JPH069773B2 - Stage feeding device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stage feed device, and more particularly to a stage feed device suitable for precision positioning with a relatively long stroke such as for fine processing or inspection in a semiconductor manufacturing apparatus such as an LSI. .

[Prior Art] In various semiconductor manufacturing apparatuses that process or inspect a fine pattern such as an LSI including an exposure apparatus that uses light, an electron beam, or an X-ray, a wafer that is a workpiece, an exposure mask, or an exposure mask Hold the reticle on the stage and position it precisely by linear feed. Since such a stage feed device requires a relatively long stroke, coarse movement feed with low positioning accuracy that performs high-speed feed to the vicinity of the target stop position, and target stop of the stage that is roughly positioned near the target stop position In general, a feed mechanism that performs both functions of positioning with high precision and fine movement feed is provided. Conventionally, a biaxial feed screw type as shown in FIG. 4 or a feed mechanism shown in FIG. Thus, the uniaxial differential feed screw type was the mainstream.

In the two-axis feed screw system shown in FIG. 4, a table 404 is linearly movable by a guide bearing 403 on a guide rail 402 arranged on a base 401, and a coarse feed screw supported by a bearing 405 on the base 401. The feed nut 407 of the table 404 is screwed to 406, the feed screw 406 is rotated by a coarse feed drive motor 408, and another guide rail 409 is arranged on the table 404.
The guide bearing 410 supports the stage 411 on the guide rail 409 so that the stage 411 can move linearly, and the table 404 supports the bearing.
Stage 411 to fine feed screw 413 supported by 412
The feed nut 414 of 4 is screwed, and the feed screw 413 is rotationally driven by the fine movement feed drive motor 415.
The double feed screw structure of 06 and 413 is used to perform the coarse / fine movement of the stage 411.

In the 1-axis differential feed screw method shown in Fig. 5, the base 50
1 Guide bearings 50 on the guide rails 502 located above
The stage 504 is supported by 3 so that it can move linearly.
A feed screw 506 and 507 having a minute lead difference is provided on a feed shaft 505 supported by a bearing (not shown) on 501, and a feed nut 508 of a stage 504 is screwed onto one feed screw 506 while A differential nut 510, which can be selectively fixed to either the base 501 or the feed shaft 505 by a switching clutch device 509, is screwed onto the feed screw portion 507, and the feed shaft 505 is rotated by a drive motor 511. The switching clutch device 509 allows the differential nut 5
When 10 is fixed to the feed shaft 505, the nut 510
Can freely rotate with respect to the base, so that the stage 504 can be fast-forwarded by the lead of the screw of the feed screw portion 506 per one rotation of the motor 511, and the differential nut 510 is fixed to the base 501 by the switching clutch 509. Then, since the feed shaft 505 itself is fed in the opposite direction by the lead of the screw of the feed screw portion 507 per one rotation of the motor, the stage 504 corresponds to the lead difference between both feed screw portions 506 and 507 per one rotation of the motor 511. A minute amount can be fed as much as it does.

However, in the conventional device shown in FIGS. 4 and 5, the center of gravity of the stage is not located on the central axis of the feed screw, in other words, the center of gravity of the stage is not located on the line of action of force, so that the base is arranged vertically. If it is used for a long time, the guide bearing will be overhung and the twist will occur between the guide rail and the guide bearing, which will impair the service life of the bearing and the guiding accuracy.In addition, the stage must be placed in a vacuum atmosphere. If there is any, there are problems such as seizure due to evaporation of lubricating oil of the feed screw and guide bearing, and that the motor must be made to be vacuum resistant. The feed screw mechanism of the structure and the motor are arranged outside the vacuum chamber, and are fed to the stage supported by the guide rails inside the chamber via the transmission mechanism. Even if the movement of the screw is transmitted, both feed screw mechanisms for coarse and fine movement must be placed outside the chamber, so an installation space more than the required total stroke of the stage is required outside the chamber. .

[Object of the Invention] An object of the present invention is to facilitate the configuration in which the center of gravity of the stage is located on the line of action of force, and to store and arrange the coarse movement feed stroke part in the stage, and to fire in a vacuum atmosphere. In particular, when the feed screw mechanism is placed outside the vacuum chamber, the protruding part outside the chamber can be made more compact than before, and the clamping force at the time of rough positioning stop can be increased and at the same time the clamping part can be An object of the present invention is to provide a stage feed device for precision positioning, which has a simple structure and can be made compact.

[Structure of the Invention] The stage feed device of the present invention includes a coarse movement feed means, a fine movement feed means, and a clamp means. The coarse movement feed means moves the stage at a high speed over a relatively large stroke by supplying and discharging fluid. It is composed of a piston cylinder assembly that moves linearly, and the clamping means can lock the relative movement between the piston and the cylinder of this piston cylinder assembly by the generated force of the piezo element, for example, by a piezo element built-in clamping mechanism that tightens the piston rod from the surroundings. Further, the fine movement feed means is constituted by a feed screw device for linearly moving the stage over a required stroke at a relatively low speed via the piston cylinder assembly locked by the clamp means.

The piston-cylinder assembly interposed between the stage and the lead screw device has a piston fixed to the feed screw device and a cylinder fixed to the stage in one embodiment, and vice versa in another embodiment.

The clap means allows the relative movement of the piston and the cylinder during coarse feed, that is, the operation of the piston-cylinder assembly by the original fluid, and during the fine feed, the strong clamping force of the piezo element allows the relative movement of the piston and cylinder in the axial direction. It is fixed and the movement for moving the stage by the feed screw device is simply transmitted. in this case,
The clamping mechanism may be such that the clamping means itself can move relative to the cylinder in the radial direction of the cylinder during clamping, and the clamping force of the clamp is applied to the piston rod center as a component force in three or more directions. May be.

[Operation of the Invention] In the stage feeding device of the present invention, since the coarse movement feeding means is constituted by the piston cylinder assembly,
Even if this is placed in the stage at a centerline position that passes through the center of gravity of the stage, the structure does not become complicated, and when it is placed in the vacuum chamber, the piston rod, the clamping means, and the guide rail are simply Since it is a rod-shaped simple one, it can be vacuum-sealed by the bellows, so the coarse feed means that takes most of the stroke can be placed inside the chamber, and only the feed screw device for fine feed can be placed outside the chamber. Since this is good, the apparatus arrangement outside the chamber becomes compact. Furthermore, since the actuator for coarse movement feed is a piston cylinder assembly, the structure is simpler than that of the feed screw method, and positioning to the final stop target position can be performed by the feed screw device of the feed means of the fine feed means, so positioning accuracy Can desire high precision. Further, since the clamp means uses the force due to the extension of the piezo element to tighten the piston rod, it is strong even in a small size and light weight, and it is possible to reduce the energy consumption for generating the holding force.

The present invention is as follows if a preferred embodiment is shown for better understanding.

[Embodiment] In FIG. 1, the stage 1 is guided and supported by linear guide shafts 2a and 2b so as to be linearly moved in the y-axis direction. A piston cylinder assembly 3 is arranged in the stage 1, and the cylinder side of the assembly 3 is in a fixed relationship with the stage 1. The assembly 3 constitutes the coarse feed means of the stage 1, and moves the stage 1 relative to the piston rod 5 by the fluid supplied and discharged through the flexible tubes 6a and 6b. A clamp device 4 is attached to the stage 1 so as to surround the piston rod 5, so that the stage 3 can be locked after the coarse positioning feed rough stop by the assembly 3, that is, the stage 1 can be locked to the piston rod 5. There is. A bifurcated fine movement feed rod 12 is connected to the tip of the piston rod 5 via a spherical joint 11. The bifurcated tip of the rod 12 is fixed to a housing block 13 having a fine feed nut 8. There is. The nut 8 is screwed on the fine feed screw 7 supported by the bearing 10, and the screw 7 by the drive motor 9 is screwed.
The rotation of the housing allows the piston rod 5 to be finely moved via the housing lock 13, and the forked rod 12 and the joint 11.

A concrete example of the clamp device 4 is shown in FIG. 2 and FIG. 2A, in which a cylindrical spring 16 having a three-way tip and fitted around the piston rod 5, a piezo element 14, and the piezo element 14 are provided. A clamping mechanism for reducing the diameter of the three-divided portion of the cylindrical spring 16 by the expansion of the element when a voltage is applied, that is, a pressure block 17 and a component force generating V block 18, is incorporated in the housing 15. That is, the housing 15 is attached to the cylinder of the assembly 3 so as to be relatively movable only in the cylinder radial direction by, for example, an elastic mechanism, and the piezo element 14 is supported in contact with the housing 15 via a position adjusting screw 19. In the clamp device 4, the piston rod 5 can freely slide in the cylindrical spring 16 when the piezo element 14 is in the non-biased state. Is expanded by several to several tens of microns, whereby the cylindrical spring 16 is pressed between the pressure block 17 and the V block 18 in three directions to reduce the diameter, so that the rod 5 is tightened. In this case, the piezoelectric element 14 is expanded. The reducing force due to becomes a frictional clamping force from three directions toward the center of the rod by both blocks 17 and 18 and tightens the piston rod 5, so that it acts as a centripetal force to the piston rod 5 and the housing 15 follows the radial direction. Thus, the rod of the clamp shaft is not twisted, the reproducibility of the clamp is improved, and the piston rod 5 is prevented from being damaged. The piezo element is small, lightweight, and has a large generating force.
Therefore, the clamping device 4 can be very compact and have a large clamping force.

In the apparatus of the embodiment shown in FIG. 1 having the above-mentioned configuration, in coarse movement feed of the stage 1, first, the motor 9 is servo-locked so that the feed screw 7 and the feed nut 8 with a rotation stop mechanism do not move relative to each other. One way is to lock it to. In this case, the piston rod 5 remains stationary at the fixed position, and the pressurized fluid (5 to 7 kgbf / cm ² ) is supplied and discharged through the flexible tubes 6a and 6b, that is, on the cylinder side of the piston cylinder assembly 3, that is, Performs forward / backward movement of stage 1 and performs coarse movement feed for the required stroke. When the stage 1 reaches a position within a predetermined coarse position accuracy near the target stop position, the piezo element of the clamp device 4
A voltage is applied to 14 to stop the movement of the stage 1, and thereby the coarse positioning of the stage 1 is performed.

Then, the fine movement is performed. In this case, the clamp device 4
Is placed in an operating state with a voltage applied to the piezo element 14. The feed screw 7 is rotated by a required number of rotations by the rotation of the drive motor 9, but at this time, since the feed nut 8 is fixed to the housing block 13, the feed screw 7 is 1
Each time it rotates, the housing block 13 is fed by the amount of the lead of the screw 7, and this movement is transmitted from the rod 12 to the piston rod 5 via the joint 11, and the stage 1 is finely fed via the clamp device 4. .

In the example of FIG. 1, the piston rod 5, the forked rod 12, the feed unit including the housing block 13 and the feed nut 8, and the feed screw 7 are all arranged coaxially, and the center of gravity of the stage 1 is coaxially arranged. The central axes of the respective coaxial elements including the guide shafts 2a and 2b are arranged in the same plane. That is,
Since the line of action of force penetrates through the center of gravity of the stage 1, it is possible to minimize the occurrence of twisting of the guide shaft and its bearing due to overhang load when this is arranged vertically. .

When the apparatus of the above-mentioned embodiment is arranged in a vacuum chamber, for example, a lubricating oil having a low vapor pressure is used for the guide shafts 2a and 2b, and the sliding surface of the piston rod of the piston cylinder assembly 3 has a vacuum seal structure. , Fitting 11
By placing the mechanism on the side of the feed screw from the above portion in the atmosphere outside the chamber and arranging the mechanism on the side of the stage 1 from the piston rod 5 in the chamber, it is possible to make it suitable for the low vacuum chamber. In this case, most of the coarse feed stroke is accommodated in the vacuum chamber, so the apparatus outside the chamber becomes very compact.

In addition to this, the guide shafts 2a, 2b, the clamp device 4, the piston rod 5, and the tubes 6a, 6b are vacuum-sealed in the vacuum chamber 35 by bellows 31, 32 and O-rings 33, 34 as shown in FIG. By doing so, it is possible to highly prevent the evaporation of the lubricating oil, and therefore, by adding these vacuum sealing elements, a system suitable for a high vacuum chamber can be obtained.

In the above embodiment, an example in which the fine movement feed side is locked and operated during coarse movement feed is described. However, for example, during coarse movement feed, the fine movement feed screw 7 is interlocked to move the feed nut 8 to coarse movement feed. By moving the clamp device 4 in the same direction while reducing the relative movement between the stage 1 and the piston rod 5, the positioning accuracy of coarse motion feed is improved and the piston rod 5 is operated by the operation of the clamp device 4. The damage may be prevented.

[Effects of the Invention] As described above, according to the present invention, in a linearly guided stage that is movable in one axis direction, a fluid-driven piston cylinder assembly is used for coarse motion feed and a feed screw device is used for fine motion feed. At the same time, a clamp device that can lock the operation of the piston-cylinder assembly by extending the piezo element is used to transmit the operation between the two, so that rough positioning clamps can be performed strongly with a compact and lightweight clamping device, and positioning accuracy is also improved. In addition, it is possible to perform precise feed regardless of the horizontal or vertical stage posture, and especially in the case of a vertical layout stage, it is easy to take a configuration that can reduce the overhang load applied to the linear guide, so the feed accuracy is improved. And bearing life can be extended, and the structure can be adapted for both in-air and in-vacuum applications. In addition, especially when it is applied to a coarse / fine movement stage arranged in a vacuum chamber, most of the coarse movement stroke can be accommodated in the chamber, and only the fine movement portion needs to be arranged outside the chamber. The device outside the chamber becomes compact.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention with a part cut away, FIG. 2 is a front view showing a concrete example of a clamp device, FIG. 2A is a perspective view showing a main part of the clamp device, and FIG. The figures are partial cross-sectional views showing an example of a vacuum seal of the main part, FIG. 4 and FIG.
Each of the figures is a side view showing a conventional example. 1: Stage, 2a, 2b: Guide shaft, 3: Piston cylinder assembly, 4: Clamp device, 5: Piston rod, 7: Feed screw, 8: Feed nut, 9: Drive motor, 11: Spherical joint, 12: Fine movement Feed rod, 13: housing block, 14: piezo element, 16: three-end cylindrical spring, 17: pressure block, 18: component force generating V block.

Claims (5)

[Claims] Claims: 1. In a stage for precisely feeding a stage for microfabrication or the like, a coarse movement feeding means constituted by a piston-cylinder assembly for linearly moving the stage by supplying and discharging a fluid, and a piston and a cylinder of the piston-cylinder assembly. Clamping means that can lock the relative movement of the stage by the generated force of the piezo element, and fine movement feeding means configured by a feed screw device that linearly moves the stage through the locked piston cylinder assembly. Stage feed device. 2. The stage feed device according to claim 1, wherein the cylinder of the piston cylinder assembly is fixed to the stage, and the piston of the assembly is linearly driven by a feed screw device. 3. The stage feed device according to claim 1, wherein the piston of the piston-cylinder assembly is fixed to the stage, and the cylinder of the assembly can be linearly driven by a feed screw device. 4. The clamp means includes a piezo element that extends by the application of a voltage, and a clamp mechanism that tightens the piston rod of the piston-cylinder assembly with respect to the axial movement of the piston rod by the extension of the piezo element. The stage feeding device according to item 1. 5. A component force generating means, wherein the clamp mechanism is relatively movable with respect to the cylinder in the radial direction of the cylinder, and exerts a tightening force on the piston rod from at least three directions on a line of action intersecting the central axis of the rod. The stage feeding device according to claim 4, which includes the stage feeding device.