JP2012141249A - Rotation control device and rotation control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation control device capable of improving accuracy of rotation control of a workbench with compact structure, and a rotation control method.SOLUTION: A rotation control method includes: a step of generating a rotational unevenness signal and a rotational run-out amount signal by processing a read signal of a rotary encoder which rotates interlocking with rotation of a rotor; a step of performing rotational speed servo control of the rotor at a rotational drive part according to the rotational unevenness signal; and a step of performing position servo control over a workpiece at a processing part according to the rotational run-out amount signal.

Description

  The present invention relates to a rotation control device and a rotation control method provided with a rotating body such as a turntable.

  With the advancement of functionality and accuracy of basic technology, it is not sufficient to improve the accuracy of parts such as motors for high-precision machining of rotary systems or high-precision position measurement. Therefore, it is necessary to detect the amount of rotation unevenness and the amount of rotation blur, determine the correction amount, and feed it back to the processing machine or measuring instrument (for example, see Patent Document 1 and Patent Document 2).

  A rotary encoder is used to detect the amount of rotation unevenness, and a laser length measuring device is used to detect the amount of rotation blur. A signal detected from a conventional high-accuracy rotary encoder is generated by detecting the position of each slit in a concentric arrangement of slits incorporated therein (see, for example, Patent Document 3 and Patent Document 4). .

International Publication No. 2007/111260 International Publication No. 2007/111126 JP-A-6-76293 JP-A-8-212552

  However, the accuracy required by the advancement of technology is on the nanometer level, and sufficient performance cannot be obtained with a conventional encoder. This is because the factor depends on the manufacturing process of the slit and the performance (resolution) of the detector. High-precision slits are manufactured with a rotary drawing device using a laser as a light source, but the resolution determined by the wavelength limit of the laser light source limits the blurring of the slit and the number of pulses depending on whether it is a long size. Can be mentioned. Further, the conventional laser length measuring device has a problem that detection accuracy is poor.

  Furthermore, in order to improve the accuracy, it was necessary to design the two detectors of the rotary encoder and the laser length measuring device and the system in a narrow space.

  Therefore, the problems to be solved by the present invention include the above-mentioned drawbacks as an example, and a rotation control device and rotation control capable of improving the accuracy of rotation control of a rotating body (work table) with a compact configuration. It is an object of the present invention to provide a method.

  A rotating body control device according to a first aspect of the present invention is a rotary worktable device including a rotation driving unit that rotates a rotatable rotating body, and a processing unit that processes a workpiece placed on the rotating body. A rotary encoder that rotates in conjunction with rotation of the rotating body, and a signal processing circuit that processes a read signal of the rotary encoder to obtain a rotation unevenness signal and a rotation blur amount signal, and the rotation The drive unit performs rotation speed servo control of the rotating body according to the rotation unevenness signal, and the processing unit performs position servo control for the workpiece according to the rotation blur amount signal.

  According to a fourth aspect of the present invention, there is provided a rotation control method comprising: a rotation drive unit that rotates a rotatable rotating body; and a processing unit that processes a workpiece placed on the rotating body. A rotation control method, comprising: processing a read signal from a rotary encoder that rotates in conjunction with rotation of the rotating body to generate a rotation unevenness signal and a rotation blur amount signal; and There are provided a step of performing rotational speed servo control of the rotating body in accordance with the unevenness signal, and a step of performing position servo control on the workpiece in accordance with the rotational blur amount signal in the processing unit.

  According to the first and fourth aspects of the invention, the read signal from the rotary encoder that rotates in conjunction with the rotation of the rotating body is processed to generate the rotation unevenness signal and the rotation blur amount signal, and the rotation drive unit rotates the rotation signal. Since the rotation speed servo control of the rotating body is performed according to the unevenness signal and the position servo control for the workpiece is performed according to the rotation blur signal in the processing unit, the accuracy of the rotation control of the rotating body can be improved with a compact configuration. it can.

It is a system diagram of a rotation control device according to the present invention. It is a block diagram of the rotary encoder in the apparatus of FIG. It is a figure which shows the production method of the rotary encoder of FIG. It is a figure which shows the method of producing | generating the amount of rotation nonuniformity. It is a figure which shows the method of producing | generating a rotational shake amount. It is a figure which shows the rotary electron beam drawing apparatus to which this invention was applied. It is a figure which shows specifically the rotary encoder and controller of the apparatus of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a rotation control system using the rotary encoder of the present invention. The system is composed of a rotary encoder 1 in which slit rows or pit rows are formed, an optical pickup that reads slits or pits, a motor 3, a shaft 4, and a turntable (rotating work table 5). 1 and the turntable 5 are coupled by a shaft 4. The shaft 4 is a drive shaft of a motor 5, and the rotary encoder 1 and the turntable 5 are rotated by the rotation of the motor 5.

  The read signal read by the optical pickup 2 is supplied to the signal generation unit 6 to generate a rotation unevenness signal S1 corresponding to the rotation unevenness amount and a rotation shake signal S2 corresponding to the rotation shake amount (axis shake amount). The generated rotation unevenness signal S1 is supplied to the motor control unit 7, and based on the detected rotation unevenness amount S1, the rotation unevenness amount is corrected to control the rotation of the motor. The rotation blur amount signal S2 is supplied to a circuit (not shown) or a control unit that performs various controls, and corrects the rotation blur.

  FIG. 2 shows the structure of the rotary encoder 5.

  The rotary encoder 5 is composed of a glass substrate, and a pattern portion composed of slits or pits is formed on one surface of the glass substrate. The example of FIG. 2 shows an example in which slits 1... N are formed in the pattern portion. The slits are arranged at equal intervals in the circumferential direction. One slit has a rectangular shape in which the length in the circumferential direction is longer than the length in the radial direction.

  FIG. 3 is a diagram illustrating a manufacturing process of the rotary encoder 5.

  The rotary encoder 5 includes an electron beam drawing process S100, a patterning process S200, a metal layer etching process S300, a resist removing process S400, a substrate etching process S500, and a metal layer removing process S600.

  For the slit drawing in the electron beam drawing step S100, for example, a rotary electron beam drawing apparatus including an electron column with a high resolution acceleration voltage of 100 kV is used. By drawing on the electron beam resist using high-energy electrons of 100 keV, it becomes possible to reduce electron forward scattering in the resist and to reduce back scattering from the electron beam resist and the substrate. The substrate on which the metal layer 101 is formed on the substrate 100 and the electron beam resist 102 is formed on the metal layer 101 is irradiated with an electron beam. As the substrate 100, for example, a glass substrate which is a material having a flatness and hardness is used.

  Further, when patterning the slit shape, it is necessary to connect the patterns produced by electron beam drawing in the radial direction. In addition, it is necessary to arrange and arrange accurately at continuous intervals with respect to the rotation direction. In electron beam drawing, performing power modulation of the light source causes deterioration in accuracy, and therefore drawing with constant power. Therefore, in order to perform patterning with high accuracy by continuous drawing, drawing is performed by CLV (constant linear velocity) control. In other words, the slit is not formed by one electron beam irradiation, but first, the innermost circumference side of the slit is drawn by the first rotation, and the next portion is in contact with the drawing position of the first rotation by the second rotation. To draw. Further, drawing is performed a plurality of times, and drawing on the outermost peripheral side of the slit is completed at the final rotation (in the example in FIG. 2, a pattern corresponding to one slit is drawn by six rotations). ), The slit shown in FIG. 2 is formed.

  Next, in the patterning step S200, the portion irradiated with the electron beam is processed, the electron resist is patterned, and a mask made of the electron beam resist is created.

  Next, in the metal layer etching step S300, the metal layer 101 that functions as a substrate etching mask located below the electron beam resist, for example, chromium (Cr) is etched using the electron beam resist as a mask. Thereby, a metal mask for substrate etching is formed.

  Next, in the resist removal step S400, the remaining resist is removed by a process such as ashing to expose the formed metal mask.

Next, the glass substrate 100 is etched using the formed metal mask. The etching depth of the glass substrate 100 is adjusted to the depth required in the development of the detector. In the etching, large area batch etching is performed.
Finally, the metal mask remaining in the metal layer removing step S600 is removed and washed to complete the rotary encoder 5 in which slits are formed on the glass substrate.

  The rotary encoder is not limited to the manufacturing method in the process shown in FIG. 3, and the state in which the metal mask remains after removing the resist in S400 may be used as the rotary encoder, or the metal layer in S600 is removed. On top of that, a new metal may be formed as a reflective film in order to increase the reflectivity so as to be a rotary encoder.

  A method for generating the rotation unevenness amount from the reading signal of the slit of the rotary encoder 5 will be described. As the slit reading means, an optical pickup 2 equipped with a blue semiconductor laser is used. For example, a detection system is configured by the optical pickup 2 equipped with a semiconductor laser having a wavelength of 405 nm, and a reproduction signal is detected from a slit formed concentrically with respect to the rotation axis of the rotary encoder 5.

  At the time of signal detection, the optical system of the optical pickup 2 focuses the slit surface, tracks the formed slit, detects the reflected light amount difference signal, generates a rotation stage rotation control signal, and A rotational shake amount signal is generated. This will be described later.

  The generation of the rotation unevenness signal S1 for detecting the rotation unevenness generated as the rotation error from the reproduction signal of the slit and performing the correction will be described with reference to FIG.

  The reproduction light from the optical pickup passes through the continuous slit in a state where the surface of the slit is focused (L1 in the figure). Thereby, a pulse-like rotation detection signal (L3 in the figure) is obtained. Compared with a rotation detection signal using a conventional rotary encoder, the accuracy of the rotation detection signal is improved by reading the slit while applying focus servo with a small beam diameter. The rotation unevenness detection signal (L4) is generated by comparing this rotation detection signal with the rotation reference signal (L2). That is, the rising position of the clock of the rotation reference signal (L2) and the rising position of the rotation detection signal (L3), or the falling position of the clock of the rotation reference signal (L2) and the falling position of the rotation detection signal (L3). Each is compared, and the difference is detected as the amount of rotation unevenness. A signal indicating the amount of rotation unevenness is the rotation unevenness detection signal (L4). The rotation unevenness detection signal is fed back to the rotation control of the motor or the like as the rotation unevenness signal S1 of the signal generator 6 in FIG.

  With reference to FIG. 5, generation of the rotational shake amount signal S2 generated as a mechanical accuracy error of a spindle motor or the like from the slit reproduction signal will be described.

When the optical pickup 2 reproduces the slit row, tracking servo signals are extracted by applying tracking. The tracking servo is performed using a three-beam method or a phase difference method that is well-known in recording and reproduction of optical disks.
The tracking signal for one rotation is detected a plurality of times and averaged to obtain the tracking signal (L10). A signal indicating that the difference between the known rotation reference value (L11) and the tracking signal (L10) indicates the amount of rotation blur is a rotation blur signal (not shown). The rotation blur amount is fed back to the beam position control of concentric pattern drawing or the position control of a processing machine for fine processing, for example, as a rotation blur amount signal S2 of the signal generator 6 in FIG.
Although the example of FIGS. 1-5 demonstrated using the structure which reads the surface in which the slit row | line | column or pit row | line | column formed in the rotary encoder 5 was formed with an optical pick-up, it is not restricted to this. For example, pickup is performed so that light is irradiated from the surface side where the slit row or pit row is formed, and light transmitted through the rotary encoder is received on the side opposite to the surface where the slit row or pit row is formed. May be configured.

  FIG. 6 is a block diagram schematically showing the configuration of the electron beam lithography apparatus 10 to which the present invention is applied. The electron beam drawing apparatus 10 is a disk mastering apparatus that uses an electron beam to create a master for manufacturing a hard disk.

  The electron beam drawing apparatus 10 includes a vacuum chamber 11, a driving device for placing, rotating, and driving the substrate 15 disposed in the vacuum chamber 11, an electron beam column 20 attached to the vacuum chamber 11, and a substrate Various circuits and control systems for driving control and electron beam control are provided.

  More specifically, the substrate 15 for the master disk is coated with a resist on the surface thereof and placed on a turntable (rotary work table, rotating body) 16. The turntable 16 is rotationally driven with respect to the vertical axis of the main surface of the disk substrate by a spindle motor 17 which is a rotational drive device that rotationally drives the substrate 15. The spindle motor 17 is provided on a feed stage (hereinafter also referred to as X stage) 18. The X stage 18 is coupled to a feed motor 19 which is a transfer (translation drive) device, and can move the spindle motor 17 and the turntable 16 in a predetermined direction (x direction) in a plane parallel to the main surface of the substrate 15. It can be done. Therefore, the Xθ stage is constituted by the X stage 18, the spindle motor 17 and the turntable 16.

  The spindle motor 17 and the X stage 18 are driven by a stage drive unit 37, and the feed amount of the X stage 18 that is the drive amount and the rotation angle of the turntable 16 (that is, the substrate 15) are controlled by the controller 30.

  The turntable 16 is made of a dielectric material, for example, ceramic, and has a chucking mechanism such as an electrostatic chucking mechanism (not shown) that holds the substrate 15. By such a chucking mechanism, the substrate 15 placed on the turntable 16 is securely fixed to the turntable 16.

  On the X stage 18, a reflecting mirror 35A that is a part of the laser interferometer 35 is disposed.

  The vacuum chamber 11 is installed via an anti-vibration table (not shown) such as an air damper, and transmission of vibration from the outside is suppressed. The vacuum chamber 11 is connected to a vacuum pump (not shown), and the interior of the vacuum chamber 11 is set to a vacuum atmosphere at a predetermined pressure by evacuating the chamber.

  In the electron beam column 20, an electron gun (emitter) 21 for emitting an electron beam, a converging lens 22, a blanking electrode 23, an aperture 24, a beam deflection electrode 25, a focus lens 27, and an objective lens 28 are arranged in this order. ing.

  The electron gun 21 emits an electron beam (EB) accelerated to, for example, several tens of KeV by a cathode (not shown) to which a high voltage supplied from an acceleration high-voltage power source (not shown) is applied. The converging lens 22 converges the emitted electron beam. The blanking electrode 23 performs on / off switching (ON / OFF) of the electron beam based on the modulation signal from the blanking control unit 31. That is, by applying a voltage between the blanking electrodes 23 to greatly deflect the passing electron beam, the electron beam can be prevented from passing through the aperture 24 and the electron beam can be turned off.

  The beam deflection electrode 25 can control the deflection of the electron beam at high speed based on a control signal from the beam deflection unit 33. With this deflection control, the position of the electron beam spot relative to the substrate 15 is controlled. The focus lens 28 is driven based on a drive signal from the focus control unit 34, and electron beam focus control is performed.

  Further, the vacuum chamber 11 is provided with a height detection unit 36 for detecting the height of the surface of the substrate 15. The photodetector 36B includes, for example, a position sensor, a CCD (Charge Coupled Device), etc., receives a light beam emitted from the light source 36A and reflected by the surface of the substrate 15, and receives the received light signal from the height detector 36. To supply. The height detection unit 36 detects the height of the surface of the substrate 15 based on the light reception signal, and generates a detection signal. A detection signal indicating the height of the surface of the substrate 15 is supplied to the focus control unit 34, and the focus control unit 34 performs focus control of the electron beam based on the detection signal.

  The laser interferometer 35 measures the displacement of the X stage 18 using the laser light emitted from the light source in the laser interferometer 35, and obtains the measured data, that is, the feed (X direction) position data of the X stage 18. This is sent to the stage drive unit 37.

  Further, the rotation signal of the spindle motor 17 is also supplied to the stage drive unit 37. More specifically, the rotation signal includes an origin signal indicating the reference rotation position of the substrate 15 and a pulse signal (rotary encoder signal) for each predetermined rotation angle from the reference rotation position. The stage drive unit 37 obtains the rotation angle, rotation speed, and the like of the turntable 16 (substrate 15) from the rotation signal.

  The stage drive unit 37 generates position data representing the position of the electron beam spot on the substrate based on the feed position data from the X stage 18 and the rotation signal from the spindle motor 17, and supplies the position data to the controller 30. Further, the stage drive unit 37 drives the spindle motor 17 and the feed motor 19 based on a control signal from the controller 30 to perform rotation and feed drive.

  The controller 30 is supplied with track pattern data, such as discrete track media and patterned media, and data (recording data) RD to be recorded (exposed).

  The controller 30 sends a blanking control signal CB, a deflection control signal CD, and a focus control signal CF to the blanking control unit 31, the beam deflection unit 33, and the focus control unit 34, respectively, and records data based on the recording data RD ( (Exposure or drawing) control. That is, the resist on the substrate 15 is irradiated with an electron beam (EB) based on the recording data RD, and a latent image is formed only at a portion exposed by the electron beam irradiation to perform recording (exposure).

  Further, the electron beam drawing apparatus 10 uses the rotary work table apparatus described above to detect rotational runout in the radial direction (hereinafter referred to as a radial direction) when the turntable 16 rotates. The controller 30 controls the beam deflection unit 33 based on the detected rotational shake and adjusts (corrects) the irradiation position of the electron beam.

  The recording control of the electron beam drawing apparatus 10 is performed based on the above-described feed position data and rotation position data. The main signal lines related to the blanking control unit 31, the beam deflection unit 33, the focus control unit 34, and the stage drive unit 37 have been shown, but these components are connected to the controller 30 in both directions to transmit and receive necessary signals. It is configured to be able to.

  In the electron beam drawing apparatus 10, the turntable 16 mounts a substrate (not shown) to be drawn on its main surface (xy plane), and is rotated by the spindle motor 17 together with the substrate.

  As shown in FIG. 7, a disc-shaped rotary encoder 54 is attached to the rotating shaft 53 of the spindle motor 17. On the glass substrate 55 of the rotary encoder 54, a pattern (not shown) composed of a plurality of slits is formed as shown in FIG. The optical pickup 56 of the rotary encoder 54 reads the slit of the glass substrate 55 and generates a pulsed rotary encoder signal.

  The rotation of the spindle motor 17 that rotates the turntable 16 is controlled by the controller 30.

  The controller 30 includes a rotation unevenness detector 62, a rotation blur amount detector 63, a beam irradiation position corrector 64, and a motor rotation controller 65.

  The rotation unevenness detector 62 operates based on a reference signal from a reference signal generator (not shown) and a rotary encoder signal from the rotary encoder 54. That is, the rotation unevenness detection unit 62 generates a difference amount between the reference signal and the rotary encoder signal as a rotation unevenness signal indicating rotation unevenness.

  The motor rotation control unit 65 receives the rotation unevenness signal, and drives the spindle motor 17 via the stage drive unit 37 so as to reduce the rotation unevenness indicated by the rotation unevenness signal. The motor rotation control unit 65 operates to reduce the rotation unevenness indicated by the rotation unevenness signal by controlling the voltage applied to the spindle motor 17 via the stage drive unit 37, for example.

  Based on the rotary encoder signal from the rotary encoder 54, the rotational blur amount detection unit 63 detects a tracking error with respect to the center of the track formed by the slit row of the glass board 55 as a rotational blur amount signal.

  The beam irradiation position corrector 64 receives a rotational shake amount signal, generates deflection correction signals in the x direction and the y direction according to the rotational shake amount signal, and supplies them to the beam deflection unit 33. As a result, the beam deflection unit 33 controls the deflection of the electron beam via the beam deflection electrode 25, so that rotational blurring in the x and y directions is corrected.

Claims (4)

A rotation control device comprising: a rotation drive unit that rotates a rotatable rotating body; and a processing unit that processes a workpiece placed on the rotating body,
A rotary encoder that rotates in conjunction with the rotation of the rotating body;
A signal processing circuit that processes a read signal of the rotary encoder to obtain a rotation unevenness signal and a rotation blur amount signal,
The rotation driving unit performs rotation speed servo control of the rotating body according to the rotation unevenness signal,
The rotation control device, wherein the processing unit performs position servo control on the workpiece in accordance with the rotation blur amount signal.     2. The rotation control device according to claim 1, wherein the rotation blur amount signal is a tracking servo signal of a slit row or a pit row provided on the rotor.   2. The rotation control device according to claim 1, wherein the rotation unevenness signal is a frequency signal having a frequency corresponding to a pitch of slits or pits of a slit row or a pit row provided on the rotor. A rotation control method for a rotation control device, comprising: a rotation driving unit that rotates a rotatable rotating body; and a processing unit that processes a workpiece placed on the rotating body,
Processing a read signal of a rotary encoder that rotates in conjunction with rotation of the rotating body to generate a rotation unevenness signal and a rotation blur amount signal;
Performing rotation speed servo control of the rotating body according to the rotation unevenness signal in the rotation driving unit;
And a step of performing position servo control on the workpiece in accordance with the rotation blur amount signal in the processing unit.