JPH0494104A - Magnetic levitation/driving device - Google Patents

Abstract

PURPOSE:To control two diameter axis-wise movements of a levitation plate by obtaining a signal which is proportional to a diameter axis-wise rotation angle of a levitation plate from a differential signal of output values between potential sensors and by controlling an excitation current of an electromagnetic coil based on the signal to change magnetic flux between a yoke part and the levitation plate. CONSTITUTION:A signal which is proportional to a diameter axis-wise rotation angle of an levitation plate 100 is obtained from a differential signal between outputs of two displacement sensors 203a, 203c on a diagonal line. An excitation current of an electromagnetic coil 303 connected to a quartered yoke part 302 is controlled based on the signal, and flux 311 between the yoke part 302 and the levitation plate 100 is changed to control two diameter axis-wise movements. The four yoke parts 302 form a pair of two yoke parts on a diagonal line, and energize the excitation coil 303 to produce magnetic flux in reverse direction each other. The magnetic flux 311 by the excitation coil 303 passes through the levitaiton plate 100, the yoke part 302, an electromagnetic core 304, a connecting yoke 305 and the levitation plate 100.

Description

Detailed Description of the Invention [Industrial Application Field] Magnetic levitation for supporting and rotationally driving a disk on which a wafer is mounted for applying etching resist to a wafer in highly integrated semiconductor manufacturing or for ion implantation into a wafer.・Regarding the drive mechanism.

[Prior Art] In the application of etching resist to wafers in the manufacturing of highly integrated semiconductors, or in the ion implantation of wafers, the disk on which the wafer is mounted is simply rotated by support such as rolling bearings, and the resist is applied, Ion implantation was performed.

[Problems to be Solved by the Invention] In the application of etching resist to wafers in the manufacture of highly integrated semiconductors, or in the ion implantation of wafers, the disks on which the wafers are mounted simply rotate by being supported by rolling bearings, etc. Apply resist, perform ion implantation,
As a result, dust was generated from the support mechanism, which worsened the yield of the product. Furthermore, since only rotational movement is required, there is room for improvement in uniformly applying etching resist to the wafer or uniformly implanting ions into the wafer.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic levitation/driving mechanism that prevents dust generation and uniformizes the application of etching resist to etching resist or ion implantation.

[Means for Solving the Problems] According to the present invention, a magnetic member (101) and an electric conductor (10
2) A floating plate (100
) and; a cylindrical axial control cylinder consisting of a magnetic yoke (201) facing above the magnetic member (101) and attracted and levitated by electromagnetic force with the floating plate (100) and an exciting coil (202); an electromagnet (200); a displacement sensor (203) for measuring the gap between the levitation plate (100) and the cylindrical electromagnet (200); and an excitation current of an excitation coil (306) facing below the levitation plate (100). a ring-shaped yoke (301) with a magnetic density close to magnetic saturation;
A yoke portion (302) divided into four in the circumferential direction for controlling the movement of the floating plate (100) around the diameter axis, and a yoke portion (302) provided on the yoke portion (302). For control around the diameter axis, it consists of an electromagnetic coil (303) and an electromagnetic core (304) that change the magnetic flux with the floating plate (100), and a connecting yoke (305) that connects the electromagnetic core (304). It is equipped with an electromagnet (300).

Further, according to the present invention, there are four linear induction servo motors (401) that face the electric conductor (102) and drive in the tangential direction to move the floating plate (100) in a non-contact manner within its plane, and the rotational speed and It includes a rotation sensor (411) and a displacement sensor (410) that measure the amount of translational displacement.

[Function] In the magnetic levitation/drive mechanism configured as described above, (1) Regarding the control of motion in the axial direction and around the diametrical axis, the excitation coil 202 is excited based on the average of the output values from the displacement sensor 203. The current is controlled to control the position of the floating plate 100 in the axial direction perpendicular to the plane.

Furthermore, the electromagnets 300 control the movement of the floating flat plates 1000 around the two diameter axes without contact. In this case, the directions of magnetic flux in the yoke parts 301 and 302 are opposite to each other due to the current of the exciting coil 306.

The floating plate 10 is determined from the difference signal between the output values between the displacement sensors 203.
A signal proportional to the rotation angle around the diameter axis of 0 is obtained, and the excitation current of the electromagnetic coil 303 is controlled based on this signal.
By changing the magnetic flux between the yoke part 302 and the floating plate 100, the movement of the floating plate 100 around the two diameter axes is controlled. In this case, the four yoke parts 302 are paired with two diagonal yoke parts, and the excitation coil 303 is energized so as to generate magnetic fluxes in opposite directions.

(2) Regarding the control of rotational and translational movements, the floating plate 10
In order to rotate and translate 0 within that plane without contact, the thrust of the four linear induction servo motors 401 is controlled as follows.

In the case of rotational motion, when all four motors 401 generate thrust in the desired rotational direction, three-phase currents with the same amplitude are output from the servo amplifier that excites the primary coil. The rotational speed of the floating plate 100 is detected by a rotation sensor 411 and fed back to maintain the rotational speed at a predetermined value.

In the case of translational motion, to generate thrust in the translational direction,
Three-phase currents with the same amplitude are output from servo amplifiers that excite the primary coils of two diagonally located motors 401.

The position of the floating plate 100 in the translation direction is determined by the displacement sensor 410.
is detected and fed back to maintain the translational position at a predetermined value.

[Example] The present invention will be described in detail below with reference to the drawings.

In FIG. 1, a floating plate 100 includes an annular magnetic member 1
01 and an electrical conductor 102 housed within the member 101.

A cylindrical axial control cylindrical electromagnet 200 is provided above and facing the floating plate 100, and the magnet 200 is connected to a magnetic material yoke 201 and an excitation coil 2 embedded in the yoke 201.
It consists of 02. In addition, the gap ΔH1 between the floating flat plate 100 and the cylindrical electromagnet 200 is measured in a non-contact manner.
Displacement sensors 203a to 203d (hereinafter, the reference numeral 203 will be used collectively) are provided at equal intervals around the circumference.

A ring-shaped electromagnet 300 is provided below and opposite the floating plate 100. The electromagnet 300 has a ring-shaped yoke portion 301 with a magnetic flux density close to magnetic saturation (see magnetic flux lines 310 due to the coil 30 in FIG. 5) generated by an excitation current of an excitation coil 306, and a magnetic field around the diameter axis of the floating plate 100. A 4-part yoke section 302 that is divided into 4 parts in the circumferential direction that controls the motion, and a magnetic flux between the yoke section 302 and the floating plate 100 provided on the yoke section 302 (see reference numeral 311 in FIG. 5). Electromagnetic coils 303a to 303c (hereinafter collectively referred to as 303) and electromagnet core 3 that change the
04 and the connecting yoke 30 that connects the electromagnet core 304.
It consists of 5.

Further, a two-way driver 400 is provided below and facing the electric conductor 102 . The board 4 of this driver 400
On the 00a are four linear induction servo motors 401a to 401d (hereinafter collectively referred to as 40
1), and a rotation sensor 411 (FIG. 1) that counts the number of small grooves 412 provided near the outer periphery of the floating plate 100 at equal intervals in the circumferential direction, and a rotation sensor 411 (FIG. 1) that measures the amount of translational displacement. displacement sensors 420a to 420d (
(hereinafter, the reference numeral 420 will be used in general). In addition, the symbol 4゜2 in the figure is a stator, and 403 is 1
Next is the coil. In FIG. 1, symbols ΔH1 and ΔH2 indicate the distances between the floating plate 100 and the electromagnets 200 and 300, respectively, and H indicates the thickness of the floating plate 100. ΔH1 and ΔH2 are very small relative to H.

FIG. 2 shows a block diagram of a control system that controls the movement of the floating plate 100 in an axial direction perpendicular to the plane.

In this control system, displacement sensors 203a to 203d
An adder 220 adds the outputs of the floating plate 100 to obtain a signal proportional to the amount of axial displacement of the floating plate 100, which is led to a compensation circuit 221 including a phase delay/lead circuit, etc., and the output of the compensation circuit is further added to a current amplifier 222. The magnetic force is amplified and the excitation coil 202 is excited to generate a magnetic attraction force between the magnetic yoke 201 and the magnetic member 101. Note that the resistance of a current feedback resistor 223 that is connected in series with the excitation coil 202 and senses the current value is fed back to the inlet of the current amplifier 222 to improve the characteristics of the amplifier 222.

FIG. 3 shows a block diagram of a control system that controls the movement of the floating plate 100 around the diameter axis.

In this control system, an excitation coil 306 that generates bias magnetic flux is excited by a constant voltage power supply 307. 2
A difference signal is obtained from the outputs of the displacement sensors 203a and 203C using a differential amplifier 321, a signal proportional to the angular position around the diameter axis of the floating plate 100 is obtained, and the signal is guided to a compensation circuit 322 including a phase delay/lead circuit. Furthermore, the output of the compensation circuit 322 is amplified by the current amplifier 323, and the output of the excitation coil 303 is amplified by the current amplifier 323.
a.

303c is simultaneously excited to make the electromagnetic yoke 302a.

The magnetic attraction force between the magnetic member 302c and the magnetic member 101 is changed. Note that the voltage of a current feedback resistor 324 connected in series to the excitation coil 306 and sensing the current value is fed back to the inlet of the current amplifier 323 to improve the characteristics of the current amplifier 323.

FIG. 4 shows a block diagram of a control system that controls the rotational and translational movements of the floating plate. In this control system, an error signal 450 between the signal from the rotation indicator 430 and the rotation sensor 411 is obtained by a differential amplifier 433,
Additionally, displacement sensors 410a and 410 measure signals from the translation indicator 440 and the movement of the floating plate 100 in the translation direction.
The signals from c are led to an adder/subtractor 434, and an error signal 45
Find 1. Also, referring to FIG. 6, the servo motor 401b has a thrust force 4 in the X direction proportional to the rotational error 450.
20b and a thrust force 421b proportional to the translational error 451, the thumbtack difference signal 450.451 is added to the adder 431b.
lead to. Three waves each having a phase difference of 120 degrees are generated by a sine wave generator 441 by rotation support of a rotation indicator 430.
1 sine wave sinθ, 5in (θ-(2/3)π), 5
in(θ-(4/3)π) and the output of the adder 431b are multiplied by multipliers 432bU, 432bV, and 432bW, and power amplifiers 405bU and 405bV are generated.

A predetermined combined thrust is obtained by amplifying the power by 405 bW and exciting coils 403bU, 403bV, and 403bW of the servo motor 401b. Further, the servo motor 401d is also configured substantially the same as the servo motor 401b, and is configured to obtain a predetermined combined thrust. These combined thrusts generate a force in the X direction and a moment in the desired rotational direction, thereby obtaining translational motion and rotational motion.

Next, the operation will be explained mainly with reference to FIGS. 5 and 6.

In FIG. 5, two displacement sensors 203a on the diagonal
, 203c, a signal proportional to the rotation angle around the diameter axis of the floating plate 100 is obtained, and based on this signal, the electromagnetic coil 3-0 connected to the four-part yoke section 302
The excitation current of 3 is controlled, and the yoke part 302 and the floating flat plate 100 are controlled.
By changing the magnetic flux 311 between
Controls the movement of 00 around two diametric axes.

At this time, the four yoke parts 302 form a pair of two diagonal yoke parts, and the excitation coil 303 is energized so as to generate magnetic fluxes in opposite directions.

The magnetic flux 311 due to this excitation coil 303 is
00, yoke part 302, electromagnet core 304, connecting yoke 30
5. The path is the electromagnet core 304 and the floating plate 100.

In FIG. 6, the floating plate 100 is rotated and translated by controlling the thrust of four linear induction servo motors 4208 to 420d as follows.

Regarding rotational movement, four servo motors 401a to 401
Three-phase currents with the same amplitude are output from the servo amplifier that excites the primary coil of the servo motor 401 so as to generate thrusts 420a to 420d in the desired rotational directions.

Therefore, thrusts 420a to 420d of the same magnitude are generated from the servo motor 401 to induce rotational movement. At this time, the rotation speed of the floating plate 100 is determined by the rotation sensor 411
The rotation speed is maintained at a predetermined value by feeding back the signal to the servo amplifier.

Regarding translational movement, the same amplitude is generated from a servo amplifier that excites the primary coils of two diagonally located servomotors 401b and 401d so as to generate thrusts 421b and 421d in the translational direction among the four servomotors 401. Outputs three-phase current. The displacement of the floating plate 100 in the translational direction is
The displacement sensor 410 detects the displacement, and the signal is fed back to the servo amplifier to maintain the translational position at a predetermined value.

[Effects of the Invention] Since the present invention is configured as described above, it is possible to use a support for a disk on which a wafer is mounted when applying an etching resist to a wafer in highly integrated semiconductor manufacturing or when implanting ions into a wafer. Dust generation from the mechanism is eliminated, and the yield of products can be improved. Furthermore, it is possible to uniformly apply an etching resist to a wafer or to uniformly implant ions into a wafer so that rotational movement and translational movement can be performed simultaneously.

[Brief explanation of drawings]

Fig. 1 is a side cross-sectional perspective view showing one embodiment of the present invention, Fig. 2 is a block diagram of a control system that controls the axial direction perpendicular to the plane of the floating plate, and Fig. 3 is a block diagram of the control system that controls the axial direction perpendicular to the plane of the floating plate. Figure 4 is a block diagram of the control system that controls the movement of the floating plate. Figure 5 is a block diagram of the control system that controls the rotation and translation of the floating plate. Figure 5 is a block diagram of the control system that controls the movement of the floating plate around its diameter axis. FIG. 6 is a side sectional view illustrating the operation, and FIG. 6 is a plan view illustrating the operation of four linear induction servo motors that control the rotational and translational movements of the floating plate. 100... Levitating flat plate 101... Magnetic member 1
02... Electric conductor 200... Cylindrical electromagnet for axial direction control 201... Magnetic material yoke 202... Excitation coil 203--Skewer/displacement sensor 300...
Electromagnet 301...Ring-shaped yoke part 302...
・Four-divided yoke part 303...Electromagnetic coil 30
4... Electromagnet core 305... Connecting yoke 30
6... Excitation coil 400... Two-way driver
401...Linear induction servo motor 4
10...Displacement sensor 411φ...Rotation sensor
412...Small groove for rotation speed measurement

Claims (2)

[Claims] (1) A levitation plate made of a magnetic member and an electric conductor and moved by magnetic levitation; a cylindrical shape made of a magnetic yoke and an excitation coil that face above the magnetic member and attract and levitate the levitation plate by electromagnetic force. a cylindrical electromagnet for controlling the axial direction; a displacement sensor for measuring the gap between the levitation flat plate and the cylindrical electromagnet; The iron department and
a yoke portion divided into four in the circumferential direction for controlling the movement of the levitation flat plate around the diameter axis; and an electromagnet provided in the yoke portion for changing the magnetic flux between the yoke portion and the levitation flat plate. A magnetic levitation/driving mechanism characterized by comprising a coil, an electromagnetic core, and an electromagnet for controlling the diameter axis, which is made up of a connecting yoke that connects the electromagnetic core. (2) Four linear induction servo motors that face the electrical conductor and drive in the tangential direction to move the floating plate non-contact within its plane, and a rotation sensor and displacement sensor that measure rotational speed and translational displacement. The magnetic levitation/drive mechanism according to claim 1, further comprising: