JPH02111272A - Feed system of rotary sample stage - Google Patents

Abstract

PURPOSE:To realize miniaturization and high reliability by low interia by fixing a plurality of permanent magnets onto the outer circumference sidewall surface of a rotary sample stage, disposing coils for generating a rotating magnetic field while being oppositely faced to the permanent magnets and turning the sample stage. CONSTITUTION:Coils 25 for generating a stator-side rotating magnetic field are arranged faced oppositely to permanent magnets 21, 21. The coils are connected to a driver 27 for generating the rotating magnetic field, and voltage or phase is changed, thus controlling the revolution of a sample stage. When voltage is applied to a piezoelectric element 3 from a DC power 15, the piezoelectric elements 21 are elongated in the vertical direction within a range of zero or approximately 100mum in response to applied voltage. A rotary sample stage 1 can be shifted in the Z direction for focusing, etc., while being rotated at thetaat high speed. Since the stator-side rotating magnetic field generating coils 25 are disposed in parallel with the permanent magnets vertically, magnetic flux density among the coils and the permanent magnets is not changed even when the rotary sample stage 1 is moved in the Z direction. Accordingly, the speed of revolution at theta is not also varied.

Description

[Detailed Description of the Invention] [Industrial Applications] The present invention is directed to a Z stage consisting of a piezo element on the underside of a rotating sample stage for holding semiconductor wafers, etc. in a foreign matter inspection device for inspecting wafers for foreign matter. Regarding the power supply method.

More specifically, the present invention relates to a power supply system that does not rely on slip rings.

[Prior Art] For example, in a conventional foreign matter inspection device for wafers, a laser beam generated from a fixed light source is irradiated onto the wafer,
The presence or absence of foreign matter on the wafer surface is inspected from the reflected light.

For this reason, the wafer is absorbed and held on the upper surface of a rotating stage called a rotating sample stage.

[Problem to be solved by the invention] Foreign matter inspection in which a Z stage made of a piezo element is disposed below a rotating sample stage, and the rotating sample stage can be moved in the Z direction (vertical direction) for focusing etc. The device is being prototyped.

However, when using a piezo element as a Z stage,
A high DC voltage must be applied.

For this reason, DC voltage has conventionally been applied using a slip ring, but this may cause contact failure and is less reliable. Additionally, there were many problems with the durability and pressure resistance of the slip ring.

Furthermore, in order to rotate the sample stage, a shaft is fixed at the center of the two stages on the do side, and the rotation shaft of a drive source such as a motor for rotating the sample stage is connected to the end of this shaft by a joint member. Ta.

In order to rotate the sample stage at high speed, a large drive source motor must necessarily be used, and the foreign object inspection apparatus itself becomes large.

Furthermore, if a motor is connected to the shaft to rotate the sample stage, precise rotational control becomes difficult due to the inertia of the sample stage.

Therefore, an object of the present invention is to provide a system for reliably supplying power to a Z stage made of piezo elements, as well as a system for rotating a single rotary test unit that can achieve miniaturization and high reliability with low inertia. .

[Means for Solving the Problems] As a means for achieving the above-mentioned object, the present invention provides a foreign matter inspection device that inspects wafers for foreign matter, in which a piezo is installed on the side of a rotating sample stage for holding semiconductor wafers, etc. A Z stage consisting of an element is fixedly installed, a rotating shaft extends from the center of the two stages, an insulating separator is interposed in the middle of the rotating shaft, and the rotating shaft passes through this insulating separator. It is supported by bearings at two places, the do part and the -1 part, and the + side or one side of the DC power supply is connected to one bearing, and the one side or the + side is connected to the other bearing. The present invention provides a power supply system for a rotating sample stage characterized by applying a DC voltage to a piezo element.

Multiple permanent magnets are fixed on the outer wall of the rotating sample stage.
By disposing a rotating magnetic field generating coil facing this permanent magnet and rotating the sample stage, it is possible to achieve miniaturization and high reliability with low inertia.

[Operation] As described above, according to the power supply system of the present invention, a high DC voltage is applied to the piezo element r from the two bearings used to support the rotating shaft of the sample stage. All the drawbacks of the conventional slip ring system are solved.

Furthermore, according to the rotating sample stage rotational force type of the present invention, the shaft of the rotating sample stage is not connected to the rotating shaft of a drive source such as a motor, but a permanent magnet is fixedly installed on the rotating sample stage and is opposed to the permanent magnet. By arranging a rotating magnetic field generating coil, the rotating sample stage itself can be rotated as a rotor of a servo motor.

Therefore, according to the rotating sample stage drive system of the present invention, frequent starting, power outage, braking, reversal, and slow motion can be performed continuously. Furthermore, the generated torque is large and the inertia is small.

The generated torque ratio to the τtil control input is high, and
Since it is constant, it has excellent controllability. In this way, it is possible to construct a rotary drive system that is smaller and more reliable than conventional rotary drive systems.

[Embodiment] The rotating sample stage driving method and driving method of the present invention will be explained in more detail below with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of the configuration of an apparatus used to implement the rotating sample stage power supply driving method of the present invention.

As shown in FIG. 1, a Z stage 3 made of a piezo element is fixedly installed on the F side of the wafer rotating sample stage 1, and a rotating shaft portion 5 extends from the lower center of the Z stage. There is. The end of the rotating shaft ffi<5 is supported by a tapered roller bearing 7, and the upper end portion of the rotating shaft 5 is rotatably supported by a cylindrical body 11 via a ball bearing 9.

An insulating separator 13 is interposed between the upper and lower support points of the rotating shaft portion 5, forming a partial shaft. One side of the DC power source J5 is connected to the tapered roller bearing 7, and the + side is connected to the ball bearing 9. Of course, the reverse connection is also possible. Two conductive wires are wired inside the rotating shaft, and the first conductive wire 17 is connected from the ball bearing 9 to the ten electrode side of the piezo element r. , the second conducting wire 19 is connected to one electrode side of the piezo element from the rotating shaft portion below the insulating separator 13. With this configuration, the shaft has an angle of 180 Or, p.

DC voltage can be reliably and stably applied to the piezo element even when rotating at high speed.

Preferably, a variable resistor is provided in the circuit to vary the applied voltage.

Next, with reference to FIG. 1, a method for rotating the sample stage will be described.

A permanent magnet 21.2 is mounted on the outer peripheral side wall of the wafer rotating sample stage 1.
1 is permanently installed. Preferably, the surface of the permanent magnet is exposed. In order to protect the wafer placed on the upper surface of the rotating sample stage from the magnetism of the permanent magnet, it is preferable to arrange a magnetic shielding material 23.23 adjacent to the permanent magnet.

A stator-side rotating magnetic field generating coil 25 is disposed facing the permanent magnets 21 and 21. Although not shown, the coil 25 is held by suitable support means. This coil is connected to a rotating magnetic field generation driver 27,
The rotation of the sample stage is controlled by changing the voltage and/or phase.

The number of permanent magnets 21 provided is not an essential requirement of the present invention. Quantity of multiple pieces - It's fine if you have one. Similarly, the coil 25 may be of a two-phase type or a three-phase type. Control of such a servo motor mechanism itself is well known to those skilled in the art, so a description thereof will be omitted.

The wafer rotating sample stage l has a shaft 5 inserted into a cylinder 11 and is supported by a tapered roller bearing 7, so it can be removed by simply pulling it upwards, depending on the size of the wafer to be inspected. The rotating sample stage can be replaced with the most suitable one.

When a voltage is applied from the DC power supply 15 to the piezo element 3, the piezo element 7'21 has a voltage of 0 to about 100 it depending on the applied voltage.
Stretch vertically within m. In this way, the rotating sample stage 1 can rotate zero at a high speed and at the same time move in the Z direction for focusing, etc. Since the stator-side rotating magnetic field generating coils 25 are arranged vertically and parallel to the permanent magnets, the magnetic flux density between the coils and the permanent magnets does not change even if the rotating sample stage 1 moves in the Z direction.

Therefore, the speed of O rotation also does not change.

The cylindrical body 11 and the tapered roller bearing 7 are supported by an X stage 30. The X stage 30 is supported by an X stage 32 so as to be movable in the X direction (horizontal direction). The X stage 32 is supported by a fixed member (not shown) so as to be movable in the front-back direction.

It should be noted that although there is naturally a means for moving each stage, it is not an essential requirement of this invention and is therefore omitted from the drawing. Similarly, in order to vacuum-adsorb the wafer to the -L surface of the rotating sample stage, an air suction hole or the like is provided inside the rotating sample stage, but this is omitted from the figure as it is not an essential requirement of the present invention. ing.

The structure of the foreign object detection system and the foreign object detection principle are disclosed in Japanese Patent Application No. 1983-212808, which is an earlier application filed by the applicant of the present invention.

[Effects of the Invention] As explained above, according to the power feeding method of the present invention, a high DC voltage is applied to the piezo element from the upper two bearings used to support the rotating shaft of the sample stage. Therefore, all the drawbacks of the conventional S'J tubing method are solved.

Furthermore, according to the sample stage rotation method of the present invention, the axis of the rotating sample stage is not connected to the rotating shaft of a drive source such as a motor, but a permanent magnet is fixedly installed on the rotating sample stage, and the shaft is placed opposite to the permanent magnet. By disposing a rotating magnetic field generating coil, the rotating sample stage itself can be rotated as a rotor of a servo motor.

Therefore, according to the rotating sample stage drive system of the present invention, frequent starting, stopping, braking, reversing, and slow motion can be performed continuously. Furthermore, the generated torque is large and the inertia is small.

Since the generated torque ratio to the control input is high and constant, it has excellent controllability. In this way, it is possible to construct a rotary drive system that is smaller and more reliable than conventional rotary drive systems.

Further, according to the present invention, the rotating sample stage can rotate zero at high speed and simultaneously move in the Z direction for focusing and the like. Since the stator side rotating magnetic field generating coils are arranged vertically and parallel to the permanent magnets, even if the rotating sample stage is moved in the Z direction by the piezo element, the magnetic flux density between the coils and the permanent magnets does not change. Therefore, the speed of θ rotation also does not change.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus configuration used to implement the rotating sample stage power supply driving force type of the present invention. 1... Rotating sample stage, 3... Piezo element Z stage. 5... Shaft, 7... Tapered roller bearing, 9... Ball bearing, 11... Cylindrical body, 13... Insulating separator, 15... DC power supply, 21... Permanent magnet, 23・・・
-Magnetic shielding material, 25... Stator side rotating magnetic field generation coil. 27...Driver for generating rotating magnetic field, 30...X stage, 32...Y stage

Claims (2)

[Claims] (1) In a foreign matter inspection device that inspects wafers for foreign matter, a Z stage made of a piezo element is fixedly installed on the lower surface of a rotating sample stage for holding semiconductor wafers, etc.
A rotating shaft extends from the center of the stage, an insulating separator is interposed in the middle of the rotating shaft, and the rotating shaft is supported by bearings at two places, a lower part and an upper part, with the insulating separator in between. , D on one bearing
A power supply system for a rotating sample stage characterized in that a DC voltage is applied to a piezo element by connecting the + side of a C power source and connecting the - side of a DC power source to the other bearing. (2) A claim characterized in that a plurality of permanent magnets are fixedly installed on the outer peripheral side wall surface of the rotating sample stage, and a rotating magnetic field generating coil is arranged opposite to the permanent magnets to rotate the sample stage. Power supply method for the rotating sample stage described in Section 1.