JP2752777B2 - Magnetic levitation and drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] Magnetic levitation that supports and rotates a disk on which a wafer is mounted in the application of an etching resist to a wafer in the manufacture of highly integrated semiconductors or the ion implantation of the wafer. -Regarding a drive mechanism.

[Prior Art] A disk on which a wafer is coated with an etching resist in the manufacture of highly integrated semiconductors or a wafer on which a wafer is mounted in ion implantation into a wafer simply rotates by supporting a rolling bearing or the like to apply the resist. Ion implantation had been performed.

[Problems to be Solved by the Invention] A disk for mounting an etching resist on a wafer in the manufacture of highly integrated semiconductors or for mounting a wafer in ion implantation on the wafer simply rotates by supporting a rolling bearing or the like. Since the application of the resist and the ion implantation were performed, dust was generated from the support mechanism, which deteriorated the yield of the product. In addition, there is room for improvement in the uniform application of the etching resist to the wafer or the uniform implantation of ions into the wafer due to only the rotational movement.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic levitation and drive mechanism for preventing dust generation and uniformizing the application of an etching resist to a wafer or ion implantation.

According to the present invention, a magnetic member (101) and an electric conductor (102) are provided.
A levitation flat plate (100) that moves by magnetic levitation;
The floating flat plate (10) faces above the magnetic member (101).
0) and magnetic yoke (201) that is attracted and levitated by electromagnetic force
And a cylindrical electromagnet (200) for controlling the axial direction, which comprises an exciting coil (202); a displacement sensor (203) for measuring a gap between the floating flat plate (100) and the cylindrical electromagnet (200); A ring-shaped yoke (301) having an electric density close to electric saturation is controlled by the exciting current of the exciting coil (306) facing the lower part of the (100) and the movement of the floating flat plate (100) around the diameter axis. Yoke part (302) divided into four parts in the circumferential direction for
An electromagnet coil (303) and an electromagnet core (304) provided on the yoke portion (302) for changing magnetic flux between the yoke portion (302) and the floating flat plate (100); (30
And 4) a connecting yoke (305) for connection, and an electromagnet (300) for controlling the rotation around the diameter axis.

According to the present invention, there are further provided four linear induction servomotors (401) that face the electric conductor (102) and move in a non-contact manner to move the floating flat plate (100) in a non-contact manner within the plane thereof; A rotation sensor (411) and a displacement sensor (410) for measuring a displacement amount of the translational movement are provided.

[Operation] In the magnetic levitation and drive mechanism configured as described above, (1) regarding the control of the movement in the axial direction and around the diameter axis, based on the average of the output values from the displacement sensor 203,
, And the position in the axial direction perpendicular to the surface of the floating flat plate 100 is controlled.

Further, the electromagnet 300 controls the movement of the floating flat plate 100 about two diameter axes in a non-contact manner. In this case, the excitation coil
Due to the current of 306, the directions of the magnetic flux in the yoke portions 301 and 302 are opposite to each other.

From the difference signal of the output value between the displacement sensors 203, a signal proportional to the rotation angle of the levitation flat plate 100 around the diameter axis is obtained, and based on this signal, the exciting current of the electromagnet coil 303 is controlled.
The movement of the floating plate 100 about two diameter axes is controlled by changing the magnetic flux between the floating plate 100 and the floating plate 100. In this case, the four yoke portions 302 are paired by two diagonal yoke portions, and energize the exciting coil 303 so as to generate magnetic fluxes in mutually opposite directions.

(2) For the control of rotation and translational motion,
To make a rotation and translational movement in a non-contact manner in that plane,
The thrust of the four linear induction servomotors 401 is controlled as follows.

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

In the case of the translational motion, a three-phase current having the same amplitude is output from a servo amplifier that excites the primary coils of the two motors 401 on the diagonal line so as to generate a thrust in the translational direction. The position of the levitation plate 100 in the translation direction is detected by the displacement sensor 410 and fed back to maintain the translation position at a predetermined value.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a floating flat plate 100 has an annular magnetic member 101.
And an electric conductor 102 housed in the member 101.

Opposed above the floating flat plate 100, a cylindrical axial control cylindrical electromagnet 200 is provided.The magnet 200 includes a magnetic yoke 201 and an exciting coil 202 embedded in the yoke 201. . Further, four displacement sensors 203a to 203a for measuring the gap ΔH1 between the floating flat plate 100 and the cylindrical electromagnet 200 in a non-contact manner.
3d (hereinafter, the reference numeral 203 is used when collectively referred to) is provided on the circumference equally.

A ring-shaped electromagnet 3 opposed to below the floating plate 100
00 is provided. The electromagnet 300 has a magnetic flux density (fifth) close to magnetic saturation generated by the exciting current of the exciting coil 306.
The ring-shaped yoke 3 of the magnetic flux line 310 by the coil 30 in the figure)
01, a quadrant yoke 302 divided into four in the circumferential direction for controlling the movement of the floating flat plate 100 around the diameter axis, and the yoke 302
Magnetic flux between the yoke portion 302 and the floating flat plate 100 (the fifth
Electromagnetic coils 303a to 303 that change the reference numeral 311)
c (hereinafter referred to collectively as 303), an electromagnet core 304, and a connecting yoke 305 connecting the electromagnet core 304.

Further, a two-way driver 400 is provided so as to face below the electric conductor 102. On the substrate 400a of the driver 400, four linear induction servomotors 401a to 401d that drive in a tangential direction to move the electric conductor 102 in a non-contact manner.
A rotation sensor 411 (first number 1d) is provided to count small grooves 412 provided at equal intervals in the circumferential direction near the outer periphery of the floating flat plate 100.
Figure) and four displacement sensors that measure the amount of translational translation
421a to 420d (hereinafter, the symbol 420 will be used when collectively referred to). Symbol 402 in the figure is a stator, 403
Is a primary coil. In FIG. 1, symbols .DELTA.H1 and .DELTA.H2 denote levitation flat plate 100 and electromagnets 200 and 300, respectively.
And H indicates the thickness of the floating flat plate 100. ΔH1 and ΔH2 are very small relative to H.

FIG. 2 is a block diagram of a control system for controlling the movement in the axial direction perpendicular to the plane of the floating flat plate 100.

In this control system, the outputs of the displacement sensors 203a to 203d are added by an adder 220, a signal proportional to the axial displacement of the floating flat plate 100 is obtained, and the signal is guided to a compensation circuit 221 including a phase delay advance circuit and the like. Further, the output of the compensation circuit is connected to a current amplifier 222.
Then, the exciting coil 202 is excited to generate a magnetic attractive force between the magnetic yoke 201 and the magnetic member 101. The resistance of the current feedback resistor 223, which is connected in series to the exciting 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 is a block diagram of a control system for controlling the movement of the floating flat plate 100 around the diameter axis.

In this control system, the excitation coil 306 that generates a bias magnetic flux is excited by a power supply 307 having a constant voltage. The differential amplifier 321 obtains a difference signal from the outputs of the two displacement sensors 203a and 203c, obtains a signal proportional to the angular position of the flying plate 100 around the diameter axis, and includes a compensation circuit 32 including a phase delay advance circuit and the like.
2, the output of the compensation circuit 322 is amplified by the current amplifier 323, and the exciting coils 303a and 303c are simultaneously excited to change the magnetic attractive force between the electromagnet yoke 302a and 302c and the magnetic member 101. It has become. The voltage of the current feedback resistor 324 connected in series with the exciting 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 is a block diagram of a control system for controlling the rotation and translational movement of the floating flat 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 the differential amplifier 433, and the signal from the translation indicator 440 and the movement of the floating flat plate 100 in the translation direction are calculated. Adders for adding and subtracting signals from displacement sensors 410a and 410c to be measured
The result is led to 434, and an error signal 451 is obtained. 6, the servo motor 401b has a thrust 420b in the X direction proportional to the rotation error 450 and a thrust 421b proportional to the translation error 451.
The two error signals 450 and 451 are led to the adder 431b in order to obtain Three sine waves sin each having a phase difference of 120 degrees created by the sine wave generator 441 according to the rotation instruction of the rotation indicator 430
The products of θ, sin {θ− (2/3) π}, sin {θ− (4/3) π} and the output of the adder 431b are formed by the multipliers 432bU, 432bV, 432bW, and the power amplifiers 405bU, 405bV , 405bW, and a predetermined combined thrust is obtained by exciting the coils 403bU, 403bV, 403bW of the servo motor 401b. Also, the servo motor 401d is configured substantially in the same way as the servo motor 401b, and obtains a predetermined combined thrust. Then, a force in the X direction and a moment in a desired rotational direction are generated by these combined thrusts, and a translational motion and a rotational motion are obtained.

Next, the operation will be described mainly with reference to FIG. 5 and FIG.

In FIG. 5, two diagonal displacement sensors 203a,
From the difference signal between the outputs of 203c, a signal proportional to the rotation angle about the diameter axis of the floating flat plate 100 is obtained, and based on this signal, the exciting current of the electromagnet coil 303 connected to the four-piece yoke 302 is controlled, and By changing the magnetic flux 311 between the iron part 302 and the floating flat plate 100, the movement of the floating flat plate 100 around two diameter axes is controlled.

At this time, the four yoke portions 302 are paired by two diagonal yoke portions, and energize the exciting coil 303 so as to generate magnetic fluxes in mutually opposite directions. The magnetic flux 311 generated by the exciting coil 303 is applied to the floating plate 100, the yoke 302, and the electromagnet core 30.
4. The path is the connecting yoke 305, the electromagnet core 304, and the floating flat plate 100.

In FIG. 6, by controlling the thrusts of the four linear induction servomotors 420a to 420d as follows, the rotation and translation of the floating flat plate 100 are performed.

Regarding the rotational motion, so that the four servo motors 401a to 401d also generate thrusts 420a to 420d in the desired rotational direction,
A three-phase current having the same amplitude is output from a servo amplifier that excites the primary coil of the servo motor 401. 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 flat plate 100 is detected by a rotation sensor 411, and a signal thereof is fed back to a servo amplifier to maintain the rotation speed at a predetermined value.

Regarding the translational motion, of the four servo motors 401, the same amplitude is generated from the servo amplifiers that excite the primary coils of the two servo motors 401b and 401d on the diagonal line so as to generate thrusts 421b and 421d in the translation direction. Is output.
The displacement of the floating flat plate 100 in the translation direction is detected by the displacement sensor 410, and the signal is fed back to the servo amplifier to maintain the translation position at a predetermined value.

[Effects of the Invention] Since the present invention is configured as described above,
In a disk on which an etching resist is applied to a wafer in the manufacture of a highly integrated semiconductor or a wafer in which a wafer is mounted in ion implantation into the wafer, dust from the support mechanism is eliminated, and the product yield can be improved. In addition, uniform rotation of the etching resist on the wafer or uniform implantation of ions on the wafer can be realized because the rotation movement and the translation movement can be performed simultaneously.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side sectional perspective view showing one embodiment of the present invention, FIG. 2 is a block diagram of a control system for controlling an axial direction orthogonal to a plane of a floating flat plate, and FIG. FIG. 4 is a block diagram of a control system for controlling the movement of the levitation plate about the diameter axis, FIG. 4 is a block diagram of a control system for controlling the rotation and translational movement of the levitation plate, and FIG. FIG. 6 is a plan view for explaining the operation of four linear induction servomotors for controlling the rotation and translational movement of the floating plate. 100: floating plate, 101: magnetic member, 102: electric conductor, 200: cylindrical electromagnet for axial control, 201: magnetic yoke, 202: excitation coil, 203: displacement sensor, 300 …
Electromagnet, 301: ring-shaped yoke, 302: 4-split yoke, 303: electromagnet coil, 304: electromagnet core, 305:
… Connecting yoke, 306… excitation coil, 400… two-way driver, 401… linear induction servomotor, 410…
… Displacement sensor, 411 …… Rotation sensor, 412 …… Groove for measuring rotation speed

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/265 H01L 21/265 E

Claims (2)

(57) [Claims] A floating plate which comprises a magnetic member and an electric conductor and moves by magnetically levitating; a magnetic yoke opposed to above the magnetic member to attract and float the floating plate by electromagnetic force; and an exciting coil. A cylindrical electromagnet for cylindrical control in the axial direction; a displacement sensor for measuring a gap between the floating flat plate and the cylindrical electromagnet; a ring shape having a magnetic density close to magnetic saturation due to an exciting current of an exciting coil opposed to below the floating flat plate. A yoke portion, a yoke portion divided into four parts in the circumferential direction for controlling the movement of the levitation plate about the diameter axis, and a portion between the yoke portion and the levitation plate provided in the yoke portion. A magnetic levitation and drive mechanism, comprising: an electromagnet coil and an electromagnet core for changing the magnetic flux of the magnetic field, and a diameter axis control electromagnet including a connecting yoke connecting the electromagnet core. 2. Four linear induction servomotors which face a conductor and move a floating flat plate in a non-contact manner in the plane thereof, and which are driven in the incision direction, a rotation sensor for measuring a rotation speed and a displacement amount of a translational movement, and The magnetic levitation and drive mechanism according to claim 1, further comprising a displacement sensor.