JPH0584626A - Fine moving device for stage - Google Patents

Abstract

PURPOSE:To make a fine adjustment without applying shearing force to a piezoelectric element by providing the stacked piezoelectric element having spherical surfaces at both ends of which spherical diameter is the same as the interval between a base and a stage, and an elastic body which works in the direction of contracting the interval between the base and the stage. CONSTITUTION:Members 4 and 5, which have spherical surface ends on the sides of a base 1 and a stage 2, are joined to both ends of a stacked piezoelectric element 3. The spherical diameter of the spherical surface is the same as the interval betweent the base 1 and the stage 2, and compressive force is given as pre-load to the base 1 and the stage 2 with springs 6 and 7. The piezoelectric element 3 is expanded or compressed in axial direction, and the stage 2 is deformed in the direction of separating form the base 1. When the stage 2 is slid to the base 1 by external force, it can finely move without causing shearing force in the piezoelectric element 3 since the contact points between the stage 2 and the base 1 and the piezoelectric element 3 are spherical, and a fine movement error by the reaction of the shearing force can be removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine movement device for a stage, such as a stage for semiconductor exposure, which requires precise positioning.

[0002]

2. Description of the Related Art In recent years, the precision required for a spatial positioning stage has become finer than ever before. For example, a semiconductor pattern requires sub-micron or quarter-micron processing, and the stage used for this processing requires extremely precise positioning with a resolution of about several nanometers.

In order to perform such ultra-precision positioning, a guide and an actuator capable of performing ultra-fine positioning are required.

A laminated piezoelectric element is often used as an actuator for performing such ultra-precision positioning. The laminated piezoelectric element has a tensile direction and a direction parallel to the laminated direction, that is, a shear direction. It has a very weak property. Therefore, it is necessary to have a structure in which the tensile force and the shearing force are not applied to the laminated piezoelectric element as much as possible regardless of the direction in which the stage is displaced with respect to the base. For this reason, as shown in FIG. 2 of JP-A-62-88008, as shown in FIG. 2, the rigidity is very low on both sides of the laminated piezoelectric element 21, that is, between the base 22 and the piezoelectric element, and between the stage 23 and the piezoelectric element. Sphere pair parts 24 and 2 of
5 are provided. In the support mechanism configured as shown in FIG. 2, when the base 22 and the stage 23 are displaced in parallel, for example, as shown in FIG. 3, the displacement is absorbed at the lowest rigidity of the ball pairs 24 and 25. Therefore, the force transmitted as a shearing force to the piezoelectric element 21 is extremely small.

[0005]

However, in the above structure, the shearing force applied to the piezoelectric element cannot be completely eliminated because the restoring force still exists in the portion having low rigidity as shown in FIG. In order to reduce this shearing force, it is necessary to further reduce the rigidity of the low-rigidity portions 24 and 25, that is, to further reduce the minimum diameter portion of the sphere pair, but in this case, the rigidity of the stage itself decreases. There is a possibility that it will end up.

Further, if an assembly error occurs, shearing force may be applied to the piezoelectric element 21 even in a static state. Similarly, if an assembly error occurs, the assembly error in the X-axis direction extends to the Z-axis as shown in FIG. There is a problem that the displacement, that is, ΔL becomes a problem, and the interference with other axis components cannot be ignored.

In order to solve the above problems, the present invention provides a fine movement device which does not apply a shearing force to a piezoelectric element and at the same time does not increase the amount of interference with other axis components even if an assembly error occurs. Is provided.

[0008]

In order to solve the above-mentioned problems, the stage fine movement device of the present invention comprises:
It is characterized in that an end face of a sphere having a diameter between the base and the stage is provided, and an elastic body is further provided in a direction of reducing the distance between the base and the stage.

[0009]

The operation will be described below with reference to FIG. Figure 4
Shows essential points of the stage fine movement device of the present invention, in which 41 is a base, 42 is a stage, and 43 is a laminated piezoelectric element. Further, 44 and 45 are members having spherical surface ends, which are located on both sides of the laminated piezoelectric element 43. Here, if the spherical surface is made equal to the distance between the base and the stage, the ball will sit on the base, and then the stage will sit on it, and the ball acts as a ball of a bearing. The stage can move in parallel with the base while keeping a constant distance. That is, even if an assembly error occurs in the X direction, it does not have any effect in the Z direction as long as the spherical surface is in contact. Further, the member having the spherical end, the base, and the stage are only in point contact with each other, and no matter how much the displacement occurs in the X direction, no force is generated on the piezoelectric element.

As described above, according to the present invention, due to the above-mentioned structure, the piezoelectric element is not subjected to shearing force, and it is possible to prevent interference with other axes due to an error due to assembly.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A stage fine movement apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a stage fine movement device according to a first embodiment of the present invention. In FIG. 1, 1 is a base, 2 is a stage, 3 is a piezoelectric element, and 4 and 5 are end surfaces of a sphere having a diameter corresponding to the distance between the contact points of the stage and the base, which are joined to both ends of the piezoelectric element. It is a member.
Further, 6 and 7 are coil springs that pull the stage with respect to the base and apply a compressive force as a preload to the piezoelectric element.

The operation of the stage fine movement apparatus configured as described above will be described below.

First, the piezoelectric element 3 expands and contracts in its axial direction. As a result, the stage is displaced in the direction away from the base. The springs 6 and 7 are used so that the piezoelectric element is always in contact with the base and the stage and operates stably. The stage is displaced by driving the piezoelectric element.

Here, consider the case where an external force is applied in the X direction or the contact between the stage and the link is displaced due to an assembly error in the X direction. Until now, as shown in FIG. 3 (a), a member having a ball pair fixed to a base and a stage is deformed at a portion considered to have the lowest rigidity,
Due to the "U" shape, the displacement due to the external force was absorbed. However, this also causes displacement in the Z direction. Δ is the amount of displacement in the X direction due to external force and assembly error
Then, the displacement amount in the Z direction accompanying this is as follows: a is the distance from the constricted portion of the spherical pair member to the fixed point, b is the distance from the stage side constricted portion including the piezoelectric element to the base constricted portion, ΔL = b− (b ² −δ ² ) ^1/2 .

On the other hand, in the embodiment of the present invention, even when an external force is applied in the X direction, the stage moves parallel to the base as shown in FIG. 6A, and the piezoelectric element and the spherical end surface are included. The contact point between the base and the stage in the link only shifts, and there is no displacement in the Z direction. That is, ΔL = 0. Here, in the conventional case, b = 50 mm as an actually possible value, and δ =
If an error of 0.1 mm occurs, ΔL = 0.1 μm, and if δ = 0.2 mm, ΔL = 0.4 μm. That is, in the present invention, the amount of interference is eliminated by this amount.

On the other hand, when these external forces or errors exist on the other components of the displacement amount of the piezoelectric element, when the conventional ball pair is used, the displacement in the X direction is Δb × δ / b, and Z The displacement in the direction is Δb × (b ² −δ ² ) ^1/2 / b.

On the other hand, in the embodiment of the present invention, the displacement in the X and Z directions with respect to the elongation of the piezoelectric element is first Δb × sin (2δ / L) in the X direction and Δb × cos (2δ in the Z direction. / L).

When L = 2b, these values are almost the same, and the present invention does not cause deterioration.

In addition, in the case of FIG. 1, there is a possibility that the positions of the link and the base and the link and the stage cannot be fixed at a fixed position, but as shown in FIG. 5, a convex projection is formed on a member having a spherical end. , A concave recess is provided on the base side and the stage side, and when they are fitted, the fitting depth c and the clearance (D-d)
Therefore, although the allowable error amount in the X direction is limited, the operation can be performed at a substantially constant position.

Although a coil spring is considered as the elastic body in FIGS. 1 and 5, a leaf spring may be used instead.

FIG. 7 shows an extension of the uniaxial mechanism shown in FIGS. 1 and 5 to a triaxial stage. In FIG.
61 is a base, 62 is a stage, 63a-c are piezoelectric elements, 64a-c and 65a-c are members having spherical ends at both ends of the piezoelectric elements, and 66 to 69 are leaf springs. Here, the stage 62 is supported by the leaf springs 66 to 69, plays the role of a guide in both the X and Y directions, and gives a compressive force as a preload to the piezoelectric element 64.

As described above, according to the present embodiment, in the fine movement apparatus of the stage, the end faces of the sphere having the diameter of the distance between the base and the stage are provided on both sides of the piezoelectric element, and the distance between the base and the stage is further increased. By providing the elastic body in the contracting direction, it is possible to eliminate the shearing force applied to the piezoelectric element and to eliminate the interference with other axes caused by the assembly error.

[0024]

As described above, according to the present invention, in a fine movement apparatus of a stage capable of relatively displacing with respect to the base, the base, the stage, and the diameter of the distance between the base and the stage. By having a laminated piezoelectric element having ends of the same spherical surface on both sides, and an elastic body that acts in a direction of reducing the distance between the base and the stage,
A fine movement device can be realized without applying a shearing force to the piezoelectric element and at the same time, even if an assembly error occurs, the amount of interference with other axis components is not increased. There is also the possibility of space saving.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a stage fine movement device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a conventional stage fine movement device.

FIG. 3 is a detailed view of a main part of FIG.

FIG. 4 is an explanatory diagram of the operation of the present invention.

FIG. 5 is a configuration diagram of a stage fine movement device according to another embodiment of the present invention.

FIG. 6 is a diagram for explaining the operation of the present invention.

7 is a configuration diagram of a stage in which the stage fine movement device shown in FIG. 1 is extended to three axes.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 base 2 stage 3 piezoelectric element 4,5 member having spherical end 6,7 elastic body 21 piezoelectric element 22 base 23 stage 24,25 member having spherical pair

Claims (2)

[Claims] 1. A fine movement device for a stage, which is capable of being displaced relative to a base, having a base, a stage, and a spherical end whose diameter is the same as the distance between the base and the stage on both sides. A fine movement device for a stage, comprising: a laminated piezoelectric element; and an elastic body that acts in a direction to reduce a distance between the base and the stage. 2. The stage fine movement device according to claim 1, wherein a protrusion is provided at a part of a spherical end of the link, and a recess for fitting with the protrusion is provided at a contact point with the link of the base or the stage. Characteristic stage fine movement device.