JP3553350B2 - XY stage - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an XY stage, and particularly to an XY stage capable of performing precise positioning suitable for mounting a sample such as a semiconductor manufacturing apparatus such as a drawing apparatus for optical lithography or a semiconductor inspection apparatus. About.
[0002]
[Prior art]
In a semiconductor manufacturing apparatus, an inspection apparatus, or the like, the sample is usually placed on an XY stage, and processing, observation, and the like are performed.
In recent years, as the degree of integration of semiconductor devices has increased, circuit wiring has become finer, and the distance between wirings has been decreasing. In particular, in the case of optical lithography of 0.5 μm or less, it is necessary to position the imaging point of the stepper with high precision.
[0003]
However, in the conventional XY stage, the positioning of the table on which the sample is mounted is controlled by feedback control in the X direction or Y direction via a ball screw or the like by an actuator placed on a mounting table, for example, a servomotor. Was. Thus, a mechanism having mechanical friction is not always sufficient for high-speed and high-accuracy alignment.
[0004]
[Problems to be solved by the invention]
For example, in the case of a scan type stepper, it is necessary to move the XY stage smoothly at high speed, with high accuracy, and smoothly. As described above, in a semiconductor manufacturing apparatus and the like, there is an increasing demand for a high-speed and high-accuracy positioning of a mounted object such as a measurement target and a processing target on an XY stage. The same applies to electron microscopes, and it is desired that positioning on the order of submicrons can be performed accurately and at high speed.
[0005]
The present invention has been made in view of the above circumstances, and has as its object to provide an XY stage that can perform a fine positioning operation stably and at high speed.
[0006]
[Means for Solving the Problems]
The XY stage of the present invention includes an upper plate on which a load is placed, a lower plate, a stage including a column connecting four corners of the upper plate and the lower plate, and a magnetic pole surface facing the lower plate of the stage. A levitation electromagnet for levitation supporting the stage, and a linear motor stator for positioning the stage in the XY directions in a non-contact manner facing a mover of a linear motor provided on a lower surface of the upper plate. It is characterized by having.
[0007]
According to the present invention described above, the stage on which the object is placed is levitated and supported by the levitating electromagnet, and the positioning operation in the X and Y directions is similarly performed without contact by the linear motor, so that the stage can be stably and quickly mounted. An object positioning operation can be performed. This makes it possible to stably perform high-magnification observation in an electron microscope or the like, and to perform fine positioning with high accuracy in a semiconductor manufacturing apparatus or the like. Therefore, a favorable effect can be exerted on, for example, the production yield of semiconductor products.
[0008]
Further, a displacement sensor for detecting a relative displacement between the stage lower plate and the electromagnet for levitating, and a control circuit for controlling a magnetic force of the electromagnet for levitating based on a signal from the displacement sensor are provided. As a result, feedback control becomes possible, and the stage can be positioned at a target floating position in the Z direction or the like.
[0009]
Further, a position sensor for detecting a position of the stage in the X and Y directions and a control circuit for positioning the stage by driving the linear motor based on a signal from the position sensor are provided. This also enables highly accurate positioning in the X and Y directions and the like.
[0010]
The floating electromagnet and the linear motor are each hermetically sealed by a partition. Thereby, it can be used even in a high cleanliness atmosphere such as a vacuum.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0012]
FIG. 1 shows an XY stage according to an embodiment of the present invention. In the XY stage 11, an upper plate 11a on which a sample is placed and a lower plate 11b are connected to each other at four corners by pillars 11c. A load 12 such as a semiconductor wafer is placed on the upper surface of the upper plate 11a. The stage 11 is levitated and supported in a non-contact manner by the electromagnets of the fixed base 13 supported by the fixed legs 13a, and is similarly driven in a non-contact manner by linear motors in the X and Y directions to perform positioning control.
[0013]
FIG. 2 is an elevation view of the XY stage. The lower surface of the fixed base 13 is provided with floating electromagnets 14 at four corners thereof. The magnetic pole surface of the levitation electromagnet 14 faces the lower plate 11b of the stage 11, and applies a magnetic attractive force to the lower plate 11b, which is a magnetic plate, to support the stage 11 in a non-contact floating manner.
[0014]
A displacement sensor is provided at a substantially central portion of each of the electromagnets 14, and a distance from the lower plate 11b made of a magnetic plate is measured. As shown in FIG. 3, based on this displacement signal, z, α, The control circuit excites the levitation electromagnet 14 to control the three degrees of freedom of β, and levitates and supports the lower plate 11b and, consequently, the entire stage 11 on which the load 12 is placed at a predetermined target levitation position.
[0015]
As shown in FIG. 4, on the upper surface of the fixed base 13, a stator 15a of a linear motor is provided. A movable element 15b for a linear motor is provided on the lower surface of the upper plate 11a of the stage 11. The mover 15b is made of, for example, a magnetic material having a comb-shaped uneven surface, and the linear motor stator 15a of the fixed base 13 is moved in the X direction and the Y direction in FIG. The stage 11 is moved and positioned by applying a magnetic attraction force. As shown in FIG. 5, the base on which the fixed base 13 is fixed is provided with a laser interferometer 17a, the upper plate 11a of the stage 11 is provided with a mirror 17b for the laser interferometer, Is detected. Accordingly, the laser interferometer 17a detects the position signal of the mirror 17b in the X, Y and γ directions in FIG. 7 and controls the primary side 15a of the linear motor by the control circuit as shown in FIG. The stage 11 can be moved.
[0016]
Thus, while the stage 11 is levitated and supported by the magnetic attracting force of the levitating electromagnet 14, the linear motors 15 a and 15 b drive the stage 11 to an arbitrary position in the X and Y directions to perform non-contact positioning control. Can be. As described above, in the XY stage, since the positioning control is performed electromagnetically in a non-contact manner, a precise and high-speed positioning operation can be performed without using a mechanical mechanism such as a conventional gear.
[0017]
In the XY stage, the fixed base 13, the motor stator (primary side) 15a, the electromagnet 14 for floating, the displacement sensor, and the like are each sealed by a can. Therefore, since these are sealed by a partition wall such as a can, it is possible to prevent contamination and the like of a load requiring high cleanliness due to generation of gas even in an environment with extremely high cleanliness such as a vacuum atmosphere. it can.
[0018]
In the above description, the lower plate 11b of the stage 11 is suspended and held by magnetic attraction by the electromagnet 14 provided on the lower surface of the fixed base. However, the lower plate 11b is formed of an aluminum plate or the like. Alternatively, a magnetic pole surface of an electromagnet that generates an alternating magnetic field may be disposed below the magnetic pole to support repulsion and floating. In addition, a metal plate such as an aluminum plate is arranged on the lower surface of the upper plate 11a to be a movable element (secondary side) of the linear induction motor, and the electromagnet 15a fixed to the fixed base 13 is a stator of the linear induction motor. (Primary side) may be driven by this.
[0019]
Further, the stage may be driven by a linear DC motor having a permanent magnet of a mover on the lower surface of the upper plate of the stage and a coil of the stator arranged on a fixed base 13.
[0020]
Further, the stage may further include a support for mounting the object on the upper plate, and the movement of the support may be controlled by an actuator such as a piezoelectric element. Thus, rough positioning can be performed using a linear pulse motor, and fine positioning can be performed using an actuator such as a piezoelectric element. Thus, various modifications can be made without departing from the spirit of the present invention.
[0021]
【The invention's effect】
As described above, according to the XY stage of the present invention, the stage can be arbitrarily positioned in the X and Y directions while being levitated and supported in a non-contact manner. Therefore, it is possible to realize an XY stage with high accuracy and excellent high-speed response, thereby improving the throughput of a device requiring fine positioning such as a semiconductor manufacturing device or an inspection device.
[Brief description of the drawings]
FIG. 1 is a perspective view of an XY stage according to an embodiment of the present invention.
FIG. 2 is an elevation view of the XY stage shown in FIG. 1;
FIG. 3 is a block diagram of a magnetic levitation control system.
4A and 4B are views showing a fixed base, wherein FIG. 4A is a plan view and FIG. 4B is a cross-sectional view taken along line AA ′ of FIG.
FIG. 5 is an explanatory diagram showing movement control of a stage.
FIG. 6 is a block diagram of a stage position control system using a linear motor.
FIG. 7 is a diagram showing a movement direction of a stage.
[Explanation of symbols]
11 Stage 11a Upper plate 11b Lower plate (magnetic material plate)
11c Column 12 Mount 13 Fixed base 14 Electromagnet for floating 15a Linear motor stator (primary side)
15b Linear motor mover (secondary side)

Claims (4)

An upper plate on which the mounted object is placed, a lower plate, and a stage including a column connecting the four corners of the upper plate and the lower plate,
A levitation electromagnet having a magnetic pole surface facing the lower plate of the stage, and a levitation electromagnet for levitation supporting the stage, and moving the stage in the XY directions facing a movable element of a linear motor provided on the lower surface of the upper plate. An XY stage comprising: a linear motor stator that performs non-contact positioning. 2. A displacement sensor for detecting a relative displacement between the stage lower plate and the electromagnet for floating, and a control circuit for controlling a magnetic force of the electromagnet for floating based on a signal from the displacement sensor. XY stage. 2. The apparatus according to claim 1, further comprising: a position sensor that detects a position of the stage in the X and Y directions, and a control circuit that drives the linear motor to position the stage based on a signal from the position sensor. XY stage. The XY stage according to claim 1, wherein each of the levitating electromagnet and the linear motor is hermetically sealed by a partition.

Images