JPS6161934B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stage feeding and positioning device in which a stage is guided and driven without contact with a guide member by hydrostatic pressure, that is, a stage is guided by a hydrostatic fluid bearing. It is something.

One of the characteristics of this type of stage feeding and positioning device is that the coefficient of friction is very small, so that the stick slip phenomenon does not occur. This is a great advantage in achieving finer stage feed, that is, higher resolution. On the other hand, however, because the coefficient of friction is extremely small, it responds sensitively to extremely small disturbances such as slipping and falling due to inclination, deviation due to uneven flow of fluid, and vibration, and the stage position easily changes. Conventionally, as means for highly accurate feed positioning of this type of stage, a means has been adopted in which a stage position detection signal from a laser length measuring device is subjected to feedback servo control to an electric motor directly connected to the stage. However, since the feedback servo cannot act within the minimum detection sensitivity range of the laser length measuring device when the stage is positioned and stopped, the stage position can freely fluctuate due to the extremely small force mentioned above. Even if a positional change is detected and the feedback servo is activated, it is not easy to position and stop within the detection sensitivity of the laser length measuring device due to overruns caused by the feedback circuit and the time constant of the servo motor. In addition to producing a positioning error that is several times worse than the sensitivity, it also has drawbacks such as stopping after a certain amplitude.

In view of the above points, the present invention provides a stage feeding and positioning device that can improve stage positioning rigidity and positioning and stopping accuracy by one or two orders of magnitude, and will be described in detail below with reference to the drawings.

FIG. 1 shows an example of a conventional feed positioning device, in which 1 is a stage guide member with a groove formed on its upper surface, 2 is inserted into the groove of the guide member 1, and is moved along the groove in a non-contact state. The stage is movable and consists of a floating member 3 and a stage main body 4 above it. Air supply hole 6 that spouts fluid toward both side walls of the groove
and the air supply hole 5, from the connection port with the pressure supply hose 8.
By supplying pressurized fluid from the pressure supply hose 8, the stage 2 floats in the groove of the guide member 1, and is not in contact with both side walls of the groove. It is maintained. 9 is floating member 3
10 is a laser length measuring device,
Reference numeral 11 denotes a support rod protruding rearward from the floating member 3. Reference numeral 12 denotes a drive device for the stage 2 consisting of a linear motor, which includes a coil 13 fixedly supported by the support rod 11, a yoke 14, an N magnetic pole 15, and an S magnetic pole 1.
It is more like 6. Therefore, when a current is applied to the coil 13 of the drive device 12, the wire of the coil 13 becomes N
Since the coil 13 crosses the magnetic flux between the magnetic pole 15 and the S magnetic pole, the coil 13 generates a driving force proportional to the current value in the direction in which the stage 2 moves. Therefore, the stage 2 is guided and driven without contact. In addition, the laser length measuring device 10 constantly observes the position of the stage.
A speed signal is obtained through a circuit that differentiates the position signal of stage 2 with respect to time.

Next, the conventional feeding positioning operation of the stage 2 will be explained. In the feed positioning operation, the command value of a given positioning point is compared with the position and speed signal of the stage 2 at that time using an electronic circuit, and the results are fed back to the drive device 12 to stop the stage 2 at a predetermined position. That is, at the positioning point, the current flowing through the coil 13 is controlled so that the command value and the position signal of the stage 2 become equal and the speed becomes zero. Therefore, if it is attempted to accelerate and decelerate the stage 2 from a distance to reach the positioning point in a short time, a large current will be passed through the coil 13, but the closer the stage 2 is to the positioning point, the smaller the current will be.

In this way, with a stage feeding and positioning device that uses non-contact guidance and a drive device, since there is no friction, it is possible to easily move a heavy object with a small driving force, making it possible to feed a large object at high speed over a long distance. If the feedback servo does not work, it is impossible to send the stage 2 to a predetermined position, and it is also impossible to simply stop it. In addition, since there is no friction, the stage 2 position easily changes as it responds sensitively to extremely small disturbance forces such as slipping and falling due to inclination, shifting due to non-uniform flow of fluid, or vibration. Therefore, the drive device 12 must be able to output a drive force that can respond to these extremely small disturbance forces, but since the feedback servo cannot operate within the minimum detection sensitivity of the laser length measuring device 10, the stage 2 The positioning and stopping accuracy cannot exceed the minimum detection sensitivity of the length measuring device, and even if positional fluctuations are detected and the feedback servo is activated, there is always a time constant based on the inductance of the electronic circuit and coil 13. Therefore, an overrun in stage 2 due to the time delay of the feedback servo is unavoidable.
Therefore, stage 2 is stopped while reciprocating near the positioning point, and stage 2
It is not easy to position and stop the laser length measuring device 10 within the detection sensitivity of the laser length measuring device 10.
This method has the drawback of causing a positioning and stopping error that is several times lower than the zero detection sensitivity to one order of magnitude lower.

In view of the above points, the present invention provides a stage feeding and positioning device that can improve stage positioning and stopping accuracy by one to two orders of magnitude.

The drawings will be explained in detail below.

FIG. 2 is a partial sectional view showing one embodiment of the present invention. In FIG. 2, the same symbols as in FIG. 1 indicate components having the same functions, and their explanation will be omitted. FIG. 3 is an enlarged sectional view of the suction device of the present invention, and FIG. 4 is an enlarged sectional view showing the suction operation state of the suction device.

In FIG. 2, 17 is an elastic body made of a leaf spring having rigidity in the feeding direction of the stage 2,
One end is fixed to the floating member 3, and the other end is fixed to the suction device 18. As shown in FIGS. 3 and 4, the suction device 18 includes a support fitting 19 and a support fitting 1.
The vacuum exhaust port 22 is supported by the plate spring 20 at the
The plate spring 20 supports the suction pad 21 in the thickness direction, and has low rigidity so that the suction pad can easily move toward the bottom surface of the groove of the guide member 1. Further, the plate surface direction faces the feeding direction of the stage 2, and has high rigidity in this direction. The suction pad 21 is arranged to face the bottom surface of the groove of the guide member 1 with an extremely small gap, and can be suctioned at all positions during the stroke of the stage 2. The vacuum exhaust port 22 is connected to a vacuum pump via a three-way valve by an exhaust hose (not shown).

Next, the operation of the apparatus of the present invention described above will be explained. First, the rough positioning operation is performed by feedback servo control of the position detection signal of the stage 2 by the laser length measuring device 10 to the coil 13, as in the conventional procedure.
After the stage 2 is positioned and stopped, the vacuum exhaust port is connected to a vacuum pump by switching the three-way valve, and the suction pad 21 is suctioned to the bottom surface of the guide groove of the guide member 1. Therefore, the stage 2 is coupled to the guide member 1 via the elastic body 17 while being guided by static pressure fluid. At this time, since the plate spring 20 has low rigidity in the plate thickness direction, the stage 2 can be positioned and stopped with high rigidity only in the feeding direction, with almost no effect on the static pressure fluid guiding accuracy. During this stoppage due to adsorption, the elastic body 17 adds rigidity in the feeding direction, which increases resistance to external disturbances such as slipping and falling due to the inclination of the stage 2, unevenness due to uneven flow of fluid, and vibration. . That is, disturbances caused by slipping and falling due to the inclination of the stage or uneven flow of fluid originally act as disturbance forces on the stage 2, but when the suction device 18 is attracted to the guide member 1, there is an elastic force between the guide member 1 and the stage 2. When the rigidity in the feeding direction by the body 17 is added, the relative displacement due to the disturbance force between the guide member 1 and the stage 2 becomes the value obtained by dividing the disturbance force by the rigidity in the feeding direction. The displacement itself becomes smaller, and the vibration disturbance caused by the vibration of the floor on which the equipment is installed is
Originally, it acts on the guide member 1 as vibration displacement, and before the suction device 18 operates, this vibration displacement itself becomes the target of the feedback servo as a relative displacement between the guide member 1 and the stage 2, but the suction device After the operation of step 18, the guide member 1 and the stage 2 vibrate almost integrally, so that the relative displacement is reduced to a value that cannot be subjected to feedback servo, and the positioning stability is significantly increased. However, in this case, to avoid resonance,
It goes without saying that the natural frequency of the stage 2 determined by the weight of the stage 2 and the rigidity of the elastic body 17 must be set to be sufficiently larger than the disturbance frequency. Next, the fine positioning operation will be explained.

If the stage 2 is driven by the drive device 12 while the suction device 18 is in the suction operation, the elastic body 17 is deformed in proportion to the driving force, so that the stage 2 can be moved finely. Therefore, the elastic body 17 is adjusted by the positioning stop error after the suction operation of the suction device 18.
The constant driving force required to deform the coil 13
When generated by , the stage 2 can be positioned and stopped at the target position with high precision within the detection sensitivity range of the length measuring device. That is, before the suction device 18 operates, the stage 2 is in a non-contact state, and after the operation, the stage 2 is driven and positioned while being elastically connected to the guide member 1 by the elastic body 17. As mentioned above, since there is no contact before the suction device 18 operates, long-distance, high-speed driving is possible with a small driving force.However, since it reacts sensitively to small forces, it is susceptible to the effects of various disturbance forces when positioning and stopping. However, after the suction device 18 operates, the amount of deformation of the elastic body 17 by the drive device 12 becomes the amount of drive of the stage 2, and the stage 2 can only be moved over a short distance with a large driving force. However, since the stage 2 is coupled to the guide member 1 via the elastic body 17, resistance to various disturbance forces increases. In addition, since the elastic body 17 has no frictional factors associated with deformation and does not cause the stick slip phenomenon, it deforms to a certain extent when a small driving force is applied to it, so that fine driving with a small driving force is possible.

Further, in the feedback servo before the operation of the suction device 18, the larger the driving force that the drive device 12 can output, the faster the stage 2 can be accelerated and decelerated, so the stage 2 can be driven at a higher speed.

On the other hand, the smaller the driving force that can be output by the driving device 12, the more precisely the stage 2 can be positioned and stopped by the feedback servo corresponding to the various small disturbance forces described above. As described above, the larger the ratio between the large driving force and the small driving force that can be output by the driving device 12, the more quickly and precisely the stage 2 can be driven and positioned. However, since the driving force is generated by controlling the current flowing through the coil 13 of the driving device 12 using an electronic circuit and providing feedback, it is easy to control the current value by about three orders of magnitude, for example from 1 ampere (A) to 1 milliampere (mA). , the ratio of the driving force output to the coil 13 is 1000:
Can be made more than 1.

Now, as described above, the positioning and stopping accuracy of the so-called conventional feedback servo before the suction device 18 operates is about one order of magnitude lower than the position detection sensitivity of the laser length measuring device 10.

On the other hand, the elastic body 1 after the operation of the suction device 18
Since the amount of drive of the stage 2 due to the elastic deformation of the stage 2 (hereinafter referred to as the elastic drive stroke) depends on the magnitude of the driving force, the elastic drive stroke of the stage 2 due to the large drive force of the drive device 12 is the amount of the elastic drive stroke of the laser length measuring device 10. By selecting the elastic body 17 having a rigidity that is about one order of magnitude greater than the detection sensitivity, the elastic drive stroke of the stage 2 caused by a small driving force can be approximately 1×10 ^-3 or less than the elastic drive stroke caused by the large driving force. In the above example, the elastic drive stroke due to the large driving force was made approximately one order of magnitude larger than the stage position detection sensitivity, so the elastic drive stroke due to the small drive force was approximately 1× this value.
10 ^-3 , which improves the stage position detection sensitivity to about 10 ^-2 . Even if the effects of the various disturbances mentioned above are taken into account, a positioning and stopping accuracy that is 10 times higher than the stage position detection sensitivity can be obtained. In other words, the positioning and stopping accuracy of the stage 2 before and after the operation of the suction device 18 is about 1/10 of the stage position detection sensitivity before the operation, that is, with the conventional drive means, and about 10 times the stage position detection sensitivity after the operation, that is, with the drive means according to the present invention. Due to the accuracy obtained, the stopping accuracy can be improved by at least a factor of 10 between the conventional case and the case according to the invention.

The reason why the positioning and stopping accuracy of the stage 2 improves after the operation of the suction device 18 has been described above, but the even bigger difference is that before the suction device 18 operates, the feedback servo is not possible unless a stage position detection signal is obtained. Therefore, it is not possible to simply stop the stage 2, but it is of course possible to stop the stage 2 after operation, and even if a stage position detection signal is not obtained, the elastic drive stroke can be applied to the coil 13 of the drive device 12. Since it depends on the current value, it is possible to finely drive and position and stop the stage 2 by using this relationship.

In the example shown above, the suction device 18 was configured to suction to the guide member 1, but it may also be configured to suction to a fixed body other than the guide member along the feeding direction of the stage 2. Not limited to. Furthermore, although the above embodiments have shown the case of a linear stage, it is of course applicable to a rotating stage. In the above example, the length measuring device is a laser length measuring device,
A linear motor was used as the drive device, but in place of that, there are also non-contact length measuring instruments that use magnetic force, capacitance, and changes in light intensity, and drive devices that use electrostatic force and differences in fluid pressure and flow rate. may also be used.

As described above, according to the present invention, when the stage is positioned and stopped, the suction device attached to the stage is adsorbed to the guide member with an elastic body having rigidity interposed in the feeding direction of the stage. The resistance to external disturbances such as falling, uneven flow of fluid, vibration, etc. increases significantly, and by driving the stage while the suction device is adsorbed to the guide member, the elastic body is elastically deformed and the stage is moved. Since fine feeding is possible, it is possible to position and stop at the target position with high precision within the detection sensitivity range of the length measuring device, and the positioning rigidity and positioning and stopping accuracy of the stage can be improved compared to the conventional stage. Therefore, by using the device of the present invention for transferring fine patterns used in semiconductor device manufacturing processes, aligning patterns in recognition devices, and feeding samples in physical or mechanical processing and measuring devices, it is possible to improve these alignments and sample feedings. etc. can be achieved with higher precision than conventional methods.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of a conventional device, Fig. 2 is a sectional view of an embodiment of the present invention, Fig. 3 is an enlarged sectional view of the suction device section, and Fig. 4 is a sectional view of the suction device during suction operation. It is an enlarged sectional view showing a state. 1... Guide member, 2... Stage, 17... Elastic body,
18...Adsorption device.

Claims (1)

[Claims] 1. In a stage feed positioning device in which the stage is guided and driven without contact with a guide member by fluid static pressure, in order to attract the stage to the guide member when the feed positioning of the stage is stopped. A stage feeding and positioning device comprising a suction device interposed with an elastic body that has rigidity in the feeding direction of the stage and is elastically deformed by a driving force in the feeding direction of the stage.