 2009-274085 A

The present invention provides a gas cluster ion beam processing method capable of processing a target shape on a workpiece not only when the workpiece has a rotationally symmetric shape but also when the workpiece has a non-rotationally symmetric shape. Objective.

Another object of the present invention is to provide a gas cluster ion beam processing apparatus used in the above-described gas cluster ion beam processing method.

In order to achieve at least one of the above-described objects, a gas cluster ion beam processing method reflecting one aspect of the present invention includes a gas cluster ion beam irradiated to a workpiece through an aperture member that squeezes the gas cluster ion beam to a predetermined size. Three-dimensional translational movement of the workpiece relative to the aperture member while maintaining a constant distance between the aperture step of the aperture member and the workpiece, and an irradiation process for irradiating the workpiece with the cluster ion beam A scanning step, and in the scanning step, the relative scanning speed is controlled to achieve the processing target. The irradiation process and the scanning process are performed in parallel.

In order to achieve at least one of the above-described objects, a gas cluster ion beam processing apparatus reflecting one aspect of the present invention includes an aperture member opening for narrowing a gas cluster ion beam to a predetermined size and a workpiece. A stage device that moves the workpiece relative to the aperture member in a three-dimensional translation while keeping the distance between them constant, and a gas cluster ion beam to be processed by causing the stage device to perform a three-dimensional translation. A stage controller that scans the object while irradiating the object and changes the relative scanning speed of the irradiation position of the gas cluster ion beam according to the processing target.

It is a section conceptual diagram explaining the processing device concerning an embodiment. It is a figure explaining a control system among the processing apparatuses of FIG. 3A is a diagram for explaining the periphery of the aperture member of the GCIB irradiation apparatus in the processing apparatus of FIG. 1, and FIG. 3B is a diagram for explaining a modification of the periphery of the aperture member of FIG. 3A. 4A to 4C are diagrams for explaining the scanning state of the GCIB. It is a conceptual diagram explaining a shape measuring apparatus. 6A and 6B are diagrams illustrating a workpiece or the like. It is a flowchart explaining the processing method using the processing apparatus of FIG.

Hereinafter, an embodiment of a gas cluster ion beam processing method and a gas cluster ion beam processing apparatus used for the processing method will be described with reference to the drawings.

[GCIB processing equipment]
As shown in FIGS. 1 and 2, the gas cluster ion beam processing apparatus (hereinafter referred to as a processing apparatus 100) of the present embodiment processes a target shape on the surface of a workpiece WO to be described later. The machining apparatus main body 10, a stage controller 96, a GCIB controller 97, and a main controller 99 are provided.

The processing apparatus main body 10 of the processing apparatus 100 includes a GCIB irradiation apparatus 20 and a stage apparatus 30. The processing apparatus body 10 is disposed in the chamber 11. During processing, the inside of the chamber 11 is depressurized by a vacuum device 12 at an appropriate degree of vacuum (for example, about 10 ⁻⁵ Pa).

The GCIB irradiation apparatus 20 is an apparatus that performs polishing or shape creation by etching that irradiates gas clusters using vacuum technology. The GCIB irradiation device 20 includes a GCIB irradiation unit 21, a shutter 22, an aperture member 23, a shutter driving device 25, and an aperture support portion 26.

In the GCIB irradiation unit 21, a GCIB beam generation gas is supplied to the GCIB irradiation apparatus 20 from a gas source (not shown) attached to the GCIB irradiation apparatus 20. The beam generating gas is a gas containing a halogen element. Thereby, the removal rate can be increased. Examples of the gas containing a halogen element include F ₂ , Cl ₂ , Br ₂ , NF ₃ , SF ₆ , CF ₄ , SF ₆ + He mixed gas, and SF ₆ + Ar mixed gas. A high pressure gas of about 0.1 to 1.0 MPa is supplied from the gas source. The gas conditions are set as appropriate depending on the material and processing amount of the workpiece WO, which will be described later. For example, assuming that SF ₆ + He mixed gas (mixing ratio is SF ₆ : He = 1: 9) is used, the gas pressure is For example, it is 0.4 MPa, and the irradiation dose can be, for example, about 2 × 10 ¹⁶ to 2 × 10 ¹⁷ ions / cm ² . When there is a target value of the irradiation dose, the theoretical irradiation time of GCIB can be obtained by the following equation.
Irradiation time = (irradiation dose x irradiation area x elementary charge e) / (detection ion current)
Since the irradiation dose of GCIB (total amount of injected material) is proportional to the irradiation time, a very small processing depth of nano-order can be controlled by the irradiation time. In the present embodiment, the GCIB irradiation dose varies depending on the position on the workpiece WO. For this reason, the irradiation time at each processing point on the workpiece WO is different, and the integrated value of the irradiation time (residence time) of the GCIB passing through each processing point on the workpiece WO is the resulting irradiation time. It has become. Further, when the GCIB is narrowed down by the aperture member 23, the irradiation area is the area of the local irradiation region on the workpiece WO. The detected ion current amount is a current flowing through the workpiece WO.

The high-pressure gas injected at supersonic speed from the gas source through the nozzle expands adiabatically, generating a gas cluster. A gas cluster on the center side is selectively beamed in the chamber of the GCIB irradiation unit 21 and further ionized and accelerated to generate a gas cluster ion beam for processing (hereinafter also referred to as GCIB). The particles constituting the GCIB are broken by the collision with the workpiece WO, and at that time, a multi-body collision between the cluster-constituting atoms or molecules and the workpiece-constituting atoms or molecules occurs, with respect to the surface of the workpiece WO. Therefore, the movement in the horizontal direction becomes remarkable. As a result, while the projections on the irradiated surface of the workpiece WO are mainly shaved, the entire irradiated surface is shaved, and flat ultra-precision polishing at the atomic size becomes possible.

The shutter 22 is a portion where a GCIB having a relatively large diameter collimated by the GCIB irradiation unit 21 is emitted, and turns on / off the GCIB at a desired timing. The shutter 22 is opened and closed under the control of the shutter driving device 25.

The aperture member 23 partially shields the GCIB that irradiates the workpiece WO, and narrows the beam to a predetermined size by the circular opening 23a. As shown in FIGS. 1 and 3A, the aperture member 23 is supported by the aperture support 26 so that the end surface 23c on the workpiece WO side faces the workpiece WO. The aperture member 23 is a thick cylindrical member having an opening 23a at the center. The aperture member 23 is positioned by the aperture support portion 26 so that the irradiation axis BX of GCIB coincides with the central axis of the opening 23a. The shape and size of the opening 23a are appropriately set according to the processing conditions, and the size depends on the performance of the GCIB irradiation device 20, but a local shape error portion (design shape and pre-processing before processing) on the workpiece WO. If there is a part having a difference from the shape), the area is equal to or smaller than the area, for example, a diameter of several mm to several tens of mm. The end surface 23b on the GCIB irradiation unit 21 side and the end surface 23c on the workpiece WO side of the aperture member 23 are annular planes perpendicular to the irradiation axis BX of the GCIB and the center axis AX of the workpiece WO. Here, the central axis AX of the workpiece WO is a reference line of the workpiece surface Mb of the workpiece WO and corresponds to the optical axis. The end surface 23c of the aperture member 23 is parallel to the bottom surface Ma of the workpiece WO when the bottom surface Ma of the workpiece WO is flat. Only GCIB that has passed through the opening 23a of the aperture member 23 is locally incident on the workpiece WO. Thereby, it is possible to precisely process the workpiece surface Mb of the workpiece WO with a local bias.

As shown in FIG. 3A, the aperture member 23 may be individually replaced depending on the conditions of the size and shape of the opening 23a, or an aperture changing mechanism 27 is provided as shown in FIG. 3B. It may be exchanged. The aperture changing mechanism 27 shown in FIG. 3B includes a disk-shaped rotating disk 28 and a driving mechanism 29 that rotates the rotating disk 28. A plurality of aperture members 23 having openings 23a having different sizes are provided on the turntable 28, and the aperture member 23 having openings 23a having a desired size can be selected by rotating the turntable 28. It has become.

The stage device 30 performs positioning and scanning movement of the workpiece WO. The stage device 30 includes an X-axis stage 32, a Y-axis stage 33, a Z-axis stage 34, a rotation stage 35, and a swing stage 36. In the illustrated example, the X-axis stage 32 and the Z-axis stage 34 are provided so as to be incorporated into a pedestal 37 of the stage apparatus 30 and indirectly move the workpiece WO in the X-axis direction or the Z-axis direction. The Y-axis stage 33 is provided above the X-axis stage 32 and the Z-axis stage 34, and moves the workpiece WO indirectly in the Y-axis direction. The stage device 30 performs a three-dimensional translational movement of the workpiece WO to an arbitrary position (that is, an orthogonal three-axis (XYZ axis)) by synchronizing the X-axis stage 32, the Y-axis stage 33, and the Z-axis stage 34. Move). The rotary stage 35 is supported by the swing stage 36, and rotates about the rotation axis (axis parallel to the irradiation axis BX and Z axis of the GCIB), so that the XY plane (GCIB of the workpiece WO) is rotated. The rotational attitude in the plane perpendicular to the irradiation axis BX is adjusted. On the GCIB irradiation apparatus 20 side of the rotary stage 35, the workpiece WO is attached in an aligned state. The swing stage 36 is supported by a support portion 33a constituting the Y-axis stage 33, and swings or swivels around a swing axis CX (axis perpendicular to the irradiation axis BX of GCIB and parallel to the Y axis). By operating, the posture or inclination of the workpiece WO is adjusted in the XZ plane (a plane parallel to the irradiation axis BX of GCIB). Each of the

stages

32, 33, 34, 35, and 36 is driven by an operation of a stage control unit 96 described later. In substantial processing of the workpiece WO, that is, relative scanning, only the X-axis stage 32, the Y-axis stage 33, and the Z-axis stage 34 are used, and the rotary stage 35 and the swing stage 36 are not used. That is, in the substantial processing, the workpiece WO is only three-dimensional translational movement. Thereby, the workpiece WO can be moved at a desired speed at a desired position in a plane parallel to the XY plane. The rotary stage 35 and the swing stage 36 are adjusted so that the workpiece WO (specifically, the bottom surface Ma or the like) is in an appropriate posture with respect to the GCIB when the workpiece WO is fixed to the stage device 30. It is only used to Each

stage

32, 33, 34, 35, 36 is equipped with a servo motor (not shown), a stepping motor, and the like, and is driven by a stage controller 96.

In the illustrated example, the workpiece WO fixed to the stage apparatus 30 has a large area compared to the GCIB beam size, and is a molding die 50 (see FIG. 6A) having a non-rotationally symmetric shape. Yes. The GCIB irradiation axis BX is parallel to the center axis AX of the workpiece surface Mb of the workpiece WO by the operation of the swing stage 36 and the like. In this case, the beam irradiation direction can be set with reference to the center axis AX of the workpiece WO. In the present embodiment, the GCIB irradiation axis BX is such that the bottom surface Ma of the workpiece WO is a flat surface and is perpendicular to the bottom surface Ma of the workpiece WO. In this case, the beam irradiation direction can be set without specifying the center axis AX of the workpiece WO.

The operation distance of the GCIB (distance between the aperture member 23 and the workpiece WO) is kept constant by the operation of the stage device 30, specifically the operation of the Z-axis stage 34. That is, the workpiece WO is displaced in the Z-axis direction according to the shape of the workpiece surface Mb. The beam emitted from the aperture member 23 tends to expand as the distance from the processing surface Mb increases. Therefore, when the irradiation distance changes, the processing range and the processing depth change. By making the irradiation distance constant, it is possible to perform stable machining while reducing the change in the beam size on the workpiece surface Mb of the workpiece WO. The irradiation distance is, for example, 5 mm or more and 25 mm or less. By setting the irradiation distance to 5 mm or more, it is possible to prevent the removed material of the processing surface Mb from adhering to the aperture member 23. Also, by setting the irradiation distance to 25 mm or less, the beam size does not spread too much, and the lateral resolution of the shape error (shape error frequency, spread in the surface direction, etc.) can be reduced.

By the operation of the stage device 30, the position or coordinates in the X-axis direction or Y-axis direction of the workpiece surface Mb of the workpiece WO and the position or coordinates in the GCIB irradiation direction (that is, the Z-axis direction) are interlocked, The GCIB and the workpiece WO can be relatively three-dimensionally translated and are raster-type scans in which the scanning speed changes according to the position, and an operation in which the irradiation distance is kept constant is possible. In the present embodiment, for main scanning, for example, the X-axis stage 32 and the Z-axis stage 34 are operated to simultaneously control the position of the workpiece WO in the X-axis direction and the position in the Z-axis direction. Further, the stage device 30 is controlled so that the relative scanning speed in the X-axis direction achieves the processing target of the workpiece WO (specifically, the shape error is corrected). That is, by controlling the relative scanning speed according to the processing target (specifically, the shape error amount), the processing amount is controlled by the beam stay time at the processing point. Here, the relative scanning speed is a speed at which the workpiece WO and GCIB move relatively (main scanning). In the present embodiment, the relative scanning speed indicates the moving speed of the workpiece WO by the X-axis stage 32. For sub-scanning, the Y-axis stage 33 is operated. That is, the Y-axis stage 33 is used for pitch feeding, and enables the workpiece WO to be processed continuously over the entire surface. Although depending on the shape of the surface to be processed Mb, the Z-axis stage 34 is also operated in conjunction with the Y-axis stage 33. For example, as shown in FIG. 4A, after the GCIB is relatively moved from end to end in the longitudinal direction of the workpiece WO by the X-axis stage 32, and then shifted by a predetermined distance in the Y-axis direction by the Y-axis stage 33. By repeating the relative movement of the GCIB in the direction opposite to the previous scanning by the X-axis stage 32, the GCIB can scan the processing surface Mb while drawing a one-stroke writing scanning locus TK. Further, as shown in FIG. 4B, the workpiece WO is displaced in the Z-axis direction by the Z-axis stage 34 interlocked according to the incident position of GCIB. As a result, the irradiation surface DR is constant and the workpiece surface GCIB is uniformly irradiated two-dimensionally along the shape of Mb. The GCIB scanning trajectory TK may be linear as viewed from the GCIB irradiation apparatus 20 side as shown in the figure, or may include a curve such as an arc according to the outer shape of the processing surface Mb. The GCIB scanning pitch (or scanning pitch) is appropriately set according to the size of the opening 23a of the aperture member 23, the irradiation distance of the GCIB, and the like. For example, the diameter size of the opening 23a of the aperture member 23 is 5 mm, and the irradiation distance DR. Is 20 mm, the scanning pitch is about 0.1 mm. The scanning pitch is preferably small, but if it is too small, the processing time increases. Further, as long as the processing is completed, the pitch may be changed instead of a constant pitch. Further, even with the same pitch, the pitch may be shifted by, for example, a half pitch.

In addition to the processing apparatus 100, in order to measure the surface state of the processing surface Mb of the workpiece WO and the surface state of the dummy member WB for calibration, a shape measuring device 40 and a shape measurement control unit 98 (see FIG. 5). The shape measuring device 40 measures a three-dimensional shape of a measurement object, and in the illustrated example, a shape measuring machine (UA3P: manufactured by Panasonic) is cited. The shape measuring device 40 includes a pedestal 41, an XY axis stage 42, and a Z axis drive unit 43. The Z-axis drive unit 43 is provided with an elevating unit 43a that supports the stylus PR so as to be elevable. The stylus PR can be raised and lowered smoothly with high accuracy in a state where a constant load is applied to the tip. By appropriately operating the XY axis stage 42 and moving the workpiece WO or dummy member WB to be measured placed in alignment with the XY axis stage 42 so as to scan two-dimensionally, the touch The tip of the needle PR can be moved two-dimensionally along the surface of the workpiece WO or the like. At this time, the tip position of the stylus PR uses a laser interferometer (not shown) provided on the pedestal 41 so as to face the XY axis stage 42 or a laser interferometer (not shown) provided on the top of the stylus PR. Detected. The shape measurement control unit 98 operates the shape measurement device 40 to measure the surface state of the workpiece WO or the like. The surface shape data measured by the shape measuring device 40 is transferred from the shape measurement control unit 98 to the main control device 99 and used for creating shape correction NC data. As the shape measuring device 40, for example, an interferometer (WYKO: manufactured by Bruker) can be used in addition to the above-described shape measuring machine.

Referring back to FIGS. 1 and 2, the stage control unit 96 enables high-precision numerical control, and drives a motor, a position sensor, and the like built in the stage device 30 under the control of the main control device 99. By doing so, each

stage

32, 33, 34, 35, 36 is appropriately operated to a target state. That is, the stage control unit 96 drives the stage device 30 to adjust the position and posture of each

stage

32, 33, 34, 35, 36. As shown in FIG. 4A and the like, the stage control unit 96 causes the X, Y, and Z axis stages 32, 33, and 34 to perform a three-dimensional translational movement in the substantial processing of the workpiece WO. Is scanned while irradiating the workpiece WO, and the relative scanning speed of the GCIB irradiation position is changed according to the processing target. Further, as will be described in detail later, the relative scanning speed takes into account the surface inclination (angle with respect to the Z axis) at the GCIB incident position on the processing surface Mb or the GCIB incident angle. In the example of FIG. 4C, the speed near the center of the workpiece WO in the longitudinal direction or the X-axis direction is slower than the speed near the outside.

As shown in FIG. 2, the stage control unit 96 includes a motor driving unit 96a and a sensor driving unit 96b. The motor drive unit 96a controls the operation of the motors mounted on the

stages

32, 33, 34, 35, and 36. The sensor driver 96b detects the position, speed, direction, and the like of each

stage

32, 33, 34, 35, 36 via an encoder (not shown) and monitors the operation of the motor.

The GCIB control unit 97 controls the operation of the GCIB irradiation apparatus 20. The GCIB control unit 97 includes a GCIB irradiation unit driving unit 97a, a shutter driving unit 97b, and an aperture driving unit 97c. The GCIB irradiation unit driving unit 97a operates the GCIB irradiation unit 21 to inject GCIB to the workpiece WO side. The shutter drive unit 97b controls the on / off operation of the shutter 22. The aperture drive unit 97 c operates the aperture support unit 26 to adjust the position of the aperture member 23.

The main control device 99 comprehensively controls the processing apparatus main body 10, the stage control unit 96, the CGIB control unit 97, and the shape measurement control unit 98. The main control device 99 includes an arithmetic processing unit 99a, a storage unit 99b, and an input / output unit 99c. The main control device 99 operates the vacuum device 12 based on the operation of the user or the like, and adjusts the degree of vacuum in the processing apparatus main body 10. The main control device 99 operates the CGIB control unit 97 to irradiate the workpiece WO with a GCIB having a desired size from the GCIB irradiation unit 21. Further, main controller 99 operates stage controller 96 to control the operation of stage device 30. The input / output unit 99c receives information on the shape of the workpiece WO (specifically, target shape data of the workpiece WO (designed shape data of the workpiece WO)) by a user or the like, and saves it in the storage unit 99b. To do. The storage unit 99b stores measurement data obtained by the shape measuring device 40 in addition to the above-described design shape data. Information on these shapes is a function of the position coordinates (XYZ) of the workpiece WO set at the reference position on the rotary stage 35, for example. In addition, shape correction NC data creation CAM for creating shape correction NC data (machining control program) and CNC software (computer numerical control software) for executing shape correction NC data are mounted in the storage unit 99b. The arithmetic processing unit 99a creates shape correction NC data from various shape data. Specifically, the arithmetic processing unit 99a reads the shape data and the like of the workpiece WO and the dummy member WB stored in the storage unit 99b, and sets each irradiation dose amount for obtaining a design shape. The relative scanning speed, pitch, etc. at the work point are calculated. The arithmetic processing unit 99a creates shape correction NC data for operating the stage device 30 based on the calculation result. The main control device 99 controls the operation of the stage device 30 by executing the shape correction NC data, and moves the workpiece WO supported by the stage device 30 in a three-dimensional translation so as to match the processing target.

[Workpiece]
Hereinafter, an example of the workpiece WO processed using the processing apparatus 100 will be described. As shown to FIG. 6A, the shaping | molding die 50 comprised by the workpiece WO is for shape | molding the combiner 60 shown to FIG. 6B. The combiner 60 includes a screen portion 60a that is a rectangular curved plate-like member, and a rod-like support portion 60b that extends from the center of one side of the screen portion 60a. The screen unit 60a includes a first optical surface 61 disposed on the viewer side and a second optical surface 62 disposed on the counter-viewer side. The first optical surface 61 is, for example, a concave aspherical surface or a free curved surface. The second optical surface 62 is, for example, a convex aspherical surface or a free curved surface. The surface angle of the combiner 60 (the angle formed between the target portion of the tangential plane and the central axis AX) is relatively loose (specifically, 45 ° or less). The first optical surface 61 is provided with a half mirror layer having a reflectance of, for example, 20 to 30% on the surface of a resin-made molding member having light transmittance. The combiner 60 is incorporated in a head-up display device that is assembled around the dashboard in the vehicle.

As shown in FIG. 6A, the molding die 50 includes a first die 51 and a second die 52. The 1st metal mold | die 51 has the 1st molding surface 51a which forms the 1st optical surface 61 side of the combiner 60 which is a molded article. The first molding surface 51 a has a transfer surface having a shape obtained by inverting the first optical surface 61. The second mold 52 has a second molding surface 52 a that forms the second optical surface 62 of the combiner 60. The second molding surface 52 a has a transfer surface having a shape obtained by inverting the second optical surface 62. The first and second molding surfaces 51a and 52a may be subjected to metal plating such as electroless Ni—P plating. In the processing apparatus 100 of FIG. 1, the first and second molding surfaces 51a and 52a of the molding die 50 are mainly processed.

In addition, the workpiece WO processed by the processing apparatus 100 is not limited to a mold having a large area such as the molding die 50 but may be a combiner 60 itself that is a molded product. The workpiece WO may be another product, for example, an optical original device or an optical element such as a mirror or a lens. Further, the workpiece surface Mb of the workpiece WO is not limited to a non-rotationally symmetric shape such as a free-form surface, and may have a rotationally symmetric shape. Further, the material of the workpiece WO is not limited to metal or resin, but may be glass or the like.

[GCIB processing method]
Hereinafter, a processing method using the processing apparatus 100 will be described with reference to FIG. In the main controller 99, target shape data (design shape data) of the workpiece WO is stored in advance in the storage unit 99b by a user operation or the like.

First, processing data (standard processing data and angle-dependent processing data) for calibration are acquired using the dummy member WB. As the dummy member WB, the same material as that of the workpiece WO is used. The processed data is angle-dependent data with respect to the GCIB removal amount. Based on the processing data, the workpiece WO can be processed without swinging by correcting the GCIB processing amount according to the surface angle of the processing point of the processing WO. Thereby, the positioning of the workpiece surface Mb of the workpiece WO and the GCIB is facilitated, and the actual machining time can be shortened. Note that the standard machining data and the angle-dependent machining data may be used if there is a ready-made database.

First, standard processing data of the dummy member WB is acquired (step S11). The main control device 99 operates the GCIB control unit 97 to irradiate the GCIB from the GCIB irradiation device 20 and process the flat dummy member WB. At this time, the main controller 99 operates the stage controller 96 to move the stage device 30 to which the dummy member WB is attached. Specifically, main controller 99 operates stage device 30 so that the incident angle of GCIB is 0 ° and the irradiation distance and the irradiation time are constant. In order to set the incident angle of GCIB to 0 °, the stage device 30 aligns the central axis AX of the dummy member WB and the irradiation axis BX of the GCIB in parallel. After processing, the surface shape of the dummy member WB is measured using the shape measuring device 40. The processed dummy member WB is removed from the stage device 30 and then set in the shape measuring device 40. The main control device 99 operates the shape measurement control unit 98 to cause the shape measurement device 40 to measure the machining shape information regarding the dummy member WB. The measured machining shape information is stored in the storage unit 99b. The machining shape information is computed by the computation processing unit 99a of the main controller 99, and as standard machining data, the relative scanning speed and machining depth data at the incident angle of 0 ° (or the relative scanning speed at the surface angle of 0 °) Correlation data with the GCIB processing amount) is stored in the storage unit 99b.

Next, angle-dependent machining data of the dummy member WB is acquired (step S12). As in step S11, the processing distance information of the dummy member WB is acquired using the GCIB irradiation device 20, the stage device 30, the shape measuring device 40, and the like, with the irradiation distance and the irradiation time being constant, but in step S12, For example, the incident angle of GCIB applied to the dummy member WB is changed using the swing stage 36 or the like. The machining shape information measured in step S12 is arithmetically processed by the arithmetic processing unit 99a of the main control device 99, and as angle-dependent processing data, data of the processing depth when the incident angle is changed (or the GCIB processing rate). Angle-dependent data) is stored in the storage unit 99b.

Next, the shape data before processing of the workpiece WO to be actually processed is acquired (step S13). The main control device 99 operates the shape measurement control unit 98 and causes the shape measurement device 40 to measure shape information regarding the workpiece WO before processing. At this time, the main control device 99 operates the shape measurement control unit 98 to move the XY axis stage 42 of the shape measurement device 40 over the entire processing range from the processing start point to the processing end point of the workpiece WO (in this embodiment, , The entire processing surface Mb is moved so as to scan. The measured shape information is stored in the storage unit 99b. The shape information is subjected to arithmetic processing by the arithmetic processing unit 99a of the main control device 99, and position coordinate and surface angle data is stored in the storage unit 99b as pre-processing shape data. The surface angle data is calculated by a predetermined design formula from an approximation formula etc. of the shape before processing, and the incident angle of GCIB coincides with the surface angle based on the central axis AX.

Next, the shape error data of the workpiece WO is acquired (step S14). The main control device 99 reads the design shape data and the pre-processing shape data from the storage unit 99b, and the arithmetic processing unit 99a calculates the difference between the design shape data and the pre-processing shape data. The calculation result is stored in the storage unit 99b as shape error data.

Next, shape correction NC data for shape error correction is created (step S15). The main controller 99 reads the standard machining data and angle-dependent machining data of the dummy member WB and the shape error data of the workpiece WO from the storage unit 99b, and uses the shape correction NC data creation CAM in the arithmetic processing unit 99a. Create corrected NC data. The shape correction NC data is calculated using, for example, a curved surface processing algorithm. Based on the standard processing data of the dummy member WB (see step S11), it is possible to obtain the irradiation dose at each position of the GCIB for removing the substance corresponding to the error. This irradiation dose is correlated with the relative scanning speed. Further, based on the standard processing data, the GCIB beam size and the processing depth within the range of the beam size (the depth from the original surface of the portion where the material on the surface of the dummy member WB has been removed by irradiation: The relationship with the GCIB processing amount) is also obtained. Further, based on the angle-dependent machining data (see step S12), the angle-dependent GCIB machining amount corresponding to the surface angle of each machining point can be calculated. Here, the angle-dependent GCIB processing amount is a GCIB processing rate corresponding to the incident angle of GCIB. Based on the angle-dependent GCIB processing amount, the GCIB processing amount corresponding to the surface angle of the processing point of the workpiece WO is corrected from the shape error data, so that the GCIB processing amount for correcting the shape error is changed for each object. It can be converted into a corrected relative scanning speed corresponding to the surface angle at the processing point. Thereby, the conditions which can be processed in the state which does not rock | fluctuate the workpiece WO can be calculated | required. The shape correction NC data includes position coordinates (data points) of processing points of the workpiece WO, relative scanning speed data for each data point, scanning pitch, the number of times of irradiation within the processing range, and the like. Of these, the number of irradiations has a primary meaning of dividing the processing amount when the processing amount is large, but has the meaning of reducing processing unevenness and preventing redeposition of removed matter. The shape correction NC data is stored in the storage unit 99b.

Next, after the workpiece WO is set on the rotary stage 35, the workpiece WO is positioned at the machining start point (step S16). The workpiece WO fixed on the stage apparatus 30 is positioned with respect to the aperture member 23 of the GCIB irradiation apparatus 20. Specifically, before starting the processing, for example, the opening 23a of the aperture member 23 is positioned on the corner (or edge) of the workpiece WO to be the reference point (or processing start point). The Further, alignment is performed so that the center axis AX of the workpiece WO and the irradiation axis BX of the GCIB are parallel to each other. That is, the central axis of the aperture member 23, that is, the GCIB irradiation axis BX is parallel to the central axis AX of the workpiece WO or perpendicular to the bottom surface Ma of the workpiece WO. In the stage device 30, the XY position coordinates of the workpiece WO are aligned so as to coincide with the XY position coordinates of the workpiece WO measured by the shape measuring device 40.

Next, GCIB irradiation and relative scanning are performed on the workpiece WO (step S17). At this time, the main control device 99 causes the stage control unit 96, the GCIB control unit 97, and the like to execute the shape correction NC data read from the storage unit 99b using the CNC software. The main controller 99 operates the stage controller 96 and drives the stage device 30 to move the workpiece WO relative to the GCIB. As a result, the workpiece WO keeps the GCIB irradiation distance constant from the machining start point (for example, the corner of the workpiece WO) to the machining end point (the corner opposite to the machining start point). However, the relative scanning speed (specifically, the speed in the X-axis direction) is changed so as to correct the shape error of the workpiece WO, and the three-dimensional translational movement relative to the GCIB is performed two-dimensionally. Raster type scanning is performed. In parallel with this, the main control device 99 operates the GCIB control unit 97 to drive the GCIB irradiation device 20 to irradiate the workpiece surface Mb of the workpiece WO with GCIB. As a result, as shown in FIG. 4A, the GCIB draws a one-stroke writing scanning trajectory TK over the entire surface to be processed Mb at a predetermined scanning pitch. Since the processing range by GCIB does not make a step at the boundary between the GCIB irradiation surface and the non-irradiation surface, it is desirable that the entire processing surface Mb is used even when local shape correction is performed. Adjustment of the irradiation dose required for processing is performed by controlling the relative scanning speed of the workpiece WO with respect to GCIB. The portion where shape correction is not required is scanned so that the beam stay time is minimized. When the relative scanning speed is slow, the irradiation dose amount increases, and the processing amount of the portion increases. On the other hand, when the relative scanning speed is high, the irradiation dose is reduced, and the partial processing amount is reduced. In the shape correction NC data, the irradiation dose amount at each processing point is calculated so that the total processing amount in irradiation corrects the shape error acquired in step S14. For this reason, it is possible to correct the shape error existing in the workpiece WO before processing. In GCIB irradiation, it is desirable to repeat scanning many times so that a removed material does not deposit more than a certain amount on the irradiated surface.

Next, the processing in one order (the entire processing range) from the processing start point to the processing end point of the workpiece WO is completed, and a shape error remains in the workpiece WO, and the irradiation process and scanning in step S17 again. When the process is performed, that is, when the predetermined number of irradiations is not reached (N in Step S18), the process returns to the positioning process in Step S16, and the processing on the workpiece WO is repeated. If there is no shape error in the workpiece WO (Y in step S18), the processing is terminated. Thereby, the workpiece WO which achieved the processing target can be obtained.

According to the processing method and the processing apparatus described above, with respect to GCIB reduced to a predetermined size, relative irradiation is performed so that the irradiation distance DR (distance between the aperture member 23 and the workpiece WO) is kept constant, and relative By controlling the scanning speed so as to achieve the processing target, the target shape can be formed on the workpiece WO so that the surface roughness is, for example, about PV 100 nm. By making the irradiation distance DR constant, for example, it is possible to cover the process of forming the target shape with the processing measurement result of one kind of dummy member WB at a certain distance. Further, since the workpiece WO is processed without swinging, the difficulty of positioning is reduced compared to when swinging, and the processing time can be shortened. Further, since the three-dimensional translational movement is performed at the time of relative scanning, it is possible to avoid uneven irradiation such as a portion where the beam is always irradiated as in the case of rotating the workpiece WO, and a steep step due to the rotation processing. Therefore, shape error correction is highly accurate and shape control is facilitated. Thereby, not only the workpiece WO having a rotationally symmetric shape but also the workpiece WO having a non-rotationally symmetric shape such as a free-form surface can be processed with high accuracy and efficiency. In order to relatively scan the workpiece WO for correcting the shape of the free-form surface, a large number of data points, speed control for each data point, multi-axis interlocking operation, and the like are necessary. This easily satisfies the above conditions. Therefore, an arbitrary shape such as a free-form surface can be handled, and the relative scanning speed can be controlled in accordance with the shape error amount. Thereby, the surface angle is relatively loose (specifically, 45 ° or less), and the shape error of the workpiece having a large area and a free-form surface can be corrected with high accuracy.

〔Example〕
Hereinafter, examples of the processing method and the processing apparatus 100 will be described. A workpiece WO having a side length of 50 cm and a rectangular outer shape was used. The workpiece WO has a convex shape on the center side. The material of the workpiece WO is a SUS material. The surface of the workpiece WO is subjected to electroless Ni—P plating. As GCIB generating gas, SF ₆ + He mixed gas (mixing ratio SF ₆ : He = 1: 9) was used. The gas pressure was 0.4 MPa, and the irradiation dose was 2 × 10 ¹⁶ to 2 × 10 ¹⁷ ions / cm ² . The aperture member 23 is made of SUS, and the size of the opening 23a is 5 mm in diameter.

The above-described workpiece WO was fixed to the stage device 30, and the workpiece WO was subjected to three-dimensional translational scanning processing (linear scanning processing). The stage device 30 is configured to simultaneously control the operation in the X-axis direction and the operation in the Z-axis direction and perform pitch feed in the Y-axis direction. The scanning pitch was 0.1 mm. The irradiation distance DR of GCIB was 20 mm.

After processing the workpiece WO, the surface shape of the processing surface Mb was measured using the shape measuring device 40. Although the shape error PV before processing was 300 nm, the shape error PV after processing after correcting the shape error was 100 nm, and the surface roughness was improved.

As mentioned above, although the processing apparatus etc. which concern on this embodiment were demonstrated, the processing apparatus etc. which concern on this invention are not restricted to said thing. For example, in the above-described embodiment, for example, the shape and size of the processing surface Mb of the workpiece WO can be appropriately changed according to the application and function. Further, as the workpiece WO, one having a non-flat bottom Ma can be used. In this case, the irradiation axis BX of GCIB is aligned with the central axis AX of the workpiece WO.

In the above embodiment, the shape and size of the opening 23a of the aperture member 23 can be changed as appropriate according to the shape and size of the processing surface Mb.

In the above embodiment, the entire processing surface Mb of the workpiece WO is processed, but a part thereof may be processed.

In the above-described embodiment, the example of processing for correcting the shape error of the workpiece WO that has been pre-processed has been described.

In the above embodiment, in step S12 of the processing method, data is acquired by changing the incident angle using one flat dummy member WB, but the data is acquired using the dummy member WB having changed incident angle. You may get it. In this case, the dummy member WB is provided with a plurality of inclined surfaces.

In the above embodiment, if there is a database related to the processing data of the dummy member WB, it is not necessary to perform steps S11 and S12 every time.

In the above embodiment, an XYZ axis stage for positioning the workpiece WO with respect to the rotary stage 35 may be provided on the rotary stage 35.

Claims

An irradiation step of irradiating the workpiece with the gas cluster ion beam through an aperture member that squeezes the gas cluster ion beam to be radiated on the workpiece to a predetermined size;
A scanning step of moving the workpiece in a three-dimensional translation relative to the aperture member while maintaining a constant distance between the opening of the aperture member and the workpiece;
With
In the scanning step, a gas cluster ion beam processing method for controlling a relative scanning speed so as to achieve a processing target.
Using a dummy member made of the same material as the workpiece, the step of obtaining angle dependency data regarding the removal amount by the gas cluster ion beam,
2. The gas cluster ion beam according to claim 1, wherein the workpiece is processed without swinging by correcting the gas cluster ion beam machining amount in accordance with a surface angle of a workpiece point of the workpiece. Processing method.
The gas cluster ion beam processing method according to any one of claims 1 and 2, wherein in the scanning step, a relative scanning speed is controlled to correct a shape error.
The gas cluster ion beam processing method according to any one of claims 1 to 3, wherein an irradiation axis of the gas cluster ion beam is parallel to a central axis of a processing surface of the workpiece.
The gas cluster ion beam processing method according to any one of claims 1 to 3, wherein an irradiation axis of the gas cluster ion beam is perpendicular to a bottom surface of the workpiece.
The gas cluster ion beam processing method according to any one of claims 1 to 5, wherein a distance between the aperture member and the workpiece is 5 mm or more and 25 mm or less.
The gas cluster ion beam processing method according to any one of claims 1 to 6, wherein a processing surface of the workpiece has a rotationally symmetric shape.
The gas cluster ion beam machining method according to any one of claims 1 to 6, wherein a workpiece surface of the workpiece has a free-form surface shape.
The gas cluster ion beam processing method according to any one of claims 1 to 8, wherein a gas generated by the gas cluster ion beam includes a halogen element.
A stage device that translates the workpiece relative to the aperture member in a three-dimensional translation while maintaining a constant distance between the opening of the aperture member that narrows the gas cluster ion beam to a predetermined size and the workpiece. When,
By causing the stage device to perform a three-dimensional translation, scanning is performed while irradiating the workpiece with the gas cluster ion beam, and the relative scanning speed of the irradiation position of the gas cluster ion beam is changed according to the processing target. A stage control unit,
A gas cluster ion beam processing apparatus comprising: